Risk Factors for Contralateral Slipped Capital Femoral Epiphysis: A Meta-analysis of Cohort and Case-control Studies

Slipped capital femoral epiphysis (SCFE) is an important cause of hip pain and disability in pediatric patients. SCFE occurs bilaterally in 12% to 80% of cases, and the risk of contralateral SCFE is noted to be 2335 times higher than the index SCFE. Several studies have reported risk factors for contralateral SCFE; however, these studies have not been systematically analyzed. The purpose of this systematic review and meta-analysis was to review and analyze risk factors for subsequent contralateral SCFE and identify the strongest risk factors for a subsequent slip.

A systematic review was performed of all observational studies focusing on risk factors for subsequent contralateral SCFE indexed in Medline, Embase, and Cochrane databases. Data extraction was performed and summarized using descriptive statistics. Meta-analysis was performed for risk factors with sufficient constituent study data. Quality assessment was performed using the Newcastle-Ottawa Scale, and funnel plots were generated to assess publication bias.

The initial search strategy identified 226 references, and after exclusions, 20 studies were included in this analysis. Demographic risk factors included age, sex, weight, body mass index, ethnicity, and urban/rural residence; clinical risk factors included endocrine abnormality, duration of symptoms, slip stability, and slip chronicity; and radiographic risk factors included slip angle, triradiate cartilage, alpha angle, posterior sloping angle (PSA), physeal sloping angle, modified Oxford score, and bone age. Younger patient age, body mass index≥95th percentile, presence of an endocrine abnormality, higher PSA of the unaffected hip, and lower modified Oxford score have been noted to be significant risk factors for contralateral SCFE. Meta-analysis showed that younger age (-0.9; confidence interval, -1.1, -0.6), and higher PSA (4.7 degrees; 95% confidence interval, 3.3-6.2 degrees) of the unaffected hip were predictive of subsequent contralateral SCFE. The majority of studies were of good quality.

There are several risk factors for subsequent contralateral SCFE. On the basis of the available data, younger patients with a high PSA of the unaffected hip would most likely benefit from prophylactic fixation of the unaffected hip.

Level II.