Skin, Fat and Cartilage Grafts

Question 1

A 63-year-old woman is scheduled to undergo autologous fat injection to improve the contour and increase the size of the right breast. She underwent reconstruction of the right breast with a latissimus dorsi flap 10 months ago because of mastectomy. The patient does not have or desire a breast prosthesis. Which of the following is the most likely sequela of autologous fat injection in this patient?
A) Calcification
B) Donor site irregularity
C) Fat resorption
D) Hypertrophic scarring
E) Skin necrosis

Answer 1

C) Fat resorption

The most common complication of fat injection remains to be the resorption of the grafted fat, ranging from 30 to 70%

Question 2

Most common complication of fat injection

Answer 2

The most common complication of fat injection remains to be the resorption of the grafted fat, ranging from 30 to 70%

Question 3

A 33-year-old man who sustained burns to 95% of the total body surface area five days ago is scheduled to undergo the initial stages of surgical reconstruction. In preparing this patient, which of the following is the advantage of using cultured epidermal autografts versus split-thickness skin grafts?
A ) Donor site
B ) Durability
C ) Elasticity
D ) Immediate availability
E ) Reduced expense

Answer 3

A ) Donor site

With use of cultured epidermal autografts, no donor site limitations exist. The patient’s own keratinocytes are expanded in tissue culture and a small skin specimen may be cultured and expanded within two to three weeks. Unfortunately, there is no dermal matrix tissue and, therefore, the graft lacks the elastic quality of normal skin or even split-thickness skin grafts. This results in wounds that are stiff, and motion is limited in the face and around joints. Likewise, the lack of a dermis results in very slow basement membrane formation; therefore, there are frequent problems with blistering and easy shearing. The use of cultured epidermal autografts is somewhat limited by its high cost and delay in availability as the tissue is cultured.

Question 4

Advantage of using cultured epidermal autografts versus split-thickness skin grafts?

Answer 4

Limited donor site with cultured epidermal autografts

Question 5

Cons regarding wound healing with cultured epidermal autografts

Answer 5

No dermal matrix:

• the graft lacks the elastic quality of normal skin or even split-thickness skin grafts. This results in wounds that are stiff, and motion is limited in the face and around joints.
• the lack of a dermis results in very slow basement membrane formation; therefore, there are frequent problems with blistering and easy shearing.

Question 6

A 34-year-old man undergoes correction of the defect shown three years after sustaining an injury to the left tip of the nose while playing football. Placement of an alar batten graft is planned. During septal graft harvest, the mucoperichondrial plane is difficult to elevate, and the cartilage is removed with an adherent perichondrial layer. Which of the following is most likely to result from the use of this graft compared with a cartilage-only graft?
A ) Extrusion
B ) Necrosis
C ) Ossification
D ) Resorption
E ) Warping

Answer 6

E ) Warping

Pure cartilage grafts tend to maintain shape, but grafts with an intact perichondrial layer can curl significantly and lead to unpredictable results. During septal graft harvest, care must be taken to elevate mucoperichondrial flaps in the proper plane. Likewise, auricular or costal cartilage grafts must be harvested in a subperichondrial plane. Removal of the perichondrium and softer outer cartilage layer leaves the more rigid cartilage core, which maintains shape more predictably.

Extrusion, necrosis, ossification, and resorption are not known to be affected by the presence or absence of the perichondrial layer.

Question 7

Extrusion, necrosis, ossification, and resorption w/ absence of perichondrial layer

Answer 7

Extrusion, necrosis, ossification, and resorption are not known to be affected by the presence or absence of the perichondrial layer.

Question 8

Properties of a cartilage graft, +/- perichondrium

Answer 8

Pure cartilage grafts tend to maintain shape, but grafts with an intact perichondrial layer can curl significantly and lead to unpredictable results.

Question 9

Alar batten grafts are used for:

Answer 9

The alar batten graft is a useful means of adding support to a deformed or weakened alar cartilage

Question 10

A 51-year-old woman has loss of vision in her left eye immediately after autogenous fat injections to the face and nasojugal regions performed under local anesthesia with 2 mL of 1% lidocaine with 1:100,000 epinephrine. The procedure was performed using small boluses of fat, which were injected slowly into the tear trough. Physical examination shows loss of vision in the left eye. Which of the following occurrences is the most likely cause of this complication?
A ) Fat embolism
B ) Glaucoma
C ) Lidocaine toxicity
D ) Retrobulbar hematoma
E ) Vasovagal response

Answer 10

A ) Fat embolism

Blindness and strokes have occurred as a result of the injection of soft-tissue fillers in almost every part of the face: glabella, forehead creases, temple, nose, cheeks, nasolabial folds, and lower lip. The injection of large boluses of soft-tissue fillers in the face and the use of needles or cannulas that can easily perforate an arterial wall should be avoided. Fat injections into the face lead to an acute local increase in pressure in highly vascularized tissue. Fragments of fatty tissue reach ocular and cerebral arteries by reversed flow through branches of the carotid arteries after they are introduced into facial vessels.

Question 11

Fat injection of the face: potential complication if the facial vessels are injected

Answer 11

Fragments of fatty tissue reach ocular and cerebral arteries by reversed flow through branches of the carotid arteries after they are introduced into facial vessels.

Question 12

Fat injections after rhytidectomy

Answer 12

Fat injections into pretraumatized soft tissue, for example, after rhytidectomy, should be avoided because of the increased risk of intravasation of fat particles

Question 13

Under average conditions, which of the following percentages represents the expected six-month resorption rate of fat injections?
(A)10%
(B)30%
(C)50%
(D)70%
(E)90%

Answer 13

(B)30%

Given the ideal conditions of minimal traumatic technique, meticulous fat graft size, and recipient bed selection, we should expect approximately 60% to 80% long-term graft survival based on several studies

Question 14

Key points of the theory of fat survival

Answer 14

1) fat is a dynamic tissue;
2) cells that suffer trauma lose more volume;
3) the recipient site makes an important difference in graft survival based on the vascularity of the bed.

Question 15

After harvesting of a split-thickness skin graft from the lateral aspect of the thigh, application of which of the following types of wound care agents will yield the most rapid epithelialization at the donor site?
(A)Normal saline wet-to-dry gauze
(B)Occlusive dressing
(C)Petrolatum-impregnated gauze
(D)Semi-occlusive dressing
(E)Silver sulfadiazine cream

Answer 15

(D)Semi-occlusive dressing

The ideal donor site dressing is one that promotes rapid re-epithelialization, causes little pain, requires little care, is inexpensive, and has a low rate of infection.

In multiple studies, the superior dressings have been shown to be semi-occlusive. These products have been shown to have the fastest healing rates (average nine days to re-epithelialization), lowest subjective pain scores, lowest infection rates (~3%), and are among the lowest in cost. They have the advantage of being transparent, which allows ongoing inspection of the site while maintaining sterility. Some fluid collects under these materials, which promotesmoist wound healing and probably accounts for the more rapid healing rates and decreased subjective pain scores.

Question 16

What dressings have been shown to be superior for skin graft donor site healing?

Answer 16

Semi-occlusive dressings

Question 17

How are semi-occlusive dressings superior for skin graft donor site healing?

Answer 17

• Fastest healing rate (~9 days to re-epithelialization)
• Lowest pain scores
• Lowest infection rate (~3%)
• Transparent

Some fluid collects under these materials, which promotesmoist wound healing and probably accounts for the more rapid healing rates and decreased subjective pain scores

Question 18

Healing rate of a STSG donor site with a semi occlusive dressing

Answer 18

~9 days

Question 19

Infection rate of a STSG donor site with a semi occlusive dressing

Answer 19

~3%

Question 20

How do STSG donor sites heal?

Answer 20

Donor sites for split-thickness skin grafts heal spontaneously from epithelial cells remaining in epithelial appendages within the dermis and at the wound edges. Healing begins within 24 hours of harvesting, and the rate of healing is directly proportional to the number of epithelial appendages remaining and inversely proportional to the thickness of graft harvested.

Question 21

Considerations in re-harvesting STSG donor sites

Answer 21

May be re-harvested, but each harvesting removes a portion of dermis that is not regenerate

Question 22

A 30-year-old man undergoes reconstruction of the right lower leg after sustaining an open fracture of the tibia. A skin graft is harvested and placed over a free muscle flap. Two days postoperatively, which of the following findings on microscopic examination of the skin graft is most likely?
(A)Early ischemic injury
(B)Increased collagen cross-linking
(C)Neovascular circulation
(D)Significant edema
(E)Venous congestion

Answer 22

(D)Significant edema

Within the first 24 hours after placement, the graft survives by serum imbibition, which is absorption of nutrients from the serum leaked from the donor site (muscle in this case). At24 hours, the healing graft will have increased in mass from edema by up to 30%. Leukocytes can be seen invading the graft, which may help stimulate endothelial migration and revascularization. By 24 hours, donor site vessels have begun to invade the graft vascular channels in a process called inosculation. The graft vessels degenerate and become replaced by the growing donor site vessels. Circulation is reestablished by day 4 to 5 at the earliest. Whereas early graft ischemia results in a lowering of the pH and a decrease in metabolism, ischemic injury and necrosis are not seen. Graft maturation and collagen turnover occur over weeks to months.

Question 23

STSG: first 24 hours

Answer 23

• Survives by serum imbibition
• at 24 hrs, the healing graft will have increased mass by ~30% from edema
• Leukocytes invade the graft

Question 24

STSG: beyond 24 hrs to re-establishment of circulation

Answer 24

• Inosculation: Beyond 24h, donor site sells begin to invade the graft vascular channels
• Circulation is re-established by 4-5 days at the earliest

Question 25

Changes in graft metabolism

Answer 25

Early graft ischemia results in a lowering of the pH and a decrease in metabolism. Ischemic injury and necrosis are not seen.

Question 26

A 27-year-old woman is scheduled to undergo rhinoplasty using homograft rib cartilage for reconstruction of the dorsum of the nose. Which of the following interventions during this procedure is most effective to reduce long-term warping of the graft? (A)Access to a peripheral segment (B)Insertion of the graft at least 30 minutes after carving (C)Scoring of the graft (D)Suture fixation (E)Use of nonirradiated material

Answer 26

(B)Insertion of the graft at least 30 minutes after carving To minimize the long-term clinical effects of cartilage warping, it is recommended to wait at least 30 minutes after carving the graft to allow initial warping to occur. The observed warping can then be accounted for in the final graft placement. Further warping may continue for some time, but the majority will occur within the first 30 to 60 minutes.

Question 27

When does cartilage warping occur after carving?

