Septic osteitis and osteomyelitis

Question 1

Septic osteitis

Answer 1

1. Begins in periosteum

2. Involves cortical bone

Question 2

Osteomyelitis

Answer 2

1. Either begins in cancellous bone, or involves cancellous bone
2. Also involves cortical bone

Question 3

Important to distinguish between osteitis and osteomyelitis because

Answer 3

prognosis and treatment are very different

Question 4

Bone responds to infection and inflammation by

Answer 4

proliferation and/or

resorption

Question 5

Septic osteitis modes of infection

Answer 5

Primary-direct trauma

Secondary-extension of infection from adj tissues

Question 6

Pathogenesis of sequestrum

Answer 6

1. cortical bone loses blood supply and dies (outer 1/3)
2. inner 2/3 gets primary blood supply from endosteum
3. live bone gets separated from dead bone becomes sequestrum
4. Involucrum (shell of new bone) produced by periosteum to wall off sequestrum and infection
5. Cloaca or draining tract may develop
6. Absorption and extrusion is rare

Question 7

Two things necessary for a sequestrum to form

Answer 7

1. Infection

2. Loss of blood supply

Question 8

Radiographic signs osteitis/sequstrum

Answer 8

Early - soft tissue swelling

7-14 days - periosteal prolif, separation sequestrum

Question 9

Treatment of sequestrum

Answer 9

1. Surgical removal and curettage of bed
2. Resect infected granulation tissue and draining tract
3. Culture sequestrum or deep tissue
4. Skin grafts may help
5. ABX may not be necessary if complete debridement possible

Question 10

Sequestrum prognosis

Answer 10

Good, depending on tendon/ligament involvement

Question 11

Osteomyelitis definition

Answer 11

Infection and resulting inflammation/remodeling of bone involving periosteum, haversian and Vokmann’s canas PLUS MEDULLARY CAVITY

Question 12

Modes of infection osteomyelitis

Answer 12

1. Primary-direct trauma
2. Secondary-extension of infection from adj tissue
3. Tertiary-hematogenous

Question 13

Osteomyelitis foals

Answer 13

Usually hematogenous

Question 14

Osteomyelitis adults

Answer 14

1. hematogenous rare

2. Usually direct trauma, open fractures, infection closed fx repaired by internal fixation

Question 15

Pathogenesis hematogenous osteomyelitis

Answer 15

Pathogen lodges in metaphyseal region of long bone where endosteal vessels form terminal venous sinusoids near growth plate

• inflammation, prostaglandin release, thrombosis blood vessels
• necrosis and osteocytic death

Question 16

Most common organisms hematogenous osteomyelitis

Answer 16

1. E. Coli
2. Strep
3. Acinobacillus
4. Salmonella
5. Rhodococcus equi

Question 17

Systemic antibiotics in Osteomyelitis

Answer 17

Useless, won’t penetrate necrotic tissues

Question 18

Osteomyelitis assoc with wounds pathogens

Answer 18

1. E. Coli
2. Enterobacter
3. Proteus
4. Klebsiella
5. Streptococcus
6. Staphylococcus
7. Pseudomonas
8. Obligate anaerobes

Question 19

TX foal hematogenous osteomyelitis

Answer 19

1. Not ush presented early enough
2. broad spectrum abx (penicillin + aminoglycoside) 4-6 weeks
3. surgical curettage if growth plate/joint not involved

Question 20

Foals with multiple sites infection

Answer 20

Euthanasia usually indicated

Question 21

Osteomyelitis assoc fx repair

Answer 21

1. Stability most important, fx will heal in presence of infection
2. replating/ex fix maybe necessary, not very successful
3. Debride and drain necrotic/infected tissues
4. Remove implants not contributing to stability
5. Daily wound care
6. Cancellous graft after infection under control