Effect of Laser Therapy on Chronic Osteoarthritis of the Knee in Older Subjects

By Sidney Jones, SPT


Osteoarthritis (OA) is a common degenerative joint disease that is usually associated with pain, limited range of motion, muscle weakness, difficulty with activities of daily living and impaired quality of life. The knee is the most common joint in the body affected by osteoarthritis. Low-level laser therapy has been studied and used for pain control, anti-inflammatory effects and its healing efficacy. The purpose of this study was to determine the effects of adding low-level laser therapy (LLLT) to an exercise training program on pain severity, joint stiffness, physical function, isometric muscle strength, knee range of motion, and quality of life in older subjects with knee OA.


Men and women between 60-72 years old with chronic osteoarthritis according to the American College of Rheumatology (ACR) criteria grades II & III and knee OA according to the Kellgren-Lawrence grade. Participants also had to have the ability to stand independently and willingness to participate in the study.

Methods – laser therapy treatment

Group1: 18 subjects 7 males & 11 females were treated with a laser dose of 6 J/cm² over 8 points around the knee. Each point received energy of 6 J/point for 60 seconds.

Group 2: 18 subjects 6 males & 12 females were treated with a laser dose of 3 J/cm² on 9 points around the knee. Each point received energy of 3 J/point for 50 seconds.

Group 3: 15 subjects 5 males & 10 females participated as the control group. Procedure was identical but without emission of energy.

Exercise Training Program

All participants in each group participated in the same exercise training program for 30 to 45-minute sessions 2 times a week for 8 weeks. The program included stretching the quadriceps, hamstrings, adductors, and calf muscles. Strengthening exercises included knee extension, straight leg raises and quadriceps setting. All participants were instructed to practice these exercises as a home program.

Each participant was evaluated pre and post 8 weeks of physical therapy interventions on:

  • Pain intensity with Visual Analogue Scale (VAS)
  • Physical function with Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).
  • Knee range of motion, active knee flexion range of motion was measured with long arm universal goniometer.
  • Isometric strength of knee flexor and extensor muscles was measured using Handheld Dynamometer


The best improvements in VAS, WOMAC pain, knee range of motion and physical function were seen in patients who were treated with 6 J/cm² then 3 J/cm² and then placebo group. Mean values for WOMAC significantly reduced, which means improved physical function. Isometric strength of the quadriceps and hamstring muscles increased significantly in each group after interventions. The largest increase in isometric strength of the quadriceps and hamstring muscles and knee flexion range of motion was seen in patients who received 6 J/cm² followed by 3 J/cm² and then the placebo group. Mean values of knee flexion range of motion increased significantly after physical therapy interventions in each group with significant differences among the 3 groups.

Discussion about adding laser therapy

The current study suggests that adding LLLT to exercise training program could be an important modality for treating older adults with OA than exercise training alone. The active laser groups either 6 J/cm² or 3 J/cm² had a significant reduction of pain intensity in VAS and WOMAC, increase in physical function, increase in isometric quadriceps and hamstring muscle strength, and increase in range of motion after treatment of knee OA.


Adding LLLT to an exercise training program is more effective than exercise training alone in treatment of patients with chronic knee OA and the rate of improvement may be dose dependent, as with 6 J/cm² or 3 J/cm².

PTF Approach to adding laser therapy 

Here at Physical Therapy First, we perform a complete evaluation and based on those findings we design a treatment plan that best addresses our patient’s needs. Our goal is to provide quality patient care and as this study suggests, multiple interventions can and should be used to treat knee osteoarthritis simultaneously. At Physical Therapy First, laser therapy and strengthening are options along with several other interventions such as soft tissue mobilization, stretching and providing our patients with a home exercise program to maximize outcomes.

Original Article about Laser Therapy

Youssef, E. F., Muaidi, Q. I., & Shanb, A. A. (2016). Effect of Laser Therapy on Chronic Osteoarthritis of the Knee in Older Subjects. Journal of Lasers in Medical Sciences,7(2), 112-119. doi:10.15171/jlms.2016.19