Hip Hemiarthroplasty for Fractured Neck of Femur Revised to Total Hip Arthroplasty: Outcomes Are Influenced by Patient Age Not Articulation Options.

BACKGROUND: Hip hemiarthroplasty is the most common arthroplasty option for fractured neck of femur (FNOF). Revision to total hip arthroplasty (THA) is occasionally required. This study aimed to assess the outcome of hemiarthroplasty revised to THA and to assess the impact of femoral head size, dual mobility (DM), and constrained liners. METHODS: All aseptic 1st revisions reported to the Australian Joint Replacement Registry after hemiarthroplasty performed for FNOF when a THA was used as the revision procedure were included from September 1999 to December 2019. The primary outcome measure was the cumulative percent revision for all-causes and dislocation. The impact of prosthesis factors on revision THA was assessed: standard head THA (≤32 mm), large head THA (≥36 mm), DM, and constrained liners. Outcomes were compared using Kaplan Meyer and competing risk. RESULTS: There were 96,861 hemiarthroplasties performed, with 985 revised to THA. The most common reasons for 1st revision were loosening (49.3%), fracture (17.7%), and dislocation (11.0%). Of the hemiarthroplasty procedures revised to THA, 76 had a 2nd revision. The most common reasons for 2nd revision were fracture (27.6%), dislocation (26.3%), loosening (23.7%), and infection (18.4%). Femoral head size, DM, or constrained liner use did not alter the incidence of all-cause 2nd revision. This did not change when solely looking at patients still alive. A 2nd revision was more likely in patients aged <75 years. CONCLUSION: The outcome of hemiarthroplasty performed for FNOF revised to THA is influenced by patient age, not by the articulation used.