Fracture Complications

Question 1

list potential fx complications

Answer 1

1. Delayed unions
2. Nonunion
3. Malunion
4. Osteomyelitis
5. Implant Failure
6. Fracture Disease
7. Implant/Fracture associated neoplasia

Question 2

Local factors of fx healing

Answer 2

1. Instability
2. Vascular impairment
3. Infection
4. Open fractures

Question 3

Systemic factors of fx healing

Answer 3

1. Old age
2. Significant concurrent disease/injury
3. Poor nutrition
4. Delayed return to function
5. Unrestricted exercise

Question 4

when is vascular supply deemed poor

Answer 4

• poor pre-existing muscle (distal tibia/radius)
• high energy comminuted/open fxs
• sx trauma/approach high

Question 5

define strain

Answer 5

% of how much a fx fragment moves on weight-bearing compared to the size of the fx gap

Question 6

amount of strain tolerated by bone tissue

Answer 6

<2%

Question 7

a highly unstable fx w/ good blood supply =

Answer 7

large callus formation

Question 8

tx of a well aligned and stable delayed union

Answer 8

give time and monitor w/ q4wkly rads

if suspect osteomyelitis –> C&S –> infected but stable = tx w/ ABs from C&S

Question 9

tx of unstable delayed union

Answer 9

• remove implants - realign and stabilise
• C&S of implants
  +/- cancellous bone graft

Question 10

tx of unstable and infected delayed union

Answer 10

• remove implants –> C&S –> longterm ABs
• 1-5L warm saline lavage
• realign + stabilise
  + cancellous bone graft

Question 11

two types of non-unions

Answer 11

1. Viable (hypervasc) non-union

2. Non-viable (avasc.) non-union

Question 12

rad appearance of hypervasc. non-union

Answer 12

abundant mineralised non-bridging callus w/ a radiolucent line separating the proximal and distal parts

Question 13

tx of hypervasc non-union

Answer 13

caused by fx instability

–> remove implants (C&S) –> replace w/ rigid fixation (plates) + lavage like hell

Question 14

rad appearance of non-viable non-union

Answer 14

Significant bone resorption @ fragment ends and no evidence of bone xn.
The bone ends are sclerotic and there is typically complete closure of the medullary canal w/ cortical bone.
Osteoporosis of the bone usu. apparent
+/- sequestra

Question 15

tx of non-viable non-union

Answer 15

1. Aggressive resection of the fibrous tissue and debridement of the fragment ends to open the medullary canal.
2. Any necrotic bone or bone w/ no soft tissue attachment should be removed and submitted for C&S in addition to implants that are removed.
3. Rigid stabilisation w/ bone plate
4. Cancellous bone graft!!! (after 1-5L lavage) *can delay if site obviously infected

Question 16

5 types of malunion

Answer 16

• overriding
• angular
• rotational
• distracted
• intra-articular

Question 17

indications to tx malunion

Answer 17

if signif. functional impairment exists/will exist

Question 18

tx of malunion

Answer 18

1. Osteotomy
2. Debridement
3. Realignment
4. Stable fixation
5. Cancellous bone graft

Question 19

2 main causes of osteomyelitis

Answer 19

endogenous (haematogenous) or exogenous

Question 20

polyostotic, metaphyseal osteomyelitis in a 9month old collie is most likely…

Answer 20

haematogenous origin

Question 21

define sequestrum

Answer 21

a piece of avascular bone separated from the surrounding living tissue. The sequestrum serves as a nidus for chronic infection - ideal for anaerobes.

Question 22

define involucrum

Answer 22

highly vascular new bone which walls off a sequestrum. the involucrum isolates infection but limits ABs and immune system access

Question 23

tx of osteomyelitis

Answer 23

empirical amoxicillin/clav whilst waiting for C&S –> ABs for 4wks (acute)/ 6-8wks (chronic) and reassess

Question 24

rad signs of osteomyelitis

Answer 24

only obvious 3wks after infection –> lysis + new bone production at the metaphysis

Question 25

methods of obtaining a sample to C&S with suspect osteomyelitis

Answer 25

- remove implants - FNA - swab of infect bone - Jamshidi biopsy needle

Question 26

approach to suspect acute exogenous osteomyelitis

Answer 26

1. If animal initially improves w/ respect to weight-bearing after sx and then lameness increases after 5-7days 2. --> take rads to rule out early implant failure 3. --> deep tissue C&S + empirical ABs (amoxicillin/clav) 4. --> implant replacement if unstable + analgesia 5. Monitor for resolution of pyrexia and inc. weight-bearing on C&S ABs

Question 27

a draining sinus tract that temporarily heals (spont/ABs) and then breaks out again is a hallmark of.....

Answer 27

chronic osteomyelitis

Question 28

why is it useless to culture a draining sinus tract?

Answer 28

full of opportunistic polymicrobes and the causative agent is rarely IDed

Question 29

if suspect chronic osteomyelitis you send a deep tissue sample for what cultures?

Answer 29

- aerobic - anaerobic - fungal

Question 30

3 factors to result in a sequstrum

Answer 30

Bacterial contam + avasc. fx fragment + high strain environment

Question 31

rule of thumb = if there are more than 3 fragments use...

Answer 31

biologic/bridging osteosynthesis approach w/ open but do not touch sx repair approach

Question 32

most common pathogen of osteomyelitis

Answer 32

B-lactamase producing Staph. intermedius and aureus

Question 33

other pathogens of osteomyelitis

Answer 33

E.coli, Pseudomonas, Strep, Proteus

Question 34

anticipated healing time of infected non-unions =

Answer 34

3-6months

Question 35

suitable options to stabilise an infected non-union fx

Answer 35

- plate | - interlocking nail

Question 36

chronic osteomyelitis req. AB for what time frame?

Answer 36

6-8wks minimum

Question 37

4 factors involved in exogenous osteomyelitis development

Answer 37

1. bacteria: number/type 2. Extent of soft tissue damage + impaired blood supply 3. Stability of fx repair 4. Formation of a biofilm (glycocalyx) over implants

Question 38

biofilms do what for bacteria

Answer 38

- facilitate bacterial adhesions to implants | - protects bacteria from phagocytes, antibodies and ABs

Question 39

how do you avoid chronic fatigue implant failure?

Answer 39

always use fracture assessment + planning

Question 40

Why does femoral fx repair by retrograde IM pin placement cause disuse atrophy?

Answer 40

the pin cannot be cut level w/ greater trochanter thus irritates the gluteal muscles/forms a fibrous seroma --> dog uses leg less

Question 41

3 types of fracture dz

Answer 41

1. Disuse atrophy 2. Adhesions/contractions 3. Joint disease

Question 42

how do you prevent fracture dz?

Answer 42

- physio - analgesia - minimising surgical trauma (Halsted's principles) - rigidly stable fixation of fxs

Question 43

when should you recommend removal of implants following fx healing?

Answer 43

1. Grade 2-3 open fxs | 2. Osteomyelitis