Relationship between Perceived Leg Length Discrepancy at One Month and Preoperative Hip Abductor Muscle Elasticity in Patients after Total Hip Arthroplasty.

OBJECTIVE: Preoperative factors related to perceived leg length discrepancy (PLLD) after total hip arthroplasty (THA) are not well studied. This study aimed to examine the preoperative factors, including hip abductor modulus, related to PLLD one month after THA. METHODS: The study included 73 patients diagnosed with osteoarthritis secondary to developmental dysplasia of the hip and a posterior approach to surgery. Multiple logistic regression analysis was performed using the presence or absence of PLLD as the dependent variable and preoperative hip abductor's modulus of elasticity, pain, hip abduction range of motion, hip abductor muscle strength and pelvic obliquity as the independent variable. Additionally, receiver operating characteristic curves were used for the extracted variables for calculating the cutoffs, sensitivity, specificity and area under the curve (AUC) to determine the presence or absence of PLLD. The significance level was set at p<0.05. RESULTS: The hip abductor modulus (odds ratio=1.13; 95% confidence interval=1.06-1.21; p<0.001) was selected as a preoperative factor. The cutoff value to determine the presence or absence of a PLLD was 16.32 kPa. The sensitivity and specificity were 81.8% and 72.5%, respectively, and the AUC was 0.8137. CONCLUSION: The hip abductor muscle elastic modulus affected PLLD one month after THA. If the preoperative hip abductor elastic modulus is higher than the cutoff value, it may affect the appearance of PLLD at one month postoperatively.

Reliability of measurements of hip abduction strength obtained with a hand-held dynamometer.

This study aimed to evaluate intrarater and interrater reliability when measuring hip abductor strength in the supine position using a hand-held dynamometer (HHD) (Study 1), and to elucidate the relationships between measured values and examiners' physical characteristics (Study 2). Three healthy examiners (1 female, 24 y.o. and 2 males 23 and 27 y.o) and 12 subjects (6 females, 24.5 ± 2.8 years and 6 males, 27.7 ± 3.5 years) participated in Study 1, and 20 healthy examiners (7 females, 22.3 ± 1.3 years and 13 males, 29.4 ± 8.2 years) and 2 subjects (1 female, 24 y.o. and 1 male 27 y.o) participated in Study 2. All healthy examiners were hospital employees. Hip abductor strength was measured by HHD with hand fixation and with belt fixation, and examiner age, sex, height, weight, BMI, and dominant hand grip strength were evaluated. The intraclass correlation coefficient (ICC) (1,1), a measure of intrarater reliability, was 0.89-0.95 with hand fixation and 0.96-0.97 with belt fixation. ICC (2,1), a measure of interrater reliability, was 0.76-0.79 and 0.90-0.93, respectively. In subjects with high muscle strength (the examiner's hand was moved), the examiner's dominant hand grip strength affected muscle strength values with hand fixation (standardized partial regression coefficient = 0.78, determination coefficient R(2 )= 0.61, p < 0.01). In subjects with low muscle strength (the examiner's hand was not moved), no variables had effect. When the muscle strength of the subject is weak, both methods can be used. When the muscle strength of the subject is strong, it is necessary to adjust the value obtained by the examiner's dominant hand grip strength in the hand fixation method.

What predicts 36-item health survey version 2 after total hip arthroplasty.

OBJECTIVE: To identify the factors having the greatest effect on the Medical Outcomes Study 36-Item Short-Form Health Survey, version 2 (SF-36v2) score after total hip arthroplasty (THA). DESIGN: Retrospective review. SETTING: Private 150-bed hospital. PARTICIPANTS: Patients (N=659) who underwent initial THA for osteoarthritis (OA) of the hip between April 2007 and January 2009. A total of 138 patients who fulfilled the inclusion criteria were seen at the first follow-up, while 108 patients were included in the second follow-up; all 30 patients excluded at the second follow-up underwent contralateral THA between follow-ups. The average time ± SD from surgery to first follow-up was 195.1±67.7 days, and that to second follow-up was 443.0±108.5 days. Patients' average age ± SD was 61.1±9.9 years at first follow-up and 61.3±10.3 years at second follow-up. Women accounted for 85.5% of patients at first follow-up and 85.2% at second follow-up. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Eight subscales of the SF-36v2, age, sex, body mass index, complications, living alone, contralateral hip OA, range of hip joint motion, walking aids, and preoperative mental health (MH) values from the SF-36v2. RESULTS: Canonical correlation analysis showed that contralateral hip OA had a major effect on the SF-36v2 score at the first follow-up. At the second follow-up, excluding the 30 patients who had undergone contralateral THA, physical function measured by the SF-36v2 was strongly affected by age, and other items were strongly affected by preoperative MH. CONCLUSIONS: When using the SF-36v2 as an assessment scale after THA, adjustments should be made for contralateral hip OA. Moreover, age and preoperative MH should also be considered.