Red Light Therapy for Knee Replacement: Timing, Evidence and Safe Use

Red light therapy for knee replacement has a small but growing body of randomised trials behind it: light added to standard rehabilitation was linked with less pain, less swelling and a wider knee bend in the first weeks and months after surgery. At home, it belongs only once the wound has fully closed, the clips or stitches are out and your surgeon agrees. Below: the trials, timing, where to aim, implants, swelling, medicines, warning signs and panel set-up.

Key takeaways

• In a three-arm randomised trial of 45 knees, people given 804 nm laser light for 3 days after surgery bent the knee to 116.8 degrees at 3 months, against 92.3 degrees in the control group. Arthroplasty Today, 2023
• In a 2023 trial of 40 people, 650 nm laser light twice a week from week 3, added to rehabilitation, brought knee bend to 86.99 degrees at 6 weeks, against 68.41 degrees with rehabilitation alone. Alghamdi, 2023
• In a 2025 trial of 30 people, red and near-infrared LED pads for the first 5 days after surgery went with a longer 2-minute walk on day 6: 27 m against 16 m. Chia, 2025
• A 2026 scoping review of three knee replacement trials concluded that "PBM has a positive effect on reducing pain and swelling". Shetty, 2026
• The NHS says a nurse removes stitches or clips after about 10 days, so home light waits until after that, once the wound has fully closed and your surgeon agrees. NHS

Does red light therapy for knee replacement help recovery?

The randomised trials point to yes for early recovery: light added to exercise was linked with less pain, less swelling and a wider knee bend than exercise alone. Most of the benefit showed in the first days to 3 months after surgery.

Study	Who	Light	What was found
Arthroplasty Today, 2023	45 knees in three groups	804 nm laser or broad polarised light, days 0 to 3	Wider bend, less pain and less swelling than control at 3 months
Alghamdi, 2023	40 people	650 nm laser, twice a week from week 3	Bend 86.99 against 68.41 degrees at 6 weeks
Chia, 2025	30 people	650 + 850 nm LED pads, days 1 to 5	Less leg swelling; 2-minute walk 27 m against 16 m
Fusakul, 2014	54 people, placebo laser as control	810 nm laser, 3 days from day 2	Less resting pain up to 2 weeks; better straightening at 6 weeks
Shetty, 2026	Review of 3 trials	Varied	Less pain and swelling, better movement and function

The Tehran trial compared three groups. Arthroplasty Today, 2023 Everyone did knee exercises with ice; two groups added light.

• Pain at 3 months: 0.7 out of 10 with laser, 2.1 with polarised light and 3.5 with exercise alone.
• Painkillers: by day 30, the laser group had used 48.3 mg of oxycodone, against 60.3 mg in the control group.

The authors wrote that light "could be helpful to control immediate and acute knee pain and swelling". A placebo-controlled Thai trial of 810 nm laser over the surgical site reported less resting pain up to 2 weeks. Fusakul, 2014 The 2026 review found the pain and range of motion results varied between trials. Shetty, 2026

A hip replacement trial found similar early effects on pain. Langella, 2018 Our guide to red light therapy after surgery covers the general timing rules for any operation.

How soon after a knee replacement can you use red light at home?

Only once the incision has fully closed, the clips or stitches are out and your surgeon agrees. For most people that falls some time after the 2-week mark.

The NHS says "A nurse will take out your stitches or clips after about 10 days". NHS The American Academy of Orthopaedic Surgeons (AAOS) says staples or stitches come out "several weeks after surgery", and advises against soaking the wound until it has "thoroughly sealed and dried". AAOS

Most trials started in hospital within days, under clinical care: not a home plan. The 2023 trial that began in week 3 is the closest to a home timeline. Alghamdi, 2023

Not yet if any of these apply:

• Wound: a dressing, clips, stitches, skin glue, a scab, weeping or an unclosed drain site.
• Infection signs: more pain, redness, swelling, leaking or a fever. Contact your care team.
• Approval: your surgeon has not yet agreed.

Can you shine red light over knee staples, stitches or a fresh incision?

No: never over stitches, staples, skin glue or an open wound. Once the wound has fully closed and your surgeon agrees, start with the inner and outer sides and the back of the knee, then add the scar line.

