Key takeaways.
- Nine studies of laser in knee osteoarthritis all reported positive effects on pain, with moderate overall evidence quality.
- The reviewers' conclusion was explicit: best used in combination with exercise.
- Frozen shoulder has sham-controlled randomised evidence, the strongest study design available for it.
- Laser does not regrow cartilage or reverse arthritis.
- In frozen shoulder, laser is most useful during the painful phase rather than the stiff phase.
Knee osteoarthritis: what the review found.
A 2023 systematic review and meta-analysis in the Journal of Back and Musculoskeletal Rehabilitation searched seven databases for trials of high intensity laser in symptomatic knee osteoarthritis. Nine studies met the criteria, and all nine reported positive effects on pain.
The quality mix matters. One study was rated excellent, six good, and two fair or poor. Two studies covering 136 people gave what the reviewers described as moderate evidence that laser beats sham laser for short-term pain relief.
Their conclusion named the condition for it working: laser is promising and recommended for knee osteoarthritis pain, especially when implemented in combination with exercises. We treat that as an instruction rather than a footnote.
What that looks like in the clinic.
An arthritic knee gets into a loop. It hurts, so you walk less and avoid stairs, so the muscles around it get weaker, so the joint is less supported and hurts more. Breaking that loop means loading the knee again, and the thing preventing that is pain.
So the laser is used at the front end to make loading tolerable, and the loading is the actual treatment. We track function rather than pain scores alone: stair tolerance, walking distance, and whether you can rise from a chair without using your arms. Those tell you whether the plan is working.
What we will not tell you is that the laser is fixing the arthritis. It is not. The osteoarthritis condition page covers the wider management picture, including when a surgical opinion is the right next step.
Frozen shoulder: the sham-controlled evidence.
Adhesive capsulitis, better known as frozen shoulder, is a painful, stiffening shoulder that develops without a clear injury and resolves slowly over many months.
A prospective, double-blinded, sham-controlled randomised trial published in Lasers in Medical Science randomised 36 patients with adhesive capsulitis into three groups: high intensity laser with therapeutic exercise, sham laser with therapeutic exercise, and therapeutic exercise alone.
That three-arm design is worth noting. Every arm received exercise, so the trial tested what laser adds on top of good rehab, and the sham arm accounts for the placebo effect that any hands-on treatment produces. It is a small study, and small studies are exactly why we describe this evidence as reasonable rather than conclusive.
Timing matters more here than anywhere else.
Frozen shoulder moves through phases. Early on it is dominated by pain, including night pain that wakes you. Later, the pain settles and stiffness becomes the main problem. Eventually range gradually returns.
Laser fits the painful phase. That is when pain is what stops you moving the shoulder, and reducing it lets gentle range work happen. In the stiff phase the limiting factor has changed, and what helps then is sustained stretching and joint mobilisation. Using a modality aimed at pain to solve a problem of stiffness is a category error.
This is also why we ask carefully about your night pain and how long the shoulder has been like this. The answers change the plan more than the diagnosis does. The shoulder condition page covers how we separate a frozen shoulder from a rotator cuff problem in the first place.
Frequently asked questions.
Does laser therapy help knee osteoarthritis?
A 2023 systematic review in the Journal of Back and Musculoskeletal Rehabilitation examined high intensity laser therapy for symptomatic knee osteoarthritis and found all nine included studies reported positive effects on pain. The reviewers rated the evidence as moderate and concluded laser is a promising option, particularly when combined with exercise. It is a pain-relief tool that makes loading the knee possible, not a way to reverse arthritis.
Can laser therapy reverse arthritis in my knee?+
No. Laser therapy does not regrow cartilage or reverse the structural changes of osteoarthritis, and the published trials measured pain and function rather than joint structure. What laser can do is reduce the pain that stops you exercising, and exercise is the intervention with the strongest evidence for keeping an arthritic knee working. That is the realistic goal we set with patients.
