Physeal Dysplasia with Slipped Capital Femoral Epiphysis
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- Slipped capital femoral epiphysis seen in dogs, foals and calves
- Associated with severe trauma
- Pigs – manifestation of osteochondrosis with only minimal trauma required
- Most common type of physeal fracture in small animals and the proximal femur is the most common site
- In horses, physeal dysplasia is synonymus with physitis
More about Physeal dysplasia
- Also seen in the coypu with minimal trauma
- Femoral head physes contribute 30-40% of longitudinal growth of the femur in small animals
- Slipped epiphysis -> Salter-Harris type I where only the physis is involved
- Most common type of physeal fracture in small animals and the proximal femur is the most common site
- In traumatic cases, the fracture crosses through mutiple zones of the physis, with chondrocytes maintaining their linear arrangement on both sides of the fracture site for 1-4d following trauma
- Slipped capital femoral epiphysis – seen in humans, mainly adolescent boys, autosominal dominant with variable penetrance
In cats:
- [Physeal dysplasia with slipped capital femoral epiphysis in 13 cats. Craig LE. Vet Path (2001) 38 92-7]
- Age 12-21months
- 90% males
- Often obese, lots of Siamese cats
- Normal growth plates close at 7-9mths so these physes should have been closed
- Histology – physeal dysplasia with persistence of an open, disorganized growth plate
- Wide physis, necrotic cartilage at the cleavage site
- Irregular clusters of chondrocytes separated by abundant chondroid matrix. Similar lesions in femoral neck.
- No necrosis of the femoral head, although there is usually a small areas of peripheral attachment at the perichondral fibrocartilagenous complex – could provide some vacularization **The ligamentum teres provides no blood supply to the femoral head
- Clusters of chondrocytes present on either side of the cleavage site
- Differs from osteochondrosis by:
- More diffuse affecting the whole physis (in OC – focal failure of endochondral ossification)
- Chondrocytes are arranged in disorganized clusters rather than parallel rows
- The cat breeds have not been selected for rapid growth
- Insulin may have a role to play – most of the cats were obese....Similar deal to horse osteochondrosis