Slipped Capital Femoral Epiphysis
Last updated: October 31, 2014
ICD-9 Code: 732.2.
ICD-10 Code: M93.011
Definition: Slipped capital femoral epiphysis is the most common disorder of the hip in adolescents.
Etiology: Etiology is unknown. Slipped capital femoral epiphysis rarely occurs as a result of trauma. It occurs in either obese adolescents and those with skeletal maturational delay or a recent growth surge. For these reasons, slipped capital femoral epiphysis is postulated to be a consequence of growth-related hormonal change. Abnormalities of growth hormone, thyroid, pituitary, or sex hormones may alter the rate of skeletal growth, especially in the capital femoral epiphysis. Slipped capital femoral epiphysis can also occur as a complication of an underlying endocrine disorder such as hypothyroidism, pituitary disorders, and pseudohypoparathyroidism.
Pathogenesis: The hip is a ball-and-socket (femoral head and acetabulum) joint. The capital femoral epiphysis makes up most of the head. The growth and development of the acetabulum and femoral head are interdependent. Disproportionate changes in skeletal growth may lead to slippage in the weakest area of the physeal plate.
Demographics: Peak onset age is 12 to 15 years, with boys affected two to five times more frequently than girls. The incidence is 0.7 to 3.4 cases per 100,000 per year.
Cardinal Findings: Patients may have little or no pain and few physical findings. Slips are more common during adolescent growth, especially in obese children. Symptoms of pain in the hip, thigh, or knee (referred pain) are seen in less than half of patients. If the child cannot walk or bear weight, the slipped capital femoral epiphysis is said to be unstable. Stable slipped capital femoral epiphysis is more likely to be minimally symptomatic. In the unstable slipped capital femoral epiphysis, the physical examination is limited as a result of severe pain with any attempted hip motion. In a stable slipped capital femoral epiphysis, the patient may have an antalgic gait. Hip range of motion often demonstrates a lack of internal rotation and increased external rotation. Also because the hip is flexed, it becomes progressively externally rotated.
Complications: Slipped capital femoral epiphysis may be complicated by osteonecrosis and chondrolysis. Osteonecrosis or avascular necrosis occurs as a result of trauma to the retinacular vessels. Chondrolysis results in degeneration of the articular cartilage of the hip.
Diagnostic Tests: If indicated by history or examination, tests for an endocrinopathy may be needed.
Imaging: The earliest radiographic finding in slipped capital femoral epiphysis is widening and blurring of the femoral epiphysis. This is followed by slipping of the capital femoral epiphysis with resultant posteroinferior tilt of the femoral head in relation to the femur. This is best seen in lateral views. The femoral neck may rotate anteriorly, resulting in a varus deformity of the femoral head and neck. With unstable or advanced slipped capital femoral epiphysis, remodeling of the femoral head ensues. Scintigraphy is helpful in identifying ischemia and risk of osteonecrosis, especially in unstable slipped capital femoral epiphysis. However, MRI is superior to other modalities in demonstrating early changes and late complications.
Keys to Diagnosis: Adolescents, especially those who are obese, with non- traumatic anterior thigh or knee pain (referred pain), should be carefully evaluated for a slipped capital femoral epiphysis. If slipped capital femoral epiphysis occurs before puberty, an endocrine disorder (hypothyroidism, growth hormone deficiency) should be suspected.
Differential Diagnosis: Legg-Calvé-Perthes disease, fractures, osteonecrosis, overuse, osteomyelitis.
Therapy: The goals of treatment for slipped capital femoral epiphysis are to prevent further slippage and minimize complications. This is accomplished with surgical or interventional in situ pinning to stabilize the capital femoral epiphysis. Screw removal after capital femoral epiphysis closure is controversial. Advanced cases may also require rotational osteotomy as well.
BIBLIOGRAPHY
Lindsley CB, Asher MA, Olney BW. Legg-Perthes and other hip diseases in children. In: Hochberg MC, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh: Mosby,2003;990–992.
