JMIR Publications

ABSTRACT

Introduction Anterior cruciate ligament (ACL) injury substantially increases the risk of premature post-traumatic knee osteoarthritis (PT-OA), resulting in long-term pain, functional limitations, and reduced quality of life. Despite rehabilitation after ACL reconstruction (ACLR), patients are often insufficiently informed about long-term osteoarthritis risk, and structured secondary prevention strategies remain uncommon. Lifestyle interventions targeting modifiable risk fac-tors, including muscle weakness, physical inactivity, and overweight, may reduce PT-OA risk. However, evidence regarding the feasibility and effectiveness of such interventions remains limited. The Knee Osteoarthritis Avoidance using a Lifestyle Approach (KOALA) was there-fore developed as a theory-informed lifestyle intervention based on previous research in the field. This pilot study evaluates its feasibility and preliminary efficacy to inform future con-firmatory trials. Methods This monocentric single-arm pilot study evaluates a 24-week telemedicine-delivered lifestyle intervention in adults aged 18–40 years undergoing ACLR after acute traumatic ACL rupture. Participants are provisionally enrolled perioperatively and formally included 6 months postop-eratively after confirmation of eligibility. The intervention consists of two 12-week phases (KOALAintense and KOALAboost) and includes knee health education and knee assessment, nutrition education, individualized counselling, and optional supervised group exercise ses-sions. Counselling is informed by motivational interviewing principles and incorporates behav-iour change techniques, including goal setting, action planning, confidence assessment, and barrier management. The primary outcome is intervention attendance. Secondary outcomes include trial-related feasibility (recruitment, retention, and data collection procedures), inter-vention-related feasibility (attendance, treatment fidelity, acceptability, and safety), and ex-ploratory health-related outcomes. Assessments are conducted perioperatively (t0), 6 months after ACLR (t1), and 12 (t2) and 24 weeks (t3) after intervention initiation. Results Funding commenced in May 2025 and was extended in April 2026. As of 29 June 2026, 51 participants had been enrolled perioperatively (t0), exceeding the target sample size (n = 46). Final inclusion at 6 months postoperatively (t6) had been completed for 31 participants, of whom 30 entered the KOALA intervention. A further 12 participants are awaiting final eligi-bility assessment at t6. The current attrition rate between preliminary inclusion (t0) and final inclusion (t6) is 15.7%, and one participant withdrew after final inclusion. The last participant is expected to complete final inclusion (t6) in August 2026, with completion of the interven-tion and final follow-up anticipated by February 2027. Study results are expected in summer 2027. Discussion This feasibility study will determine whether the KOALA intervention achieves sufficient participant engagement to justify further evaluation. Findings will provide insights into inter-vention and trial feasibility and generate preliminary evidence regarding potential efficacy in a German clinical setting. An additional qualitative study is planned to further identify barriers and facilitators to participation and inform the optimization of intervention content, delivery, tailoring, and outcome assessment. If feasibility is demonstrated, the findings of this pilot study, will inform the optimisation of the intervention and study design, as well as the sample size estimation, of a future randomised controlled trial evaluating the efficacy of KOALA.