Investigation of Sarcopenia in Patients With Knee Osteoarthritis and the Effect of Low-Level Laser Therapy on Sonographically Measured Femoral Cartilage and Quadriceps Thickness, Clinical Outcomes, and Regional Sarcopenia

It was designed as a single-center, prospective, randomized controlled study. The study consists of two groups. Both groups of patients will receive a conventional home based exercise program.

In addition to the conventional exercise program, patients in the first group will also receive low-level laser therapy (LLLT). If the laser group is found to be superior at the end of the study, the patients who only received the exercise program will be recalled and administered LLLT. Patients who meet the inclusion criteria will be enrolled in the study.

Sample size calculations were based on data from a previous study by Alghadir et al. Using a mean of 3.25 and a standard deviation of 2.61 for the WOMAC pain subscale, the number of participants was calculated with 95% power and a 5% significance level. As a result, it was determined that at least 29 patients would be included in each group. Written informed consent will be obtained from each patient before enrollment. Randomization will be performed according to the order of patient admissions. Patients will be evaluated before treatment, and at the 1st and 3rd months post-treatment.

The dosage of laser application was selected based on the recommendations of the World Association for Photobiomodulation Therapy (WALT). Patients will be treated 5 sessions per week for 2 weeks. The treatment will be applied using the BTL SMART 4000 laser device at a wavelength of 835 nm and a dose of 10 J/point.

The conventional home based exercise program includes: range of motion (ROM) exercises, stretching, strengthening, relaxation and aerobic exercises. The program will begin with ROM, stretching, relaxation, aerobic, and isometric strengthening exercises. After one week, concentric and eccentric strengthening exercises will be added using elastic bands. The home exercise program will be performed 3 days a week, each exercise in 3 sets of 10 repetitions and 2 minutes of rest between sets. Aerobic walking at a moderate pace for 30 minutes will be recommended. Each patient will be shown and taught the exercises to be performed at home, and will also be provided with illustrated instructions. The home based exercise program will continue for 12 weeks. Patients will be contacted by phone weekly during the first month, and then every two weeks thereafter, to assess their adherence to and continuation of the home based exercise program.

Before starting treatment, demographic information will be collected, medical history will be taken, and a physical examination will be performed. Pre-treatment evaluations include:

• Measurement of height, weight, and calculation of body mass index (BMI)
• Femoral cartilage thickness and quadriceps muscle thickness measurement via ultrasound
• Determination of the Sonographic Thigh Adjustment Ratio (STAR)
• Application of the SARC-F screening test; those scoring over 4 will undergo whole-body muscle mass measurement
• Handgrip strength (HGS) measurement using a Jamar hand dynamometer
• Five-times chair stand test (CST)
• Timed Up and Go (TUG) test
• Six-minute walk test
• Visual Analog Scale (VAS) for pain
• Western Ontario and McMaster Universities Arthritis Index (WOMAC)
• Short Form-36 (SF-36) quality of life questionnaire

Post-treatment evaluations (At the end of the 1st month and at the end of the 3rd month) include:

• Calculation of body mass index (BMI)
• Femoral cartilage thickness and quadriceps muscle thickness (USG)
• STAR index calculation
• Handgrip strength using Jamar dynamometer
• Five-times chair stand test
• Timed Up and Go test
• Six-minute walk test
• Visual Analog Scale (VAS) for pain
• WOMAC
• SF-36 Quality of Life Questionnaire