Answer 27

Further warping may continue for some time, but the majority will occur within the first 30 to 60 minutes.

Question 28

When should a cartilage graft be inserted after carving?

Answer 28

To minimize the long-term clinical effects of cartilage warping, it is recommended to wait at least 30 minutes after carving the graft to allow initial warping to occur. The observed warping can then be accounted for in the final graft placement.

Question 29

Irradiation and cartilage warping

Answer 29

Use of nonirradiated graft material may predispose more warping than irradiated material; however, this may depend on the dose of radiation. Doses of 3 to 4 million rads are less likely to result in graft warping compared with no radiation, but at doses of 1.5 to 2.5 million rads, the warping may be similar to that of nonirradiated grafts.

Question 30

Suture fixation and graft warping

Answer 30

Suture fixation will not prevent graft warping.

Question 31

Compared with cortical bone, which of the following best characterizes autologous cancellous bone grafts? (A)Effective in bridging defects larger than 6 cm (B)Greater structural strength (C)Less osteoconductive (D)Less osteoinductive (E)More readily revascularized and remodeled

Answer 31

(E)More readily revascularized and remodeled Relative to cortical bone, cancellous bone grafts are more osteoconductive (the property of the scaffold-like matrix to accommodate the ingrowth of new bone) and more osteoinductive (the capacity to induce mesenchymal cells from the recipient bed to produce active osteoblasts). Cancellous bone is more quickly revascularized, which usually occurs within two weeksof grafting, whereas cortical bone can take up to two months to revascularize. Cancellous grafts are also more easily remodeled.

Question 32

Osteoconduction

Answer 32

The property of a scaffold/matrix to accommodate the ingrowth of new bone

Question 33

Osteoinduction

Answer 33

Induction of mesenchymal cells from the recipient bed to produce active osteoblasts

Question 34

Cancellous bone grafts are ideal for bridging what size of bone gaps?

Answer 34

Cancellous bone grafts are ideal for bridging bone gaps of less than 5 to 6 cm

Question 35

Structural rigidity of cortical versus cancellous bone grafts

Answer 35

Cancellous grafts suffer from a lack of structural rigidity until 6 to 12 months after grafting, when they are generally as strong as cortical bone grafts.

Question 36

Osteoconduction of cancellous versus cortical bone grafts

Answer 36

Cancellous grafts are more osteoinductive

Question 37

Osteoinduction of cancellous versus cortical bone grafts

Answer 37

Cancellous grafts are more osteoinductive

Question 38

``` A 26-year-old woman of Asian descent who underwent rhinoplasty five years ago has erosion of the silicone rubber (Silastic) prosthesis through the skin of the nasal tip. Physical examination shows a depressed scar in this region. Secondary rhinoplasty is planned. Use of which of the following grafts for this procedure is most appropriate to minimize volume loss? (A)Dermis (B)Fat (C)Muscle (D)Cartilage (E)Bone ```

Answer 38

(D)Cartilage A cartilaginous graft would be most appropriate to correct the deformity described. The low metabolic rate of cartilage leads to minimal volume loss. Considerable resorption is seen in nonvascularized bone grafts.

Question 39

Volume loss of cartilage graft and why?

Answer 39

The low metabolic rate of cartilage leads to minimal volume loss.

Question 40

Adipocyte survival in muscle versus dermis

Answer 40

Animal studies have demonstrated that adipocytes implanted in a vascularized bed (muscle) survive better than those in dermis.

Question 41

A 45-year-old woman undergoes placement of a dorsal only cartilage graft during secondary rhinoplasty. Which of the following operative steps is most likely to minimize warping of the cartilage graft? (A) External stabilization (B) Maintaining recipient bed vascularity (C) Precise graft fixation (D) Preservation of perichondrium (E) Symmetrical design

Answer 41

(E) Symmetrical design Studies have shown that the compact outer subperichondrial layer regulated the tendency of a loose inner cartilaginous mass to warp. Symmetric graft design was found to more evenly regulate the stresses that caused warping. When considering donor sites for the nasal dorsum, costal cartilage ribs have been shown to be particularly useful because of the availability of a generous and naturally straight segment requiring minimal trimming and carving. Precise graft fixation is important in the avoidance of external distortion due to graft migration or displacement

Question 42

Internal stabilization versus rib cartilage grafts

Answer 42

Internal stabilization of autogenous rib cartilage grafts with Kirschner wires has been found to effectively prevent graft warpage.

Question 43

Precise graft fixation is important in:

Answer 43

Precise graft fixation is important in the avoidance of external distortion due to graft migration or displacement

Question 44

Acellular dermal matrix (AlloDerm) is used in plastic surgery for each of the following purposes EXCEPT (A) correcting retraction of the lower eyelid after blepharoplasty (B) decreasing adhesions after repair of an abdominal hernia (C) reducing incidence of oronasal fistulas after cleft palate repair (D) resurfacing thin pockets in mammaplasty (E) treating osteomyelitis of the tibia

Answer 44

(E) treating osteomyelitis of the tibia Although AlloDerm seems to be used ubiquitously in plastic surgery; it is not indicated for management of osteomyelitis. One of the principles in management of osteomyelitis is the transfer of healthy vascularized tissue. Although AlloDerm provides a substrate for tissue ingrowth, it does not bring in any blood supply.

Question 45

``` Which of the following is the best donor site for delayed multiple harvesting of split-thickness skin grafts? (A) Back (B) Lateral forearm (C) Medial arm (D) Medial forearm (E) Medial thigh ```

Answer 45

(A) Back The selection of a donor site depends largely on donor site morbidity and skin thickness. The back provides a nearly ideal donor site for repeated harvesting of split-thickness skin grafts and has large areas of thick skin available for harvesting. The lateral forearm exhibits unacceptable donor site morbidity. The medial arm, medial forearm, and medial thigh have skin of insufficient thickness to allow multiple harvesting

Question 46

Where is the ideal site for multiple harvesting of STSG?

Answer 46

The back provides a nearly ideal donor site for repeated harvesting of split-thickness skin grafts and has large areas of thick skin available for harvesting.

Question 47

How does the donor site of a STSG heal?

Answer 47

The donor site of a split-thickness graft heals by migration from the remnant epithelia of the dermal appendages, such as hair roots and sweat and sebaceous glands. Therefore, the epidermis regenerates but the dermis does not.

Question 48

``` Which of the following bone grafts exhibits the greatest inductive capacity? (A) Allogenic (B) Autologous cancellous (C) Autologous cortical (D) Free vascularized (E) Xenogenic ```

Answer 48

(B) Autologous cancellous Cancellous bone grafts have the greatest inductive capacity (ability to stimulate the formation of new bone) because they contain bone morphogenic proteins that stimulate bone growth. Cortical bone grafts and allogenic and xenogenic grafts have less inductive capacity. Free vascularized bone grafts have no inductive capacity because they do not rely on stimulating new bone formation.

Question 49

Cancellous bone grafts and inductive capacity

Answer 49

Cancellous bone grafts have the greatest inductive capacity (ability to stimulate the formation of new bone) because they contain bone morphogenic proteins that stimulate bone growth.

Question 50

Free vascularized bone grafts and inductive capacity

Answer 50

Free vascularized bone grafts have no inductive capacity because they do not rely on stimulating new bone formation.

Question 51

``` Which of the following is an advantage of using the dermal regeneration template (Integra) instead of a thin split-thickness autograft for reconstruction of the hand? (A) Elimination of donor site (B) Improved cosmesis (C) Increased wound contraction (D) Reduced risk of hematoma (E) Shorter healing time ```

Answer 51

(B) Improved cosmesis Wound contraction with Integra is typically less than that with single-stage split-thickness skin grafting. The advantages of Integra include the availability of large quantities, the simplicity and reliability of the placement technique, and the pliability and cosmetic appearance of the resulting cover.

Question 52

Integra vs STSG: healing time

Answer 52

Because Integra requires a second surgery after 3 to 4 weeks for coverage with a thin split-thickness skin graft, it has a longer healing time until final wound coverage.

Question 53

Integra vs STSG: hematoma rate

Answer 53

Compared with autologous skin, Integra purportedly has no decrease in the hematoma rate.

Question 54

Integra vs STSG: contracture

Answer 54

Wound contraction with Integra is typically less than that with single-stage split-thickness skin grafting.

Question 55

Integra vs STSG: Skin graft

Answer 55

The skin graft used at the second stage is typically thinner than that used in single-stage grafting, so Integra does avoid the use of a deep donor site, which decreases the risk of infection, scarring, and permanent pigment changes.

Question 56

``` Which of the following grafts has minimal resorption and loss of volume? (A) Bone (B) Cartilage (C) Macro-fat (D) Micro-fat (E) Muscle ```

Answer 56

(B) Cartilage Although all of these tissues may be used for grafts, autologous cartilage grafts offer minimal resorption and loss of volume and provide good results in many clinical settings.

Question 57

Metabolic rate of cartilage

Answer 57

The metabolic rate of cartilage is 1/100 to 1/500 the rate of other human tissues. It has low glycolytic activity and consumption because of its small cell population and relative isolation by the cartilage matrix. This isolation helps protect cartilagenous tissue from resorption.

Question 58

``` Which of the following bone grafts does NOT rely on creeping substitution as a mode of remodeling? (A) Allogenic (B) Autologous cancellous (C) Autologous cortical (D) Free vascularized (E) Xenogenic ```

Answer 58

(D) Free vascularized Free vascularized bone grafts do not rely on creeping substitution: they do not need to stimulate new bone formation because they are used when little or no bone has been lost.

Question 59

Creeping substitution

Answer 59

Replacement of necrotic bone with osteoblasts and new vascular ingrowth

Question 60

What bone grafts undergo creeping substitution

Answer 60

All nonvascularized bone grafts undergo a degree of resorption and remodeling, including creeping substitution, and have some degree of inductive capacity.

