Less of the Lesser: Postero-lateralization of the Lesser Trochanter was Associated with Symptomatic Iliopsoas Tendinitis Following Total Hip Arthroplasty.

Abstract

Iliopsoas tendinitis following total hip arthroplasty (THA) has been described to result from acetabular component overhang and prominent femoral collars. However, a portion of patients experience iliopsoas tendinitis in the setting of well-positioned components. The purpose of this study was to assess anatomic factors predisposing to iliopsoas tendinitis after THA. Total hip arthroplasties performed at three academic institutions that underwent subsequent arthroscopic iliopsoas release were retrospectively reviewed from 2015 to 2025 and propensity matched in a one-to-three manner to a control group of THAs without subsequent iliopsoas release. Controls were matched by age, sex, surgery date, laterality, surgical approach, and implanted femoral component. Patients who had symptomatic iliopsoas tendinitis and subsequent release (THA-IPR) were evaluated for acetabular component and femoral collar overhang. The absolute and relative profiles of the lesser trochanter were evaluated on antero-posterior radiographs to assess the relationship between the lesser trochanter radiographic profile and the development of iliopsoas tendinitis. There were 45 THA-IPR patients (mean age 57 years [range, 33 to 82]; 71% women; 19 direct anterior, 10 antero-lateral, 16 posterior) who were analyzed and matched to 135 controls. Anterior cup overhang of ≥ two mm was present in 49% (n = 26) of THA-IPR patients, with 18% who had collared femoral components and 9% who demonstrated collar overhang of ≥ two mm. The THA-IPR patients who had less than two mm of cup or collar overhang demonstrated relative postero-lateralization of the lesser trochanter compared to those with ≥ two mm overhang (P = 0.010) and THA controls (P = 0.037). Visualizing "less of the lesser" trochanter on antero-posterior radiographs and associated postero-lateralization of the lesser trochanter may be a risk factor for iliopsoas tendinitis following THA, even in the presence of appropriately positioned components.