Trauma Flashcards
1
Q
A
2
Q
What is recommended for bridge plating?
[JAAOS 2016;24:711-719]
A
- Opt for titanium when possible
- Longer plates preferred
- A. Longest plate that is anatomically feasible
- B. Minimum 2-3x the length of comminuted fractures
- Less than 50% screw fill
- ≤4 diaphyseal screws
- Increase working length
3
Q
What are the pin placement locations in respective bones for external fixation?
[J Am Acad Orthop Surg 2015;23:683-690]
A
oHumerus = 5mm pins placed anterolaterally (avoid axillary n, radial n, and olecranon fossa)
oUlna = 4mm pin proximally and 3mm pin distally along subcutaneous border (preferred over radius)
oRadius = 4mm pin along radial border (posterior to radial artery and superficial radial n)
o2nd metacarpal = 3mm pin entering radial border of 2nd MC base
- Flex fingers at time of pin insertion, avoids entrapment of extensor tendon which would prevent finger flexion
oFemur = 5mm pins placed anterolaterally or direct lateral
oTibia = 5mm pins placed anteromedial
oCalcaneus = 5mm pin placed medial to lateral in safe zone (posterior to the halfway point from the posteroinferior calcaneus to the inferior medial malleolus and posterior to the one-third mark from the posteroinferior calcaneus to the navicular tuberosity)
- Structures at risk = calcaneal nerve (medial), sural nerve (lateral)
oFoot = 3 or 5 mm pin medially into the talar neck, cuneiforms, or first metatarsal base, or laterally into the cuboid or fifth metatarsal base. For cuneiform pin placement, the pin should enter the dorsal half of the medial cuneiform
4
Q
What are the 3 most common sites for lower extremity skeletal traction?
[J Am Acad Orthop Surg 2016;24:600-606]
A
- Distal femur
- Indications
- Acetabular fractures not involving the weightbearing dome
- Pelvic fractures with a displaced hemipelvis
- Adult proximal third femur fracture
- Pediatric femoral shaft fracture (90/90 traction)
- Any contraindication to a proximal tibia pin
- Pin location
- Placed from medial to lateral
- >0.7 cm proximal to the adductor tubercle near the metaphyseal flare
- Avoids joint and femoral artery in the adductor hiatus
- Proximal tibia
- Indications
- Femoral fractures located in the distal 2/3 of the shaft
- Contraindications
- Ligamentous knee injuries
- Tibial plateau fractures
- TKA with a long stemmed implant
- Pin location
- Placed from lateral to medial
- 2.5cm posterior and 2.5cm distal to the tibial tubercle parallel to the joint
- Calcaneus
- Indications
- Tibial shaft fractures
- Distal tibia fractures
- Subtalar dislocation
- Intra-op distraction during ankle arthroscopy
- Pin location
- Placed medial to lateral
- Safe zone is 3.1cm radius around the posterior inferior calcaneus
- Calcaneal nerve (medial) and sural nerve (lateral) at risk
5
Q
What are the indications for skeletal traction in acetabular and pelvic fractures?
[J Am Acad Orthop Surg 2016;24:600-606]
A
- Mainly a temporizing measure until definitive surgery
- Immediate treatment of acetabular fractures with:
- Incarcerated intra-articular fragments
- Persistent subluxation of the femoral head
- ***Injuries often associated with posterior wall fractures
- Medialization of the femoral head secondary to quadrilateral plate disruption
- Traction pin should be placed in distal femur
- Only use trochanteric pins intraop, due to increased infection risk with prolonged use
- Pelvic ring injuries with complete disruption of the posterior sacroiliac complex, as seen in vertical shear injuries, may require skeletal traction to help reduce the displaced hemipelvis.
- Traction may also be an adjunct for a combined acetabular and pelvic ring injury that has been temporarily stabilized with an external fixator.
6
Q
What are the definitions of nonunion and delayed union?
[Rockwood and Green 8th ed. 2015]
A
- Nonunion = fracture has failed to heal in the expected time and is not likely to heal without new intervention
- Delayed union = fracture has failed to heal in the expected time but still has the potential to heal without further intervention
7
Q
When is a fracture of a long bone considered nonunion?
