Clinical results of femoral shaft remodeling with tapered stems after total hip arthroplasty in the elderly patients

Abstract

Objective To investigate periprosthetic femoral shaft remodeling with tapered femoral stems after total hip arthroplasty （THA） for elderly patients and evaluate the mid-term clinical outcomes.Methods The study involved 30 elderly （70-90 years） patients （34 hips） treated with femoral shaft remodeling with tapered stems after THA from January 2003 to January 2005. The postoperative X-ray images were collected and perioperative periprosthetic bone mineral density was analyzed by dual-energy X-ray absorptiometry （DEXA）. The Harris score was applied in follow-up observation, and Kaplan-Meier method was used to evaluate the working life of the femoral prosthesis. Results Four patients were died of lung cancer. The remaining 26 patients （ 30 hips） were followed up for 5-7 years （ mean, six years）. The postoperative X-ray measurements showed that total hip prosthesis subsidences were less than 1.5 mm within one year in 12 hips, with no prosthesis loosening observed. Bone proliferations were seen in Gruen zones 2, 3, 4, 5, 6, 11 and 12, and bone resorptions were seen in zones l and 7. DEXA showed that bone mineral density was increased in Gruen zones 2,3,4 and 5, but decreased mainly in Gruen zones 1,6 and 7. The increase of bone mineral density in zones 2 and 5 was faster compared to other sites six months after the operation （ P 〈 0.05 ） and the change of bone mineral density was prone to be stable in two years （ P 〉 0.05 ）. Within one year after initial implantation, periprosthetic bone mineral density was significantly decreased （ P 〈 0.05 ）. Two years after the operation, rare changes of periprosthetic bone mineral density were found （ P 〉 0.05 ）, with only regional redistribution of bone mass from the proximal to the distal femur. The Harris score of hip joint function was increased from preoperative 38.56 ± 8.21 to 86.32 ± 6. 01 at the final follow-up. The 6-year survival rate of the prosthesis was 100%. Conclusion Femoral shaft remodeling with tapered stems after total hip arthroplasty for the elderly patients shows good periprosthetic bone remodeling and satisfactory mid-term clinical results. Key words: Arthroplasty, replacement, hip; Hip prosthesis ; Bone remodeling