Delayed Bone Healing

Question 1

What are the 4 major open fracture fixation types?

Answer 1

1. external coaptation - no wound access
2. IM pin/interlocking nail - spreads contamination
3. external fixator - preserves blood supply, no implant at fracture site, access to wound
4. bone plate

Question 2

What are degloving injuries? What are the 2 types?

Answer 2

result of shearing forces that severe cutaneous vessels supplying the skin

1. PHYSIOLOGIC - skin devitalized, but still in place
2. ANATOMIC - skin avulsed from underlying tissue

Question 3

Physiologic degloving:

Answer 3

• skin devitalized, but still in place
• if left untreated, the skin is a harbor of major contamination

Question 4

Anatomic degloving:

Answer 4

• skin avulsed from underlying tissue
• want to support degranulation tissue for functional ankylosis to maintain ability to walk

Question 5

What is the main concern with missile wounds?

Answer 5

increased soft tissue trauma underneath small entrance wound due to vibration of bullets

Question 6

What is osteomyelitis?

Answer 6

inflammation of bone marrow, cortex, and periosteum, usually secondary to bacterial infection (also fungal or mixed infections)

• biopsy: fungal hyphae
• culture: bacteria

Question 7

What are the most common monomicrobial, polymicrobial, and anaerobic infections isolated from osteomyelitis?

Answer 7

MONO - Staphylococcus intermedius or aureus

POLY - Streptococcus, Proteus, E. coli, Klebsiella

ANAEROBIC - Actinomyces, Clostridium, Bacteroides

Question 8

What are the 4 causes of osteomyelitis?

Answer 8

1. iatrogenic surgical inoculation/contamination
2. open fracture
3. hematogenous spread - septic translocation from GIT to the metaphyseal region (Parvo puppies)
4. extension from adjacent soft tissue infection

Question 9

What 4 factors are required for iatrogenic osteomyelitis development?

Answer 9

1. inoculum of pathogenic bacterial in sufficient numbers, typically from FB that potentiate infection
2. soft tissue damage - hematoma, lack of blood supply
3. formation of biofilm (glycocalyx)
4. unstable repair

Question 10

What is bioflim?

Answer 10

combination of bacterial slime and host cellular debris that acts to promote bacterial adherence and protects bacteria from phagocytosis, host antibodies, and antibiotics

• reservoir for infection!

Question 11

When is hematogenous osteomyelitis most common?

Answer 11

• immature dogs
• metaphysis of long bone
• fracture sites

Question 12

What are the 5 most common acute findings on physical/laboratory exams with osteomyelitis?

Answer 12

1. pain on palpation
2. swollen and inflamed soft tissues
3. pyrexia, anorexia, lethargy
4. d/c from sinus tracts
5. neutrophilia with left shift

Question 13

What are the 2 most common radiographic findings in the acute phase of osteomyelitis?

Answer 13

1. soft tissue swelling
2. gas shadows if gas-producing bacteria present

Question 14

What are the 6 most common physical exam findings in the chronic stage of osteomyelitis?

Answer 14

1. lameness
2. d/c from sinus tracts
3. pain on deep palpation of bone
4. disuse muscle atrophy
5. intermittent soft tissue swelling
6. instability at fracture site

Question 15

What are the 2 types of draining tracts?

Answer 15

1. SINUS - communication between mesothelial surface and skin, often associated with FB migration
2. FISTULA - communication between 2 epithelial surfaces (e.g. tracheoesophageal fistula)

Question 16

What is the most common cause of sinus tracts? What is required for complete healing?

Answer 16

plant material FB (grass awns, small twigs) that are swallowed, inhaled, or penetrates skin and migrates significant distances which creates a draining tract lined by granulation tissue

“pseudo” heals with antibiotic treatment, but requires FB removal (excision of tract not necessary if FB is removed!)

Question 17

What are the 5 most common radiographic findings seen in the chronic stage (2+ weeks) of osteomyelitits?

Answer 17

1. bone lysis and sclerosis in cortex and medullary cavity
2. periosteal new bone in lamellar pattern oriented perpendicular to bone in a sunburst, columnar, or radial appearance
3. cortical thinning
4. sequestrum and involucrum formation
5. delayed fracture healing or nonunion

Question 18

What surgical and medical treatments are used for osteomyelitis?

Answer 18

debridement to remove all devitalized bone and soft tissue and provide drainage or stabilization of fracture, if needed

prolonged antibiotic therapy based on culture and sensitivity

Question 19

What is important to limit the spread of osteomyelitis? What can be done to make it easier?

Answer 19

early aggressive removal of all necrotic bone and soft tissue

injection of 2/5 methylene blue into sinus tract 24 hours before surgery

Question 20

What is an involucrum? Sequestrum?

Answer 20

layer of living bone formed around dead bone

necrotic bone separated from living bone

Question 21

How is osteomyelitis treated when large amounts of discharge is present?

Answer 21

treat as an open wound

• pack with dilute Nolvsan swabs, cover with sterile dressing
• change swabs daily under heavy sedation
• once discharge resolves, close or allow to heal by second intention

Question 22

How are infected, unstable fractures treated?

Answer 22

replace or supplement implants with external fixators or bone plates that will be removed following fracture union to resolve infection (can add a bone graft!)

(don’t remove any stable implants!)

Question 23

What is the prognosis of osteomyelitis?

Answer 23

• conservative treatment = guarded, creates highly resistant organisms
• surgical treatment, removal of sequestra and infected tissue = good

Question 24

What treatment is used for hematogenous osteomyelitis?

Answer 24

• prolonged course of antibiotics or antifungals
• remove sequestra (may solve infection!)
• exercise restriction
• surgical curettage in recalcitrant cases or discospondylitis or focal osteomyelitis

Question 25

What is fracture-associated sarcoma? What 2 things are they most commonly associated with? In what bone is it most common?

Answer 25

highly malignant tumors that occur at sites of previous fractures (avg lag time of 6 years) 1. internal fixation 2. complicated fractures or fracture healing diaphysis of femur

Question 26

What is fracture disease? What are the 4 most common conditions?

Answer 26

complications that limit the use of limb, often after the fracture has healed (secondary to immobilization) 1. quadriceps and flexor tendon contracture 2. muscle atrophy and disuse osteoporosis 3. articular and periarticular changes 4. growth disturbances

Question 27

How can fracture disease be prevented?

Answer 27

- chose means to repair conducive to early ambulation - passive ROM exercises (NO RUNNING OR JUMPING) - hydrotherapy - strengthening of weak opponent muscle

Question 28

What treatment can be used for fracture disease?

Answer 28

- physical therapy - NSAIDs prevention is important - reversal of severe problems is unlikely

Question 29

What are pathological fractures? What are 3 common causes?

Answer 29

fracture without excessive trauma as a result of pre-existing bone disease 1. neoplasia 2. osteomyelitis 3. secondary hyperparathyoidism

Question 30

How are the causes of pathological fractures typically treated?

Answer 30

- neoplasia: amputation or limb salvage - osteomyelitis: rigid fixation, treatment of infection - secondary hyperparathyroidism: correction of endocrine or nutrition conditions, corrective osteotomy after bone has improved

Question 31

What kind of fractures may need amputations for repair?

Answer 31

Type III open fractures

Question 32

In what 2 situations is arthrodesis indicated?

Answer 32

1. severe fractures of the carpal and tarsal bones 2. chronic pain and instability of other joints