Slipped Capital Femoral Epiphysis

Updated: Sep 29, 2023
  • Author: Kevin D Walter, MD, FAAP; Chief Editor: Craig C Young, MD  more...
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Overview

Practice Essentials

Slipped capital femoral epiphysis (SCFE) is one of the most important pediatric and adolescent hip disorders encountered in medical practice. [1, 2, 3, 4, 5]  Although SCFE is a rare condition, an accurate diagnosis combined with immediate treatment is critical. [6, 7]  Despite the fact that the underlying defect may be multifactorial (eg, mechanical and constitutional factors), SCFE represents a unique type of instability of the proximal femoral growth plate.

Signs and symptoms

Clinically, the patient may report hip pain, medial thigh pain, and/or knee pain; an acute or insidious onset of a limp; and decreased range of motion of the hip.

See Presentation for more detail.

Diagnosis

On plain radiographs, the femoral head is seen displaced, posteriorly and inferiorly in relation to the femoral neck and within the confines of the acetabulum. [8]  See the image below.

A Klein line is a line drawn along the superior bo A Klein line is a line drawn along the superior border of the femoral neck that would normally pass through a portion of the femoral head. If not, slipped capital femoral epiphysis is diagnosed.

See Workup for more detail.

Management

Treatment is primarily operative internal fixation. The goal is to prevent complications such as avascular necrosis (AVN). [2, 9, 10, 11, 12]  See the image below.

X-ray of a hip following operative percutaneous fi X-ray of a hip following operative percutaneous fixation of a slipped capital femoral epiphysis.

See Treatment and Medication for more detail.

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Epidemiology

United States statistics

The overall incidence for SCFE in the United States is 10.8 cases per 100,000 children. [13] The incidence rate in boys (13.35 per 100,000) is higher than in girls (8.07 per 100,000). When compared with White children, Black children have a higher incidence rate at 3.94 times, and Hispanic children have a 2.54 times higher incidence rate.

Rates of SCFE per 100,000 children are higher in the Northeast (17.15) and West (12.70) than in the Midwest (7.69) and South (8.12). [14] Evidence also points to a seasonal variation in SCFE occurrence. In areas north of 40º latitude, 57.4% of SCFEs occurred during the summer, whereas in areas south of 40º latitude, 57.3% of SCFEs occurred during the winter months. [13]  A study by Loder et al reported new seasonal variation findings in 10,350 cases of slipped capital femoral epiphysis. The study found a peak in August/September in both the Southern and Northern US with a second peak in March/April found only in the Southern US. Areas with more seasonal variability in temperature, humidity and sunlight were more likely to have greater variability. [15]  

SCFE mainly occurs between the ages of 10 and 16 years. [1, 13] A slight downward trend has occurred for average ages over several years, with some data finding the average age for boys at 12.7 years and girls at 11.2 years. This change could be due to the phenomenon of children maturing at a younger age. [16]

In general, about 20% of patients have bilateral involvement at the time of presentation. It is felt that an additional 20-40% will subsequently progress to bilateral slips. When the presentation is sequential, the second hip usually presents within 18 months of the first SCFE. [17, 18]

The risk of SCFE is increased in children who are obese, as well as in children with other medical issues such as hypothyroidism, low growth hormone level, pituitary tumors, craniopharyngioma, Down syndrome, renal osteodystrophy, and adiposogenital syndrome.

In a study by Benson et al, the investigators reexamined the incidence of SCFE in New Mexico (previous studies had reported almost a 5-fold lower incidence of SCFE in New Mexico compared with Connecticut). The discharge databases for the 11 major medical centers in New Mexico from 1995 to 2006 were analyzed by comparison with the 2000 New Mexico census data. The incidence data are reported as cases per 100,000 boys aged 10-17 years and girls aged 8-15 years, as per the earlier study data. [19]

The investigators found an incidence rate of SCFE in New Mexico for the study period was 5.99, which was a statistically significant change that was more than double the reported incidence in the 1960s (2.13). Obesity was noted as a patient factor that changed since 1971 (tripled), although the national incidence of SCFE appeared to have remained fairly constant at 10.8 per 100,000. Benson et al theorized that "increased obesity in children and improved access to pediatric orthopaedic evaluation may have contributed to a significant increase in reported incidence of SCFE in New Mexico." [19]

A retrospective review by Loder et al found that SCFE was associated with a sporting activity in 33% of the children in the study. The most common sport was basketball, followed by football and baseball/softball. [20]

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Functional Anatomy

SCFE results from a Salter-Harris type physeal fracture. In patients with SCFE, the epiphyseal growth plate is unusually widened, primarily due to expansion of the zone of hypertrophy. The hypertrophic zone, which constitutes 15-30% of the normal physis, can account for up to 80% of the width of the physeal plate in affected patients. Histologically, abnormal cartilage maturation, endochondral ossification, and perichondral ring instability occur. This leads to less organization of the normal cartilaginous columnar architecture. Slippage occurs through this weakened area.

The position of the proximal physis normally changes from horizontal to oblique during preadolescence and adolescence, redirecting hip forces from compression forces to shear forces. There is an association between femoral neck retroversion and a reduced neck-shaft angle with SCFE. These changes can increase the shear forces across the hip, leading to SCFE. [21] Other concomitant findings in the hip include inflammatory synovitis and disorganized collagen fibrils with accumulations of proteoglycans and glycoproteins within the growth plate; however, whether these changes are a cause or a result of SCFE remains undetermined.

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Prognosis

Most patients with SCFE who are treated with urgent in situ fixation do well. However, in those cases with severe slippage and resultant deformity, long-term sequelae may result (eg, AVN, chondrolysis, leg-length discrepancy, stiffness, osteoarthritis). Although conservative modalities (eg, therapy, analgesics, orthotics, assistive aids) are used initially for symptomatic relief, urgent operative intervention is indicated. Young patients with unremitting pain, loss of motion, and stiffness secondary to chondrolysis, AVN, or osteoarthritis may require salvage hip arthrodeses. In hips that are incompletely damaged, proximal osteotomies may aid in redirecting the joint forces to less damaged areas of the articular femoral head.

Complications

Untreated SCFE may result in progressive deformity and pain, destabilization of the femoral epiphysis, and decreased range of motion of the hip joint.

AVN of the femoral head is thought to result from vascular damage during the time of the initial traumatic event, but it may result from forceful reduction during the time of surgery. The amount of energy, magnitude of epiphyseal damage and displacement, level of increased intra-articular pressure, and degree of vascular occlusion have been implicated in this process. The risk of AVN is up to 47% with an unstable SCFE. Treatment options are limited (eg, bone grafting, osteotomy to change the position of the femoral head), but often these patients will eventually need a total hip replacement.

Chondrolysis is the destruction of articular cartilage, which can cause joint space narrowing. Intra-articular penetration of hardware and violation of the joint has been associated with chondrolysis. It is believed to occur irrespective of the method of treatment; however, chondrolysis has occurred in patients who have not undergone any treatment.

Osteoarthritis is a late complication. There is evidence that increased risk of early degenerative change may result from AVN, chondrolysis, or alterations of the hip biomechanics following slippage. In general, the more severe the deformity and/or SCFE, the higher risk of developing arthritis. Mild deformities may have few consequences.

Leg-length inequality may result from incomplete reduction, AVN, chondrolysis, or secondary coxa vara.

Hardware failure and "outgrowing" hardware may cause loss of fixation. Although rare, postoperative infection may occur.

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