[JAAOS 2013;21:538-547]
A
- Lack of healing 6-9 months following injury
* Delayed union after 4 months - No interval healing on two consecutive radiographs 6-8 weeks apart
8
Q
What are factors that contribute to nonunion?
[Rockwood and Green 8th ed. 2015]
A
1.Fracture factors
- A. Fracture location
- Anatomic sites with limited or watershed vascular supply (eg. diaphysis of long bones, talar neck, scaphoid waist, femoral neck, proximal meta-diaphysis of 5th MT)
- B. High-energy fractures
- Comminution
- Bone loss
- Periosteal stripping
- Soft tissue stripping
- C. Open fracture
- Host factors
- Smoking and nicotine products
- Diabetes
- Peripheral vascular disease
- Medications – steroids, NSAIDs, chemotherapy, bisphosphonates
- Poor nutrition – protein, calcium, Vit D
- Osteoporosis
- Advanced age
- Immunosuppression
- Radiation exposure
- Surgeon factors
- Inadequate fixation stability
- Soft tissue disruption
4.Infection
9
Q
What are the treatment options for non-union?
[Rockwood and Green 8th ed. 2015]
A
Nonoperative:
- Indirect intervention
- Smoking cessation
- Nutrition optimization
- Discontinue offending medications
- Optimize endocrine and metobolic disorders
- Direct intervention
- Weight bearing
- Cast or orthosis
- Electromagnetic stimulation
- Ultrasound stimulation (LIPUS – low intensity pulsed ultrasound) – better evidence
- Parathyroid hormone (PTH)
Operative:
- Plate and screw fixation
- Reamed exchange nailing
- Nail dynamization
- Circular ring external fixator
- Arthroplasty for periarticular nonunions in the elderly
- Amputation
- Arthrodesis
- Fragment excision in certain locations (eg. ulnar styloid, olecranon)
- Resection arthroplasty (eg. radial head nonunion, proximal pole of scaphoid)
10
Q
What are the autograft options for nonunion treatment?
[J Orthop Trauma 2018;32:S52–S57)]
A
- ICBG (iliac crest bone graft)
* Yield = 30cc - RIA (reamer-irrigator-aspirator)
* Yield = up to 60cc
11
Q
What is the management of an infected nonunion?
[J Orthop Trauma 2018;32:S7–S11)]
A
- Diagnosis -.WBC, ESR, CRP (most accurate predictor)
- Initial surgical stage
- A. Removal of all loose or chronically infected hardware
- B. Debridement of all infected or nonviable bone or soft tissue
- C. Minimum 3-5 deep tissue biopsies for culture and sensitivity
- D. Revision of fracture fixation
- Temporary fixation – ex-fix, casting, antibiotic nail
- Permanent fixation – plate fixation, IM nail, locked antibiotic nail
- E. Placement of local antibiotic
- Antibiotic nail, antibiotic impregnated osteoconductive pellets (eg. Osteoset T), antibiotic powder, antibiotic cement beads, antibiotic cement spacers (combined with induced membrane)
- Interim culture specific antibiotics and monitoring clinically and serologically for resolution of infection
- Second surgical stage
- A. Definitive fracture fixation (if temporary fixation was used)
- B. Reconstruction of the bone defect
12
Q
What are the surgical options to manage critical segmental bone defects and what size defects are the options amenable to?
[JAAOS 2015;23:143-153] [J Orthop Trauma 2018;32:S7–S11)]
A
- Induced membrane technique (Masquelet) >10cm (5-24)
- Distraction osteogenesis 5-10cm
- Acute limb shortening 1-3cm
- Vascularized fibula transfer 10-20cm
- Amputation
13
Q
What are the 3 main benefits of the Masquelet technique?
[JAAOS 2015;23:143-153]
A
- “Priviledged compartment” limits autograft resorption
- Maintains the defect space for delayed bone grafting
- Induced membrane is rich in growth factors which improve graft consolidation
14
Q
What is the function of the PMMA spacer in Masquelet Technique?
