Effect of lower-limb isokinetic muscle strengthening on knee function and joint contact force in knee osteoarthritis patients awaiting total knee arthroplasty: study protocol for a randomized controlled trial.

Background: Knee osteoarthritis (OA) is a common and serious joint disease and patients mainly suffer from knee pain and dysfunction, significantly impacting their quality of life and daily activities. Non-pharmacological treatments and total knee arthroplasty (TKA) are the two major treatments for knee OA. TKA is the primary treatment for severe knee OA patients, however, the postoperative rehabilitation results are not entirely satisfactory. To enhance postoperative rehabilitation outcomes, preoperative lower-limb muscle strengthening has aroused attention and demonstrated significant results on functional recovery after TKA. Specifically, isokinetic muscle strengthening (IMS) has been highly anticipated as an efficient training method. Nevertheless, its effects in perioperative and long-term periods of TKA require further investigation. This study aims to evaluate the impact of preoperative lower-limb IMS during the 4 weeks before TKA on the perioperative and postoperative outcomes, with particular attention on knee function, pain, and inflammatory response.

Methods: In this study, 104 patients awaiting TKA will be randomized to 2 groups: the IMS and health education groups. All patients will be evaluated at baseline, post-intervention, discharge day, and postoperative day 14, with follow-up assessments at 6 weeks, 3, 6, and 12 months after discharge. The primary outcome will be the Knee Injury and Osteoarthritis Outcome Score 3 months after TKA and the medial-to-lateral knee contact force ratio. The secondary outcomes will be changes in lower-limb muscle strength, knee pain, inflammation response, active range of motion, performance-based function (5-times Sit-to-Stand Test, Time Up-and-Go Test, 3 m walking speed), Berg Balance Scale, and surgical need.

Discussion: Lower-limb IMS can improve muscle strength, pain, and function for early knee OA patients. However, the effects of different doses of IMS on perioperative and postoperative knee pain, inflammation response, and function after TKA are inconclusive. This study will provide high-quality evidence to assess the efficacy of IMS in end-stage patients who will undergo TKA. Understanding IMS in end-stage knee OA patients will help guide future surgical management for this population. Trial Registration Chinese Clinical Trial Registry ChiCTR2400088136.