Effect of low-level laser therapy plus exercise therapy on pain, range of motion, muscle strength, and function in knee osteoarthritis – a systematic review and meta-analysis

Knee osteoarthritis (KOA) is commonly associated with multiple musculoskeletal impairments.The purpose of this review was (1) to investigate the effectiveness of LLLT plus ET on pain, ROM, muscle strength, and function in KOA immediately after therapy and (2) whether the effectiveness of LLLT plus ET could be sustained at follow-up (4 - 32 weeks).Six databases were systematically searched upto December 2021 to find relevant articles. Included studies were RCTs written in English, which compared LLLT plus ET with placebo LLLT plus ET in KOA. Three independent reviewers extracted data and assessed the quality of included studies. Standard mean difference (SMD) was used in meta-analysis using random effect model.Of the 6307 articles, 14 RCTs (820 patients) met the inclusion criteria. The results demonstrated that there was a significant difference in pain immediately after therapy (SMD: -0.58, p = 0.001) and at follow-up (SMD: -1.35, p = 0.05) in LLLT plus ET group. There were no significant differences in knee ROM, muscle strength, and knee function outcomes immediately and at follow-up.Our findings indicate that LLLT plus ET could be considered to alleviate pain in the KOA. LLLT reduces pain at 4-8J with a wavelength of 640-905nm per point applied for 10-16 sessions at a frequency of 2 sessions/week. An exercise therapy program at prescribed dosage involving major muscle groups might help. However, LLLT plus ET is no more effective than placebo LLLT plus ET in improving ROM, muscle strength, and function in KOA.