The Tehran trial treated the back of the knee only. The authors chose that site "due to surgical wound hygiene and possible wound complications". The Taiwan trial placed its LED pads on the thigh and lower leg rather than over the wound. Chia, 2025

The week 3 trial also treated the incision line, the sides and the back of the knee.

Once the wound has fully closed and your surgeon agrees, the scar can be included. Light will not erase a scar; the best evidence is for new surgical scars. Take off silicone and creams before each session. See red light therapy for scars for scar care alongside light.

Is red light safe over a metal knee implant?

Ask your surgeon first. Three trials shone light on freshly replaced knees and reported no major side effects.

• Tehran trial: no clots and no major side effects; one wound problem in the polarised light group was treated conservatively.
• Taiwan trial: no wound infections, wound breakdown or clots in either group, and "all wounds healed uneventfully by two weeks".
• Thai trial: "No side effect was reported from laser therapy." Fusakul, 2014

Does red light reduce swelling after knee replacement?

Three sources point that way: the Tehran trial at 3 months, the Taiwan trial by day 6, and the 2026 review. Light sits alongside raising the leg, ice and compression stockings, not in place of them.

In the Taiwan trial, swelling in the operated leg, compared with the other leg, was clearly lower with light. Chia, 2025 In the Tehran trial, knee circumference at 3 months was smaller in both light groups than in the control group.

Swelling after a knee replacement takes a while to settle. The AAOS says "You may have mild to moderate swelling for about 3 to 6 months after surgery." AAOS The NHS advises keeping the leg raised and avoiding long standing. New or severe swelling may signal a clot, so report it.

Can red light help you bend the knee further, and does it replace physio?

It may help you get there sooner: knee bend improved more with light plus rehabilitation than with rehabilitation alone at 6 weeks and at 3 months. Light does not replace physio, and every trial added it to exercise.

In the week 3 trial, both groups had 60 to 90 minutes of intensive rehabilitation per session, 12 sessions in 6 weeks. Alghamdi, 2023

• Bend with light: 46.70 to 86.99 degrees.
• Bend without light: 44.87 to 68.41 degrees.
• WOMAC score: 83.15 to 28.15 with light, against 82.75 to 48.50 without; lower means less pain and stiffness.

In the Tehran trial, the laser group's 3-month bend was 116.8 degrees, against 92.3 without light. By one year, the groups were close: 119.7, 116.0 and 113.7 degrees. That points to a faster early recovery. In the 5-day Taiwan trial, bend on day 6 was not significantly different.

Keep doing your exercises. The AAOS calls exercise "a critical component of home care" and advises physical therapy exercises for "at least 2 months after surgery". If your other knee has arthritis, see red light therapy for knee pain for the osteoarthritis evidence.

What settings did the knee replacement light trials use?

Trials used red light around 650 nm, near-infrared at 804 to 850 nm, or both, mostly daily for 3 to 5 days in hospital or twice a week for 6 weeks in a clinic. All of them shone light on the skin from outside the body.

Trial	Light	Dose	Time	Sessions	Start	Where
Arthroplasty Today 2023, laser	804 nm laser	5 J per point, 2 points	About 10 seconds per point	Daily, 3 days	Days 0 to 3, hospital	Back of the knee
Arthroplasty Today 2023, polarised light	480 to 3,400 nm	2.4 J/cm²	10 minutes at 10 cm	Daily, 3 days	Days 0 to 3, hospital	Back of the knee
Alghamdi 2023	650 nm laser, continuous	6 J/cm² per point	60 seconds per point	2 a week, 6 weeks	Week 3, clinic	Incision line, sides, above and below the kneecap, back
Chia 2025	650 + 850 nm LED pads	15.2 and 24.3 J/cm²	30 minutes per wavelength	Daily, 5 days	Day 1, hospital	Thigh and lower leg
Fusakul 2014	810 nm laser	80 J per session	Not stated	Daily, 3 days	Day 2, hospital	Over the surgical site

Laser joules per point do not convert into a panel session. What carries over is the pattern: red and near-infrared light, on bare skin around the knee, regular sessions alongside exercise.

Can you use red light with compression stockings, blood thinners or antibiotics?

