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Purpose: In older patients requiring a hip arthroplasty, the cemented straight collarless polished tapered stems (PTSs) have been linked to an increased risk of periprosthetic femur fractures (PFFs) when compared to anatomically shaped stems (ASs). This study aims to perform a 6-year follow-up of PFF rates and other adverse events of an orthopaedic department's full transition from a cemented PTS to a cemented AS.

Methods: A prospective single-centre cohort study included 1077 patients operated with a cemented hip replacement at Danderyd Hospital, Stockholm, Sweden, between 2012 and 2015. Patients were divided into two groups based on stem design: PTS (n = 543) and AS (n = 534). Outcomes included the PFF rate, periprosthetic joint infection (PJI) and prosthetic dislocation. A Cox proportional hazards model was used to estimate outcomes.

Results: Most patients (77.2%, mean age 82 years) underwent surgery for a hip fracture. The 6-year PFF rate was 4.6% for the PTS group and 0.9% for the AS group. PFF patterns differed between groups, with Vancouver B fractures being more common in the PTS group. The AS group had lower rates of PJIs (3.6% vs. 1.7%) and dislocations (4.4% vs. 1.3%) than the PTS group.

Conclusion: Transitioning from a PTS to an AS could reduce the PFF rate and other adverse events in hip arthroplasty. The findings are relevant for hospitals treating older and frail patients, as the mean age in this study was >80 years. Further research in different settings is warranted to confirm these results.

Level of Evidence: Level II.