Eladl H.M. et al. - Photobiomodulation in Rehabilitation Following Knee and Hip Arthroplasty: A Systematic Review

This systematic review of 4 randomized trials—involving 133 patients who underwent knee or hip replacement surgery—reports a reduction in pain and swelling after surgery in 3 of the trials. The authors, however, consider the evidence to be insufficient due to the heterogeneity of the treatment parameters.

What this study measured

Total knee and hip replacements relieve chronic pain and improve joint function. However, recovery after surgery is often hindered by pain, swelling, limited range of motion, and muscle weakness, which necessitates a structured rehabilitation program.

Hadaya Mosaad Eladl’s team evaluated whether photobiomodulation, used as an adjunct therapy, improves these outcomes compared to a placebo or standard physical therapy. The search covered PubMed, ProQuest, ScienceDirect, and Google Scholar from their inception through May 31, 2025. Only prospective controlled trials measuring postoperative pain, swelling, joint range of motion, or functional performance following joint replacement were included. Case reports and uncontrolled studies were excluded. The review is registered on PROSPERO under number CRD420251123169.

Key Findings

The final dataset is very limited. Four randomized controlled trials met the inclusion criteria, three of which focused on knee replacements and one on hip replacements.

• 4 randomized trials included, with a total of 133 participants
• 3 trials involving knee replacements, 1 trial involving a hip replacement
• Postoperative pain and swelling improved significantly in 3 trials
• Improved joint range of motion and functional outcomes in 2 trials
• Methodological quality: PEDro scores ranging from 8 to 10, considered moderate to high

No meta-analysis was conducted: the results are presented on a study-by-study basis, without a pooled estimate.

How Photobiomodulation Affects Pain

The proposed mechanism remains hypothetical. Red and near-infrared light is thought to be absorbed by mitochondrial cytochrome c oxidase, which would increase ATP production in the periarticular tissues subjected to surgical trauma. This energy supply could accelerate the resolution of edema and moderate the local inflammatory response, two major components of pain in the first few days. An effect on nociceptive fiber conduction and on algogenic mediators has also been proposed. By reducing pain and swelling, photobiomodulation would indirectly facilitate early mobilization, which would explain the observed improvements in joint range of motion.

Limits You Should Know

The authors are clear: the evidence remains insufficient to draw conclusions. A total of four trials and 133 participants is a small sample size for two distinct surgical procedures, especially since the hip is represented by only one trial. Treatment parameters differ significantly from one protocol to another, which makes it impossible to establish a standard treatment regimen or to pool the data. The benefits described are short-term, with no documented long-term follow-up. No GRADE certainty rating is reported; quality is assessed using the PEDro scale, which evaluates trial conduct rather than the overall level of evidence.

What This Means in Practice

Photobiomodulation appears to be a potential adjunct to rehabilitation following knee or hip replacement, helping to alleviate pain and swelling during the first few weeks. It is not a substitute for surgery or the rehabilitation program, and its benefits have yet to be confirmed. The study abstract does not specify the wavelength, power, or number of sessions: it is precisely this lack of consistency that the authors highlight. They call for large randomized trials using standardized parameters and long-term follow-up before any conclusions can be drawn about clinical efficacy.

Frequently Asked Questions

Does photobiomodulation help with recovery after knee replacement surgery?

In the included trials, it was associated with reduced pain and swelling after surgery, and with better functional outcomes in two trials. The authors, however, consider the evidence to be insufficient, given the small number of trials and the variability in protocols.

How many patients were included in the study?

A total of 133 participants, distributed across 4 randomized controlled trials. Three trials involved knee replacements and only one involved a hip replacement, which severely limits what can be said about the hip.

What processing parameters were used?

The abstract does not provide details on them. The authors merely note that the parameters varied from one trial to another and consider this heterogeneity to be one of the main obstacles to reaching a definitive conclusion.

Reference

Eladl HM, Alrashedi SN, Allam NM, et al. Systematic Review on the Effectiveness of Photobiomodulation Therapy in Improving Musculoskeletal Rehabilitation Outcomes Following Total Knee and Hip Arthroplasty. Photobiomodulation, Photomedicine, and Laser Surgery, 2026. PMID 42581717. View the study on PubMed

This summary is provided for informational purposes only and does not constitute medical advice. Photobiomodulation is not a substitute for prescribed treatment. Consult a healthcare professional.