| Objective To study periprosthetic femoral shaft bone remodeling, clinical results with biological tapered femoral stems after total hip arthroplasty and the relationship of them.Methods 30 patients (33 hips) treated with femoral shaft bone remodeling by tapered femoral stems were selected from January 2003 to January 2005 after total hip arthroplasty. The postoperative X-ray images were collected and the perioperative and postoperative periprosthetic bone mineral density was analyzed by dual-energy X-ray absorptiometry (DEXA). We also measured body mass index (BMI), the outer diameter of isthmus, canal bone radio (CBR), canal flare index (CFI) and prosthesis intramedullary filling rate, and analysis the relationship of the patient's age, sex, BMI ,the outer diameter of isthmus, CBR, CFI, Harris score and the variation of early postoperative prosthesis surrounding bone mineral density. The Harris score was applied in follow-up observation, and Kaplan-Meier method was used to evaluate the working life of the femoral prosthesis. End point was radiographical loosening or revision of the femoral component for any reason.Results Three patients were died of lung cancer. the remaining 27 patients (30 hips) were followed up for 6-8 years (mean, seven years). The postoperative X-ray measurements showed that the total hip prosthesis subsidences were less than 1.5mm within one year in 12 hips, with no prosthesis loosening observed. Bone proliferations were seen in Gruen zones 2, 3, 5, 6, 11 and 12, and bone absorptions were seen in Gruen zones 1, 3 , 5and 7. DEXA showed that bone mineral density was increased in Gruen zones 2, 3, 4 and 5, but decreased in Gruen zones 1, 6 and 7. The increase of bone mineral density in Gruen zone 2 and 5 was faster compared to other sites(P<0.05) and the periprosthetic bone mineral density was significantly decreased(P<0.05) six months after operation. The recovery of the periprosthetic bone mineral density was faster compared to other times from six months to one year(P<0.05) The change of bone mineral density in every zones was prone to be stabe (P>0.05) and rare change of periprosthetic bone mineral density was found(P>0.05) two years after the operation, with only regional redistribution of bone mass from the proximal to the distal femur. The outer diameters of isthmus of patients were the important factor of the influence to the variation of the early postoperative prosthesis bone mineral density(P<0.05). The patients'age, sex, BMI, CBR, and CFI were non-statistics significance to the variation of the early postoperative prosthesis bone mineral density after operation(P>0.05).The variation of the postoperative prosthesis bone mineral density and the Harris score of hip joint function after operation presented positive correlation(P<0.05). The Harris score of hip joint function was increased from preoperative 42.56±7.34 to 91.32±6.02 at the final follow-up. The rate of thigh ache was 3.3℅. The incidence of the degree of heterotopic ossificationⅠwas 43.3℅, and the degree of heterotopic ossificationⅡ,Ⅲ,Ⅳwas not happed. The osteolysis of the femoral prosthesis side was also not happed. The 7-year survival rate of the prosthesis was 100%.Conclusions 1,Femoral shaft remodeling with biological tapered stems after total hip arthroplasty showed good modes of periprosthetic bone remodeling, mechanics load transmission was good.2,The degrees of femoral shaft remodeling with biological tapered stems after total hip arthroplasty depended on the, factors of stem design, materials, microporous coating and patients' femoral bone cortex thickness closely, and the factors of patients'age, sex, body weight, Medulla cavity shape and the situation of osteoporosis etc for themselves were not obvious influence.3,The good were the degrees of femoral shaft remodeling with biological tapered stems, the better were clinical results after early total hip arthroplasty.4,For all age groups of patients, it showed good mid-term clinical results with biological tapered stems after total hip arthroplasty. |
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