Comparison of the Effects of Two Different Home Exercise Programs on Femoral Cartilage Thickness and Clinical Parameters in Individuals With Knee Osteoarthritis: A Randomized Controlled Trial

June 14, 2026 updated by: MERVE ARBAY, Pamukkale University

Knee osteoarthritis (OA) is one of the most common joint disorders worldwide and is a leading cause of pain, limited mobility, and functional disability, particularly in the elderly population (1). According to 2020 data, approximately 654 million individuals aged 40 years and older are affected by knee OA worldwide, with a global prevalence of 22.9% in this age group (2). In our country as well, OA is reported as the second most common rheumatologic disease. The disease not only negatively affects individuals' quality of life but also creates a significant socioeconomic burden through work loss, hospital admissions, and the need for surgical interventions (3).

The pathogenesis of knee OA is a complex process involving articular cartilage degeneration, subchondral bone sclerosis, synovial tissue proliferation, and osteophyte formation. Once cartilage damage begins, its capacity for spontaneous healing is extremely limited; therefore, early interventions aimed at slowing or halting disease progression are of critical importance (4,5). In this context, non-pharmacological interventions, particularly exercise programs that may contribute to maintaining cartilage integrity, are strongly recommended as first-line treatment options in current clinical guidelines (6-8).

The beneficial effects of exercise therapy on pain and function in patients with knee OA are well documented. However, the structural effects of exercise on femoral cartilage thickness have been relatively less investigated. Tuna et al. evaluated femoral cartilage thickness using ultrasonography in 40 patients with knee OA following a 12-week quadriceps strengthening program and reported statistically significant increases in cartilage thickness in the medial condyle, lateral condyle, and intercondylar region at 3 months (9). This pioneering study suggests that muscle strengthening programs may have not only symptomatic but also structural benefits. Similarly, Bozan et al. reported a strong positive correlation between quadriceps muscle thickness (rectus femoris + vastus intermedius) and femoral cartilage thickness, supporting the idea that muscle loss parallels cartilage degeneration (10). However, these studies focused exclusively on the quadriceps muscle, and the effects of hip musculature on femoral cartilage thickness have not been investigated. Recent biomechanical studies indicate that hip abductor and adductor muscles play a critical role in knee joint loading patterns.

Hip abductor muscles provide pelvic stability during gait and directly influence knee adduction moments. Weakness of the gluteus medius leads to contralateral pelvic drop, increasing medial compartment loading on the ipsilateral knee and accelerating medial tibiofemoral cartilage wear (11-14). Indeed, Segal et al., using data from the Multicenter Osteoarthritis Study (MOST), demonstrated via MRI that greater hip abductor strength significantly reduces the risk of progression of medial patellofemoral and lateral tibiofemoral cartilage damage (15). On the other hand, hip adductor muscles are also thought to contribute to knee adduction moments by eccentrically controlling femoral varus motion; however, this relationship has been studied far less compared to quadriceps and abductors (13,16-18).

Systematic reviews and meta-analyses have shown that individuals with knee OA have up to 24% lower isometric hip abductor strength compared to healthy controls (13,14,19). Randomized controlled trials investigating combined hip and quadriceps strengthening programs have reported significant improvements in pain and function. However, none of these studies have used femoral cartilage thickness measured by ultrasonography as a primary outcome.

A review of the current literature reveals that although studies exist examining the effects of quadriceps strengthening on femoral cartilage thickness, no randomized controlled trial has compared hip abductor and adductor strengthening exercises with a quadriceps strengthening program, using ultrasonographic femoral cartilage thickness as the primary outcome measure. This study aims to address this gap. All interventions will be applied as non-invasive home exercise programs, and all measurements will be performed using ultrasonography. Baseline, 1-month, and 3-month assessments will also allow evaluation of the temporal effects of exercise on cartilage structure. The findings are expected to provide scientific evidence regarding the structural protective effects of hip exercises in knee OA rehabilitation and serve as pilot data for future large-scale multicenter studies.

The aim of this study is to compare patients with knee OA receiving quadriceps strengthening exercises alone with those receiving additional hip abductor/adductor strengthening exercises in terms of changes in femoral cartilage thickness, and to evaluate whether there is a correlation between femoral cartilage thickness and the thickness of the rectus femoris, gluteus medius,

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

56

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Turkey (Türkiye)
      • Kütahya, Turkey (Türkiye)
        • Kütahya Physical Therapy and Rehabilitation Hospital
        • Contact:
        • Sub-Investigator:
          • Hasan Celtek

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Age ≥18 years
  2. Diagnosis of knee osteoarthritis according to ACR criteria, Kellgren-Lawrence grade 2-3
  3. Knee pain for at least 3 months
  4. Having the physical capacity to perform a home exercise program
  5. Willingness to provide written informed consent

Exclusion Criteria:

  1. History of knee, hip, or spine surgery
  2. Active inflammatory arthritis (e.g., rheumatoid arthritis, gout, psoriatic arthritis)
  3. Intra-articular injection within the last 3 months
  4. Neurological or neuromuscular disorders
  5. Body mass index (BMI) > 40 kg/m²
  6. Pregnancy
  7. Cardiovascular or orthopedic contraindications preventing participation in a regular exercise program
  8. Cognitive impairment

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Quadriceps Plus Hip Strengthening Group

For 3 months, 3 days per week, participants will perform quadriceps strengthening exercises combined with hip abductor and adductor strengthening exercises.

