Hip decompression of unstable slipped capital femoral epiphysis: a systematic review and meta-analysis

Purpose Slipped capital femoral epiphysis (SCFE) is one of the most common adolescent hip conditions. Unstable SCFE is characterized by sudden and severe hip pain with the inability to weight bear, even with crutches. Osteonecrosis of the femoral head is increased in patients with unstable SCFE. The aim of our study was to systematically review the literature that compares hip decompression to no hip decompression of unstable SCFE. Methods We searched several databases from 1946 to 2014 for any observational or experimental studies that evaluated hip decompression and osteonecrosis of unstable SCFE. We performed a meta-analysis using a random effects model to pool odds ratios (ORs) for the comparison of osteonecrosis between patients undergoing hip decompression and no hip decompression. We also investigated the type of hip decompression performed. Descriptive, quantitative, and qualitative data were extracted. Results Of the 17 articles identified, nine studies (eight case series and one retrospective cohort study) were eligible for the meta-analysis, with a total of 302 unstable SCFE. The pooled OR = 0.91 of osteonecrosis between hip decompression and no hip decompression was in favor of hip decompression, but was not statistically significant [95 % confidence interval (CI): 0.47, 1.75; p = 0.54, I-2 = 0 %]. No significant differences in the rates of osteonecrosis were detected in unstable SCFE with open and percutaneous hip decompression alone (OR = 0.97, 95 % CI: 0.36, 2.62; p = 0.69, I-2 = 19.1 %) or hip decompression with bony procedures (OR = 0.99, 95 % CI: 0.35, 2.79; p = 0.69, I-2 = 0 %). Conclusions The cumulative evidence at present does not indicate an association between hip decompression and a lower rate of osteonecrosis of unstable SCFE. However, hip decompression of unstable SCFE remains an option that can potentially decompress the intracapsular hip pressure and optimize the blood flow to the femoral head. Thus, multicenter prospective cohort studies are required and will be able to answer this question with more certainty and a higher level of evidence.