Effect Of The Prostheses Position And Orientation On Total Hip Arthroplasty

Objective: A group of patients who had been applied total hip arthroplasty were followed up clinically and radiolocally to explore the effect of prostheses position and orientation on total hip arthroplasty, by the measurements of the anteversion angle ,the abduction angle ,the position of the femoral head center and the femoral offset which could be used as a basis to evaluate clinical practice.Methods: A series of 370 hip joints(352patients)were followed up. The average follow up period was 37monthes. Harris evaluation system was used ,and the anteversion angle ,the abduction angle ,the position of the femoral head center and the femoral offset were measured with AutoCAD 2005.The results were statistically analyzed,with a P value less than 0.05 indicating significant difference.Results: 93.0% patients got the Harris score more than 80. Ten patients was found to have dislocation and 16 patients show moderate or severe painness. patients who got the Harris score higher than 90 had the most appropriate position and orientation of the prostheses. The anteversion angle less than 15°or the abduction angle more than 56°was found to be associated with greater risk of dislocation . The large femoral offset was associated with severe pain .Conclusion: Based on the results of the study , the anteversion angle ,the abduction angle ,the position of the femoral head center and the femoral offset should be considered as the most important factors of the healing effect after total hip arthroplasty. We believe that the position and orientation of the prostheses should be controlled appropriately: the anteversion angle in the range from 15°to 25°,the abduction angle in the range from 45°to 56°,the appropriate position of the femoral head center and the femoral offset.