Question 61

``` Which of the following biologic dressings contains only human-derived materials? (A) Alloderm (B) Apligraf (C) Biobrane (D) Integra (E) Transcyte ```

Answer 61

(A) Alloderm Alloderm is lyophilized acellular human cadaveric dermis. This dressing contains only human-derived materials. Because it is devoid of immunogenic cells, it does not undergo the rejection that occurs with cadaveric skin. Alloderm can also be used as soft-tissue filler in patients undergoing cosmetic procedures. In some instances, thin layers of this dressing can be placed on a wound bed to vascularize and support a skin graft

Question 62

Apligraf

Answer 62

Apligraf is comprised of a bilayer of neonatal epidermal keratinocytes and dermal fibroblasts within a matrix of bovine collagen. This dressing is used for coverage of venous stasis ulcers and foot ulcers. Its mechanism of action involves graft adherence and subsequent remodeling on the wound bed.

Question 63

Biobrane

Answer 63

Biobrane is a synthetic wound dressing composed of nylon and silicone fabric coated with porcine collagen. It provides temporary coverage of partial-thickness wounds and can be removed when epithelialization of the wound occurs.

Question 64

Integra

Answer 64

Integra is a bioengineered dermal substitute that consists of a dermal matrix of bovine collagen and shark-derived chondroitin-6-sulfate covered by a bilayer of Silastic epidermis. When the dermal replacement layer becomes infiltrated with capillaries, fibroblasts, and inflammatory cells, the Silastic cover can be removed and autografting can be performed.

Question 65

Transcyte

Answer 65

Transcyte is a dermal substitute comprised of neonatal dermal fibroblasts cultured onto a thin, semipermeable membrane of silicone that is bonded to a nylon mesh and bovine collagen. The fibroblasts secrete structural proteins and growth factors, creating a dermal matrix for future grafting or temporary coverage of partial-thickness burns.

Question 66

Which of the following is the primary advantage of using Integra (artificial skin) for coverage of full-thickness burns? (A) Allowing for immediate use of cultured epithelial autografts (B) Allowing for use of thinner autografts (C) Avoidance of autografting (D) Complete revascularization within seven days (E) Prevention of fibroblast ingrowth into the dermal replacement layer

Answer 66

(B) Allowing for use of thinner autografts Following its application, the dermal matrix of the Integra dressing acts as a template, becoming infiltrated with host fibroblasts, endothelial cells, and inflammatory cells. The host collagen gradually replaces the bovine collagen during the healing process, and the silicone cover controls moisture loss and protects the wound. Adequate revascularization occurs within two to three weeks, at which time the superficial silicone layer will have sloughed off as a result of ingrowth through the collagen and glycosaminoglycan matrix. At this time, the Integra graft can be removed, and a thinner autograft, such as a very thin sheet of split-thickness skin graft, can be applied for durable coverage.

Question 67

Prior to use, testing for sensitivity to which of the following should be performed? (A) Acellular dermal homograft (Alloderm) (B) Botulinum toxin (Botox) (C) Bovine collagen (Zyderm) (D) Fat (E) Polytetrafluoroethylene (Gore-Tex)

Answer 67

(C) Bovine collagen (Zyderm) Prior to treatment, sensitivity testing to collagen should be performed in an inconspicuous location. Following intradermal injection of a test dose of bovine collagen (Zyderm), the patient should be monitored for four weeks because a hypersensitivity reaction may be delayed.

Question 68

Hypersensitivity to bovine collagen after prior successful treatment/tolerance

Answer 68

Because patients may develop sensitivity to collagen even after successful prior treatment, sensitivity testing should be performed before every treatment

Question 69

Contraindication to botox re: hypersensitivity

Answer 69

Botulinum toxin should not be injected in persons who have a known hypersensitivity to botulinum toxin or to eggs and/or albumin

Question 70

Definition of hypersensitivity reaction to bovine collagen

Answer 70

A hypersensitivity reaction is defined as erythema, induration, tenderness, or swelling to any degree, with or without pruritus, that appears more than 24 hours after implantation and/or persists longer than six hours.

Question 71

Zyderm is made of..

Answer 71

Bovine collagen

Question 72

``` Which of the following is the most common complication of autologous fat grafting? (A) Contour irregularities (B) Infection (C) Migration (D) Undercorrection ```

Answer 72

(D) Undercorrection Inadequate correction isthe most common complication of autologous fat grafting. This can result from inadequate graft volume initially or graft resorption following the procedure.

Question 73

Most common complication of autologous fat grafting

Answer 73

Undercorrection

Question 74

Distribution of greatest/least resorption of fat grafting in the face

Answer 74

The greatest amount of resorption occurs along the nasolabial lines, and the least resorption occurs in the buccal fat pad.

Question 75

Infection in liposuction is most commonly associated with:

Answer 75

Infection is commonly associated with violation of the oral mucosa during the infiltration process. Only 1% of patients undergoing autologous fat grafting develop Staphylococcus or Streptococcus infection at either the donor or the injection site.

Question 76

``` Which of thefollowing soft-tissue fillers is derived from hyaluronic acid? (A) Dermalogen (B) Fascian (C) Isolagen (D) Restylane (E) Zyderm ```

Answer 76

(D) Restylane Restylane is a cross-linked, stabilized, third-generation hyaluronic acid gel that is a byproduct of processed bacteria. Hyalform gel is also comprised of hyaluronic acid, but is culled instead from an animal-based compound.

Question 77

Source of hyaluronic acid for Restylane vs Hyalform gel

Answer 77

Restylane is a cross-linked, stabilized, third-generation hyaluronic acid gel that is a byproduct of processed bacteria. Hyalform gel is also comprised of hyaluronic acid, but is culled instead from an animal-based compound.

Question 78

Dermalogen is made of:

Answer 78

Dermalogen (dermis): homologous sources of injectable filler derived from human tissue.

Question 79

Fascian is made of:

Answer 79

Fascian (fascia lata): homologous sources of injectable filler derived from human tissue.

Question 80

Isolagen is made of:

Answer 80

Isolagen is an autologous agent derived from human skin cells that consists of cultured fibroblast media with an extracellular matrix.

Question 81

``` Which of the following soft-tissue fillers is derived from hyaluronic acid? (A) Dermalogen (B) Fascian (C) Isolagen (D) Restylane (E) Zyderm ```

Answer 81

(D) Restylane Restylane is a cross-linked, stabilized, third-generation hyaluronic acid gel that is a byproduct of processed bacteria.

Question 82

``` Which of the following is the most common unfavorable result of lip augmentation with acellular dermal homograft? (A) Exposure (B) Hematoma (C) Infection (D) Rejection (E) Resorption ```

Answer 82

(E) Resorption Graft resorption has been reported as the most common complication of lip augmentation with acellular dermal homograft (Alloderm), a product derived from human cadaveric skin for use in soft-tissue augmentation. During harvest of the graft, the dermal and extracellular matrices are left intact, while the immunogenic components are removed.

Question 83

Most common complication of lip augmentation with Alloderm

Answer 83

Graft resorption

Question 84

``` Injection of autologous fat at which of the following sites is associated with increased risk for fat embolism and subsequent blindness and/or central nervous system damage? (A) Forehead (B) Glabella (C) Lateral orbit (D) Nasolabial fold (E) Tear trough ```

Answer 84

(B) Glabella Although the risk for injury exists with injection into the periorbital and nasal regions, it is less than that seen with injection into the glabellar region. The surgeon should be particularly cautious when injecting fat into the glabellar region, as the ophthalmic artery, which connects directly to the glabellar vasculature, can be inadvertently divided. Methods to help minimize complications of fat injection include the use of blunt tip large bore cannulas, as well as retrograde injection techniques.

Question 85

Which region of the face is most associated with blindness or CNS damage after lipo injection?

Answer 85

Although the risk for injury exists with injection into the periorbital and nasal regions, it is less than that seen with injection into the glabellar region. The surgeon should be particularly cautious when injecting fat into the glabellar region, as the ophthalmic artery, which connects directly to the glabellar vasculature, can be inadvertently divided.

Question 86

``` What is the lowest bacterial count that will result in infection of cultured epithelial autografts? (A) 101 (B) 102 (C) 103 (D) 104 (E) 105 ```

Answer 86

(B) 102 Tissue-cultured grafts such as cultured epithelial autografts have a low degree of resistance to infection. They will tolerate bacterial counts to a maximum of 102 to 103 cm3 before developing an infection, as compared with 104 to 105 cm3 for split-thickness skin grafts

Question 87

What is the lowest bacterial count that will result in infection of cultured epithelial autografts?

Answer 87

They will tolerate bacterial counts to a maximum of 102 to 103 cm3 before developing an infection.

Question 88

What is the lowest bacterial count that will result in infection of STSGs?

Answer 88

They will tolerate bacterial counts to a maximum of 104 to 105 cm3 before developing an infection.

Question 89

In a patient undergoing lip enhancement using sheet acellular dermal homograft, which of the following is the correct anatomic placement of the graft? (A) Subdermal placement along the white roll of the lip (B) Subdermal placement along the wet/dry vermilion border of the lip (C) Submucosal placement along the white roll of the lip (D) Submucosal placement along the wet/dry vermilion border of the lip (E) Intramuscular placement

Answer 89

(D) Submucosal placement along the wet/dry vermilion border of the lip Following adequate anesthesia, sheet acellular dermal homograft (Alloderm) should be placed submucosally along the wet/dry vermilion border of the lip. Because subdermal placement is too superficial, the patient will be predisposed to the development of contour irregularities if the implants are placed at this level. Submucosal placement of the Alloderm along the white roll will result in unnatural lip aesthetics. Alloderm should not be placedwithin the muscle.

Question 90

Where should alloderm be placed for lip augmentation?

Answer 90

Following adequate anesthesia, sheet acellular dermal homograft (Alloderm) should be placed submucosally along the wet/dry vermilion border of the lip.

Question 91

Procedure for placement of Alloderm for lip augmentation

Answer 91

Into the submucosal space along the wet/dry vermilion border of the lip. In order to effectively enhance the lips, the surgeon should first place bilateral incisions approximately 0.5 cm from the commissure on both the upper and lower lips; this will allow for tunneling of the Alloderm along this border. After the Alloderm is placed, the lip is stretched, allowing proper sealing of the graft. The ends should then be tapered and placed in a submucosal pocket near the commissure. Suturing is associated with the development of dynamic lip deformities and thus should not be performed.

Question 92

Subdermal placement of Alloderm for lip enhancement

Answer 92

Because subdermal placement is too superficial, the patient will be predisposed to the development of contour irregularities if the implants are placed at this level.

Question 93

Intramuscular placement of Alloderm for lip enhancement

Answer 93

Submucosal placement of the Alloderm along the white roll will result in unnatural lip aesthetics.

Question 94

Submucosal placement of Alloderm along the white roll for lip enhancement

Answer 94

Alloderm should not be placed within the muscle.

Question 95

``` Which of the following processes involves the transformation of recipient mesenchymal cells into osteoprogenitor cells resulting from the stimulation of bone morphogenetic protein? (A) Endochondral ossification (B) Membranous ossification (C) Osteochondrosis (D) Osteoconduction (E) Osteoinduction ```

Answer 95

(E) Osteoinduction

Question 96

Endochondral ossification

Answer 96

Endochondral ossification involves the formation of new bone within a hyaline cartilage framework in the epiphysis of the long bones.

