The effect of low-level laser therapy on knee osteoarthritis: prospective, descriptive study
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- Soleimanpour, H., Gahramani, K., Taheri, R. et al. Lasers Med Sci (2014) 29: 1695. doi:10.1007/s10103-014-1576-6
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Osteoarthritis (OA) is one of the most common joint disorders in the elderly which could be associated with considerable physical disability.
Patients and methods
In a descriptive, prospective study, 33 patients enrolled in the study from which 15 people were excluded due to incomplete course of treatment, leaving the total number of 18 patients with knee osteoarthritis. Gal-Al-As diode laser device was used as a source of low-power laser. Patients were performed laser therapy with a probe of LO7 with a wavelength of 810 nm and 50 mW output power in pulse radiation mode (F = 3,000, peak power = 80 W, Δt = 200 ns, density = 0.05 W/cm2, dose = 6 J/cm2, area = 1 cm2) and also a probe of MLO1K with a power output of 30 mW and a wavelength of 890 nm in pulse radiation mode (F = 3,000 Hz, peak power = 50 W, Δt = 200 ns, density = 0.017 W/cm2, total dose = 10 J/cm2), and were given low-level laser therapy (LLLT) three times a week with a total number of 12 sessions. Data were analyzed using SPSS ver. 15, and the obtained data were reported as mean ± SD and frequency (%). To analyze the data, repeated measurement and marginal homogeneity approaches were used.
In the current study, a significant reduction was observed regarding the nocturnal pain, pain on walking and ascending the steps, knee circumference, distance between the hip and heel, and knee to horizontal hip to heel distance at the end of the treatment course.
In brief, the current study focuses on the fact that LLLT is effective in reducing pain in knee osteoarthritis.
KeywordsKnee osteoarthritis Low-level laser therapy Pain
Low-level laser therapy
Transcutaneous electrical nerve stimulation
Western Ontario and McMaster Universities
Osteoarthritis (OA), one of the most common joint disorders in the elderly, is defined as increased damage and decreased repair processes within the joints following mechanical insults . OA could be associated with considerable physical disability, regardless of the type of the affected joints. Knee osteoarthritis, the most common type of OA, is the chronic degeneration of the articular cartilages. Injured intra-articular cartilage triggers inflammation and swelling of the synovia which in turns could lead to increased pain, stiffness, and bone spurs and decreased range of motion [2, 3, 4]. Although non-steroid anti-inflammatory drugs (NSAIDs) are broadly used for the treatment of the pain and rigidity caused by osteoarthritis, their undesirable gastrointestinal complications have contributed to numerous limitations in their administration . To reduce or eliminate these complications, different approaches including ultrasound, transcutaneous electrical nerve stimulation (TENS), and physical exercises have been utilized [6, 7, 8, 9]. Low-level laser therapy (LLLT) is used for the treatment of pain in neuromuscular disorders. Despite its broad administration, controversial reports have been made on the efficacy of LLLT. Some of the studies confirm the efficacy of LLLT in pain reduction in cervical osteoarthritis  and lateral and medial epichondylitis , whereas some confirm its efficacy on lateral and medial epichondylitis , rotator cuff tendinitis , and rheumatoid arthritis . Nevertheless, very few studies have been conducted on the efficacy of LLLT on knee osteoarthritis, and the results obtained from these studies are controversial [14, 15, 16]. In the study of Stelian et al., LLLT was suggested to reduce pain and disability . However, Bulow et al. found no significant differences between case and control groups . In similar studies carried out by Mokmeli et al., Rayegani et al., and Hegedus et al., the efficacy of LLLT on reducing pain in knee osteoarthritis was proposed [17, 18, 19]. Over the years, more than 100 double-blind, placebo-controlled studies have been published on the effects of LLLT emphasizing the favorable anti-inflammatory effects of LLLT [20, 21, 22]. LLLT has been used as a non-invasive modality in the pain management of the patients with musculoskeletal disorders. Although the efficacy of LLLT has been compared to that of NSAIDs , thanks to its low complication rates and dose-dependent ability of modulating inflammatory processes which can also be titrated, LLLT has turned it into a distinguishable alternative in the pain management of osteoarthritis . Considering the controversial findings and administration of different laser doses and the existing two different criteria for the efficacy of the evaluation i.e., the distance between the hip and heel and the knee to horizontal hip to heel distance, we aimed at evaluating the efficacy of LLLT on reducing pain and disability in patients with knee osteoarthritis.
