Modular Femoral Stems for Revision Total Hip Arthroplasty

Abstract

Modular femoral stems are one option for revision THA surgeons and allow offset restoration, leg length discrepancy correction, and stability independent of distal stem fixation. The complexity of revision THA usually leads surgeons to use multiple revision hip designs to address these issues. We evaluated functional outcomes with a revision modular system and determined whether such a system achieved initial distal fixation, femoral offset restoration, leg length equalization, and hip stability. We prospectively followed 118 patients in whom a modular stem system was used for reconstruction of their failed index femoral stem. Sixty-nine hips were classified as Type I (classification of Paprosky et al.), 35 as Type II, 17 as Type III, and one as Type IV. Functional assessment was achieved using patient- and physician-administered outcome evaluations (SF-36, WOMAC, Lower Extremity Activity Scale, Harris hip score). Stem fixation, offset restoration, leg length discrepancy, and hip stability were evaluated radiographically. Complications were also recorded. Minimum followup was 2 years (average, 4 years; range, 2-7 years). Average values on all functional outcome evaluations showed improvement at latest followup. Distal bone ingrowth fixation was obtained in 100% of the patients, offset was corrected in 66%, leg length discrepancy was corrected in 78%, and stability was achieved in 97%. No failures or fractures at the body to stem junction were seen at latest followup. Modular femoral components achieved functional outcomes and were useful to address distal fixation, femoral offset restoration, leg length equalization, and hip stability when revising failed femoral components. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.