Question 97

Membranous ossification

Answer 97

The process of membranous ossification is primarily responsible for bone formation in the cranial vault and face; this process involves condensation of mesenchymal tissue.

Question 98

Osteochondrosis

Answer 98

Osteochondrosis describes a group of ossification disorders in children. These disorders, which may affect solitary or multiple sites of ossification, are characterized by degeneration of aseptic necrosis of bone followed by reossification.

Question 99

``` According to Wolff's law, which of the following factors is critical to the long-term survival of grafted bone? (A) Presence of membranous bone (B) Preservation of the periosteum (C) Preservation of vascularity (D) Stress ```

Answer 99

(D) Stress Wolff's law states that stress is necessary for preservation of the strength and volume of grafted bone. This law has been used to correctly predict the resorption of bone grafted to heterotopic recipient sites and areas lacking the required stress

Question 100

Wolff's law and bone grafting

Answer 100

Wolff's law states that stress is necessary for preservation of the strength and volume of grafted bone. This law has been used to correctly predict the resorption of bone grafted to heterotopic recipient sites and areas lacking the required stress.

Question 101

Periosteum and graft survival

Answer 101

Preservation of an intact periosteum increases graft survival at all stages following transplantation. Delayed revascularization and decreased peripheral bone growth have been demonstrated in bone grafted without periosteum.

Question 102

In a patient undergoing lip enhancement using sheet acellular dermal homograft (Alloderm), which of the following is the correct anatomic placement of the graft? (A) Subdermal placement along the white roll of the lip (B) Submucosal placement along the white roll of the lip (C) Submucosal placement along the wet/dry vermilion border of the lip (D) Intramuscular placement

Answer 102

(C) Submucosal placement along the wet/dry vermilion border of the lip

Question 103

``` Which of the following types of skin graft can be expected to grow proportionately with a young child? (A) Split-thickness (B) Full-thickness (C) Epidermal (D) Cultured epithelial autograft ```

Answer 103

(B) Full-thickness Full-thickness skin grafts can be expected to grow proportionately with a young child. In contrast, split-thickness skin grafts will exhibit some growth, although secondary and/or revision grafting is often required. Epidermal grafts and cultured epithelial autografts will not demonstrate proportionate growth with expansion of the surrounding tissues.

Question 104

Which of the following is a characteristic of unilaminar skin substitutes? (A) Increased bacterial counts within the wound (B) Inhibition of granulation tissue (C) Poor fluid absorption (D) Poor mechanical protection

Answer 104

(D) Poor mechanical protection Although unilaminar skin substitutes have been proven to aid in wound debridement and fluid absorption, as well as to decrease the bacterial count within the wound and stimulate granulation tissue, the mechanical protection provided by this synthetic material is poor. Other skin substitutes such as hydrocolloids, hydrogels, and vapor-permeable membranes have been shown to have similar properties

Question 105

Pros/cons of unilaminar skin substitutes

Answer 105

- aid in wound debridement and fluid absorption - decrease the bacterial count within the wound - stimulate granulation tissue, - poor mechanical protection

Question 106

``` Bovine collagen is most effective when injected into which of the following anatomic regions? (A) Epidermis (B) Dermis (C) Immediate subdermis (D) Subcutaneous fat ```

Answer 106

(B) Dermis Bovine collagen provides the most effective aesthetic result when it is injected into the dermal layer. If injected too deeply (ie, into the subdermal or subcutaneous layers), its effects are highly transitory because resorption is often immediate. However, even with appropriate injection, the desired effect of bovine collagen can only be maintained for a maximum of three to four months, and repeat injections are required for a sustained effect. Injection of bovine collagen into the epidermal layer is often associated with contour deformities.

Question 107

Injection of bovine collagen into the epidermal layer

Answer 107

Injection of bovine collagen into the epidermal layer is often associated with contour deformities.

Question 108

Where is bovine collagen injection most effective?

Answer 108

Bovine collagen provides the most effective aesthetic result when it is injected into the dermal layer. If injected too deeply (ie, into the subdermal or subcutaneous layers), its effects are highly transitory because resorption is often immediate.

Question 109

How long does bovine collagen last?

Answer 109

Even with appropriate injection into the dermal layer, the desired effect of bovine collagen can only be maintained for a maximum of three to four months, and repeat injections are required for a sustained effect.

Question 110

Which of the following is most characteristic of hydroxyapatite bone cement? (A) Exothermic damage to the underlying dura and brain tissue (B) Gradual loss of contour over time (C) Osteoinductive growth of new bone (D) Peripheral ingrowth of bone

Answer 110

(D) Peripheral ingrowth of bone Hydroxyapatite bone cement has been shown to have osteoconductive properties, resulting in growth of new bone over several months following its use in reconstruction. This bone cement is a mixture of amorphous and crystalline calcium phosphate compounds and is recommended for use in nonstress skeletal areas. Because the cement sets endothermically at body temperature, patients are not at risk for any endothermic reactions such as those seen with the use of methylmethacrylate cement. In addition, it maintains its original contour over time. Scatter effect is not seen on CT.

Question 111

Hydroxyapatite and CT scan

Answer 111

Scatter effect is not seen on CT

Question 112

Hydroxyapatite has been recommended for what type of areas?

Answer 112

Non-stress areas

Question 113

``` A deep split-thickness skin graft that has been harvested from the scalp has approximately two thirds of the follicular unit (shaft) within the dermis. The percentage of the follicular unit that can be expected to produce hair growth is closest to (A) 0% (B) 30% (C) 50% (D) 85% (E) 100% ```

Answer 113

(B) 30% If the upper two thirds of the follicular unit (shaft) are transplanted, approximately 30% of the follicles will produce new hair growth. Although the new hairs will be thinner, normal coloring can be expected. The middle third of the hair follicle is partially responsible for hair growth; in contrast, the hair bulb, which in the past was believed to be responsible for hair growth, is actually not required in order to grow new hairs. The bulb is located in the subcutaneous fat beneath the dermis and does contribute somewhat to the growth and health of the hair but is not a necessary factor for growth

Question 114

The middle third of the hair follicle is _______ responsible for hair growth

Answer 114

The middle third of the hair follicle is partially responsible for hair growth

Question 115

If the upper 2/3 of a follicular unit are transplanted, approximately ____% of the follicles will produce new hair growth

Answer 115

If the upper two thirds of the follicular unit (shaft) are transplanted, approximately 30% of the follicles will produce new hair growth.

Question 116

``` Which of the following graft types exhibits the lowest relative volume loss and resorption? (A) Bone graft (B) Cartilage graft (C) Macro-fat graft (D) Micro-fat graft (E) Muscle graft ```

Answer 116

(B) Cartilage graft

Question 117

Which of the following characteristics of a full-thickness skin graft has the greatest effect on inhibition of wound contraction? (A) Epidermal-to-dermal ratio (B) Percentage of grafted dermis (C) Presence of muscle at the base of the recipient bed (D) Skin thickness of the recipient bed (E) Thickness of the entire graft

Answer 117

(B) Percentage of grafted dermis Full-thickness skin grafts inhibit wound contraction by accelerating the rate of dissolution of myofibroblasts from the wound. Because of this, it is the percentage of grafted dermis, rather than the absolute thickness of the total graft, that has the greatest effect on inhibition of wound contraction.

Question 118

How do full thickness skin grafts inhibit recipient wound contraction?

Answer 118

Full-thickness skin grafts inhibit wound contraction by accelerating the rate of dissolution of myofibroblasts from the wound.

Question 119

What characteristics of a full-thickness skin graft has the greatest effect on inhibition of wound contraction?

Answer 119

It is the percentage of grafted dermis, rather than the absolute thickness of the total graft, that has the greatest effect on inhibition of wound contraction.

Question 120

Following split-thickness skin grafting, which of the following dressings can be used at the donor site to minimize discomfort, reduce the risk for infection, and decrease healing time? (A) Bismuth tribromophenate-impregnated gauze (Xeroform) (B) Heterograft (C) Hydrocolloid polymer complex (DuoDerm) (D) Silicone membrane-nylon fabric composite (Biobrane) (E) o-Tolylazo-naphthol-(Scarlet Red-) impregnated gauze

Answer 120

(C) Hydrocolloid polymer complex (DuoDerm) An occlusive dressing consisting of a polyurethane foam and a hydrocolloid polymer complex (DuoDerm), or a semiocclusive dressing consisting of synthetic adhesive moisture vapor permeable films (eg, Op-Site, Tegaderm) will minimize patient discomfort, reduce the risk for infection, and decrease healing time.

Question 121

A 45-year-old man undergoes excision of a basal cell carcinoma of the mid cheek. A 3.6 × 4.7-cm oval skin defect with exposed subcutaneous fat is present. Skin grafting is planned. Which of the following is most likely to minimize long-term scar contracture? A) Choosing a donor site with appropriate color match B) Defatting of the skin graft C) Harvesting with a mechanical dermatome D) Immobilizing with negative pressure wound therapy E) Including the entire dermis

Answer 121

E) Including the entire dermis The defect is a full-thickness skin defect with exposed subcutaneous fat. Coverage with a local flap and skin graft are possible reconstructive options. If skin grafting were to be performed, then a full-thickness skin graft would minimize the amount of long-term contracture (secondary contracture). A skin graft can be either split- or full-thickness. Split-thickness grafts can be harvested with a mechanical dermatome, or free hand with a scalpel. Split-thickness skin grafts do not include the entire thickness of the dermis and have less initial contracture at the time of harvest (primary contracture). Full-thickness skin grafts contain both the epidermis and the dermis and would have less long-term contracture. Harvesting with a mechanical dermatome is useful for obtaining split-thickness skin grafts. Typical thicknesses may range from 8/1000th of an inch to 14/1000th of an inch. Adequate immobilization of a skin graft is critical for “take” of the graft. Negative pressure wound therapy can be employed to promote adherence of the graft to the wound bed. Defatting of the skin graft in the case of a full-thickness graft is important to optimize graft “take” in the early postoperative period. Obtaining skin from a donor site with a close color match to the recipient site is an important aesthetic consideration, but does not affect long-term contracture.

Question 122

``` A 29-year-old woman is evaluated because of a bump that developed on the nasal dorsum 6 months after she underwent reconstruction with an onlay auricular cartilage graft to treat a post-traumatic nasal deformity. Which of the following is the most likely cause of this patient’s complication? A) Infection B) Ossification C) Rejection D) Resorption E) Warping ```

Answer 122

E) Warping Warping is one drawback of auricular cartilage grafts. They can curl over time. Warping is more common when the perichondrial layer is left on the graft. Pure cartilage grafts tend to warp less often. Auricular cartilage and pure cartilage warping would occur gradually over a period of weeks or months. Cartilage is a versatile graft material that is useful for providing structural support or treating contour problems. The rib, nasal septum, and ear are the most common donor sites. Grafts are primarily composed of hyaline and elastic cartilage, with only a 1 to 10% volume of cells, so they can easily survive transplantation. Graft nutrition relies on diffusion of nutrients through the matrix of proteoglycans, interstitial fluid, and chondrocytes. Early contour deformities could result from malposition or shifting of the graft. In this clinical case, the deformity occurs at 6 months postoperatively, when the graft should be stable in the soft-tissue envelope. Rejection is not likely with autologous cartilage and would likely occur with extrusion or fluid drainage. Rejection or failure to incorporate would typically be associated with an inadequately vascularized soft-tissue envelope or infection, and these complications would be expected within the first few weeks. Resorption can occur gradually but is uncommon. A contour indentation would be more likely to result than a protruding bump. Ossification of the graft is not a known complication.