[J Orthop Trauma 2018;32:S7–S11)]
A
- Induces formation of biologically active pseudomembrane
- Maintains space for bone graft
- Delivers antibiotics
15
Q
What is the function of the induced membrane in Masquelet Technique?
[J Orthop Trauma 2018;32:S7–S11)]
A
- Provides vascularization of bone graft
- Prevents graft resorption
- Provides growth factors which promote graft consolidation
16
Q
Describe the Masquelet technique
[J Orthop Trauma 2018;32:S7–S11)]
A
Two stage procedure
- Stage 1
- Debridement of bone and soft tissue
- Stabilization with external or internal fixation
- Placement of PMMA spacer (with or without antibiotics)
- Stage 2
- 6-8 weeks later the membrane is incised
- The PMMA spacer is removed and the preserved defect is bone grafted
- Autograft is gold standard
- RIA +/- allograft or bone substitute (do not exceed 3:1 ratio of allograft to autograft)
- Autograft is gold standard
17
Q
What is the main limiting factor in acute limb shortening?
A
Vessel kinking with shortening beyond 3-5cm
18
Q
What is heterotopic ossification?
[JBJS 2015;97:1101-11]
A
Formation of ectopic lamellar bone in soft tissues
19
Q
What are the risk factors for HO formation?
[JBJS 2015;97:1101-11][JOT 2012; 26(12): 684–688]
A
- Male
- Traumatic brain injury
- Spinal cord injury
* HO commonly forms caudad to the level of injury - Burns
* >20% BSA significantly increases risk - Delay in treatment
- Revision surgery
- Certain injury locations/surgeries
* Acetabulum, THA, elbow fractures, distal humerus - Ankylosing spondylitis/DISH
- Blast injuries
20
Q
What are the classification systems for HO of the hip and elbow?
[JBJS 2015;97:1101-11]
A
- Brooker Classification System for HO at the hip
- Class 1 - Islands of bone within soft tissues of the hip
- Class 2 - Bone spurs in the pelvis or femur but with ≥1cm between bone surfaces
- Class 3 - Bone spurs within the pelvis or femur with <1cm between bone surfaces
- Class 4 - Ankylosis of the hip
- Hastings and Graham Classification System System for HO at the Elbow
- Class I - radiographic evidence without functional deficit
- Class IIA - radiographic evidence with limitation in flexion-extension axis
- Class IIB - radiographic evidence with limitation in pronation-supination axis
- Class IIIA - ectopic bone formation and ankylosis of joint in flexion-extension axis
- Class IIIB - ectopic bone formation and ankylosis of joint in pronation-supination axis
- Class IIIC - ectopic bone formation and ankylosis of joint in pronation-supination and flexion-extension axes
21
Q
What is the workup for the evaluation of HO?
[JBJS 2015;97:1101-11] [JOT 2012; 26(12): 684–688]
A
- History and physical examination (may be asymptomatic)
- Radiographs
- CT scan – preoperative planning
- MRI – preoperative planning if NV structures in close proximity
- Bone scan
* Can detect HO earlier
22
Q
What are the available HO prophylaxis methods?
[JBJS 2015;97:1101-11] [JOT 2012; 26(12): 684–688]
A
- NSAIDS
- Typically, indomethacin 25mg po TID for 6 weeks
- Disadvantages:
- Nonunion
- Patient noncompliance
- GI upset
- Radiation
- Typically single fraction dose 700-800cGy given 24 hours preop to 48-72 hours postop
- Disadvantages:
- Cost
- Malignancy risk
- Soft tissue contracture
- Delayed wound healing
- Nonunion
- Inhibited ingrowth of pressfit implants
23
Q
What is the indication for surgical management of HO?
[JBJS 2015;97:1101-11] [JOT 2012; 26(12): 684–688]
A
- Persistent symptomatic HO despite nonoperative management
- Others:
- Restricted range of motion (primary or secondary athrofibrosis or ankylosis)
- Pain
- Nerve entrapment
- Skin ulceration
- Difficulties with prosthesis fitting/use
24
Q
What is the workup and timing of HO excision?
