Controlled fracture of medial wall versus structural autograft with bulk femoral head to increase cup coverage by host bone for total hip arthroplasty in osteoarthritis secondary to developmental dysplasia of hip: a retrospective cohort study

Abstract

Background: Many methods have been proposed to increase cup coverage by host bone during primary total hip arthroplasty (THA) in hip osteoarthritis secondary to developmental dysplasia of hip (DDH). However, there was no study comparing results of controlled fracture of medial wall with structural autograft with bulk femoral head. Methods: 67 hips classified as Crowe II/III were retrospectively included in this cohort study, which consisted of 33 controlled fracture (group A) and 34 structural autograft (group B). The Harris Hip Scores (HHS) was recorded. The radiological assessments were analyzed. Also, complications are assessed. The paired sample t test was used for data analysis before and after operation, while independent sample T test was used for the comparison between the two groups. The Pearson chi-square test or Fisher exact test was used to analyze the qualitative comparative parameters. Kaplan-Meier was utilized in the analysis of survivorship with the end points as a revision for any component.Results: All patients were reconstructed acetabulum at anatomical location. HHS increased greatly for both groups (P=0.18). No statistic difference was observed for two groups in postoperative leg-length discrepancy ((0.51±0.29) cm for group A and (0.46±0.39) cm for group B, P=0.64 ), postoperative height of hip center ((2.25±0.42) cm for group A and (2.09±0.31) cm for group B, P=0.13), inclination of cup ((39±4)°for group A and (38±3)°for group B, P=0.65 ). The rate of cup coverage for group B ((94±2)% ) was better than group A ((91±5)%), ( P=.009). Rate of cup protrusio was (48±4)% for group A. For both groups, No statistic difference was observed in cup diameter (P＞.05), while group A showed less operation time than group B (P＜.001). No complications were observed at the latest follow-up. Conclusion: Controlled fracture of medial wall to increase cup coverage by host bone at anatomical location can act as an alternative technique for DDH Crowe II/III with advantage of shorter operation time and less technically demanding.