Does laser therapy work for frozen shoulder?+
A double-blinded sham-controlled randomised trial published in Lasers in Medical Science studied 36 patients with adhesive capsulitis, randomly assigned to high intensity laser plus exercise, sham laser plus exercise, or exercise alone. Trials of this design are the most useful evidence available for frozen shoulder, because the sham arm controls for the strong placebo response that any hands-on treatment produces.
When in frozen shoulder is laser most useful?+
Laser is most useful in the painful phase of adhesive capsulitis, when the shoulder hurts constantly and night pain disrupts sleep. That is the stage where pain, rather than stiffness, is what stops you moving. Once the shoulder settles into the stiff phase and the limiting factor becomes tightness rather than pain, stretching and joint mobilisation matter more than any modality.
How many laser sessions for knee osteoarthritis?+
A course for knee osteoarthritis at Medstar generally runs 6 to 10 sessions, clustered two to three per week at first. We track specific functional markers rather than pain alone: stair tolerance, how long you can walk, and whether you can get out of a chair without pushing off. If those have not moved after the first block, more of the same is the wrong plan.
Is laser therapy an alternative to knee replacement surgery?+
No, and it should not be presented that way. Laser therapy is a pain-management tool that can help you exercise, and severe end-stage osteoarthritis with significant joint damage is a surgical conversation with an orthopaedic surgeon. Where laser genuinely helps is in earlier or moderate arthritis, and in the period before surgery when staying strong improves how well you do afterwards.
Does laser work better than exercise for knee osteoarthritis?+
The evidence points the other way. The 2023 systematic review concluded high intensity laser is recommended for knee osteoarthritis pain especially when implemented in combination with exercises, not as a replacement for them. Exercise has the stronger and longer-standing evidence base for osteoarthritis. Laser earns its place by reducing the pain barrier that stops people starting or sticking with an exercise programme.
Will laser therapy help my shoulder move further?+
Indirectly. Laser reduces pain, and in a painful shoulder that pain is often what limits how far you are willing to move. Reduce it and the stretching and mobilisation work in the same appointment becomes tolerable, which is what actually restores range. Expecting the laser alone to increase your range of motion, without the movement work attached, is not realistic.
How long does frozen shoulder take to recover?+
Adhesive capsulitis is characteristically slow, typically running over many months through a painful phase, a stiff phase, and a gradual thawing phase. Anyone quoting you a fixed number of weeks is guessing, because the course varies considerably between people. What treatment can influence is how much pain you carry through those phases and how much range you keep along the way.
Is laser therapy safe for arthritic joints?+
Yes, for the joints discussed on this page. High intensity laser therapy applied over an arthritic knee or a painful shoulder is well tolerated, and the published trials in these conditions have not reported significant adverse effects. The standard safety rules still apply: protective eyewear for everyone in the room, and no treatment over an active cancer, an implanted electronic device, or broken skin.
Sources.
- High-intensity laser therapy on pain relief in symptomatic knee osteoarthritis: a systematic review and meta-analysis. Journal of Back and Musculoskeletal Rehabilitation, 2023
- Efficacy of high-intensity laser therapy in patients with adhesive capsulitis: a sham-controlled randomized controlled trial. Lasers in Medical Science, February 2021
Sources checked 4 September 2026.
Not sure laser is the right tool?
Book an assessment. We'll tell you honestly whether the laser helps your injury, or whether something else will do more.
Reviewed by Sanaz Davarian, PT, MSc, Owner & Director, Registered Physiotherapist, College of Physical Therapists of British Columbia (CPTBC). Medstar was the first physiotherapy clinic on the North Shore to install a Class 4 high intensity laser.
This page is for general information only and does not constitute medical advice. High intensity laser therapy is one tool among several, and it is not appropriate for every injury or every person. Nothing here is a promise of a particular outcome. Treatment suitability is determined case-by-case during clinical assessment. Physiotherapy at Medstar Sport Physio & Health is provided by physiotherapists registered with the College of Physical Therapists of British Columbia (CPTBC).