Enhancing Medial Knee Pain Rehabilitation : A Clinical Trial On The Effectiveness Of Blood Flow Restriction In Combination With Targeted Exercises For Adult With Varus Deformity

Medial knee pain in the presence of varus malalignment is a frequent clinical presentation in active adults and is strongly associated with increased medial compartment loading, progressive cartilage degeneration, and an elevated risk of symptomatic knee osteoarthritis. In patients with persistent symptoms and structural progression, realignment surgery such as high tibial osteotomy (HTO) is considered when the hip-knee-ankle (HKA) angle exceeds approximately 3° of varus and is often recommended at 5°-6° or more of symptomatic varus in relatively young, active individuals with preserved lateral compartment cartilage. In this context, mild, moderate, and severe varus deformities have been described in the literature as roughly 3°-5°, 6°-8°, and ≥9° of varus alignment, respectively. For many patients, however, there is a substantial window in which optimized conservative management could delay or possibly reduce the need for surgical realignment while improving pain and function.

Conventional physiotherapy and strengthening programs for medial knee pain and early knee osteoarthritis typically emphasize quadriceps and general lower-limb strengthening, flexibility, and neuromuscular training. These approaches can reduce pain and improve function but may not always achieve optimal muscle adaptation because patients often cannot tolerate high-load resistance exercise due to joint pain or fear of aggravating symptoms. As a result, clinicians are frequently constrained to suboptimal loading intensities, which may limit gains in strength and neuromuscular control that are needed to better support the varus knee and potentially reduce medial compartment load during everyday and sports activities.

Blood flow restriction (BFR) training has emerged as a promising adjunct in musculoskeletal rehabilitation, enabling meaningful improvements in muscle strength and hypertrophy at relatively low external loads. By applying a pneumatic cuff to partially restrict venous outflow while maintaining arterial inflow, BFR produces a metabolic and mechanical environment that mimics high-load training, but with considerably less joint stress. This is particularly relevant in populations with painful knee osteoarthritis or varus deformity, where high-load training is often poorly tolerated. Recent trials in knee osteoarthritis populations suggest that low-load BFR-enhanced exercise can lead to clinically important improvements in pain, muscle strength, and quality of life compared with similar exercise performed without BFR. However, the specific role of BFR in active adults with medial knee pain and varus malalignment has not been adequately explored.

This randomized controlled trial is designed to compare a targeted lower-limb strengthening and neuromuscular program alone with the same program combined with BFR in active adults with medial knee pain, mild to moderate varus deformity, and radiographic knee osteoarthritis (Kellgren-Lawrence grade 1-3). Eligible participants will be recruited from an outpatient physical therapy setting and will meet predefined clinical and radiographic criteria (detailed in the Eligibility section), including age range, body mass index, degree of varus malalignment on long-leg radiographs, and activity level. The sample size was determined a priori using G*Power to detect a moderate effect size in repeated-measures analyses with two groups and multiple time points, with additional allowance for attrition to yield an enrollment target of approximately 80 participants.

Participants will be allocated in a 1:1 ratio to either a control group receiving a specific exercise program or an experimental group performing the same exercises with the addition of BFR. The specific exercise program is designed to address key muscle groups that contribute to frontal-plane control and dynamic alignment of the lower limb, with a particular focus on the hip adductors, abductors, internal rotators, and knee extensors. Exercises will be delivered in a progressive manner over a 6-week supervised intervention period in the outpatient clinic, with standardized progression criteria and an accompanying home-exercise component to reinforce clinic-based training.