The Effectiveness of High-intensity Laser Therapy on Post-surgical Rehabilitation After Total Knee Arthroplasty

The Effectiveness of High-intensity Laser Therapy on Post-surgical Rehabilitation: a Randomized Controlled Trial

This randomized controlled trial aims to evaluate the effectiveness of high-intensity laser therapy (HILT) as an adjunct to conventional rehabilitation in patients undergoing total knee arthroplasty (TKA).

Persistent pain and functional limitations are common after TKA despite standard rehabilitation, highlighting the need for adjunctive therapies to optimize postoperative recovery. High-intensity laser therapy has been proposed as a non-invasive intervention with potential analgesic and anti-inflammatory effects; however, its effectiveness in this population remains unclear.

Participants will be randomly allocated to one of two groups: an experimental group receiving HILT in addition to conventional physiotherapy and a control group receiving sham laser therapy combined with the same rehabilitation program. Both groups will undergo standardized rehabilitation sessions lasting 60 minutes, including 15 minutes of active or sham laser therapy and 45 minutes of conventional physiotherapy.

The primary outcome is postoperative pain. Secondary outcomes include joint swelling, range of motion, muscle strength, physical function, and quality of life.

Assessments will be conducted at baseline (preoperative), at 1 month after surgery (prior to the start of rehabilitation), during the rehabilitation program (after the fourth, seventh, and tenth physiotherapy sessions), and at 4 months postoperatively (follow-up).

A total of 46 participants (23 per group) will be enrolled in the study.

Study Overview

• Status: Not yet recruiting
• Conditions: Pain, Postoperative; Arthroplasty Complications
• Intervention / Treatment: Device: High level laser therapy; Other: Sham laser therapy

• Study Type: Interventional
• Enrollment (Estimated): 46
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Lisa Berti, MD; Phone Number: 0516366197; Email: lisa.berti@ior.it

Study Locations

• Italy
  • Bologna, Italy, 40136
    • IRCCS Istituto Ortopedico Rizzoli

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Patients undergoing primary unilateral total knee arthroplasty for primary knee osteoarthritis
• Age between 50 and 80 years
• Pain intensity greater than 30/100 on the Visual Analog Scale (VAS)
• Ability and willingness to provide written informed consent

Exclusion Criteria:

• Psychiatric disorders
• Cognitive impairments
• Previous major trauma or surgery involving the affected knee
• Rheumatic diseases or fibromyalgia
• Vascular diseases
• Neoplastic diseases
• Infectious diseases
• Neurological disorders
• Hemophilia or bleeding disorders
• Current anticoagulant therapy
• Presence of a pacemaker
• History of epileptic seizures
• Known hypersensitivity or contraindication to laser therapy
• Suspected conditions in which tissue heating is contraindicated
• Use of photosensitizing medications or known photosensitivity
• Skin lesions or abrasions at the treatment site
• Tattoos in the treatment area
• Intra-articular steroid injections in the target knee within the previous 2-3 weeks
• Recent significant trauma or injury
• Use of anti-inflammatory or analgesic medications or other pain-relieving treatments (if not controlled or standardized)
• Pregnancy or breastfeeding
• Positive status for human immunodeficiency virus

