Immediate responses of multi-focal low level laser therapy on quadriceps in knee osteoarthritis patients

Low-level laser therapy (LLLT) applying on knee osteoarthritis (OA) patients has shown positive outcomes in analgesic effect and functional recovery. However, few studies applied such therapy on large area of quadriceps muscle in these patients. The aim of this study was to evaluate immediate effect of multi-focal LLLT on quadriceps of knee OA patients in pain and functional performance. Fifty-one participants with knee OA were enrolled and evaluated before (T1) and immediately after intervention (T2) by knee joint pain in numeric rating scale (NRS), walking speed, timed five-chair stands, and quadriceps strength by isokinetic dynamometer. Intervention with two multi-focal Gallium-Aluminum-Arsenide laser devices, each device with 36 laser diodes (wavelength 808 ± 10 nm, continuous, mean power 50 mW, 30 minutes), applied simultaneously over bilateral quadriceps with a total dose of 180 J for each thigh. The multi-focal LLLT significantly improved knee joint pain as measured by the NRS (54% reduction), timed five-chair stands, and walking speed (P < .05). Knee extensor strength also increased in terms of peak torque and force of concentric and eccentric contraction as measured by isokinetic dynamometer (P < .05). In conclusion, single-session multi-focal LLLT on quadriceps in knee OA patients has immediate beneficial effect on knee pain reduction, quadriceps strengthening and functional performance recovery. Long-term effect requires further investigation. Multi-focal LLLT on quadriceps might serve as an alternative non-invasive treatment option in these patients.