[JBJS 2015;97:1101-11] [JOT 2012; 26(12): 684–688]
A
- Traditionally
* Delaying surgical intervention until alkaline phosphatase levels normalize and the heterotopic bone is mature on radiographs and quiescent on bone scan. - Contemporary
* Proceed once no further improvement with nonoperative management, fractures have healed and radiographs are stable- Rule out other causes of pain (nonunion, infection, arthritis, etc)
- Images should include:
- Radiographs
- CT with 3D recon
- +/- MRI if close to NV structures
- Generally, prophylactic radiation preferred
25
What are the principles and techniques to achieve a successful arthrodesis?
1. Optimize patient condition
* Address modifiable risk factors (smoking, malnutrition, diabetes control, vascular intervention, avoid NSAIDs)
2. Meticulous handling of soft tissue
3. Joint preparation
* Denude cartilage, expose bleeding subchondral bone
4. Obtain maximal bony contact
5. Bone graft as necessary
6. Select arthrodesis position
7. Obtain compression and rigid internal fixation
26
What are the causes of acute compartment syndrome?
[JAAOS 2005;13:436-444]
1. Fracture
2. Soft-tissue trauma without fracture
3. Intracompartmental bleeding
4. Tight casts, dressings or external wrappings
5. Thermal injury
6. Burn eschar
7. Extravasation of IV infusion
8. Venous obstruction
9. Reperfusion injury following prolonged ischemia
10. Penetrating trauma
27
What are the 6 P’s of compartment syndrome?
[JAAOS 2005;13:436-444]
1. Pain, pressure, pulselessness, paralysis, paresthesia, and pallor
* Pain out of proportion to the injury, aggravated by passive stretching of muscle groups in the corresponding compartment, is one of the earliest and most sensitive clinical signs of compartment syndrome
28
Intracompartmental pressure measurment thresholds for diagnosis include?
[J Am Acad Orthop Surg 2013;21:657-664]
1. Absolute pressure measurements ≥30mmHg
2. Pressure measurements within 30mmHg of the diastolic pressure
29
What is the appropriate management of arm compartment syndrome?
2 incision fasciotiomy
* Anterior and posterior compartment release through two separate midline longitudinal incisions
30
How many compartments are in the forearm?
[J Am Acad Orthop Surg 2011;19:49-58]
1. Three – volar, dorsal and mobile wad (volar is the most common compartment involved in the upper extremity)
31
What is the appropriate management of forearm compartment syndrome?
[J Am Acad Orthop Surg 2011;19:49-58]
1. First release the vdlar compartment – this often decompresses the dorsal compartment and mobile wad
2. Volar compartment release
* A. Longitudinal incision just radial to FCU – extends radially at the antecubital fossa curving up the lateral arm, extends to the midline at the wrist
* B. Release the transverse carpal ligament, lacertus fibrosis, and fascia over the deep muscles by retracting FCU ulnar and FDS radial
3. Dorsal compartment and mobile wad release
* A. Longitudinal incision starting 2cm distal to the lateral epicondyle extending to the midline of the wrist, deep dissection is between ECRB and EDC
32
How many compartments are in the hand?
[J Am Acad Orthop Surg 2011;19:49-58]
Ten
* 4 dorsal interossei
* 3 volar interossei
* adductor pollicis
* thenar
* hypothenar
33
What is the appropriate management of hand compartment syndrome?
[J Am Acad Orthop Surg 2011;19:49-58]
4 incision fasciotomy
* A.Dorsal longitudinal incisions over the 2nd and 4th metacarpal
* B.Longitudinal incisions at the junction of the glaborus and non-glaborus skin over the thenar and hypothenar eminences
34
How many compartments are in the thigh?
Three – anterior, posterior, medial
35
What is the appropriate management of thigh compartment syndrome?
Single incision fasciotomy
* A. Direct lateral extensile incision, fascia lata is incised in line with incision and vastus lateralis can be elevated to allow release of the posterior compartment
* B. Rarely a separate medial incision is needed to release the adductor compartment
36
What is the appropriate management of lower leg compartment syndrome?
[JBJS Essent Surg Tech. 2015 Dec 23; 5(4): e25.]