Pain reduction at different sessions in patients received low-level laser therapy
After sixth session
After 12th session
Pain in walking
After sixth session
After 12th session
Pain in ascending the stairs
After sixth session
After 12th session
Comparison of the mean value of VAS, the knee circumference, the hip to heel distance, and the knee to horizontal hip to heel distance between patients
7.39 ± 1.68
3.61 ± 1.91
2.22 ± 1.7
Knee circumference (cm)
43.11 ± 4.07
41.88 ± 4.18
41.38 ± 3.88
The hip to heel distance(cm)
17.55 ± 5.79
12.55 ± 6.37
11.72 ± 5.83
The knee to horizontal hip to heel distance(cm)
5.38 ± 2.06
4.05 ± 1.47
3.55 ± 0.98
LLLT, firstly introduced almost a decade ago, is considered as a non-invasive modality for treating joint diseases. Other usages of LLLT include treatment of soft tissue injuries, rheumatoid arthritis, and musculoskeletal pain . Numerous clinical and basic science studies have confirmed medical and physiological effects of LLLT including its positive effect on osteoblastic  and fibroblastic  proliferation, collagen synthesis , and bone regeneration . Laboratory researchers have confirmed the significant effect of LLLT on the activity of alkaline phosphatase enzyme and calcium accumulation . Pathological changes initiate cartilage damage and alter bone metabolism through reduction in cartilage circulation and degenerative changes. Increased microvascularization has been reported following LLLT in some studies [31, 32]. Shakouri et al. showed that callus development at the early stages of the healing process could be enhanced following LLLT administration . Lin et al. suggested that the helium–neon (632 nm) low-power laser improves stress protein production in arthritic chondrocytes which is linked to the therapeutic effects of low-power laser via preserving chondrocytes and the repair of arthritic cartilage . Enwemeka et al. highlighted laser phototherapy as a highly effective therapeutic modality which not only repairs the damaged tissues but also alleviates pains . The results obtained from the current study are suggestive of the fact that considerable improvements were achieved in patients following LLLT regarding pain, swelling, and flexion and extension degrees of the knee joint, and this trend continued for 3 weeks during the treatment course.
The distance between the hip and heel in supine position with knee flexion
The distance between the knee and horizontal hip to heel line with knee extension
Another difference in the present study is the administration of higher total energy doses of Laser (46 vs. 30 J).
Based on the results obtained from our study, it can be assumed that LLLT leads to osteoarthritis improvement from different aspects as pain severity tends to decrease considerably throughout the LLLT sessions. It can be hypothesized that these effects are conducted via reduction in tissue inflammation and vasodilation . On the other hand, as can be seen in Table 2, a significant reduction in knee circumference was achieved following LLLT sessions i.e., LLLT was efficient regarding reducing the peri-articular swelling and inflammation. Furthermore, reduction in the two other previously existing criteria (the distance between the hip and heel and the knee to horizontal hip to heel distance) could indicate improvement in joint range of motion. These findings are in line with those of Stelian et al., Mokmeli et al., and Rayegani et al. [15, 17, 18].
As can be seen, the results obtained from different studies on the efficacy of LLLT in the treatment of the patients with osteoarthritis are controversial. The differences in the used devices and laser types could have contributed to this discrepancy. Another consideration that should be kept in mind is the lack of a definite required dose regarding wavelength, frequency and intensity of laser pulse, and maximum dose of radiation. Therefore, further future studies are required focusing on these pitfalls.
The current study was associated with some limitations. As the patients referring to the office were selected, dividing the patients into two groups of case and control was impractical. Furthermore, other evaluation criteria such as WOMAC were not used; a strong correlation between pain criteria and WOMAC tools exists. This does not seem to have had a negative effect on our study. Furthermore, it should be mentioned that our study was a descriptive one rather than a clinical trial which could have been considered as one of the limitations of the present study.
Overall, the results obtained from the present study are suggestive of the fact that LLLT is efficient in reducing pain and increasing ability of the knee joint in patients with knee osteoarthritis.
We would like to offer our special thanks to the Iranian Laser Association for assisting us throughout the current study.
The authors declare they have no financial disclosure.
This article is not supported by any funding organization. There is no sponsor for this work.