Importance: Even without evidence, rehabilitation practitioners continue to introduce new interventions to enhance the mobility outcomes for the increasing population with a recent total knee arthroplasty (TKA).

Objective: To compare post-TKA functional mobility outcomes among 3 newly developed physical therapy protocols with a standard-of-care post-TKA rehabilitation protocol.

Design, setting, and participants: This randomized clinical trial included 4 study arms implemented in 15 outpatient clinics within a single health system in the Baltimore, Maryland, and Washington, District of Columbia, region from October 2013 to April 2017. Participants included patients who underwent elective unilateral TKA, were aged 40 years and older, and began outpatient physical therapy within 24 days after TKA. A total of 505 patients were screened and 386 participants were enrolled. Patients provided informed consent and were randomly assigned to 1 of 4 groups. Blinding patients and treating therapists was not feasible owing to the nature of the intervention. Analysis was conducted under the modified intent-to-treat principle from October 2017 to May 2019.

Interventions: The control group used a standard recumbent bike for 15 to 20 minutes each session. Interventions used 1 of 3 modalities for 15 to 20 minutes each session: (1) a body weight-adjustable treadmill, (2) a patterned electrical neuromuscular stimulation device, or (3) a combination of the treadmill and electrical neuromuscular stimulation.

Main outcomes and measures: Outcomes included the Activity Measure for Post-acute Care basic mobility score, a patient-reported outcome measure, and the 6-minute walk test. Outcomes were measured at baseline, monthly, and on discharge from outpatient therapy.

Results: Data from 363 patients (mean [SD] age, 63.4 [7.9] years; 222 [61.2%] women) were included in the final analysis, including 92 participants randomized to the control group, 91 participants randomized to the treadmill group, 90 participants randomized to the neuromuscular stimulation device group, and 90 participants randomized to the combination intervention group. Activity Measure for Post-acute Care scores at discharge were similar across groups, ranging from 61.1 to 61.3 (P = .99) with at least 9.0 points improvement (P = .80) since baseline. The distances as measured by the 6-minute walking test were not statistically different across groups (range, 382.9-404.5 m; P = .60).

Conclusions and relevance: This randomized clinical trial found no statistically or clinically significant differences in outcomes across the 4 arms. Because outcomes were similar among arms, clinicians should instead consider relative cost in tailoring TKA rehabilitation.

Trial registration: ClinicalTrials.gov Identifier: NCT02426190.

Muscle inactivity reduces muscle protein synthesis (MPS), whereas a subsequent period of rehabilitation resistance training (retraining) increases MPS. However, less is known regarding muscle protein breakdown (MPB) during such conditions. Furthermore, nonsteroidal anti-inflammatory drugs (NSAIDs) may have a dampening effect on MPB during periods of inactivity in older individuals. Thus, we measured the average MPB, by use of the deuterated water methodology, during an immobilization period and a subsequent retraining period in older individuals with and without NSAID treatment. Eighteen men (60-80 years: range) were randomly assigned to ibuprofen (1200 mg/d, Ibu) or placebo (Plc). One lower limb was immobilized in a cast for 2 weeks and retrained for 2 weeks, and 2 × 20 g of whey protein was ingested daily during both periods. Besides MPB, the protein expression of different muscle degradation signaling molecules was investigated. MPB was lower during immobilization compared to retraining (p < 0.01). NSAID treatment did not affect the MPB rate during immobilization or retraining (p > 0.05). The protein expression of muscle degradation signaling molecules changed during the study intervention but were unaffected by NSAID treatment. The finding that MPB was lower during immobilization than during retraining indicates that an increased MPB may play an important role in the muscle protein remodeling processes taking place within the initial retraining period. Moreover, NSAID treatment did not significantly influence the MPB rate during 2 weeks of lower limb immobilization or during 2 weeks of subsequent retraining in older individuals.