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Physeal Dysplasia with Slipped Capital Femoral Epiphysis in Cats. James Montgomery, DVM September 22, 2008. Femoral capital physeal fractures. Trauma is the most common cause Most frequently in cats between 4 and 11 months Highest incidence in cats 6 to 9 months Treatment Conservative
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Physeal Dysplasia with Slipped Capital Femoral Epiphysis in Cats James Montgomery, DVM September 22, 2008
Femoral capital physeal fractures • Trauma is the most common cause • Most frequently in cats between 4 and 11 months • Highest incidence in cats 6 to 9 months • Treatment • Conservative • Surgical • Femoral head excision • Surgical reduction and stabilization with multiple pins • Physis typically closes between 30 and 40 weeks of age in cats
Spontaneous capital physeal fractures • No history of trauma • Common presenting complaints • Lameness • Weakness • Decreased ability to jump • Common physical exam findings • Pain • Crepitus during flexion and extension of the hip • Muscle atrophy (less common)
Spontaneous capital physeal fractures • Diagnosis may be challenging • Acute fractures • Minimal displacement • Chronic fractures with substantial metaphyseal osteolysis and sclerosis • Serial radiographs may be required • In children, ultrasonography can be used to diagnose acute slippage of the capital femoral epiphysis • Open leg lateral and frog leg views beneficial
Spontaneous capital physeal fractures • More likely to be overweight, neutered males with delayed physeal closure • Radiographic abnormalities: • Salter Harris Type I • Variable degrees of fragment displacement • Osteolysis • Sclerosis • More severe changes in cats with more chronic fractures • Many cats are affected bilaterally (5 of 13 in Craig study) McNicholas, et al. JAVMA, 2002
Histology • Growth plate thicker than normal • Loss of characteristic zonal stratification • Chondrocytes lack normal columnar arrangement • Grouped in clusters • Randomly interspersed within the physis • Also a feature of normally closing physes • Normal metaphyseal bone interspersed with fibrous tissue and necrotic tissue • More prominent in cats with chronic fractures McNicholas, et al. JAVMA, 2002
Risk factors • Sex • Reproductive status • Delayed physeal closure • Abnormally high body weight
Risk factors • McNicholas study (JAVMA 2002): • 25 of 26 cats male • All 26 neutered • 14 of 16 cats (those for which neutering age was recorded) were neutered at < 6 months of age • All had at least 1 radiographically open physis • Mean age of cats in study was 94.5 weeks • Hypothesize hypotestosteronism leads to delayed closure of the capital physeal growth plate • Increased exposure to cyclic shear forces
Risk factors • Craig study -13 cats (Vet Pathol 2001) • 85% male • Average age 16.3 months (range 4.5 – 24 months) • 9 of 10 cats (for which weights were available) were overweight or obese • 23% were Siamese • Significantly greater than the percentage of Siamese in the control population (5%; 662/13,250)
Slipped capital femoral epiphysis (SCFE) • Well-described entity in humans • Pathogenesis poorly understood • Primarily affects overweight adolescent boys • 13 years old on average • Male to female ratio ranges from 2:1 to 4:1 • Onset is atraumatic and often insidious • 21% to 80% of reported cases are bilateral • Undiagnosed cases are thought to be a frequent cause of DJD in later life
Slipped capital femoral epiphysis (SCFE) • Good correlation between human syndrome and feline syndrome • A genetic etiology is supported • Male predominance • Siamese cats (Craig) • Endocrine disorders possibly contribute • Unclear if obesity is a symptom of underlying endocrine disorder or related to gonadectomy • Hypothyroidism and growth hormone deficiency diagnosed most commonly in humans with SCFE • No cats had signs of endocrine imbalance other than obesity (Craig)
References Craig LE. Physeal dysplasia with slipped capital femoral epiphysis in 13 cats. Vet Pathol 2001;38:92-7. Fischer HR, Norton J, Kobluk CN, et al. Surgical reduction and stabilization for repair of femoral capital physeal fractures in cats: 13 cases (1998-2002). J Am Vet Med Assoc 2004;224:1478-82. McNicholas WT Jr, Wilkens BE, Blevins WE, et al. Spontaneous femoral capital physeal fractures in adult cats: 26 cases (1996-2001). J Am Vet Med Assoc 2002;221:1731-6.