Does Stem Design Affect the Incidence of Periprosthetic Femoral Fractures in Arthroplasty for Femoral Neck Fractures? A Secondary Analysis of the HEALTH Trial.

Abstract

Introduction: The aim of this study was to evaluate how stem design influences the risk of periprosthetic femoral fractures (PFFs) after hemiarthroplasty (HA) and total hip arthroplasty (THA) for femoral neck fractures (FNFs).

Methods: We performed a secondary analysis of the Hip Fracture Evaluation with Alternatives of Total Hip Arthroplasty versus Hemi-Arthroplasty (HEALTH) trial, a multicenter, prospective, randomized control trial that assessed THA versus HA for low-energy FNFs. Between 1,374 patients (414 men, 960 women) that were assessed, 72 sustained PFFs (5.2 %). Intraoperative PFFs were recorded in 42 patients, early postoperative PFFs in 15 and late PFFs in 15 patients. The incidence of PFFs was compared between cemented and cementless stems. Within the cemented group (n = 896), we analyzed the effect of taper-slip (n = 482) versus composite-beam (n = 414) designs, while within the cementless group (n = 478), we assessed the impact of single-wedged (n = 206) versus metaphyseal-filling stems (n = 272). The role of collars (n = 87) was also examined within the press-fit stems. Clinical outcomes were recorded with the Western Ontario and McMaster Universities Arthritis Index (WOMAC).

Results: Cemented stems had a significantly lower incidence of PFFs compared to their cementless counterparts (2.6 versus 10.3%, P < 0.001). There was no difference in fracture rates between taper-slip and composite-beam stems (2.3 versus 2.9%, P > 0.05). Most of the composite-beam PFFs occurred intraoperatively (75 %), while most of the taper-slip PFFs occured late (55%). There was no difference between the press-fit stems, while the presence of a collar did not show protective results (P > 0.05). Patients who underwent HA with taper-slip stems demonstrated inferior WOMAC scores and higher incidence of reoperation for pain compared to those treated with composite-beam stems (2.6 versus 0.4%, P = 0.048).

Conclusion: Cementless stems have a high PFF rate, regardless of the stem type or presence of the collar. Taper-slip stems are responsible for late fractures, raising concerns about their performance in the long term. Patients treated with HA may present a higher risk of reoperation for pain when taper-slip stems are used.