Effects of Laser Therapy on Chronic Knee Joint Osteoarthritis Patients

Osteoarthritis (OA) is a degenerative joint disease characterized by the loss of articular cartilage, subchondral bone remodeling, joint space narrowing and the formation of bone spurs. The initiation of cartilage breakdown is stimulated by mechanical stress or injury and the degenerative process progresses slowly over many years. In the advanced stage of OA, the abnormal remodeling of cartilage and subchondral bone results in the formation of osteophytes at the joint surface and margins, which irreversibly destroys the affected joint. Obesity, previous trauma, female gender and older age are considered the most common risk factors for knee OA. The prevalence of radiographic KOA for all age groups and found a value of 27.3 % for women and 21.0 % for men.Clinical manifestations include joint pain, stiffness, decreased range of motion (ROM), muscle weakness, proprioceptive changes, difficulties in activities of daily living (ADL) such as walking, climbing / descending stairs and housekeeping[5]Many physical therapy agents such as ultrasound[6], electrical stimulation, strengthening exercise[8]and thermal therapy[9] have been introduced.

Because of the non-invasiveness and advantage of inciting nearly no adverse side effects, low-level laser therapy (LLLT) has been widely used to relieve pain in different musculoskeletal disorder. It also promotes fibroblasts, collagen synthesis, cell oxygen recovery, and bone remodeling. Laser efficacy depends on 4 factors of wavelength, duration of treatment, dose, and areas of the application.Low level laser therapy induces photochemical physiological actions in living tissues at the cellular level. Some of these effects include cellular oxygenation, release of neurotransmitters associated with pain modulation and release of anti-inflammatory, endogenous mediators. LLLT consists of a monochromatic light source without any thermal effect that stimulates reparative properties in human cartilage. Moreover, it has an analgesic effect, although the mechanisms through which this occurs remain uncertain. The suggested mechanisms include: increased mitochondrial ATP and tissue oxygenation, increased levels of neurotransmitters implicated in pain modulation (such as serotonin) and anti-inflammatory effects. Study stated that the reduction in pain through using LLLT might be due to mechanisms such as physiological effects mediated by photochemical actions at cellular level in animal or human tissue, and through increased levels of the neurotransmitters implicated in pain modulation, such as serotonin. Some researchers have also concluded that LLLT has an effect on joint cartilage regeneration, achieved through proliferation of chondrocytes and synthesis and secretion of extracellular matrix.

A study on "Effect of laser therapy on chronic osteoarthritis of the knee in older subjects" showed that there was a significant reduction in VAS and pain intensity, an increase in isometric muscle strength and range of motion of the knee as well as increase in physical functional ability in three treatment groups.

A study on "Efficacy of low-level laser therapy on pain and disability in knee osteoarthritis: systematic review and meta-analysis of randomized placebo-controlled trials" showed that LLLT reduces pain and disability in KOA at 4-8 J with 785-860 nm wavelength and at 1-3 J with 904 nm wavelength per treatment spot.

A study on "effectiveness of low-level laser therapy in patients with knee osteoarthritis: a systematic review and meta-analysis" this study indicated that low level laser therapy has neither early nor later benefits in reducing pain or improving function in patients with KOA.