Comparing pinning in situ and capital realignment procedures for severe, stable slipped capital femoral epiphysis: a systematic review

In severe, stable slipped capital femoral epiphysis, it is unclear whether pinning in situ (PIS) or capital realignment procedures (CRPs) are superior. Our primary aim was to compare patient-reported outcome measures (PROMs) following each strategy. Secondary aims were to compare rates of femoral head avascular necrosis (AVN) and complications. MEDLINE, Embase and Cochrane databases were searched according to an agreed strategy. Narrative review articles, case reports, letters to the editor and articles not written in English were excluded. The risk of bias was assessed using the Newcastle-Ottawa Scale. Of the 132 citations identified, 127 were excluded following de-duplication and application of the exclusion criteria. Three observational studies comparing PIS with CRP and two case series considering CRP alone were identified. One article was considered fair quality, and four articles were considered poor. In total, 198 hips from five studies were included (66 PIS, 132 CRP). PIS was associated with moderate-good functional outcomes, and CRP with good-high outcomes. Two comparative studies reported significantly better PROMs following CRP. AVN was reported in 1.5% following PIS and 10.6% following CRP. Regarding other complications, chondrolysis occurred in 3.0% following PIS and 2.4% following CRP. Femoroacetabular impingement rates were markedly higher following PIS (60.6% versus 2.3%). Reoperation rates were also greater following PIS (34.5% versus 13.3%). PIS tends to be associated with favourable AVN rates, but CRP with favourable PROMs and complication rates. However, comparisons were drawn from heterogeneous studies lacking long-term follow-up. Further high-quality research is required.