Relationship between life quality and prosthesis position parameters after cementless total hip arthroplasty

Abstract

Objective To analyze the conditions of hip prosthesis reconstruction and to probe into the relationship of the life quality and the safe range of the prosthesis position parameters. Methods Based on a prospective study design, from March 2013 to March 2015, 52 eligible patients (52 hips) who had had total hip arthroplasty were interviewed and measured by the short form 36-item health survey (SF-36) before and two years after the operation. The anteroposterior pelvis, anteroposterior and lateral hip joint X-rays were taken at the third day after the operation to analyze the prosthesis position parameters of acetabulum and the femoral prosthesis, including acetabulum abducent and anteversion angles, femoral head rotation center position, femoral eccentricity, femoral vertical setover, length of abductor and gravity lever arm, femoral prosthesis varus and valgus, neck shaft angle. SF-36 was used to evaluate the patient′s quality of life before and two years after the operation. SPSS 17.0 was applied to analyze the reliability and validity of SF-36 and evaluate the relationship between quality of life and prosthesis position parameters after cementless total hip arthroplasty by Pearson analysis and t test. Results All the patients (52 hips) completed the follow-up, and prosthesis position parameters were obtained from X-ray after THA. Except role emotional (RE), the internal consistency of before and after opration of SF-36 determined by Cronbach's alpha coefficient were greater than 0.7. Test-retest reliability of SF-36 expressed by intraclass corre-lation coefficient(ICC) were greater than 0.80. The half-split reliability expressed by Pearson correlation coefficient(CC) was greater than 0.874. The validity was good at showing the life quality changes of patients before and after the surgery. Except vitality(VT), content validity evaluated by Pearson CC were higher than 0.7 between most dimensions and items of SF-36. CC between the prosthesis position parameters and the items of SF-36 were positive value. Except general health(GH), CC between the items of SF-36 and acetabulum prosthesis position parameters were greater than 0.6, and highly relevant between the items of SF-36 and femoral head rotation center position; CC were greater than 0.7 between femoral vertical setvover and VT, social function(SF), RE and mental healt(MH), the same to femoral eccentricity; CC were larger than 0.8 between length of abductor and gravity lever arm and SF and MH, the left data were greater than 0.7; CC between femoral prosthesis and items of SF-36 ranged from 0.329 to 0.757; CC between the items of SF-36 and neck shaft angle were greater than 0.7. Conclusions SF-36 has good reliability and validity so that they can be used to evaluate the quality of life for THA patient. The life quality of patients with femoral neck fracture is lower than normal, while it can get much better after the operation. SF-36 can reflect the patient's psychological, physiological and social life of quality of life. The suitable range of acetabulum abducent and anteversion angles are (45±5)° and (15±5)°. The neck shaft angle should be kept in (125±10)°. Acetabulum prosthesis should be placed in the acetabulum anatomy, and the contralateral normal side as reference to rebuild femoral head rotation center position. The length of the operated hip joint is shorter than the contralateral side, which should not be more than 10 mm. Shortening of femoral eccentricity, length of abductor and gravity lever arm should be avoided, and femoral prosthesis shall be kept at neutral position. Key words: Bioprosthesis; Arthroplasty, replacement, hip; Quality of life