Bilateral Quadriceps Muscle Strength Correlate with Gait Speed and Endurance Early after Unilateral Total Knee Arthroplasty : A Cross-Sectional Study

Abstract

Background: The objective of this study was to determine the associations between objective performance-based physical function and gait function 1 month after unilateral total knee arthroplasty (TKA). Methods: Cross-sectional data from one-hundred and ninety-five patients who underwent a unilateral primary TKA were enrolled in this study. Two weeks after TKA, all patients were transferred to the rehabilitation department and performed rehabilitation program for a 2-week period. The isometric knee extensor and flexor strength of both surgical and nonsurgical knees, gait parameters, 6 minute walk test (6MWT), timed up-and-go (TUG) test, timed stair climbing test (SCT), knee flexion range of motion (ROM) and extension ROM of surgical knee, Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) pain, stiffness, and functional levels, EuroQol five-dimensions (EQ-5D) questionnaire and visual analog scale (VAS) were assessed 1 month after TKA. Results: In the bivariate analyses, postoperative gait speed had a significant positive correlation with postoperative peak torque (PT) of the extensor of the surgical knee (r = 0.35, p < 0.001), postoperative PT of the extensor of the non-surgical knee (r = 0.43, p < 0.001), postoperative PT of the flexor of the surgical knee (r = 0.22, p < 0.001), postoperative PT of the flexor of the non-surgical knee (r = 0.21, p = 0.003), 6MWT, cadence, stride length, and a significant negative correlation with TUG, SCT-ascent, SCT-descent, VAS, WOMAC pain, stiffness, and function score. The postoperative gait endurance had a significant positive correlation with postoperative PT of the extensor of the surgical knee (r = 0.36, p < 0.001), postoperative PT of the extensor of the non-surgical knee (r= 0.49, p < 0.001), postoperative PT of the flexor of the surgical knee (r = 0.25, p < 0.001), postoperative PT of the flexor of the non-surgical knee (r = 0.34, p < 0.001), gait speed, cadence, stride length, EQ5D, and a significant negative correlation with TUG, SCT-ascent, SCT-descent, VAS, and WOMAC pain, stiffness, and function scores. In the linear regression analyses, the postoperative PT of the extensors of the surgical knee (β = 0.16, p = 0.04) and non-surgical knee (β = 0.27, p < 0.001) and VAS (β = −0.15, p = 0.03) were factors associated with postoperative gait speed (R2 = 0.25). The postoperative PT of the extensors of the surgical knee (β = 0.15, p = 0.04) and non-surgical knee (β = 0.38, p < 0.001) and VAS (β = −0.13, p = 0.03) were factors associated with postoperative endurance (R2 = 0.33). Conclusion: These results demonstrate that the quadriceps muscle strength of both surgical and non-surgical knees significantly associate with gait speed and endurance 1 month after unilateral TKA.