Modular Tapered Implants for Severe Femoral Bone Loss in THA: Reliable Osseointegration but Frequent Complications

Background Modular tapered stems have been suggested as the optimal implants for patients with severe femoral bone loss (Paprosky Type IIIB and IV) undergoing revision total hip arthroplasty (THA); however, there are few data describing survivorship and hip scores associated with this treatment.

Questions/purposes At minimum 2 years, we sought to determine the (1) survivorship of these implants; (2) radiographic evidence of osseointegration; and (3) the Harris hip scores of patients revised with a modular tapered stem for severe femoral bone loss including the complications associated with their use.

Methods Between 1999 and 2010, we performed 1124 femoral revisions; of those, 135 (12%) were performed using a modular tapered stem. General indications for use of this device included bone loss, poor quality bone, leg length discrepancy, difficulty adjusting version, proximal femoral remodeling, and ectatic medullary canals in the setting of revision THA. This report reviewed 70 of those that were performed in Type IIIB and IV femurs. Of those 70 patients, 11 had died and one was lost before 2-year followup; the remaining 58 (83%, 33 with a Type IIIB femur and 25 with a Type IV femur) were followed for a minimum of 24 months (average, 67 months; range, 24-151 months). Survivorship free from revision, radiographic analysis for signs of subsidence or stem loosening, and Harris hip scores were tallied.

Results One patient underwent stem revision for early subsidence followed by failure of ingrowth for a survivorship free from repeat revision of 98% (57 of 58 patients). Five other stems (for a total of six [10%]) subsided early but nonetheless achieved radiographic signs of ingrowth and were not revised again. All other stems demonstrated osseointegration without subsidence and remained radiographically well fixed. In patients with surviving implants, the mean Harris hip score improved from 34 (range, 11-49) preoperatively to 74 (range, 14-100; p < 0.001) postoperatively. Overall, 15 of 58 patients (26%) experienced a complication, of whom 10 (17%) underwent reoperation.

Conclusions We found that modular tapered stems resulted in 98% survivorship at a mean of 67 months in patients with Type IIIB and IV femurs undergoing femoral revision, although the overall complication rate in this complex subset of patients is high.

Level of Evidence Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.