Good long-term outcome of the untreated contralateral hip in unilateral slipped capital femoral epiphysis

Abstract

PurposeThere is no consensus regarding prophylactic fixation of the contralateral hip in slipped capital femoral epiphysis (SCFE). In order to further study this question, we evaluated the long-term natural history of untreated contralateral hips.MethodsForty patients treated for unilateral SCFE without evidence of subsequent contralateral slip during adolescence were reviewed with a mean follow-up of 36 years (range 21–50 years). The deformity after SCFE may demonstrate radiographic signs of cam-type femoroacetabular impingement. We, therefore, measured α-angles in the contralateral hips on anteroposterior (AP) and frog-leg lateral radiographs. The angles were compared with those of a control group of adults without SCFE. Five years after the radiographic examination, with a mean follow-up of 41 years, all patients were evaluated by telephone interview. As range of motion and deformity could not be examined, a modified Harris hip score (HHS) (maximum score of 91 points) was used. A modified HHS <76 points and/or radiographic osteoarthritis (OA) was classified as a poor long-term outcome.ResultsThe mean value of the AP α-angle was significantly higher in the contralateral hips in SCFE patients than in the control group (55° vs. 46°), while the mean value of the lateral α-angle was not. Abnormally high values for one or both α-angles were found in 16 contralateral hips (40 %), of which five patients had abnormal values for both α-angles and were considered to have had an asymptomatic contralateral slip. Five patients (13 %) had a poor outcome in the contralateral hip, of which three patients (8 %) had OA. There was a significant association between hips with both α-angles that were abnormal and poor outcome.ConclusionsSince the natural history showed good long-term radiographic and clinical outcome in 35 of 40 patients and only three had OA, we conclude that routine prophylactic fixation of the contralateral hip is not indicated.

Morphologic Features of the Contralateral Femur in Patients With Unilateral Slipped Capital Femoral Epiphysis Resembles Mild Slip Deformity: A Matched Cohort Study

“…A previous study showed higher mean a angle in the contralateral untreated hip in patients treated for unilateral SCFE and followed for a mean of 41 years when compared with control hips [36]. That study [36] and others [11,18,25,35] suggest a subclinical slip as the etiology of cam FAI deformity. Other studies suggest that cam FAI may develop because of an abnormal extension of the epiphysis into the metaphysis possibly in the context of vigorous sporting activities during childhood [1,8,32].…”

“…The superoanterior plane is the most common location of cam FAI deformity [30]. A previous study showed higher mean a angle in the contralateral untreated hip in patients treated for unilateral SCFE and followed for a mean of 41 years when compared with control hips [36]. That study [36] and others [11,18,25,35] suggest a subclinical slip as the etiology of cam FAI deformity.…”

“…Although both hips are in theory similarly exposed to these factors, unilateral SCFE is more common than bilateral involvement at initial presentation [19]. A few long-term studies have reported a relatively high prevalence of proximal femoral deformity in the contralateral uninvolved hip in patients treated for unilateral SCFE during adolescence [10,12,16,36]. However, the morphologic features of the asymptomatic contralateral hip in patients with unilateral SCFE and its association with sequential slip or development of cam FAI deformity are poorly understood.…”

“…The posterior sloping angle, which measures orientation of the femoral head in relation to the neck-diaphysis axis, has been used as a predictor for the risk of sequential SCFE [3,4,20,28,29,38]. Although two studies showed higher posterior sloping angle in the contralateral hip of patients with unilateral SCFE in comparison to control normal hips [3,17], there are limited data regarding morphologic features of the contralateral hip assessed by contemporary measurements of femoroacetabular impingement (FAI) [7,10,36]. Elevated a angle suggesting FAI with cam-type morphologic features in the contralateral hips of patients with unilateral SCFE was reported in two long-term studies [10,36].…”

“…Although two studies showed higher posterior sloping angle in the contralateral hip of patients with unilateral SCFE in comparison to control normal hips [3,17], there are limited data regarding morphologic features of the contralateral hip assessed by contemporary measurements of femoroacetabular impingement (FAI) [7,10,36]. Elevated a angle suggesting FAI with cam-type morphologic features in the contralateral hips of patients with unilateral SCFE was reported in two long-term studies [10,36]. However, it is unclear whether the abnormal a angle in these patients was a consequence of silent SCFE or the development of an idiopathic cam given the lack of information regarding other morphometric parameters that distinguish different types of cam-type FAI deformity [2,11].…”