Slipped capital femoral epiphysis (SCFE) is a condition which affects mostly obese children in their prepubertal years.
It is generally not preceded by any trauma to the hip, though a minority of cases are an acute sequel to a fall or minor injury.
SCFE in Children
In children, it is thought that a combination of physiological weakness of the growth plate in the proximal femur and excessive mechanical loading are responsible for the SCFE. It occurs invariably before the growth plate closes, between 10-14 years in girls and 12-16 years in boys.
The risk factors for SCFE in children are linked to reduced shear resistance and increased mechanical stress on the growth plate, and include:
- Obesity: About 80% of children who develop SCFE are obese, with body mass indexes over the 95th percentile. Obesity can lead to SCFE via multiple mechanisms, including increased load on the growth plate, a more retroverted femur than normal, and a more vertical growth plate than normal, coupled with the rapid increase in height and weight around this age. Bone remodeling that normally occurs during this period may also lead to skeletal weakness. Other coexisting metabolic or endocrine disturbances contribute to the excessive body weight and to the reduced bone strength.
- Metabolic disorders: SCFE is more common in children with hypothyroidism and diabetes, as well as the rare panhypopituitary disorders. Renal osteodystrophy is another predisposing condition.
- Femoral retroversion: A femur which is retroverted, or twisted more laterally than normal, is more likely to undergo SCFE than a normal femur.
- Ethnic factors: SCFE is almost 4 times more common in African-Americans, and more than 2.5 times more common in Hispanics, than in Caucasian children.
- Medication: Certain drugs including inhaled corticosteroids may adversely affect bone health and may lead to slippage of the epiphysis.
- Radiation: Radiotherapy can increase the risk of SCFE due to bone dysplasia.
- Metabolic conditions: Children with hypothyroidism or with diabetes mellitus are at greater risk for SCFE. Renal failure with osteodystrophy can also predispose to this condition. A metabolic cause may be sought if the child with SCFE is less than 10 years old, or has a body weight which is below the 50th percentile.
- Trauma: The unstable form of SCFE , when the individual is unable to put any weight on the affected hip, is often preceded by a fall or minor injury which may not seem to be very severe.
- Family history: Having other family members who had SCFE may increase a person’s risk of developing the condition.
- Climatic and seasonal factors: One study has also suggested that there is seasonal variation in the incidence, with a rise in cases north 40 degrees latitude during the summer and south of this line during the winter. Geographically, the northeastern and western parts of the USA have a higher incidence than the midwestern and southern states.
In children, the left hip is affected more often than the right. The contralateral hip is affected within 18 months of the first in 40% of younger children with this condition (below the age of 10 years). Treatment involves pinning the femoral head through the growth plate.
SCFE in Adults
SCFE in adults is rare with only a handful of cases having been published so far. Most are sporadic but a few seem to show a familial inheritance. In adult SCFE, growth hormone deficiency leading to prolonged growth plate persistence seems to be a common factor.
These patients may have hypogonadotropic hypogonadism and a eunuchoid constitution, with long arms and legs as a result of an excessive period of growth at the epiphyses of the long bones. The growth plate fuses in the third decade instead of the second in this case.
The pituitary deficiency is occasionally iatrogenic, such as following the excision of a benign pituitary tumor without pituitary hormone replacement. It is necessary to consider the differential diagnosis of endocrinopathies, in order to initiate and continue appropriate hormonal management in addition to surgical fixation of the hip by in situ pinning or other techniques as indicated. A dult patients were found to have the following associated endocrine disorders :
- Pituitary microadenoma
- Post-irradiation hypoestrogenism