Feasibility of rehabilitation using the single-joint hybrid assistive limb to facilitate early recovery following total knee arthroplasty: A pilot study

We aimed to evaluate the feasibility of robot-assisted rehabilitation in an early postoperative setting to improve knee mobility following total knee arthroplasty (TKA). A total of 20 patients were alternatively assigned to robotassisted rehabilitation (n = 10; all women) or a control group (n = 10; 2 men and 8 women). The use of a single-joint hybrid assistive limb (HAL-SJ) in active assistive knee exercise was performed for the robot-assisted rehabilitation group while the control patients underwent conventional active assistive knee exercise. We measured the extension lag (defined as the difference between active and passive range of knee extension). We also evaluated the visual analog scale score (VAS) during active movements and active assistive movement. Concerning the extension lag, the robot-assisted rehabilitation group showed 89.4% ± 15.7% improvement (p < 0.01) while the control group showed 34.8% ± 32.1% improvement (p = 0.016). As to the VAS, the robot-assisted rehabilitation group showed 40.7% ± 23.5% improvement while the control group showed 20.4% ± 25.8% improvement (p < 0.01). The use of HAL-SJ may facilitate early recovery from knee surgery and prevent long-term complications such as quadriceps arthrogenic muscle inhibition.