The Effect of Therapeutic Exercise on Cartilage Morphology and Physical Function for Individuals at High Risk of Knee Osteoarthritis

This randomized controlled trial aims to evaluate the efficacy of progressive resistance exercises (PRE) versus aerobic exercises on cartilage morphology and physical function in patients with degenerative meniscus tears. 54 participants, aged 35-55, will be randomly assigned to one of three groups: PRE, aerobic exercise, or control (standard of care physical and medical therapy). The study will utilize MRI T2 mapping to assess changes in cartilage composition and patient-reported and performance-based measures to evaluate clinical outcomes. This pilot study will also determine the feasibility and issues related to recruitment and retention for a larger trial.

Background: Degenerative meniscus tears are common in individuals over 35 and are associated with early stages of knee osteoarthritis (OA) (1,2). Metabolic and microstructural changes within the cartilage occur before surface breakdown, which can now be detected using advanced MRI techniques such as T2 mapping. Exercise therapy, specifically progressive resistance and aerobic exercises, has shown benefits for knee OA patients, but its effects on early cartilage degeneration are poorly understood.

Objective: The primary objective of this study is to determine the efficacy of PRE and aerobic exercises on the metabolic function and microstructure of cartilage in individuals with degenerative meniscus tears but without radiographic evidence of knee OA. Secondary objectives include evaluating the impact of these exercises on clinical outcomes, such as pain, disability, and physical function, and assessing the feasibility of recruitment and retention for a larger trial.

Methods: The study will enroll 54 participants, who will be randomized into three groups: PRE, aerobic exercise, and control. Each group will undergo a 3-month supervised exercise program. MRI scans will be used to measure changes in cartilage composition, while clinical outcomes will be assessed using patient-reported and performance-based measures.

Intervention Groups:

Group 1 (PRE): Participants will perform progressive resistance exercises focusing on strengthening the quadriceps. The exercises will be adjusted based on the Daily Adjustable Progressive Resistance Exercise (DAPRE) technique.

Group 2 (Aerobic Exercise): Participants will engage in aerobic exercise sessions using a stationary bike, aimed at improving cardiovascular fitness and knee joint mobility.

Group 3 (Control): Participants will receive standard of care, including general strength and balance exercises as per current clinical guidelines.

Assessments:

MRI Imaging: Advanced MRI techniques (T2 mapping) will be used at baseline and after 3 months to assess changes in cartilage composition.

Clinical Outcomes: Patient-reported outcomes will include the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) score. Performance-based outcomes will include the single-leg squat, single-leg hop test, sit-to-stand on a one-foot test, step-up test, and Bruce treadmill test.

Inclusion Criteria:

Adults aged 35-55 years Symptomatic degenerative medial meniscus tears. No radiographic evidence of knee OA (Kellgren-Lawrence grade 0-1). Ability to provide informed consent. Willingness to participate in the exercise intervention.

Exclusion Criteria:

Existing diagnosis of knee OA (Kellgren-Lawrence grade 2 or higher). Repairable meniscus injuries or prior meniscus repair. Previous knee surgery or significant knee injury within the past 6 months. Presence of inflammatory arthritis or other significant comorbidities. Contraindications to MRI or inability to participate in exercise programs.

Study Outcomes:

Primary Outcomes: Changes in T2 relaxation times in the cartilage, indicating alterations in cartilage composition and health.

Secondary Outcomes: Improvements in clinical outcomes, including pain, disability, and physical function as measured by KOOS, IKDC, and performance-based tests.

Feasibility Metrics: Recruitment rates, adherence to the exercise program, and retention rates over the study period.

Analysis: A mixed ANOVA will be used to compare changes in outcomes between groups, with adjustments for multiple comparisons. Baseline characteristics will be compared using t-tests and chi-square tests.

Eligibility Criteria:
Inclusion Criteria:

1. Are between 35 and 55 years of age.
2. Have a symptomatic degenerative medial meniscus tear as evidenced by:

   * Presence of medial knee pain.
   * Medial joint line tenderness.
   * Pain and limited motion when attempting to perform a full squat and
   * Increased intra-meniscal signal on at least 2 consecutive MRI slices and
3. Have clearance from their personal physician to participate in an exercise program.

Exclusion Criteria:

1. Radiographic evidence of OA (K-L grade 2 or above).
2. A repairable meniscus injury (longitudinal tear in the outer 1/3 of the meniscus).
3. A meniscus injury that requires meniscectomy (locked knee).
4. Prior or current ligament injury or surgery of the involved knee.
5. Prior or current injury or surgery to contra-lateral knee.
6. Pathological ligamentous laxity upon examination of the knee
7. An inflammatory arthritic condition or
8. Any injury or condition involving the lower extremities that affects their ability to walk.

Because participation in this study requires undergoing MRI, subjects will be excluded if they:

1. If female, pregnant at the time of enrollment.
2. Had prior surgery for an aneurysm; any medical illness that may interfere with the patient's general fitness or exercise capability.
3. Had any contraindication with MRI.
4. Had surgery within the past two months.
5. Have a cardiac pacemaker.