Idiopathic Slipped Capital Femoral Epiphysis: Demographic Differences and Similarities between Stable, Unstable, and Valgus Types

Abstract

Idiopathic slipped capital femoral epiphysis (SCFE) is a known disorder in pre/adolescent children with vague hip/knee pain. We wished to study the demographic differences between stable varus, unstable varus, and valgus idiopathic SCFEs using a retrospective review over a 10-year period of SCFE children seen at a tertiary children's hospital. Standard demographic data was collected, and radiographs were measured to determine the Southwick angle and status of the tri-radiate cartilage. There were 190 patients; 138 had stable varus SCFEs, 45 unstable varus SCFEs, and 7 valgus SCFEs. All unstable SCFEs were varus, and all valgus SCFEs were stable. There were significant differences between the three groups by age at diagnosis, sex, race, SCFE severity, weight percentile, and duration of symptoms. The average age at diagnosis was 11.0 ± 1.2, 11.8 ± 1.8, and 12.3 ± 1.7 years for the valgus, unstable varus, and stable varus groups (p = 0.019), and similarly, SCFE severity was 25° ± 15°, 48° ± 18°, and 35° ± 19° (p = 0.0002) for the three same groups. Patients with valgus SCFEs were mostly female (86%) compared to the stable varus (39.9%) and unstable (47%) groups (p = 0.05) and mostly non-White (86%) (0.011). The duration of symptoms was 4.1 ± 4.1, 2.3 ± 5.0, and 4.5 ± 5.0 months for the valgus, unstable varus, and stable varus groups (p = 0.00005). These three types of idiopathic SCFEs demonstrated differences by age at diagnosis, sex, race, weight percentile, and duration of symptoms.

Keywords: demographics; slipped capital femoral epiphysis; stable; unstable; valgus.

Figure 1

Age at diagnosis in years by SCFE type. The black circles represent each patient; the upper and lower boundaries of the boxes represent the upper and lower quartiles, while the bar inside the box is the median. These differences were statistically significant (p = 0.019). STVALG = stable valgus SCFE, STVAR = stable varus SCFE, UNST = unstable varus SCFE.

Figure 2

SCFE severity using the lateral epiphyseal shaft angle [20]. The black circles represent each patient; the upper and lower boundaries of the boxes represent the upper and lower quartiles, while the bar inside the box is the median. STVALG = stable valgus SCFE, STVAR = stable varus SCFE, UNST = unstable varus SCFE. These differences were statistically significant (p = 0.0002).

Figure 3

Symptom duration in months was less in the unstable SCFE group, and relatively equal between the stable varus and valgus groups. The black circles represent each patient; the upper and lower boundaries of the boxes represent the upper and lower quartiles, while the bar inside the box is the median. STVALG = stable valgus SCFE, STVAR = stable varus SCFE, UNST = unstable varus SCFE. These differences were statistically significant (p = 0.002).

Figure 4

SCFE severity using the lateral epiphyseal shaft angle [20]. The circles represent each patient; the upper and lower boundaries of the boxes represent the upper and lower quartiles, while the bar inside the box is the median. N = tri-radiate cartilage not open, P = closing, and Y = open. These differences were statistically significant (p = 0.0004).