Question 123

``` Which of the following bone substitutes has the capacity for osteoconduction and osseointegration? A) Hydroxyapatite B) Polymethylmethacrylate C) Porous polyethylene D) Silicone E) Titanium ```

Answer 123

A) Hydroxyapatite Osteoconduction is the ability of a material to encourage bone to grow toward and along its surface. Osseointegration is defined as the direct chemical bonding of an alloplast to the surface of bone without an intervening layer of fibrous tissue. These qualities are important in identifying an appropriate bone substitute in craniofacial reconstruction. Hydroxyapatite is a bone substitute that has capacity for both osteoconduction and osseointegration and is the base for many of most widely used bone substitutes. Hydroxyapatite is the principal mineral component of bone and comprises 60% of the calcified human skeleton. It has been used clinically for more than 25 years. It is biocompatible, and all forms are resistant to absorption after implantation. Silicone products do not osseointegrate or osteoconduct. Polymethylmethacrylate causes an extreme exothermic reaction associated with the setting process and is deleterious to adjacent bone and soft tissue, even with vigorous saline irrigation. It can be designed or shaped ex vivo to avoid thermal injury. Titanium osseointegrates, but it does not osteoconduct. It provides ideal protection and reconstruction in certain clinical situations where infection is of higher concern. High-density porous polyethylene implants have pore sizes ranging from 100 to 300 ?m. These aid in tissue ingrowth and implant fixation. These implants may be coated with polyhydroxyethylmethacrylate and calcium hydroxide. The hydrophilic nature and calcium coating result in osteoconductivity and a fibro-osseous matrix.

Question 124

``` A 40-year-old man desires correction of the appearance of his nose after traumatic injury 14 months ago. Examination shows collapse of the nasal bones and mid vault. The patient is concerned about additional scarring and donor site pain and requests a procedure with the least amount of donor site morbidity. Which of the following options is most appropriate for this patient? A) Bone allograft B) Costal cartilage graft C) Iliac crest graft D) Split calvarial graft E) Temporal fascia graft ```

Answer 124

A) Bone allograft Freeze-dried bone allograft has been used extensively for orthopedic trauma and tumor reconstruction and has been demonstrated to be safe for nasal augmentation. The advantage of allograft is the avoidance of donor site harvesting and morbidity. Fresh autografts probably have more osteoinductive capacity and are likely to incorporate donor bone beds more thoroughly. Although this is important in bone grafting to injured bone, such as in a tibia fracture, it is less important in nasal grafting to a nasal soft-tissue bed. Freeze-dried allografts, much like acellular dermal grafts, are extensively processed to denture all cellular elements and therefore do not elicit immunologic rejection response. Irradiated costal cartilage allografts have also been used with success for nasal reconstruction. There is also a rare chance of disease transmission from the cadaveric donor. Autologous costal cartilage is one of the more commonly used graft materials for nasal reconstruction, although both donor site scarring and pain are prominent. Iliac crest is a useful graft site for cortical and cancellous bone, though the shape is not ideal for nasal contouring. Donor site pain is an issue as well. The same limitations apply to split calvarial grafts, which are most useful when a bicoronal incision has already been used for craniofacial exposure. Temporal fascia is a versatile graft source, especially when wrapped around diced cartilage. The resulting graft is pliable, soft, and has been reported to have minimal absorption. Although it is an excellent choice for this case, it does require a scalp donor site, which this patient does not want. Alloplastic materials such as silicone are also used, though they are prone to extrusion over time.

Question 125

``` An 18-year-old woman with a history of cleft lip and palate presents for secondary alveolar bone grafting. An iliac crest bone graft is planned. Which of the following characteristics of iliac crest bone graft is an advantage over the use of bone morphogenetic protein in this patient? A) Greater volume of graft material B) Osteoconductive properties C) Osteoinductive properties D) Reduced operative time E) Reduced recovery time ```

Answer 125

B) Osteoconductive properties The majority of cleft lip and cleft palate patients undergo secondary bone grafting of the alveolar cleft between the ages of 8 and 12 years. A commonly used source of graft material, iliac crest bone, is associated with morbidity including significant pain, impaired ambulation, and prolonged recovery. Some authors have proposed the use of bone morphogenetic protein for alveolar cleft closure. Advantages to this technique include reduced operative time, quicker recovery, and a greater volume of graft material, which can be limited when harvesting iliac crest bone graft in smaller children. Osteogenesis requires both osteoconductive materials and osteoinductive factors. Iliac crest bone graft displays necessary properties, while bone morphogenetic protein provides significant osteoinductive properties, but requires an additional carrier, such as demineralized bone putty, for osteoconduction. Bone morphogenetic protein is not FDA-approved for patients younger than 12 years of age.

Question 126

``` A 33-year-old woman sustains trauma to the right thigh. She undergoes debridement of the wounds. Two days later, the right anterior thigh has a 15 × 25-cm wound with areas of exposed fat and muscle. Which of the following is the most appropriate intervention to achieve wound closure? A) Free latissimus dorsi flap B) Full-thickness skin graft C) Local fasciocutaneous flap D) Negative pressure wound therapy E) Split-thickness skin graft ```

Answer 126

E) Split-thickness skin graft Split-thickness skin grafts can provide wound coverage over a large area. A mechanical dermatome is often used for obtaining split-thickness skin grafts. Typical thicknesses may range from 8/1000th of an inch to 14/1000th of an inch. The graft can be meshed in various ratios such as 1:1.5, 1:2, and 1:3 to allow for a larger area of coverage per unit of harvested skin. It is important that the underlying wound bed be viable and free of necrotic tissue or infection in order to allow for healing of the skin graft (“skin graft take”). Adequate immobilization of a skin graft is important for take of the graft, and can be achieved with negative pressure wound therapy, or tie-over-bolster dressing. The thigh has an abundant amount of soft tissue and muscle, which is why skin grafts are often sufficient for wound coverage rather than flaps. The patient has a complex wound of the anterior thigh that is best described as a degloving injury in which the skin has been sheared off of the underlying tissues. Undermining of the skin is a hallmark of this type of injury. This type of injury disrupts the blood supply to the skin and can result in tissue ischemia and necrosis. In the acute period, it can be difficult to determine the extent of tissue injury as the skin viability evolves over this time such that areas of marginal blood supply may worsen and progress to full-thickness necrosis. Before definitive wound closure can be achieved, it is critical to debride all devitalized tissue such that there is a healthy viable wound bed. Hence, performing repeat debridement is often necessary. In some cases, debriding the surrounding skin as well as the underlying fat and muscle is required to remove all necrotic tissue. Debridement should continue until healthy tissue is encountered, which can be identified by visual inspection and the presence of punctate bleeding. The surgeon must consider several things when deciding between a flap and a graft. The reconstructive ladder may be used as a guide for management in this case. The defect is too large to achieve primary closure. The use of negative pressure wound therapy for such a large wound may be helpful as a temporary measure, but as a method of definitive wound closure would result in healing by secondary intention, scarring, and prolonged wound care. A full-thickness skin graft is not appropriate because of the large size of the defect and the amount of skin graft that would be required. A full-thickness graft would result in a major defect in another part of the body that would require primary closure. A local fasciocutaneous flap for such a large defect would require significant mobilization of tissue, and similarly, would result in a large donor site defect that would require grafting. A free flap is not necessary when there is viable soft tissue in the wound base. There is no exposed bone, tendon, nerves, blood vessels, or significant dead space, which would make a stronger argument for a flap-over-skin graft. Although not provided as an option in this question, the use of biosynthetic materials or dermal matrix tissues has been reported in the literature as an intermediate step to skin grafting, but it is important to consider the necessity of these materials in effecting outcomes in light of the significant cost of using them.

Question 127

``` A 67-year-old woman comes to the office for evaluation of abscesses on her face 5 weeks after undergoing autologous fat grafting for augmentation of the cheek. Physical examination shows multiple erythematous nodules, areas of induration, and microabscesses on both cheeks. Temperature is 99.5°F (37.5°C). Liposuction donor sites show no abnormalities. A 1-week course of ciprofloxacin prescribed by the patient’s family doctor failed to resolve the problem. Results of Gram stain and routine culture and sensitivity are negative. Which of the following is the most likely diagnosis? A) Atypical mycobacterial infection B) Herpes zoster infection C) MRSA infection D) Mucocutaneous candidiasis E) Staphylococcus epidermidis infection ```

Answer 127

A) Atypical mycobacterial infection Mycobacteria are ubiquitous in soil and water, and infections caused by these organisms can complicate aesthetic liposuction and autologous fat-grafting procedures. The postoperative symptoms include cellulitis, abscess formation, draining sinuses, and postoperative wound infection. Patients often do not have fever, chills, or other signs of systemic infection. While patients on immunosuppressive medications seem to be at higher risk, the problem also occurs in patients with healthy immune systems. More than 50% of patients will test negative for acid-fast bacilli, in addition to negative routine culture results. Polymerase chain reaction assay testing is now available for the most common species of nontuberculous mycobacterium, and is a useful rapid screening test for patients suspected of having this diagnosis. Bacterial infections (MRSA) would tend to show symptoms earlier, have systemic signs, and are usually easily cultured. Herpetic infections usually present with fluid-filled vesicles earlier in the postoperative course, and often have pain as a primary complaint. There is no history of previous injectable fillers, or implants, to suggest a biofilm-related infection in this patient. Mucocutaneous candidiasis is a chronic disease of the skin, nails, and mucosal surfaces.

Question 128

A healthy 30-year-old woman undergoes autologous fat grafting of the buttocks. The patient receives a dose of antibiotics before incision with sterile skin preparation and draping. Tumescent liposuction is performed. Gravity separation of the fat is performed intraoperatively, and 350 mL of fat is reinjected into each buttock. Postoperatively, the patient reports some areas of discrete tenderness, firmness, and limited erythema. Incision and drainage shows oily, cloudy fluid. Which of the following is the most likely cause of this patient’s complication? A) Inadequate administration of antibiotics preoperatively B) Inappropriate length of time for tumescent effect before aspiration C) Lack of antibiotic administration postoperatively D) Method of fat injection delivery E) Use of gravity fat separation rather than centrifugation

Answer 128

D) Method of fat injection delivery The most likely cause of this patient’s complication is inadequate attention to injection delivery of microaliquots of fat, leading to fat necrosis. Liposculpting, or liposuction and fat grafting, for buttock contour improvement is increasing in popularity and becoming a frequently performed procedure. Good results can be obtained, and patient satisfaction can be high. However, complications may also occur and should not be ignored. Proper technique is an essential component of effective liposculpting. Delivery of overly large amounts of fat into inadequate substrate can lead to inadequate revascularization and fat necrosis, described in the scenario as “tenderness, firmness, and drainage of cloudy, oily fluid.” Superinfection of nonviable tissue can occur, creating “limited erythema” responsive to “a short course of oral antibiotics,” but the most likely cause is not related to preoperative or postoperative antibiotics because the patient received what can be considered appropriate antibiotic therapy for a “clean,” elective case. Neither the described 3:1 fat-to-fluid ratio nor the use of gravity fat separation is considered an inappropriate liposuction technique.

Question 129

