Phase 3 trials of enhanced versus usual care physical therapy for patients at risk of poor outcome following knee arthroplasty: a perspective on meaning and a way forward

Physical therapy is routinely delivered to patients after discharge from the hospital following knee arthroplasty. Posthospitalization physical therapy is thought to be beneficial, particularly for those patients most at risk of poor outcome, the subgroup with persistent function-limiting pain, despite an apparently successful surgery. Research teams have undertaken 3 large-scale multicenter Phase 3 randomized clinical trials designed specifically for patients at risk of poor outcome following knee arthroplasty. All 3 trials screened for poor outcome risk using different methods and investigated different physical therapist interventions delivered in different ways. Despite the variety of types of physical therapy and mode of delivery, all trials found no effects of the enhanced treatment compared with usual care. In all cases, usual care required a lower dosage of physical therapy compared with the enhanced interventions. This Perspective compares and contrasts the 3 trials, speculates on factors that could explain the no-effect findings, and proposes areas for future study designed to benefit the poor outcome phenotype.