No differences in clinical and radiographic outcomes between standard offset and high offset short cementless stems.

Abstract

To compare clinical and radiographic outcomes of total hip arthroplasty (THA) using standard offset versus high offset short cementless stems. We reviewed a consecutive series of 204 primary THAs performed over 5years using a short cementless collared stem. At a minimum follow-up of 2years, 6 patients had deceased, 6 were not evaluated radiographically and, 2 were lost to follow-up. This left a final cohort of 190 hips, of which 72 had received a standard offset stem and 118 had received a high offset stem. Outcomes collected included: Oxford hip score (OHS), forgotten joint score (FJS), canalfill ratio (CFR),canal-bone ratio (CBR), stem subsidence (≥ 3mm), stem misalignment (> 5°), radiolucent lines (≥ 2mm), cortical hypertrophy, and calcar modifications. There were no significant differences in postoperative clinical and radiographic outcomes between the standard offset and high offset groups, except for incidence of stems in varus (6% vs 17%; p = 0.001). Multivariable analyses revealed that OHS was significantly worse for patients of greater age (β = 0.1; p = 0.001), higher BMI (β = 0.2; p = 0.018), or with inflammatory arthropathy (β = 4.7; p = 0.005); while FJS was significantly worse for patients with higher BMI (β = -0.7; p = 0.003); and cortical hypertrophy was significantly associated with CBR (OR > 100; p = 0.008). There were little to no differences in clinical or radiographic outcomes of THA performed using standard offset versus high offset short cementless stems. Although high offset stems are more frequently aligned in varus, while cortical hypertrophy occurs in wider intramedullary canals.