1. 2 incision fasciotomy (although 1 incision has been described through a single lateral incision)
* A. Anterolateral incision
* i. Longitudinal incision ~2cm anterior to the fibula centered over the anterior intermuscular septum approximately 15cm in length, elevate full thickness skin flaps ~2-3cm anterior and posterior
* ii. Release the anterior compartment with fascial incision ~1cm anterior to the intermuscular septum
* iii. Release the lateral compartment with fascial incision ~1cm posterior to the intermuscular septum
* iv. Structure at risk = superficial peroneal nerve
* B. Posteromedial incision
* i. Longitudinal incision ~2cm posterior to the medial border of the tibia approximately 15cm in length
* ii. Release the deep posterior compartment along the posterior border of the tibia
* iii. Release the soleus origin off the tibia (aka. Soleus bridge)
* iv. Release the superficial posterior compartment with a separate fascial incision ~2cm posterior to the incision for the deep posterior compartment
* v. Structure at risk = saphenous vein and nerve
37
How many compartments are in the foot?
The most accepted number is 9 [J Am Acad Orthop Surg 2013;21:657-664]
* Medial, lateral, superficial central, deep central (calcaneal), 4 interosseous, adductor hallucis compartment
38
What is appropriate management of foot compartment syndrome?
[J Am Acad Orthop Surg 2013;21:657-664]
1. Initial management
* Remove constrictive dressings, elevate foot, prevent systemic hypotension, serial exam and compartment pressure measurements
2. Definitive management once diagnosis established
* A. 3 incision fasciotomy
* i. Medial incision (6cm long, 4cm anterior to posterior heel and 3cm superior to plantar surface)
* ii. Two dorsal incisions (1st webspace and 4th webspace)
* B. Fix forefoot and midfoot fractures at time of fasciotomy, delay fixation of calcaneal fractures until soft tissues allow
* C. Dorsal incisions closure with split thickness skin grafts 5-7 days after fasciotomy
* D. Medial incision primary or delayed closure
39
Following a fasciotomy how are the wounds best managed?
[J Am Acad Orthop Surg 2011;19:49-58]
1. Do not close the wound, leave open with sterile wet-to-dry dressings
* Consider VAC or shoelace closure [CORR trauma]
2. ~48 hours later repeat irrigation and debridement and remove necrotic tissues
* A. Consider primary delayed closure at this time if no necrotic tissue, or split thickness skin graft if cannot be closed
* B. If necrotic tissue present perform I&D, leave wound open and return in ~48 hours for repeat I&D
3. If wound cannot be closed primarily consider vacuum-assisted wound closure – may allow primary closure later
* If cannot be closed primarily perform split thickness skin grafting
40
What are the general principles of tendon transfer?
[J Am Acad Orthop Surg 2013;21:675-684][ASSH Manual of Hand Surgery]
1. The donor tendon must be expendable (minimal loss of function)
2. The strength of the donor tendon decreases by one grade following transfer
* Donor muscles must have 5/5 or 4/5 strength
3. The tendon excursion of the donor must be sufficient to restore lost function of the recipient tendon
* Difficult for a muscle to replace one with greater excursion
* Excursion of muscles available to transfer:
* \*\*\*3-5-7 rule
* Wrist extensors and flexors = 30mm
* ECRL, ECRB, ECU, FCR, FCU
* Digital extensors = 50mm
* EDC, EIP, EDQ, EPL
* Digital flexors = 70mm
* FDS
4. The direction of pull of the recipient tendon should be in line with the donor
5. A single transferred tendon should perform a single function
6. Transferred tendon should cross only one joint
7. Tendon transfers should not be placed through heavily scarred soft-tissue planes (limits excursion)
* Allow scars to mature or pass through healthy tissue
8. The joints controlled by the transferred tendon should have near full passive ROM
9. Tendons with in-phase functions should be used preferentially
41
What is the recommended method of joining donor to recipient tendon in a tendon transfer?
[JAAOS 2013;21:675-684]
Pulvertaft weave
* Minimum of 3 weaves is recommended
* Slits in the recipient tendon are made at 90° to each other
* Mattress suture is made at each pass through the recipient tendon
42
What is the difference between a high and a low radial nerve palsy?
