Rate of torque development is the primary contributor to quadriceps avoidance gait following total knee arthroplasty.

Only 24 participants completed, from 119 screened; 54 were unable to contact or not interested, and 41 were excluded, so the sample was small and selected. Participants had to be able to walk at least 10 minutes without an assistive device and had no neurological or balance disorder requiring an assistive device, so more impaired total knee replacement patients were not represented. Rehabilitation was not controlled or monitored; total visits, frequency, and activities were decided by the surgeon and treating clinician, so differences in care may have affected outcomes. Preoperative strength, function, gait, pain, symptom duration, and physical activity level were not measured, so baseline differences cannot be accounted for. The regression considered only 16 predictors, and the authors note other contributors may influence knee flexion excursion. Rate of torque development was sampled at 100 Hz, less than the minimum 1000 Hz typically recommended, which may have affected identification of contraction onset. The authors state that statistically significant improvements were not clinically meaningful: mean five-time sit-to-stand improvement was 1.6 seconds within the 2.5-second minimal detectable change, and mean Knee Injury and Osteoarthritis Outcome Score Pain and Activities of Daily Living improvements were 6.6 and 4.8 points, below the 8 to 10 point threshold they cite. This was an observational cohort and regression study, so it identifies associations rather than proving that quadriceps rate of torque development, pain, or hip strength caused the gait pattern or that treating them would change gait.

The paper is listed as supported by NIH extramural research. The article text does not include an author conflict-of-interest declaration.

Do not conclude that training quadriceps rate of torque development will improve gait after total knee replacement. This was an observational cohort study with no randomised intervention, and the regression only identified factors associated with knee flexion excursion.