In addition to all exercises included in the Quadriceps Strengthening Group, participants will perform:

Hip abduction (side-lying position with ankle weights) Clamshell exercise (for gluteus medius activation) Hip adduction (supine position with isometric contraction using a pillow) Side-lying hip abduction with a resistance band
Other: Quadriceps Plus Hip Strengthening Exercises
quadriceps strengthening exercises combined with hip abductor and adductor strengthening exercises
Active Comparator: Quadriceps Strengthening Group

For 3 months, 3 days per week, participants will perform a quadriceps strengthening exercise program only.

The program will include:

Knee extension (in a seated position, with and without resistance) Terminal knee extension Straight leg raise Mini squat (0-30° knee flexion)
Other: Quadriceps Strengthening Exercises
quadriceps strengthening exercise program

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Medial femoral condyle cartilage thickness (mm)
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
All ultrasonographic measurements will be performed using a Clarius L7 HD3 linear high-frequency transducer (7.5-12 MHz) with the knee positioned in 90° flexion in a standardized manner. Three measurements will be obtained at each anatomical location, and the mean value will be recorded for analysis.
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Lateral femoral condyle cartilage thickness (mm)
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
All ultrasonographic measurements will be performed using a Clarius L7 HD3 linear high-frequency transducer (7.5-12 MHz) with the knee positioned in 90° flexion in a standardized manner. Three measurements will be obtained at each anatomical location, and the mean value will be recorded for analysis.
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Intercondylar area cartilage thickness (mm)
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
All ultrasonographic measurements will be performed using a Clarius L7 HD3 linear high-frequency transducer (7.5-12 MHz) with the knee positioned in 90° flexion in a standardized manner. Three measurements will be obtained at each anatomical location, and the mean value will be recorded for analysis.
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Ultrasound Femoral Cartilage Degeneration Grade
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).

Evaluation will be performed with the symptomatic knee positioned in maximum flexion.

Cartilage degeneration will be classified as follows:

Grade 1: Blurred margins or partial loss of sharpness without thickness change Grade 2: Blurred margin space with partial loss of sharpness without thickness change Grade 3: Blurred margins with loss of clarity Grade 4: Poorly defined margins with a completely opaque band Grade 5: Evident thickness alteration Grade 6: Cartilage band cannot be visualized
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Synovial Hypertrophy Grade
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).

Ultrasound assessment will be performed in accordance with the EULAR and Outcome Measures in Rheumatology Clinical Trials (OMERACT) guidelines using both longitudinal and axial views.

For evaluation of synovial hypertrophy, the suprapatellar, medial parapatellar, and lateral parapatellar recesses will be scanned with the knee positioned in 30° flexion.

Synovial hypertrophy will be graded as follows:

Grade 0: No synovial thickening Grade 1: Mild synovial thickening Grade 2: Moderate synovial thickening Grade 3: Severe synovial thickening
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Rectus femoris muscle thickness (cm)
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Rectus femoris muscle thickness will be measured with the participant in the supine position and with the hip and knee in extension. The ultrasound transducer will be placed axially over the muscle. Measurements will be obtained at the junction between the lower one-third and upper two-thirds of the distance from the anterior superior iliac spine (ASIS) to the superior pole of the patella, which will serve as the anatomical reference point.
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Gluteus medius (GMed) muscle thickness (cm)
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Participants will be positioned in side-lying with the left leg uppermost. The left hip region will be exposed, and a towel will be placed under the ankle to maintain a neutral alignment of the hip, knee, and ankle joints. To assess the gluteus medius muscle, the ultrasound transducer will be placed longitudinally on the lateral aspect of the hip, just superior to the greater trochanter, at the anterior one-quarter of the line connecting the anterior superior iliac spine (ASIS) and posterior superior iliac spine (PSIS).
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Adductor longus muscle thickness (cm)
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Participants will be positioned in the supine position, with the thigh in abduction and external rotation and the knee flexed to 20-30°. The knee will be supported with a rolled towel. Measurements will be obtained at the junction between the upper one-third and lower two-thirds of the distance from the pubic symphysis to the medial femoral epicondyle, which will serve as the anatomical reference point.
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
Visual Analog Scale (VAS)
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
The Visual Analog Scale is used to assess pain intensity. Participants will be asked to indicate the severity of their knee pain on a scale ranging from 0 (no pain) to 10 (worst imaginable pain) by selecting the point that best represents their pain level.
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
WOMAC Osteoarthritis Index
Time Frame: Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).
The WOMAC Osteoarthritis Index consists of 24 items rated on a 5-point Likert scale. It includes three subscales: pain, stiffness, and physical function. The pain subscale contains 5 items and is scored from 0 to 20. The stiffness subscale includes 2 items and is scored from 0 to 8. The physical function subscale consists of 17 items and is scored from 0 to 68. Higher scores indicate greater pain, increased stiffness, and poorer functional status. The Turkish validity and reliability study of the WOMAC scale was conducted by Tüzün et al.
Participants receiving treatment will be evaluated at baseline (T0), at Month 1 (T1), and at Month 3 (T2).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Pamukkale University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

August 20, 2026

Primary Completion (Estimated)

April 1, 2027

Study Completion (Estimated)

July 1, 2027

Study Registration Dates

First Submitted

June 14, 2026

First Submitted That Met QC Criteria

June 14, 2026

First Posted (Actual)

June 18, 2026

Study Record Updates

Last Update Posted (Actual)

June 18, 2026

Last Update Submitted That Met QC Criteria

June 14, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • PamukkaleU.ftr-MArbayCeltek-01

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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