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High level laser therapy group; High-intensity laser therapy (HILT) will be delivered using the HIRO TT device (ASA S.r.l.), which employs a patented pulsed laser system (FDA-approved in 2003) based on a solid-state Nd:YAG source emitting near-infrared (NIR) radiation at a wavelength of 1064 nm. The device operates with a mean power of 10.5 W and a peak power of 3 kW. Three treatment areas (each measuring 15 × 10 cm) will be targeted: two longitudinal areas over the quadriceps muscle and one transverse area over the knee joint. The treatment will be delivered at a frequency of 15 Hz, with a total energy dose of 2000 J, corresponding to an energy density of 4.5 J/cm². The total treatment time will be 14 minutes and 30 seconds.	Device: High level laser therapy; High-intensity laser therapy (HILT) will be delivered using the HIRO TT device (ASA S.r.l.), which employs a patented pulsed laser system (FDA-approved in 2003) based on a solid-state Nd:YAG source emitting near-infrared (NIR) radiation at a wavelength of 1064 nm. The device operates with a mean power of 10.5 W and a peak power of 3 kW. Three treatment areas (each measuring 15 × 10 cm) will be targeted: two longitudinal areas over the quadriceps muscle and one transverse area over the knee joint. The treatment will be delivered at a frequency of 15 Hz, with a total energy dose of 2000 J, corresponding to an energy density of 4.5 J/cm². The total treatment time will be 14 minutes and 30 seconds.
Sham Comparator: Sham laser therapy group; The sham laser intervention will be delivered using the same HIRO TT device and identical treatment procedures as the active HILT group. The same anatomical areas (two longitudinal areas over the quadriceps muscle and one transverse area over the knee joint) will be targeted, with identical session duration and positioning. During sham treatment, the device will remain switched on; however, no therapeutic laser emission will be delivered. This approach is intended to ensure participant blinding by replicating the visual and procedural aspects of the active intervention without providing any active therapeutic effect.	Other: Sham laser therapy; The sham laser intervention will be delivered using the same HIRO TT device and identical treatment procedures as the active HILT group. The same anatomical areas (two longitudinal areas over the quadriceps muscle and one transverse area over the knee joint) will be targeted, with identical session duration and positioning. During sham treatment, the device will remain switched on; however, no therapeutic laser emission will be delivered. This approach is intended to ensure participant blinding by replicating the visual and procedural aspects of the active intervention without providing any active therapeutic effect.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Visual Analogue Scale	The VAS consists of a 100-mm horizontal line anchored by two descriptors: "no pain" (0 mm) and "worst imaginable pain" (100 mm). Participants will be asked to mark a point on the line corresponding to their perceived level of pain. The score will be determined by measuring the distance in millimeters from the left end of the line to the patient's mark, with higher scores indicating greater pain intensity.	after 3 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Visual Analogue Scale	The VAS consists of a 100-mm horizontal line anchored by two descriptors: "no pain" (0 mm) and "worst imaginable pain" (100 mm). Participants will be asked to mark a point on the line corresponding to their perceived level of pain. The score will be determined by measuring the distance in millimeters from the left end of the line to the patient's mark, with higher scores indicating greater pain intensity.	Baseline, after 1 week, after 2 weeks, after 4 months follow-up
Range of Motion	Knee range of motion (ROM) will be assessed bilaterally, both actively and passively, including maximum flexion and full extension. Measurements will be obtained using a digital goniometer. The axis of rotation will be aligned with the lateral femoral condyle. The stationary arm will be aligned with the longitudinal axis of the femur, using the greater trochanter as a proximal reference point, while the movable arm will be aligned with the longitudinal axis of the fibula, using the fibular head and lateral malleolus as reference points. ROM values will be recorded in degrees, with higher flexion values and lower extension deficits indicating better joint mobility.	Baseline, after 1 week, after 2 weeks, after 3 weeks, after 4 months follow-up
Swelling	Knee swelling will be assessed using circumferential measurements (cm) obtained with a flexible measuring tape. Measurements will be performed with the participant in the supine position and the lower limbs in full extension. Circumference will be recorded at standardized anatomical landmarks: 1 cm below the inferior pole of the patella (knee joint line), 10 cm and 20 cm above the patellar base, and 5 cm below the patellar apex. Two measurements will be taken at each site, and the mean value will be used for analysis. Higher circumference values will indicate greater swelling.	Baseline, after 1 week, after 2 weeks, after 3 weeks, after 4 months follow-up
Lower limb muscle strength	Lower limb muscle strength will be assessed using a handheld dynamometer during isometric knee extension and flexion of the operated limb. Participants will perform three maximal voluntary isometric contractions for each movement, each lasting 5 seconds, with a 30-second rest interval between repetitions. The mean value of the three trials will be used for analysis. For knee extension assessment, participants will be seated with the hip and knee flexed at 90°. For knee flexion assessment, participants will be positioned prone with the knee flexed at 90°. In both conditions, limb positioning will be standardized using a digital goniometer and stabilized with a fixation strap. The dynamometer will be placed at the distal third of the leg, approximately 10 cm proximal to the ankle joint. The device will be manually stabilized by the assessor to ensure consistent positioning and minimize compensatory movements. Higher values will indicate greater muscle strength.	Baseline, after 1 week, after 2 weeks, after 3 weeks, after 4 months follow-up
Western Ontario and McMaster Universities Osteoarthritis Index	The WOMAC is a patient-reported outcome measure specifically designed for individuals with knee osteoarthritis. It consists of three subscales assessing pain, stiffness, and physical function. The physical function subscale includes items related to activities of daily living such as walking, stair use, sitting, and standing. Each item is scored on a Likert scale, and total scores are calculated by summing item responses. Higher scores indicate worse pain, stiffness, and functional limitation.	Baseline, after 1 week, after 2 weeks, after 3 weeks, after 4 months follow-up

Collaborators and Investigators

• Sponsor: Istituto Ortopedico Rizzoli

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): September 1, 2028

Study Registration Dates

• First Submitted: April 28, 2026
• First Submitted That Met QC Criteria: April 28, 2026
• First Posted (Actual): May 5, 2026

Study Record Updates

• Last Update Posted (Actual): May 5, 2026
• Last Update Submitted That Met QC Criteria: April 28, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Rehabilitation; Total knee arthroplasty; Physical therapy; Post-operative pain; Laser therapy; High-level laser therapy
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative
• Other Study ID Numbers: LASER_KNEE

Drug and device information, study documents

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