``` A 32-year-old woman comes to the office because of capsular contracture of the right breast. She underwent bilateral augmentation mammaplasty with saline implants 9 years ago. Revision surgery using simultaneous implant exchange with fat grafting is planned. Which of the following is the most likely fat retention volume over a 6-month period in this patient? A) 25% B) 45% C) 65% D) 85% ```

Answer 129

C) 65% Previously published work using radiologic volumetric data analysis with fat grafting for cosmetic augmentation mammaplasty demonstrates volume retention over 6 months of 64 ± 11%. Such loss of breast volume may be attributable to an element of apoptosis, a reduction in adipocyte volume after transplantation and survival, or a reduction in the fluid content of the grafted slurry. In reality, all three of these factors are likely to contribute to volume reduction over time.

Question 130

A 56-year-old man with type 1 diabetes mellitus comes to the office because of a foot ulcer over the first metatarsal head without evidence of exposed bone or osteomyelitis. A bioengineered cellular bilayered skin substitute (Apligraf®) is considered for treatment. Which of the following is the primary mechanism of action of this skin substitute to stimulate wound healing in this patient's ulcer? A) Creation of a moist environment through creation of a barrier B) Enzymatic degradation of the wound bed C) Inhibition of growth factor release D) Integration of the graft and creation of neo-dermis E) Release of matrix proteins

Answer 130

E) Release of matrix proteins Several biologic dressings have been FDA-approved for the treatment of diabetic foot ulcers. Apligraf® (Organogenesis, Inc., Canton, MA) and OrCel® (Ortec International, New York) are bilayered constructs of bovine collagen with human keratinocytes and fibroblasts. Although it appears like normal skin, it does not take like a skin graft, but rather the viable cells in the construct release and stimulate growth factors and matrix proteins to encourage wound healing. Neo-dermis creation is the primary function of Integra ™ (Integra LifeSciences Corp, Plainsboro NJ) which is an acellular construct composed of collagen and chondroitin-6-sulfate covered with a silicone top layer to prevent evaporative losses. It does not have any active cells or release growth factors or matrix proteins. Enzymatic degradation of a wound bed is not a function of biologic grafts, but is the main function of topical wound treatments like the collagenase Santyl® (Healthpoint Biotherapeutics, Fort Worth TX).

Question 131

``` A 35-year-old man undergoes reconstruction of a degloving injury of the palmar surface of the hand. Full-thickness skin grafting from the groin is planned. Which of the following structures of healthy palmar skin will be missing from this graft? A) Dermal neural mechanoreceptors B) Dermal sweat ducts and glands C) Irregular dermal-epidermal border D) Pilosebaceous structures E) Sensory and autonomic nerve fibers ```

Answer 131

A) Dermal neural mechanoreceptors The skin on the palm has specialized, encapsulated nerve endings called Meissner corpuscles in the dermal papillae and Vater-Pacini corpuscles in the deep dermis. These special dermal neural mechanoreceptors are unique to glabrous skin. Skin grafts from nonglabrous donor sites lack this feature and will have poor return of sensibility. There are a few features that are common between palmar and regular skin. Both contain intraepidermal nerve endings and sweat ducts and glands. Both have an irregular border between the basal layer of the epidermis and dermis, at which juncture are the dermal papillae and epidermal rete ridges. A network of blood vessels and sensory and autonomic nerve fibers in the dermis is shared by all skin. Palmar skin has deeper papillae and ridges, as the keratin layer is considerably thicker; however, glabrous donor sites for grafting are limited. Finally, pilosebaceous structures are absent in the palm.

Question 132

A 77-year-old woman undergoes excision of a basal cell carcinoma of the mid cheek. Physical examination shows a 4 × 4-cm circular skin defect with exposed subcutaneous fat. Reconstruction with skin grafting is planned. Use of which of the following is most appropriate to minimize long-term graft contracture? A) Cultured epidermal autografting B) Full-thickness skin grafting C) Split-thickness skin grafting with meshing D) Split-thickness skin grafting with no meshing

Answer 132

B) Full-thickness skin grafting The defect is a full-thickness skin defect with exposed subcutaneous fat. A local flap or skin grafting are possible reconstructive options. If skin grafting were to be performed, then a full-thickness skin graft would minimize the amount of long-term contracture (secondary contracture). A skin graft can be either split-thickness or full-thickness. Full-thickness skin grafts contain both the epidermis and the dermis and would have less long-term contracture. Defatting of the skin graft is important in the case of a full-thickness graft to optimize graft “take” in the early postoperative period. Various donor sites are available for skin grafting. Cultured epidermal autografts (CEAs) are useful when there are limited areas on the body to be used as skin graft donor sites, such as in a massive burn patient. However, CEAs are costly, and the resulting skin is often very thin and fragile. Therefore, judicious use of CEAs is warranted. Split-thickness grafts can be harvested with a mechanical dermatome or a free hand with a scalpel. Split-thickness skin grafts do not include the entire thickness of the dermis and have less initial contracture at the time of harvest (primary contracture) but are expected to have long-term contracture (secondary contracture). Harvesting with a mechanical dermatome is useful for obtaining split-thickness skin grafts. Typical thicknesses may range from 8/1000 to 14/1000 of an inch. Meshing allows for a broader surface area to be covered by a skin graft but will lead to greater contracture within the open interstices of the graft. Of note for deeper wounds extending below the superficial musculoaponeurotic system, evaluation of facial motor nerve function and status of the parotid duct may be important considerations.

Question 133

``` A 35-year-old Asian woman desires dorsal augmentation to achieve a more "Western" nose. Autologous rib cartilage grafting is planned. Which of the following complications is most common with this procedure? A) Extrusion B) Infection C) Pneumothorax D) Resorption E) Warping ```

Answer 133

E) Warping The most consistent complication of costal cartilage grafting is the propensity to warp or change shape over time. This may be due to the presence of perichondrium or the nonuniform composition of the matrix that can affect the shape when it is placed. Although there is a risk of pleural violation and pneumothorax, these complications are uncommon and can be recognized intraoperatively with the Valsalva maneuver. Through the same exposure for harvesting the rib graft, a red rubber catheter is placed in the chest to evacuate intrathoracic air. As long as the visceral pleura remain intact, a thoracostomy tube is unnecessary. Fresh autologous grafts easily survive transplantation procedures and do not appear to resorb over time. Autologous cartilage from septum, concha, or rib is considered the ideal graft material. These grafts have very low risk of infection or extrusion compared with an alloplast. Cartilage grafts are tolerated well by nasal tissue.

Question 134

``` A 24-year-old Chinese-American, right-hand-dominant man undergoes cadaveric hand transplantation after traumatic amputation at the right wrist from a machinery accident. The donor is a Hispanic man. Which of the following terms best describes the antigenicity of the transplant? A) Allograft B) Autograft C) Isograft D) Xenograft ```

Answer 134

A) Allograft Any tissue transplantation from another genetically nonidentical human is termed allograft, previously referred to as homograft. As these transplanted tissues are immunologically different from the recipient, they will eventually undergo rejection from the host immune system without immunosuppressive medications. There are many distinct antigens responsible for the rejection process, the most important of which are the major histocompatability complex (MHC) antigens, known as HLA-1 and HLA-2, which reside on the surface of cells. Autograft implies that the donor tissues come from the same patient – such as the common autologous skin graft. Isograft comes from a genetically identical donor, namely an identical twin. While such donations are very rare, it is of important historical note that the first human kidney transplantation was performed by Dr. Joseph Murray between identical twin donor and recipient. In this clinical scenario, as one patient is Asian and the other Hispanic, it is clear that the transplant is not an isograft. Xenograft is a cross-species graft. Porcine skin grafts are commonly used as temporary skin substitutes to promote granulation formation in difficult wound beds.

Question 135

An otherwise healthy 7-year-old boy is brought to the office because of a 4-year history of progressive soft-tissue atrophy of the left forehead with coup de sabre. Examination shows skin atrophy, discoloration, and alopecia at the hairline in the V1 distribution. Which of the following is the most appropriate method to correct the deformity? A) Forehead contouring with a calcium phosphate ceramic B) Free tissue transfer C) Implantation of a custom silicone prosthesis D) Injection of hyaluronic dermal filler E) Serial fat grafting

Answer 135

E) Serial fat grafting Parry-Romberg syndrome can be associated with underlying neurologic disease. The symptoms generally first manifest in the first or second decade of life and can involve bone, cartilage, fat, or skin. Free tissue transfer performed once the disease has stabilized has been shown to be a highly satisfactory correction. However, in recent years, fat grafting has become a more utilized option. Although more procedures are required, it can begin in younger patients even if the disease is still active. It also has demonstrated high patient satisfaction. Hyaluronic acid dermal fillers are not FDA-approved in children and are unlikely to provide long-term correction. Custom prostheses or calcium phosphate ceramics would not reconstruct with like tissue; one would be less likely to have a stable, soft aesthetically pleasing result.

Question 136

