ObjectiveTotal knee arthroplasty (TKA) is aimed mainly at reducing pain and restoring mobility. However, mobility deficits can persist even longer than 1 year. The trunk function and movement velocity of any region have been recently recognized to be critical for determining mobility in older people. Therefore, the main goal of this quasi-randomized trial is to clarify the effectiveness of a novel training method, the seated side tapping (SST) training, for improving mobility by focusing on movement velocity of trunk function in the short term after TKA.MethodsSST training consists of side trunk movements repeated as quickly as possible in a seated position. All participants after TKA were randomly assigned to the SST training group (n = 37) or control training group (n = 38). The participants in the SST group performed SST training plus the standard rehabilitation program 5 days per week for 3 weeks after TKA, while the control group performed only the standard rehabilitation programs. The primary outcome was the effect of SST training on mobility, indicated by gait speed and the timed up and go test (TUG) time. Measurements were performed before and 1, 2, and 3 weeks after surgery.ResultsAt all-time points, the patients in the SST group showed significantly better mobility, despite that knee function, represented by muscle strength, range of motion, and degree of pain at the knee joint, was similar in both groups. The difference in gait speed between the groups was >0.1 m/s at all time points, which is clinically significant.ConclusionSST training significantly improved patients’ mobility within 3 weeks after TKA, despite that no additional benefit was observed in knee function. The findings in this study indicate that SST training may be considered as a part of the rehabilitation program after TKA, although further evaluation of its long-term effectiveness is needed.Trial registrationUniversity Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR; UMIN000027909).

[Purpose] Improved quadriceps strength is a primary target of rehabilitation early after total knee arthroplasty. However, patients demonstrate varying improvement trends in gait function and quadriceps strength. This study evaluated the relationship between improvements in quadriceps strength and gait function. [Participants and Methods] The study included 49 patients who were scheduled to undergo unilateral total knee arthroplasty. Gait function, bilateral quadriceps strength, and pain were assessed in all patients. All assessments were performed preoperatively and at 2 and 3 weeks postoperatively. [Results] A significant correlation between gait function and the quadriceps strength on the operated side was observed preoperatively and 3 weeks postoperatively. The quadriceps strength on the non-operated side was significantly correlated with gait function at all time points. Multiple regression analysis showed that the quadriceps strength on the non-operated side was significantly associated with gait function, except the gait speed at 2 weeks. However, the quadriceps strength on the operated side was not observed to be an independent variable at all time points. [Conclusion] The quadriceps strength on the operated side is not an important determinant of gait function. It may be necessary to reconsider typical rehabilitation programs by focusing on the quadriceps strength on the operated side in patients undergoing total knee arthroplasty.