Subclinical bilateral involvement of the hip in patients with slipped capital femoral epiphysis: a multicentre study.

PURPOSE: This study was conducted to assess the posterior inclination of the contralateral femoral epiphysis in patients with unilateral slipped capital femoral epiphysis (SCFE).

METHODS

The posterior sloping angle (PSA) was measured using lateral radiographs in 67 patients with a unilateral SCFE and in 41 age-matched normal controls. A symptomatic epiphyseal slip was defined as the development of SCFE.

RESULTS

The contralateral PSA in SCFE patients was more widely distributed and significantly larger compared to controls (15.0° vs. 9.0°, p < 0.0001). Forty-seven hips (70.1%) had a PSA of greater than 12.8°, which was +2SD of the control hips. Of the 65 hips excluding the two cases with prophylactic pinning, 11 hips (16.9%) eventually developed a contralateral SCFE during adolescence and their PSA at the initial visit was significantly larger compared to patients without a contralateral SCFE (18.0° vs. 14.3°, p < 0.005) with a cutoff value of 19°.

CONCLUSIONS

These findings suggested the possibility of bilateral hip involvement in SCFE patients. Hips with greater degrees of PSA (> 19°) are likely to become symptomatic.