Bilateral slipped capital femoral epiphysis: predictive factors for contralateral slip.

The primary goal in treatment of slipped capital femoral epiphysis (SCFE) is to prevent further slip by stabilizing the physis. Debate exists concerning prophylactic fixation of the uninvolved hip at presentation. Our goal was to determine predictive factors for a contralateral slip after presentation with a unilateral SCFE. Ninety patients with SCFE and complete radiographs were followed up until the bilateral closure of the proximal femoral physis. Chronological age at presentation, sex, and race were recorded. Open or closed triradiate cartilage was recorded, and a modified Oxford bone age assessment was performed. Twenty patients (22%) had bilateral SCFE at presentation, and 70 patients (78%) were unilateral. Of these 70 patients, 16 (23%) later developed a contralateral SCFE. Analysis revealed that chronological age was the only significant (P = 0.010) predictor for developing a contralateral slip. All girls younger than 10 years and all boys younger than 12 years who presented with unilateral SCFE developed a contralateral slip. Twenty-five percent of girls younger than 12 years and 37% of boys younger than 14 years developed a contralateral slip. No girl older than 13 years and no boy older than 14 years developed a contralateral slip in our series. Surgical complications were infrequent and isolated to the side of the initial SCFE. Chronological age is a predictor for a contralateral slip in patients presenting with a unilateral SCFE. The authors recommend that all girls younger than 10 years and all boys younger than 12 years presenting with unilateral SCFE should undergo strong consideration for prophylactic screw fixation on the contralateral side. In older age groups, prophylactic treatment may be considered on a case-by-case basis.