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Mid-Term Results of Modular Tapered Femoral Stems in Revision Total Hip Arthroplasty.

BACKGROUND
In revision total hip arthroplasty (THA), modular femoral components aid the surgeon in reconstructing joints compromised by loss of bone and soft-tissue integrity, providing customization to address bony deficits, deformity, limb length, and offset challenges. The purpose of this study was to review the survival and outcomes at minimum five-year follow up of patients who underwent revision THA at our center with a single modular femoral revision hip system offering a wide range of proximal body and distal stem geometries and sizing options.


MATERIALS AND METHODS
A query of our practice arthroplasty registry revealed 66 consented patients (69 hips) who underwent revision THA using a modular femoral stem between December 2009 and July 2013 with minimum five-year follow up. There were 35 men (53%) and 31 women (47%). Mean age was 65.2 years (range, 36-87). Etiology for index revision was 32 aseptic loosening, 20 infection, nine periprosthetic fracture, three nonunion of internal fixation, three instability, one stem breakage, and one metal complication.


RESULTS
Mean follow up was 6.3 years (range, 5-9). Harris Hip Scores improved from a mean of 45.4 preoperatively to 72.0 at most recent evaluations. There have been four re-revisions of the femoral stem: one infection, two periprosthetic femoral fracture, and one (proximal segment only) for instability. Radiographic assessment revealed satisfactory position, fixation, and alignment in all hips. Radiographic subsidence of 6-10mm occurred in four (none revised), and none had subsidence > 10mm. There were no modular junction failures. Kaplan-Meier survival to endpoint of femoral revision was 93.3% (95% CI ±3.3%) at 8.7 years.


CONCLUSIONS
The minimum five-year results of this modular THA revision system are promising, with low rates of aseptic failure, minimal subsidence, and no modular junction failures. While there may be roles for the use of non-modular revision stems, the mid-term clinical results in this cohort of patients was found to be acceptable.