[JAAOS 2013;21:675-684]
1. High radial nerve palsy = injury proximal to elbow joint involving the radial nerve proper
* Motor deficits = inability to extend the wrist and fingers at the MCP joints
* Wrist drop and decreased grip strength
* Sensory deficits = increased two-point discrimination or complete anesthesia over the dorsum of the first web space
2. Low radial nerve palsy = injury distal to the elbow joint involving the PIN
* Motor deficits = inability to extend fingers at the MCP
* Wrist extension has substantial radial deviation
* ECRL functions but ECU is lost
* Sensory deficits = none
43
What are the tendon transfers for radial nerve palsy?
[JAAOS 2013;21:675-684]
1. Wrist extension – PT to ECRB
* ECRB preferred over ECRL as it is more central
2. Finger extension – FCR to EDC
* FCR routed either through the IOM or radially around forearm
3. Thumb extension – PL to EPL
* FCR of ring in absence of PL
44
What is the difference between a high and low median nerve palsy?
[JAAOS 2013;21:675-684]
1. High median nerve palsy = injury proximal to the elbow joint
* Motor deficits:
* Inability to flex thumb, DIP and PIP joints in index and middle finger
* Loss of thumb opposition
* Weakened forearm pronation
* Wrist flexion intact due to FCU
* Sensory deficits:
* Palmar surface of thumb, index, middle and radial half of ring finger
2. Low median nerve palsy = injury distal to the elbow joint
* Motor deficits = loss of thumb opposition (weak APB)
45
What are the tendon transfers for median nerve palsy?
[JAAOS 2013;21:675-684] [ASSH Manual of Hand Surgery]
1. Thumb opposition – opponensplasty = EIP/FDS ring/PL to APB (Bunnels)
* High median nerve – EIP
* Low median nerve – FDS ring
2. Thumb flexion – BR to FPL
3. Index/middle finger flexion – FDP ring and small to FDP index and middle side-to-side transfer
46
What is the difference between high and low ulnar nerve palsy?
1. High ulnar nerve palsy = injury proximally at the elbow
* Motor deficits = FCU, FDP of small and ring, intrinsics
* Clawing is less prominent due to loss of FDP of small and ring
* Sensory deficits = ulnar palm and small and ulnar half of ring
2. Low ulnar nerve palsy = injury at the wrist
* Motor deficits = intrinsic paralysis
* Clawing
* Pinch and grip weakness
* Lack of finger abduction/adduction
* Sensory deficits = small and ulnar half of ring
47
What are tendon transfers for ulnar nerve palsy?
[ASSH Manual of Hand Surgery]
1. Power pinch weakness – adductorplasty = ECRB with graft/(FDS long finger) to adductor pollicis
2. Clawing – FDS ring to lateral bands (radial bands of ring and small) OR (Zancolli procedure)
3. Index abduction – EIP to 1st dorsal interosseous
4. Loss of FDP 4/5 – Side-to-side ring/small FDP to index/middle FDP
48
Tendon transfers for musculocutaneous nerve palsy?
[ASSH Manual of Hand Surgery]
Elbow flexion
* Pectoralis major sternocostal head to biceps tendon
* Elongation with fascia lata autograft
* Latissimus dorsi to biceps tendon
* Steindler flexorplasty
* Flexor pronator mass transfer 5cm to anterior humeral shaft
* Triceps transfer to biceps tendon
49
What are tendon transfers for axillary nerve palsy?
[ASSH Manual of Hand Surgery]
Shoulder external rotation
* L’Episcipo procedure – latissimus dorsi and teres major transfer to posterolateral GT
* Latissimus dorsi transfer to GT (without teres major)
50
What are tendon transfers for tendon ruptures?
[AAOS Comprehensive Review, 2014]
Differs in that innervation is maintained to surrounding muscles so local/intracompartment transfers are possible
1. Extensor tendons
* EIP to EPL
* 3 incision technique (over 2nd MCP, radiocarpal joint and STT joint levels)
* End-to-side transfers of EDC tendons
2. Flexor tendons
* FDS ring to FPL (Mannerfelt)
51
What is the order of function loss and recovery in a peripheral nerve injury?
