Proximal femoral valgus osteotomy for the treatment of developmental coxa vara: a systematic review of the literature

Background: Developmental Coxa Vara (DCV) consists on a pathological reduction in head-shaft angle (HSA) and increased femoral retroversion. Several case series reported outcomes on proximal femoral valgus osteotomy (PFVO), but no evidence synthesis had been conducted. This systematic review aimed to (1) analyze success rate and complications, (2) report the degree of correction according to the HSA and the Hilgenreiner Epiphyseal Angle (HEA), compare success rate and degree of correction of subtrochanteric (SVO) vs intertrochanteric (IVO) osteotomy, and (4) difference in success rate and correction between patients in which an internal (IF) or external fixation (EF) technique was used. Methods: Four databases (PubMed, Scopus, Embase, and Cochrane Database of Systematic Reviews) were searched until February 20th(,) 2024 according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies presenting outcomes on PFVO for DCV with >2 years follow-up and >5 patients were included. Review articles, language other than English and coxa vara secondary to other conditions were excluded. Study quality was evaluated through MINORS criteria. Results: 10 case series (level of evidence IV) were located for a total of 153 patients and 192 hips. Baseline results were as follows: male/female ratio was 1.45, mean age at surgery was 6.7 +/- 1.5 and follow-up 5.1 +/- 5.5 years. Overall success rate was 88.8%, with failure considered as any indication to revision surgery. Complications included loss of correction (10.9%), deep (1.0%) or superficial wound infection (2.6%). Revision surgery was performed in 18 hips (9.4%). Average correction was measured through HSA (preoperative 94.6 +/- 8.1, postoperative 134.4 +/- 10.2, change 38.2 +/- 7.5 degrees, p < 0.001) and HEA (preoperative 71.9 +/- 5.5, postoperative 31.7 +/- 5.7 degrees, change 33.7 +/- 10.5 degrees, p < 0.001). Success rate was similar between osteotomy techniques (SVO: 91.0%; IVO: 94.1%; p = 0.48) and fixation strategy (IF: 85.4%; EF 95.8%; p = 0.096). Conclusions: PFVO presented satisfactory results for the treatment of DCV, with similar outcomes concerning the osteotomy site and fixation technique used. HSA and HEA correction were correlated to PFVO success rate. However, coxa vara is a tridimensional deformity, thus other parameters such as posterior sloping angle, mechanical axial deviation and proximal femoral offset should be included in future studies.