SCREW FIXATION OF GRADE-III SLIPPED CAPITAL FEMORAL EPIPHYSIS

From 1987 to 1992, 161 children were treated at The Children's Hospita l of Philadelphia for slipped capital femoral epiphysis. Of these, 23 patients (23 hips) had Grade III slips (>50%). Fixation was achieved b y 1 or 2 screws in all patients. Twenty-one of 23 patients were availa ble for followup (average followup, 2.8 years). Four slips were acute, 11 were acute-on-chronic, and 6 were chronic. At the most recent foll owup, radiographs were taken and a Harris Hip Score was assigned for e ach patient. Stabilization without progression of slip at followup was achieved in ail patients. Screw placement was satisfactory per the cr iteria of Stambough in all patients. Four children (19%) had major com plications: Three (1 acute slip and 2 acute-on-chronic slips) had avas cular necrosis of the femoral head; One (chronic slip) had chondrolysi s. There were no immediate postoperative complications. The mean Harri s Hip Score for these 4 patients was 85 points, versus a mean score of 94 points for all 21 patients. Chronic Grade III slipped capital femo ral epiphysis can be treated safely and effectively by screw fixation. Five of 6 patients had satisfactory results; the only exception had e vidence of chondrolysis preoperatively. Acute and acute-on-chronic Gra de III slipped capital femoral epiphyses treated with screw fixation a re less predictable. In 15 patients, reduction occurred in 9 hips desp ite deliberate avoidance of forceful manipulative maneuvers. Avascular necrosis developed in 3 (33%) of these 9 hips. Reduction of the acute component of the slip during screw fixation, whether deliberate or no t, indicates gross instability. It is hypothesized that avascular necr osis may be associated with injury to the epiphyseal vasculature occur ring at the time of the acute slip.