The role of obesity, biomechanical constitution of the pelvis and contact joint stress in progression of hip osteoarthritis.

OBJECTIVE: The aim of our study was to explore whether earlier hip arthroplasty for idiopathic osteoarthritis (OA) might be explained by enlarged contact stress in the hip joint, and to what amount can that be attributed to obesity and biomechanical constitution of the pelvis. METHOD: Fifty subjects were selected from a list of consecutive recipients of hip endoprosthesis due to idiopathic OA; standard pelvic radiographs made years prior to surgery were the main selection criteria. For 65 hips resultant hip force and peak contact hip stress normalized to the body weight (R/Wb and p(max)/Wb) were determined from the radiographs with the HIPSTRESS method. Body weight and body mass index (BMI) were obtained with an interview. Regression analysis was used to correlate parameters of obesity (body weight, BMI), biomechanical constitution of the pelvis (R/Wb, p(max)/Wb) and mechanical loading within the hip joint (R, p(max)) with age at hip arthroplasty. RESULTS: Younger age at hip arthroplasty was associated with higher body weight (P=0.009), higher peak contact hip stress normalized to the body weight - p(max)/Wb (P=0.019), higher resultant hip force -R (P=0.027) and larger peak contact hip stress - p(max) (P<0.001), but not with BMI (P=0.121) or R/Wb (P=0.614). CONCLUSION: Our results suggest that enlarged contact stress (p(max)) plays an important role in rapid progression of hip OA with both obesity (increased body weight) and unfavorable biomechanical constitution of the pelvis (greater p(max)/Wb) contributing.

Impact of electromyographic findings on choice of treatment and outcome.

The subsequent clinical course of patients examined in the EMG laboratory has not been adequately studied before. It is not known how EMG findings in practice affect patients' final diagnosis, treatment and outcome. The aim of the present study was to test the hypothesis that EMG results have an important impact on the choice of patients' treatment and on outcome. Three years after EMG examination, a short questionnaire asking about initial symptoms, the final diagnosis, treatment and current symptoms was sent to 300 consecutive EMG patients. Responses concerning 186 of them (39% men) were received either from patients and/or from their referring physicians. Information obtained during EMG examination was also added. Data was analyzed using methods of bivariate and multivariate statistics. We found that patients with a pathologic EMG had a better clinical outcome 3 years later. Pathologic EMG has an independent effect, pointing to more favorable disease courses, which was further improved by more active treatment approaches received by these patients. The study demonstrated the important impact of EMG findings on the treatment choice and clinical outcome in population consisting mainly of patients with carpal tunnel syndrome and radiculopathy. Studies in other patient populations are needed.