Changes In Muscle Mass, Strength, And Quality Of Life After Total Hip Replacement Surgery

PURPOSE: To quantitatively measure the changes in muscle mass, strength, and quality of life evaluated before and 1 year after surgery in a group of patients who underwent total hip replacement for avascular necrosis or hip dysplasia. METHOD: This is prospective, observational study and 57 patients who underwent total hip replacement were enrolled. Demographic data were collected. Grip strength(GS), knee extension strength(KES) were measured and Dual-energy X-ray absorptiometry was performed before and 1-year after surgery. Appendicular skeletal muscle mass (ASM), and muscle mass of all extremities were quantitatively measured. In addition, gait speed, chair stand test, and patient-reported outcome measurements including modified Harris hip score (MHHS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were evaluated. The mean difference of variables was analyzed using the paired t-test. Patient-reported outcome measurements and variables evaluated before and one year after surgery were analyzed using multivariate linear regression. RESULTS: KES, both leg muscle mass, ASM, gait speed, MHSS, and WOMAC score have been significantly improved (Table 1). In multivariate linear regression, pre-surgery both leg muscle mass and ASM divided by weight and post-surgery GS, KES, both leg muscle mass, and ASM divided by weight and BMI were significantly associated with patient-reported outcomes(Table 2). CONCLUSION: Patients undergoing total hip replacement experience improvement in muscle strength, performance, and quality of life. Table 1. - Differences in variables before and after the surgery Pre op Post op 1 yr Variables Mean ± SD Mean ± SD P-value Body weight, kg 66.21 ± 13.46 65.09 ± 12.42 0.09 BMI, kg/m2 25.77 ± 4.22 25.36 ± 4.03 0.08 Grip strength, kg 27.57 ± 8.45 27.97 ± 8.92 0.31 Knee extension strength (affected), kg 22.97 ± 10.88 29.25 ± 11.47 0.00* Knee extension strength (sound), kg 30.11 ± 12.51 32.12 ± 13.19 0.01* Mass of both arms, kg 4.82 ± 1.3 4.9 ± 1.29 0.17 Mass of both legs, kg 13.1 ± 3.23 13.63 ± 3.35 0.00* Appendicular skeletal mass, kg 17.95 ± 4.4 18.53 ± 4.39 0.00* Leg mass of affected side, kg 6.31 ± 1.59 6.63 ± 1.67 0.00* Leg mass of sound side, kg 6.82 ± 1.73 7.0 ± 1.78 0.02* Gait speed, m/sec 1.11 ± 0.32 1.45 ± 0.27 0.00* Chair stand test, sec 8.15 ± 0.6 6.7 ± 5.37 0.16 MHHS score 53.25 ± 20.9 81.4 ± 8.95 0.00* Womac score 40.05 ± 21.43 14.68 ± 11.69 0.00* Table 2. - Linear regression analysis by multivariate variables Preoperative Postoperative 1 year MHHS WOMAC MHHS WOMAC Standardized Coefficients P Standardized Coefficients P Standardized Coefficients P Standardized Coefficients P Grip strength 0.178 0.456 -0.249 0.300 0.335 0.101 -0.295 0.116 Grip strength per HT2 0.156 0.446 -0.220 0.287 0.207 0.241 -0.231 0.153 Grip strength per WT 0.163 0.395 -0.107 0.581 0.242 0.180 -0.341 0.038* Grip strength per BMI 0.190 0.403 -0.131 0.569 0.385 0.071 -0.446 0.021* Knee extension 0.156 0.383 -0.211 0.244 0.241 0.178 -0.362 0.025* Knee extension per HT2 0.147 0.369 -0.195 0.235 0.207 0.201 -0.337 0.021* Knee extension per WT 0.144 0.395 -0.135 0.431 0.191 0.235 -0.384 0.008* Knee extension per BMI 0.157 0.404 -0.152 0.424 0.223 0.209 -0.423 0.008* Both arms mass -0.056 0.785 -0.052 0.803 0.019 0.926 0.227 0.218 Both arms mass per HT2 -0.068 0.687 -0.034 0.844 -0.099 0.536 0.233 0.110 Both arms mass per WT -0.053 0.819 0.020 0.934 -0.089 0.674 0.180 0.351 Both arms mass per BMI -0.047 0.891 0.024 0.945 0.184 0.551 0.116 0.682 Both legs mass 0.235 0.187 -0.245 0.172 0.248 0.144 -0.151 0.337 Both legs mass per HT2 0.269 0.076 -0.269 0.080 0.172 0.241 -0.136 0.317 Both legs mass per WT 0.591 0.002* -0.417 0.032* 0.283 0.067 -0.330 0.026* Both legs mass per BMI 0.536 0.025* -0.382 0.117 0.379 0.039* -0.368 0.029* ASM 0.182 0.339 -0.218 0.256 0.234 0.212 -0.081 0.640 ASM per HT2 0.200 0.215 -0.231 0.156 0.123 0.440 -0.044 0.762 ASM per WT 0.612 0.008* -0.439 0.063 0.307 0.095 -0.340 0.043* ASM per BMI 0.556 0.054 -0.399 0.175 0.465 0.037* -0.406 0.048*