``` A 25-year-old man is scheduled to undergo reconstruction of a 5 × 5-cm, full-thickness calvarial defect. A titanium/hydroxyapatite cement cranioplasty reconstruction is planned. Which of the following mechanisms best describes the healing process involved? A) Endochondral ossification B) Osteochondrosis C) Osteoconduction D) Osteogenesis E) Osteoinduction ```

Answer 136

C) Osteoconduction Restoration of craniofacial contour after infection, tumor resection, or trauma can be quite challenging. Autologous bone grafts have long been considered the gold standard due to their high likelihood of osseointegration/healing and low risk of rejection or infection. Autologous bone grafts, however, have several drawbacks, including unpredictable resorption, donor site morbidity, limited availability, prolonged operative times, and difficulty in contouring. As a result, there has been an ongoing search for alternative means of reconstruction with alloplastic material. The ideal bone substitute should be chemically inert, easily contoured, retain a stable shape over time, strong, resistant to infection or foreign body reaction, inexpensive, and capable of osseointegration and tissue ingrowth. Methylmethacrylate has been used frequently for calvarial reconstruction but suffers several drawbacks, including infection requiring removal of implant, plate fracture, lack of osseointegration, difficulty shaping after polymerization, and necrosis of surrounding tissue due to the exothermic nature of the curing process. Some of the most promising and well-tolerated alloplastic materials for craniofacial skeletal reconstruction are the calcium phosphate-based compounds. Hydroxyapatite [Ca(PO4)6(OH)2] forms the principal mineral component of bone and constitutes 60% of the calcified human skeleton. Calcium phosphate compounds are bioactive and capable of osteoconduction and osseointegration. Osseointegration refers to the direct chemical bonding of an alloplast to the bony surface without an intervening fibrous tissue layer. During osteoconduction (creeping substitution), the alloplast acts as a nonviable scaffold for ingrowth of blood vessels and osteoprogenitor cells from the recipient site. Subsequently, the graft/alloplast is resorbed and replaced with new bone. This mechanism is also associated with the healing of cortical bone grafts. Hydroxyapatite cement is a mixture of tetracalcium phosphate and dicalcium phosphate anhydrous which reacts in an aqueous environment to form a paste that can be easily applied and sculpted to fit the surgical defect. Hydroxyapatite cement sets isothermically, so there is no risk of thermal damage to the surrounding tissues. Additional benefits of hydroxyapatite include “off the shelf” ease of use, maintenance of volume over time, lack of radiologic scatter, and low incidence of infection. Osteoinduction refers to the direct stimulation of mesenchymal cells at the recipient site by bone morphogenetic protein to differentiate into osteoprogenitor cells. This mechanism of action is associated with the healing of cancellous bone grafts and demineralized bone matrix. Endochondral ossification is the process by which the cartilaginous soft callus covering a fracture is transformed into bone. Osteogenesis is the process by which vascularized bone grafts heal. Viable osteocytes survive the transplantation process and produce new bone at the recipient site. Osteochondrosis refers to a family of ossification disorders in children.

Question 137

Which of the following techniques minimizes fat necrosis and increases the viability of fat grafting? A) Avoidance of pressure on grafted areas postoperatively B) Avoiding placement of the grafts in irradiated tissue C) Centrifuging the fat grafts D) Placing the graft in multiple small volumes in a lattice-like framework E) Using ultrasound-assisted liposuction to harvest grafts

Answer 137

D) Placing the graft in multiple small volumes in a lattice-like framework The results of fat grafting are dependent upon the surgeon’s experience and technique. Strategies to increase the take of the fat graft and decrease fat necrosis include atraumatic harvest techniques. Placement of the graft in multiple small aliquots increases the availability for vascularity and creating a lattice-like framework when depositing the grafts avoids large-volume deposits. Placement of the grafts in a few large-volume deposits is avoided to minimize fat necrosis and creation of fatty oil cysts. Fat grafting has been refuted for soft tissues that have been affected by radiation.

Question 138

``` Which of the following is the most common long-term complication of auricular cartilage harvesting? A) Cauliflower ear B) Hematoma C) Necrosis D) Perichondritis E) Sensory impairment ```

Answer 138

E) Sensory impairment The external ear provides a versatile cartilage source for reconstructive procedures, especially for augmentative rhinoplasty. Short- and long-term morbidity associated with ear cartilage harvest using concha, tragus, and scapha as donor sites were evaluated. The relevant morbidity factors in the early postoperative period were hematoma formation (6.7%) and sensory impairment (3.3%). In long-term follow-up, sensory impairment was the most frequent condition objectively assessed and subjectively complained of (12.9%). Overall, sensory impairment was confined to concha as the donor site. Anthropometric measurements showed a mean difference in the length of the affected ear compared with the contralateral ear of 1.8 mm, a width difference of 2.5 mm, a difference in tragus/lateral canthus distance of 1.4 mm, and a difference in protrusion angle of 2.4 degrees. Aesthetically relevant complications were rare and their occurrence restricted to single cases. Long-term cases of necrosis, infection, and perichondritis were exceedingly rare. Cartilage graft harvest from the auricle can be considered as a relatively safe procedure with a favorable aesthetic outcome. Cauliflower ear may result from long-standing loss of blood supply to the ear cartilage and formation of neocartilage from disrupted perichondrium. This complication is almost never seen from harvest but from auricular trauma.

Question 139

``` A 21-month-old male infant is scheduled to undergo reconstruction of a 12-cm² cranial defect after a cranial vault reshaping procedure. Which of the following materials is most appropriate for cranioplasty in this patient? A ) Bone dust B ) Hydroxyapatite C ) Particulate bone D ) Split calvarium E ) Split rib ```

Answer 139

C ) Particulate bone Although alloplastic materials and bone substitutes have been used to reconstruct the pediatric cranium, autogenous bone is the best option. Unlike synthetic materials, autogenous grafts undergo rapid osseointegration because they are osteogenic, osteoinductive, and osteoconductive. Once healed, the grafted site has the same properties as native bone: strength, growth potential, stability, and resistance to infection. Compared with other sources of autogenous graft, calvarial bone is the preferred donor site for cranioplasty, especially in pediatric patients, because it is in the operative field, volume retention and strength of the graft are excellent, and harvest causes no additional discomfort. Extracranial sources of autologous bone (rib or iliac crest) provide little volume in toddlers, have a higher resorptive rate than cranial bone, and are associated with greater donor-site morbidity. Bone dust is the powder-like bone that results from using a high-speed burr. Bone dust is ineffective and resorbs when used for cranioplasty, possibly because of its smaller particle size and/or thermal injury during harvesting. Autogenous bone, the standard material used for cranial reconstruction, is of limited supply in young children. Calvarial bone is difficult to split until a diploic space has formed, usually after 4 years of age, and some authors do not recommend in situ harvest before 9 years of age. Cranial particulate bone grafting, however, can be harvested at any age, and studies have demonstrated that it is as effective as split calvarial bone graft for closure of cranial defects. Particulate cranial graft consists of tiny pieces of bone harvested with a low-speed, hand-driven bit and brace. It has shown in animal models as well as clinical studies to effectively heal full-thickness cranial defects.

Question 140

``` A 42-year-old woman with a history of progressive facial atrophy comes to the office because of a moderately sized soft-tissue deficit on the left side of the face. She is scheduled to undergo a single fat transfer procedure for correction. Which of the following is the most likely outcome of this procedure in this patient? A ) Donor site seroma B ) Facial nerve injury C ) Fat embolism D ) Hypertrophic scarring E ) Inadequate correction ```

Answer 140

E ) Inadequate correction Romberg disease, or progressive facial atrophy, is a rare pathologic process characterized by an acquired, idiopathic, self-limited, unilateral atrophy of the face, variably involving skin, subcutaneous tissues, fat, muscle, and less frequently, the underlying bone structures. Methods of restoration of facial contour and volume in these patients include synthetic implants, bone grafts, free tissue transfer, and fat grafting. Fat injections have been used for over 20 years to correct soft-tissue deformities throughout the body. Fat grafts are often used for ?touch-up? of various reconstructive procedures. This technique has been found to be helpful as an adjunct to free tissue transfer in cases of progressive facial atrophy and congenital hemifacial microsomia. Although fat embolism has been rarely reported during fat transfer in the face, complication rates of fat grafting are low, especially when compared with complications of free tissue transfer for reconstruction of facial deformities, which may include donor site seroma, facial nerve injury, and hypertrophic scarring. The most common adverse outcome of fat grafting is likely to be inadequate correction with a single-stage procedure. A recent study found that no statistically significant difference was found in satisfaction rates between free flap reconstruction and serial fat grafting of soft-tissue deficits in hemifacial microsomia.

Question 141

A 10-year-old boy comes to the office because of difficulty turning his head and looking up 2 years after sustaining burns in a gasoline fire involving nearly 50% of the total body surface area. Bilateral skin grafting of the distal upper extremities and proximal upper thighs was performed 2 years ago to treat deep partial-thickness burns. Current physical examination shows severe burn scar contracture on the neck (shown) and healed skin grafting of the neck and anterior trunk. After release and excision of the burn scar contracture, a 10 × 20-cm defect results. Which of the following is the most appropriate method of reconstruction to provide the most aesthetic and functional outcome? A ) Anterolateral thigh perforator free tissue transfer to the neck B ) Dermal regeneration template (Integra) C ) Full-thickness skin graft from the inguinal region D ) Split-thickness skin graft from the back E ) Split-thickness skin graft from the posterior thigh

Answer 141

B ) Dermal regeneration template (Integra) While Integra artificial skin substitute has been used traditionally in the acute management of burns, there have been many successful reports incorporating its use in general reconstructive plastic surgery. Integra is a bioengineered dermal substitute consisting of a bilayer membrane system. The dermal replacement layer is composed of a cross-linked bovine tendon collagen-glycosaminoglycan (chondroitin-6-sulfate) matrix coated on one side with a synthetic polysiloxane polymer (silicone) layer. Integra "take" mirrors skin graft "take" and follows the sequence of (1) imbibition; (2) fibroblast migration; (3) neovascularization; and (4) maturation. As the host tissue infiltrates the dermal layer, the collagen layer is biointegrated with the wound to form a vascular neodermis capable of accepting a split-thickness skin graft following a period of 3 to 4 weeks. Proper patient selection and careful monitoring for infection or hematoma accumulation are crucial in this time period. After approximately 4 weeks, the silicone layer is removed and a thin (0.008- to 0.010-in) skin graft can be applied. Advantages of Integra use include improved cosmesis; diminished burn scar contracture or development of hypertrophic scar; off-the-shelf availability in large quantities; increased elasticity; and the ability to use thinner skin grafts with subsequent improvement in donor site morbidity, scar, and time to heal. Other cited advantages include commensurate growth of the grafted tissue in children, potential avoidance of a microsurgical procedure, and placement over tendons with no significant reduction in tendon mobility. The disadvantages of Integra include its high cost, steep learning curve, need for at least two stages with subsequent increased time to final closure, potential for infection under the silicone layer, and lack of adnexal structures with patient complaint of skin dryness. In the patient described, use of Integra with delayed, thin split-thickness skin grafts at 4 weeks will give the best outcome in terms of cosmesis and function. Free tissue transfer is an excellent technique for resurfacing the contracted neck following burns, but the thigh donor site has already been treated with skin grafts in the scenario described, and the aesthetic result would be suboptimal. A better choice would be the scapular or parascapular donor site, perhaps in combination with a preliminary tissue expansion of that location. Coverage with a full-thickness skin graft would diminish the risk of secondary contraction; however, harvesting enough tissue to cover the entire neck would be difficult with the inguinal region as a donor site. Coverage with a split-thickness skin graft is not an appropriate option in this location because of the risk of secondary contraction and recurrence of the neck contracture.

Question 142

