Effects of High-Intensity Laser Therapy Combined With Exercise in Patients With Knee Osteoarthritis (HILT-KOA)

Effects of High-intensity Laser Therapy on Muscle Strength in People With Knee Osteoarthritis

The goal of this clinical trial was to determine whether high-intensity laser therapy (HILT) combined with exercise improves pain, physical function, and muscle strength in people with knee osteoarthritis.

The main questions the study aimed to answer were:

• Did HILT combined with exercise lower pain more than sham laser combined with exercise?
• Did HILT combined with exercise improve physical function more than sham laser combined with exercise?
• Did HILT combined with exercise improve knee extensor muscle strength more than sham laser combined with exercise?

Researchers compared HILT plus exercise with sham laser plus exercise to determine whether HILT provided additional benefits beyond those achieved with exercise alone.

Participants:

• Received either HILT or sham laser treatment for four weeks.
• Participated in a standardized exercise program.
• Completed assessments of pain, physical function, and muscle strength before and after treatment.

Study Overview

• Status: Completed
• Conditions: Osteoarthritis (OA) of the Knee; Osteoarthritis in the Knee; Osteoarthritis (Knee); Osteoarthritic Knee Pain; Osteoarthitis; Osteo Arthritis of the Knee
• Intervention / Treatment: Device: High Intensity Laser Therapy; Other: Exercise; Device: Sham Laser

Detailed Description

Knee osteoarthritis is a common musculoskeletal condition associated with pain, reduced physical function, and muscle weakness. Exercise therapy is widely recommended as a first-line treatment; however, the additional benefits of high-intensity laser therapy (HILT) remain uncertain. Previous studies have reported improvements in pain and function following HILT, but results have been inconsistent, and its effects on muscle strength have not been fully established.

The purpose of this randomized, participant-blinded, sham-controlled clinical trial was to evaluate the effects of HILT combined with exercise on pain, physical function, and knee extensor muscle strength in people with knee osteoarthritis.

Participants with clinically diagnosed knee osteoarthritis were randomly assigned to one of two groups. The experimental group received HILT combined with a standardized exercise program, while the control group received sham laser treatment combined with the same exercise program. The intervention lasted four weeks and included ten treatment sessions.

Pain intensity, physical function, and knee extensor muscle strength were assessed before and after the intervention using validated clinical outcome measures. The primary objective was to determine whether HILT provides additional benefits beyond those achieved with exercise alone.

The findings of this study may help clarify the role of HILT as an adjunct treatment in rehabilitation programs for people with knee osteoarthritis and contribute to the development of evidence-based clinical recommendations.

• Study Type: Interventional
• Enrollment (Actual): 31
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Chile
  • Santiago Metropolitan
    • Santiago, Santiago Metropolitan, Chile, 7760197
      • Departamento de Kinesiología

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Clinical diagnosis of knee osteoarthritis.
• Age between 45 and 77 years.
• Pain intensity of at least 3 points on the Visual Analogue Scale (VAS).

Exclusion Criteria:

• Presence of other musculoskeletal conditions affecting the lower limbs.
• History of lower limb surgery.
• Tattoos in the laser application area.
• Recent intra-articular corticosteroid injection.
• Comorbidities limiting participation in physical exercise, such as chronic obstructive pulmonary disease, stroke, or severe heart failure.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High Intensity Laser Therapy + Exercise; Participants received high-intensity laser therapy (HILT) combined with a standardized exercise program. HILT was delivered using an MLS laser device (MPHI D, ASA Laser, Italy) over four periarticular knee application points during 10 treatment sessions over four weeks. The exercise program included strengthening, flexibility, and balance exercises and was identical to that provided to the sham comparator group.	Device: High Intensity Laser Therapy; High-intensity laser therapy (HILT) was delivered using an MLS laser device (MPHI D, ASA Laser, Italy), which combines synchronized 808 nm and 905 nm wavelengths. Treatment was applied to four periarticular knee regions, including the medial and lateral patellar borders, the suprapatellar region, and the medial tibiofemoral joint line. Participants received 10 treatment sessions over four weeks. HILT was administered in combination with a standardized exercise program.; Other Names: Photobiomodulation; HILT; MLS Laser Therapy; Laser Therapy; Other: Exercise; The exercise program was performed during each treatment session and included strengthening, flexibility, and balance exercises targeting the lower extremities. Exercises included stationary cycling, hamstring and gastrocnemius stretching, straight-leg raises, knee extensions, heel raises, step-ups, and single-leg balance activities. The program was standardized for both study groups and was delivered over 10 sessions during a four-week period.; Other Names: Therapeutic exercise; Rehabilitation exercise; Exercise Program; Physical Therapy exercise
Sham Comparator: Sham Laser + Exercise; Participants received sham laser treatment combined with the same standardized exercise program used in the experimental group. Sham treatment was delivered using the same laser device and treatment schedule as the active intervention but with subtherapeutic parameters designed to maintain participant blinding. The intervention consisted of 10 treatment sessions over four weeks. The exercise program included strengthening, flexibility, and balance exercises.	Other: Exercise; The exercise program was performed during each treatment session and included strengthening, flexibility, and balance exercises targeting the lower extremities. Exercises included stationary cycling, hamstring and gastrocnemius stretching, straight-leg raises, knee extensions, heel raises, step-ups, and single-leg balance activities. The program was standardized for both study groups and was delivered over 10 sessions during a four-week period.; Other Names: Therapeutic exercise; Rehabilitation exercise; Exercise Program; Physical Therapy exercise; Device: Sham Laser; Sham laser treatment was delivered using the same laser device, treatment schedule, and application sites as the active intervention. Subtherapeutic parameters were used to mimic the treatment procedure while minimizing biological effects and maintaining participant blinding. Participants received 10 treatment sessions over four weeks in combination with the same standardized exercise program used in the experimental group.; Other Names: Sham Laser Therapy; Placebo Laser; Sham High Intensity Laser Therapy

