PICO Question: Among children presenting with unilateral slipped capital femoral epiphysis, should the opposite, asymptomatic, radiographically normal hip also undergo surgical fixation to prevent later slip?
Question type: Intervention
Study design: Case series
These authors, from the United Kingdom, reported on outcomes of 86 children who underwent hip fixation for unilateral slipped capital femoral epiphysis (SCFE). Most pediatricians are aware that there is some risk that the "normal" hip will develop SCFE in the future, and controversy exists whether to perform prophylactic fixation of the contralateral hip at the same time as the original procedure. In this group of children, 50 underwent unilateral fixation, and 36 underwent bilateral fixation at the initial procedure. The decision about unilateral versus bilateral fixation was made by the attending physician in this retrospective study.
Of the 36 children who underwent bilateral fixation, none had problems with any further slippage. However, 23 of the 50 children who underwent fixation just of the affected hip subsequently had slippage of the contralateral side. This sounds like a big vote in favor of repairing both hips at the initial procedure, but it's just not that straightforward when you're looking at retrospective data. In particular, we don't know how patients were chosen for unilateral versus bilateral fixation.
SCFE on plain xray. From Filip em via Wikimedia.
Suspected risk factors for subsequent slippage for the contralateral hip include age, gender, weight, presence of endocrine disorder, socioeconomic factors, and something called the posterior slope angle (PSA) of the hip, measured from a plain radiograph. When the authors examined these factors in the 2 groups of children, they found no differences. I would have expected differently; it seems likely that clinicians might choose to fixate both hips more often in children with high risk factors for future problems. However, looking just at the children in the unilateral fixation group, those who had subsequent slippage were more likely to have a higher PSA.
Both the study researchers and Dr. Hennrikus suggest that it will take a randomized controlled trial to settle the matter. Although some clinicians consider it very difficult to perform a randomized controlled trial with a surgical intervention, it's been done successfully many times. It seems like it's time to do this study for SCFE patients.