1. Order of loss:
* Motor
* Proprioception
* Touch
* Temperature
* Pain and sympathetic
2. Order of recovery = reverse (motor last to recover)
52
What are the nerve structures from deep to superficial?
* Axon
* Myelin
* Endoneurium
* Fascicle
* Perineurium
* Epineurium
53
What is Wallerian degeneration?
After transection of the axon the distal axon and myelin degenerates along with the proximal axonal segment to the next adjacent node of Ranvier
54
What are the classification systems for peripheral nerve injuries?
1.Seddon classification
* Neuropraxia = segmental myelin damage with an intact axon
* Coincides with Sunderland Type 1
* Axonotmesis = axonal injury where the connective tissue and nerve continuity remain intact
* Coincides with Sunderland Type 2-4
* Neurotmesis = complete physiological and anatomical transection of both axons and connective tissue
* Coincides with Sunderland Type 5
2. Sunderland classification (histological)
* Increasing grades based on the tissue injured
* Type 1 - local myelin damage usually secondary to compression
* Type 2 - loss of continuity of axons
* Endoneurium, perineurium, and epineurium intact
* Type 3 - loss of continuity of axons and endoneurium
* Perineurium and epineurium intact
* Type 4 - loss of continuity of axons, endoneurium and perineurium
* Epineurium intact
* Type 5 - complete physiologic disruption of entire nerve trunk
55
What is the timeline for functional recovery of a nerve injury?
1. Rate of axonal regeneration is 1mm/day
2. 12–18 month window for muscle reinnervation to occur in order to achieve functional recovery before irreversible motor end plate degeneration occurs
56
components of monolateral/unilateral ex-fix and how is the stability increased
*Monolateral/Unilateral External Fixation
* Components = pins, clamps, connecting rods
* Stability is increased by:
* Larger diameter half pins (most important)
* Increasing the number of pins
* Increasing pin spread in each fragment
* Minimize the pin-fracture site distance
* Minimize the bone-connecting rod distance
* Place pins out of plane to one another
* Adding an additional connecting bar in parallel (‘double stacking’)
* Increase the stiffness of the connecting rod (increase diameter, carbon fibre \> stainless \> titanium)
* Add a second unilateral fixator for multiplanar fixation
57
RF for nec fasc
1. DM
2. advanced age
3. obesity
4. multiple comorbidities
5. IVDU
6. smoking
7. trauma
8. prior mrsa infection
9. HIV/AIDS
10. NSAID use
11. exposure to person infected with Group A Strep
58
clinical presentaiton of nec fasc
1. pain out of proportion (most common)
2. skin chages
* may be absent early,
* early signs incl erythema, edema, swelling, induration
* late signs incl skin anaesthesia, crepitations (presence of gas), ecchymosis, bullae
59
what are hard signs of nec fasc that warrant surgical intervention
1. clinical decompensation
2. progression of infection despite broad antibiotic management
3. increasing serum lactate
4. CRP>150 mg/L
5. leukocytosis >25,000/mm3
60
recommended management of nec fasc
1. Surgical debridement
- a. Longitudinal incision over the nidus of infection (i..., entry site, site of abscess, site of original erythema/necrosis)
* i. Dual incisions required in the extremities
* ii. Incisions are extended proximally until uninvolved tissue is encountered
- b. Devitalized tissue should be removed in all affected layers (e.g., skin, subcutaneous fat, fascia, muscle, bone) until healthy tissue margins are reached
- c. Send multiple deep tissue cultures
- d. Wound dressed with moist gauze or VAC
- e. Repeat debridement is recommended within 24-48 hours
- f. Following recovery, wounds are closed primarily or skin/soft tissue grafts as required
- g. Amputation is indicated if rapid progression, limb is not salvageable, or condition of patient would not tolerate repeat debridement
2. Broad spectrum empiric antibiotics
a. Commonly piperacillin/tazobactam + clindamycin
b. Antibiotics can be tailored based on cultures by infectious disease team once available
3. Adjuncts (weak evidence)
a. IVIG
b. Hyperbaric oxygen
4. ICU resuscitation