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Knee Extensor Muscle Strength After 4 Weeks of Treatment	Change in knee extensor muscle strength measured with a dynamometer. Results were expressed in Newtons (N). Higher values indicate greater muscle strength.	Baseline and Week 4

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Pain Intensity After 4 Weeks of Treatment	Change in pain intensity measured using the Visual Analogue Scale (VAS). Scores range from 0 to 10, with higher scores indicating greater pain intensity.	Baseline and Week 4
Change From Baseline in WOMAC Total Score After 4 Weeks of Treatment	Change in symptoms and functional status measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Higher scores indicate greater impairment.	Baseline and Week 4

Collaborators and Investigators

• Sponsor: Universidad Metropolitana de Ciencias de la Educacion
• Investigators: Principal Investigator: Ivan Patricio Silva-Satlov, Magister, Universidad Metropolitana de Ciencias de la Educación

Publications and helpful links

General Publications

• Song HJ, Seo HJ, Kim D. Effectiveness of high-intensity laser therapy in the management of patients with knee osteoarthritis: A systematic review and meta-analysis of randomized controlled trials. J Back Musculoskelet Rehabil. 2020;33(6):875-884. doi: 10.3233/BMR-191738.
• Akaltun MS, Altindag O, Turan N, Gursoy S, Gur A. Efficacy of high intensity laser therapy in knee osteoarthritis: a double-blind controlled randomized study. Clin Rheumatol. 2021 May;40(5):1989-1995. doi: 10.1007/s10067-020-05469-7. Epub 2020 Oct 19.
• Jang S, Lee K, Ju JH. Recent Updates of Diagnosis, Pathophysiology, and Treatment on Osteoarthritis of the Knee. Int J Mol Sci. 2021 Mar 5;22(5):2619. doi: 10.3390/ijms22052619.
• Siriratna P, Ratanasutiranont C, Manissorn T, Santiniyom N, Chira-Adisai W. Short-Term Efficacy of High-Intensity Laser Therapy in Alleviating Pain in Patients with Knee Osteoarthritis: A Single-Blind Randomised Controlled Trial. Pain Res Manag. 2022 Oct 21;2022:1319165. doi: 10.1155/2022/1319165. eCollection 2022.

Study record dates

Study Major Dates

• Study Start (Actual): November 29, 2023
• Primary Completion (Actual): August 26, 2025
• Study Completion (Actual): August 26, 2025

Study Registration Dates

• First Submitted: June 1, 2026
• First Submitted That Met QC Criteria: June 1, 2026
• First Posted (Actual): June 5, 2026

Study Record Updates

• Last Update Posted (Actual): June 5, 2026
• Last Update Submitted That Met QC Criteria: June 1, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Rehabilitation; Pain; Randomized Controlled Trial; Physical Function; Knee Osteoarthritis; Musculoskeletal Disorders; Photobiomodulation; Laser Therapy; High Intensity Laser Therapy; HILT; Excercise Therapy; Músculo Strength
• Additional Relevant MeSH Terms: Neurologic Manifestations; Arthritis; Joint Diseases; Rheumatic Diseases; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain; Osteoarthritis; Osteoarthritis, Knee; Musculoskeletal Diseases; Motor Activity; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Therapeutics; Surgical Procedures, Operative; Physical Therapy Modalities; Patient Care; Rehabilitation; Aftercare; Continuity of Patient Care; Physical Conditioning, Human; Phototherapy; Ablation Techniques; Exercise; Exercise Therapy; Resistance Training; Low-Level Light Therapy; Laser Therapy
• Other Study ID Numbers: 422/2023

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the results reported in publications arising from this study will be available upon reasonable request. Data that support the primary and secondary outcome analyses, including pain, functional status, and muscle strength measurements, may be shared after publication of the primary study results. Requests will be evaluated by the Principal Investigator and must include a scientifically sound research proposal. All shared data will be fully de-identified to protect participant confidentiality.
• IPD Sharing Time Frame: Individual participant data and supporting documents will be available beginning 6 months after publication of the primary study results and will remain available for 5 years thereafter.
• IPD Sharing Access Criteria: Researchers who provide a methodologically sound research proposal may request access to de-identified individual participant data and supporting documents. Requests should be directed to the Principal Investigator. Data will be shared only after review and approval of the proposed use and may require a data sharing agreement to protect participant confidentiality and ensure appropriate use of the data.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No