``` A 9-year-old girl with a unilateral cleft lip and palate undergoes alveolar bone grafting with a cancellous iliac graft. Which of the following is the most likely mechanism by which the bone graft will heal in this patient? A ) Endochondral ossification B ) Osteoconduction C ) Osteogenesis D ) Osteoinduction E ) Progenitor cell recruitment ```

Answer 142

C ) Osteogenesis The most likely mechanism of cancellous bone graft healing is by osteogenesis. Cancellous and vascularized bone grafts heal primarily by osteogenesis. Because these grafts are rapidly revascularized, osteoblasts survive the transplantation and produce new bone at the recipient site. Endochondral ossification is the embryologic process by which bones of the appendicular skeleton, vertebral column, and skull base are formed. The maxilla develops by membranous ossification. Osteoconduction, or "creeping substitution," is the mechanism by which cortical bone grafts heal (e.g., split cranial bone graft). After cortical bone is separated from its blood supply, it serves as a nonviable scaffold for the ingrowth of blood vessels and osteoprogenitor cells from the recipient site. This leads to resorption and replacement of most of the graft with new bone. The graft becomes fully osseointegrated with the recipient site. Osteoinduction involves the stimulation of mesenchymal cells at the recipient site to differentiate into bone-producing cells. Demineralized bone and bone-morphogenic protein produce new bone by osteoinduction. Although progenitor cells might be recruited to an area where bone grafting has occurred, they are not a primary mechanism for cancellous bone graft healing.

Question 143

``` A 34-year-old woman is referred for evaluation because of a 9 × 7-cm lateral soft-tissue deformity of the right thigh with skin thickening. She has a history of oncologic resection and external beam radiation of 50 Gy. Which of the following is the most appropriate step in management? A ) Acellular dermis B ) Dermal-fat grafting C ) Full-thickness skin grafting D ) Lipoaspirate injection ```

Answer 143

D ) Lipoaspirate injection Radiation has deleterious effects on local vascularity, fibroblast activity, growth factor levels, and mesenchymal stem cell populations. Microscopic examination of irradiated tissue shows microvascular thrombosis and abnormal vasculature. Clinically, irradiated wounds are associated with slower epithelialization, decreased tensile strength, and higher infection and dehiscence rates. Although data are still limited, marked improvements in irradiated tissues have been reported with autologous fat injection. Lipoaspirate injected in areas of chronic radiation wounds improved the wound quality by either promoting a more vascular wound amenable to reconstruction or spontaneous closure. Adipocytes contain stem cells which improve wound vascularity. Acellular allogeneic dermis is produced from human cadaveric allograft skin. During the skin processing, immunogenic components that include all viable cells are extracted, leaving acellular dermis and extracellular matrix intact. The entire epidermis and all of the dermal cells are removed during a freeze-drying process. The resultant matrix has undamaged collagen types IV and VII, elastin, and laminin. The acellular and porous dermal matrix allows ingrowth and colonization by host fibroblasts and endothelial cells. Acellular allogeneic dermis provides a template for fibrous ingrowth, resulting in an integrated graft that is not rejected. It can be used for almost any area as long as there is adequate blood supply to support the graft. Acellular allogeneic dermis survival in less vascular areas is unknown. Dermal-fat grafts are usually harvested from the same areas as full-thickness skin grafts are. These include the lower abdomen, the suprapubic or periumbilical regions, the gluteal or inframammary folds, the subiliac crest, and even the forearm for hand surgery purposes. An ellipse of skin with dimensions appropriate to fill the recipient defect is outlined. The epithelium can be removed by sharp excision with a scalpel or dermabrasion. Previous radiation, excessive cicatrization, deficiency of circulation, and poor healing qualities caused by poor nutrition and systemic diseases all militate against a satisfactory result. Skin grafts are used in a variety of clinical situations. The essential indication for the application of a skin graft is wound closure. In general, full-thickness skin grafts are applied to the regions of the face, ears, and hands. Split-thickness skin grafts are usually placed on the trunk and genitalia. Skin grafts are usually the initial treatment of choice for many open wounds that cannot be closed primarily. Grafting offers the simplest method of wound closure in the reconstructive ladder, assuming that primary closure is not possible or would lead to undue tension. Skin grafts are generally avoided in management of more complex wounds. Conditions with deep spaces and exposed bones, such as open sternal wounds, pressure sores, and open fractures, normally require the use of skin flaps or muscle flaps for stable wound coverage. Skin grafts have limited success in wounds with a compromised blood supply, such as irradiated wounds and ischemic ulcers.

Question 144

``` A 34-year-old woman is referred for evaluation because of a 9 × 7-cm lateral soft-tissue deformity of the right thigh with skin thickening. She has a history of oncologic resection and external beam radiation of 50 Gy. Which of the following is the most appropriate step in management? A ) Acellular dermis B ) Dermal-fat grafting C ) Full-thickness skin grafting D ) Lipoaspirate injection ```

Answer 144

D ) Lipoaspirate injection Radiation has deleterious effects on local vascularity, fibroblast activity, growth factor levels, and mesenchymal stem cell populations. Microscopic examination of irradiated tissue shows microvascular thrombosis and abnormal vasculature. Clinically, irradiated wounds are associated with slower epithelialization, decreased tensile strength, and higher infection and dehiscence rates. Although data are still limited, marked improvements in irradiated tissues have been reported with autologous fat injection. Lipoaspirate injected in areas of chronic radiation wounds improved the wound quality by either promoting a more vascular wound amenable to reconstruction or spontaneous closure. Adipocytes contain stem cells which improve wound vascularity. Acellular allogeneic dermis is produced from human cadaveric allograft skin. During the skin processing, immunogenic components that include all viable cells are extracted, leaving acellular dermis and extracellular matrix intact. The entire epidermis and all of the dermal cells are removed during a freeze-drying process. The resultant matrix has undamaged collagen types IV and VII, elastin, and laminin. The acellular and porous dermal matrix allows ingrowth and colonization by host fibroblasts and endothelial cells. Acellular allogeneic dermis provides a template for fibrous ingrowth, resulting in an integrated graft that is not rejected. It can be used for almost any area as long as there is adequate blood supply to support the graft. Acellular allogeneic dermis survival in less vascular areas is unknown. Dermal-fat grafts are usually harvested from the same areas as full-thickness skin grafts are. These include the lower abdomen, the suprapubic or periumbilical regions, the gluteal or inframammary folds, the subiliac crest, and even the forearm for hand surgery purposes. An ellipse of skin with dimensions appropriate to fill the recipient defect is outlined. The epithelium can be removed by sharp excision with a scalpel or dermabrasion. Previous radiation, excessive cicatrization, deficiency of circulation, and poor healing qualities caused by poor nutrition and systemic diseases all militate against a satisfactory result. Skin grafts are used in a variety of clinical situations. The essential indication for the application of a skin graft is wound closure. In general, full-thickness skin grafts are applied to the regions of the face, ears, and hands. Split-thickness skin grafts are usually placed on the trunk and genitalia. Skin grafts are usually the initial treatment of choice for many open wounds that cannot be closed primarily. Grafting offers the simplest method of wound closure in the reconstructive ladder, assuming that primary closure is not possible or would lead to undue tension. Skin grafts are generally avoided in management of more complex wounds. Conditions with deep spaces and exposed bones, such as open sternal wounds, pressure sores, and open fractures, normally require the use of skin flaps or muscle flaps for stable wound coverage. Skin grafts have limited success in wounds with a compromised blood supply, such as irradiated wounds and ischemic ulcers.

Question 145

A 27-year-old man is scheduled to undergo excision and skin grafting after sustaining a full-thickness burn to the dorsum of the hand. To optimize graft take in this patient, which of the following is the most important aspect of management? A ) Meshing of the skin graft B ) Meticulous hemostasis C ) Negative pressure wound therapy D ) Use of fibrin glue E ) Use of a thin split-thickness skin graft

Answer 145

B ) Meticulous hemostasis The most important aspect of recipient site management to optimize graft survival and outcome in this patient undergoing dorsal hand skin grafting is meticulous hemostasis. This is because hematoma is the leading cause of skin graft loss. Meshing a skin graft may promote graft survival by providing a mode of egress for blood and seroma that might form below the graft. However, it is associated with an increased rate of secondary contraction and unfavorable cosmetic results. Both of these factors make meshing undesirable when grafting the dorsum of the hand. Use of a negative pressure wound therapy dressing can result in improved graft survival, especially in recipient sites with irregular contours. However, it is not critical for the hand. A good dressing and proper immobilization should achieve the same result. Use of this type of dressing is not as important as meticulous hemostasis for ensuring graft survival and outcome. Fibrin glue has been used to promote graft survival by improving hemostasis and graft adherence. There is also some evidence that fibrin glue may inhibit wound contraction. Nevertheless, it is no substitute for meticulous hemostasis and should only be used as an adjunct to the fundamental techniques of skin graft placement. Use of a thin split-thickness skin graft is associated with improved graft survival when compared with a thick split-thickness or full-thickness skin graft, but it is also associated with an increased rate of secondary contraction that is not desirable on the dorsum of the hand. Balancing the need for graft survival versus the need to avoid secondary contraction is an important consideration in burn surgery. Using thinner grafts will optimize graft survival, but this is not as critical as ensuring good hemostasis.