Dual Mobility for Oncological Hip Reconstruction: Significantly Reduced Dislocation Rates at 5 years.

ABSTRACT

BACKGROUND: Although dual mobility total hip arthroplasty has become increasingly common in recent years, limited remains known on dual mobility in surgical oncology. This university-based investigation compared dislocation and revision rates of DMs, conventional total hip arthroplasty (THA), and hemiarthroplasties (HAs) for oncological hip reconstruction. METHODS: An institutional tumor registry was used to identify 221 patients undergoing 45 DMs, 67 conventional THAs, and 109 HAs, performed for 17 primary hip tumors and 204 hip metastases between 2010 and 2020. The median age at surgery was 65 years, and 52% were female. The mean follow-up was 2.5 years. Kaplan-Meier survivorship curves and log-rank tests were done to compare dislocation and revision rates among all 221 patients, after a one-to-one propensity match, based on age, sex, tumor type (metastasis, primary tumor), and tumor localization (femur, acetabulum). RESULTS: The 5-year survivorship free of dislocation was 98% in DMs, 66% in conventional THAs ( P = 0.03; all P values compared with DMs), and 97% among HAs ( P = 0.48). The 5-year survivorship free of revision was 69% in DMs, 62% in conventional THAs ( P = 0.68), and 92% in HAs ( P = 0.06). After propensity matching, the 5-year survivorship free of dislocation was 42% in 45 conventional THAs ( P = 0.027; compared with all 45 DMs) and 89% in 16 matched HAs ( P = 0.19; compared with 16 DMs with femoral involvement only). The 5-year survivorship free of revision was 40% in matched conventional THAs ( P = 0.91) and 100% in matched HAs ( P = 0.19). CONCLUSIONS: DMs showed markedly lower rates of dislocation than conventional THAs, with overall revision rates remaining comparable among different designs. DMs should be considered the option of choice for oncological hip reconstruction if compared with conventional THAs. HAs are a feasible alternative when encountering femoral disease involvement only. LEVEL OF EVIDENCE III.