Light needs bare skin, and the NHS says to wear compression stockings at all times, usually for at least 6 weeks, so ask your care team before taking one off for a session. With blood thinners, antibiotics or painkillers, check with your doctor or pharmacist first.

• Stockings: the NHS says to wear them "at all times and only take them off to wash them". Fabric blocks most of the light, as our guide to red light through clothes explains, so either agree a short session with the stocking off or wait until you no longer need them.
• Blood thinners: Mayo Clinic says they may be needed for several weeks after surgery. Mayo Clinic Ask your doctor before adding light and never stop a prescribed medicine, as in our bruises guide.
• Antibiotics and painkillers: doxycycline, ciprofloxacin, ibuprofen and naproxen can make skin more sensitive to light. Our precautions rule out use with photosensitising medication, so anyone taking a medicine should check with their pharmacist or doctor before using the device. See is red light therapy safe.
• Numb skin: Mayo Clinic notes nerve damage can cause "numbness, weakness and pain". Skin around the scar is often numb, so you may not feel warmth well. Stay dimmed at 12 inches and check the skin afterwards.

Which warning signs after knee surgery need a doctor, not a light?

Signs of infection or a blood clot need urgent medical advice, and light should wait. Chest pain or sudden breathlessness is an emergency.

• Infection: the NHS lists a high temperature or feeling "hot, cold or shivery", "oozing or pus from your wound", and redness, swelling or pain that is getting worse. Contact a GP or NHS 111 urgently. NHS
• Fever: the AAOS lists fever "higher than 100°F orally" and chills. In the US, call your surgeon.
• Clot in the leg: "throbbing or cramping pain in your leg", increasing calf pain, or new swelling in the calf, ankle or foot.
• Clot in the lung: leg pain and swelling with difficulty breathing or chest pain. Call 999 or go to A&E.

How do you use red light therapy after knee surgery with a Kivorla panel?

Once the wound has fully closed and your surgeon agrees, start at 12 inches with the channels dimmed for 5 to 10 minutes every other day, goggles on. Build to about 6 inches and 10 to 15 minutes per area, 3 to 5 times a week, and judge it at 3 to 4 weeks.

The 9-Spectrum Red Light Therapy Panel carries 480, 590, 630, 660, 670, 810, 830, 850 and 1060 nm, each dimmable from 1 to 100%. Its 660 and 670 nm channels sit near the trials' 650 nm red, and 810, 830 and 850 nm inside their 804 to 850 nm range.

• Position: hang it low on a door or wall with the included door hook, pulley, hanging cables and screws, or stand it upright on the floor. Sit with the leg straight and supported, knee at the centre of the panel.
• Aim: inner side of the knee, then the outer side, then the back of the knee. Add the front and the scar line only once the wound has fully closed and your surgeon agrees.
• Channels: 660, 670, 810, 830 and 850 nm on; 480 and 590 nm at their lowest setting; pulse off.
• Skin: bare skin, one knee at a time. The surface stays at or below 40°C, so do not rest the knee on it. Warm is fine, hot means stop.
• Eyes: goggles on, and do not look into the panel.
• Log: pain out of 10, swelling and how far the knee bends, noted each day.

The trials gave modest doses. To stay near them, keep the channels below full brightness, use a shorter timer (it starts at 1 minute) or step back to 12 inches. If no time is set, the panel stops at 5 minutes. Leave at least 6 hours between 30-minute sessions. Keep your physio, raised leg, ice and stockings as your team advised.

Do not use the panel if you are pregnant, breastfeeding or preparing for pregnancy, have epilepsy or light-triggered seizures, have a thyroid condition or take thyroid medication, take photosensitising medication, have had sunburn on your body in the past 2 weeks, have Fitzpatrick skin type V or VI, or have an open wound on the area. It is not for use while asleep. The Kivorla mask is a face device and is not meant for the knee.

Standard shipping to the US, UK and Germany is free. Read the precautions before ordering. Under our return and refund policy, returns are accepted within 30 days: an unopened device with its seals intact is refunded less a 10% restocking fee, and an opened device that is undamaged and complete is refunded less 20%.

Kivorla devices are general wellness devices, not medical devices, and are not intended to treat any condition after knee replacement. Use light only once your wound has fully closed and your surgeon agrees, ask your surgeon about your implant first, and keep the physio, medicines and wound care your team has prescribed.