Short-Term Effects of 890-Nanometer Radiation on Pain, Physical Activity, and Postural Stability in Patients With Knee Osteoarthritis: A Double-Blind, Randomized, Placebo-Controlled Study

Current advances of photobiomodulation therapy in treating knee osteoarthritis

Knee osteoarthritis (KOA) is manifested by low-grade joint inflammation, irreversible cartilage degeneration, subchondral bone remodeling and osteophyte formation. It is one of the most prevalent degenerative diseases in the elderly. KOA usually results in chronic joint pain, physical impairment even disability bringing a huge socioeconomic burden. Unfortunately, there is so far no effective interventions to delay the progression and development of KOA. There is a pressing need for explorations and developments of new effective interventions. Photobiomodulation therapy (PBMT), also known as low-level light therapy (LLLT), has attracted widespread attention in treating KOA because it is drug-free, non-invasive, safe and useful with rarely reported side effects. It provides the biological stimulatory effects primarily by enhancing the activity of mitochondrial cytochrome c oxidase. This stimulation, in turn, fosters cell proliferation and tissue regeneration. In addition to this, the paper provides a concise overview of the light parameters and the effectiveness of PBMT when applied in the treatment of KOA patients in clinical settings. It also delves into the experimental evidence supporting the modulatory effects of PBMT and its potential underlying mechanisms in addressing synovitis, cartilage degeneration, and pain resolution.

Adjunctive therapies in addition to land-based exercise therapy for osteoarthritis of the hip or knee

BACKGROUND

Land-based exercise therapy is recommended in clinical guidelines for hip or knee osteoarthritis. Adjunctive non-pharmacological therapies are commonly used alongside exercise in hip or knee osteoarthritis management, but cumulative evidence for adjuncts to land-based exercise therapy is lacking.

OBJECTIVES

To evaluate the benefits and harms of adjunctive therapies used in addition to land-based exercise therapy compared with placebo adjunctive therapy added to land-based exercise therapy, or land-based exercise therapy only for people with hip or knee osteoarthritis.

SEARCH METHODS

We searched CENTRAL, MEDLINE, PsycINFO, EMBASE, CINAHL, Physiotherapy Evidence Database (PEDro) and clinical trials registries up to 10 June 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs of people with hip or knee osteoarthritis comparing adjunctive therapies alongside land-based exercise therapy (experimental group) versus placebo adjunctive therapies alongside land-based exercise therapy, or land-based exercise therapy (control groups). Exercise had to be identical in both groups. Major outcomes were pain, physical function, participant-reported global assessment, quality of life (QOL), radiographic joint structural changes, adverse events and withdrawals due to adverse events. We evaluated short-term (6 months), medium-term (6 to 12 months) and long-term (12 months onwards) effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data, and assessed risk of bias and certainty of evidence for major outcomes using GRADE.

MAIN RESULTS

We included 62 trials (60 RCTs and 2 quasi-RCTs) totalling 6508 participants. One trial included people with hip osteoarthritis, one hip or knee osteoarthritis and 59 included people with knee osteoarthritis only. Thirty-six trials evaluated electrophysical agents, seven manual therapies, four acupuncture or dry needling, or taping, three psychological therapies, dietary interventions or whole body vibration, two spa or peloid therapy and one foot insoles. Twenty-one trials included a placebo adjunctive therapy. We presented the effects stratified by different adjunctive therapies along with the overall results. We judged most trials to be at risk of bias, including 55% at risk of selection bias, 74% at risk of performance bias and 79% at risk of detection bias. Adverse events were reported in eight (13%) trials. Comparing adjunctive therapies plus land-based exercise therapy against placebo therapies plus exercise up to six months (short-term), we found low-certainty evidence for reduced pain and function, which did not meet our prespecified threshold for a clinically important difference. Mean pain intensity was 5.4 in the placebo group on a 0 to 10 numerical pain rating scale (NPRS) (lower scores represent less pain), and 0.77 points lower (0.48 points better to 1.16 points better) in the adjunctive therapy and exercise therapy group; relative improvement 10% (6% to 15% better) (22 studies; 1428 participants). Mean physical function on the Western Ontario and McMaster (WOMAC) 0 to 68 physical function (lower scores represent better function) subscale was 32.5 points in the placebo group and reduced by 5.03 points (2.57 points better to 7.61 points better) in the adjunctive therapy and exercise therapy group; relative improvement 12% (6% better to 18% better) (20 studies; 1361 participants). Moderate-certainty evidence indicates that adjunctive therapies did not improve QOL (SF-36 0 to 100 scale, higher scores represent better QOL). Placebo group mean QOL was 81.8 points, and 0.75 points worse (4.80 points worse to 3.39 points better) in the placebo adjunctive therapy group; relative improvement 1% (7% worse to 5% better) (two trials; 82 participants). Low-certainty evidence (two trials; 340 participants) indicates adjunctive therapies plus exercise may not increase adverse events compared to placebo therapies plus exercise (31% versus 13%; risk ratio (RR) 2.41, 95% confidence interval (CI) 0.27 to 21.90). Participant-reported global assessment was not measured in any studies. Compared with land-based exercise therapy, low-certainty evidence indicates that adjunctive electrophysical agents alongside exercise produced short-term (0 to 6 months) pain reduction of 0.41 points (0.17 points better to 0.63 points better); mean pain in the exercise-only group was 3.8 points and 0.41 points better in the adjunctive therapy plus exercise group (0 to 10 NPRS); relative improvement 7% (3% better to 11% better) (45 studies; 3322 participants). Mean physical function (0 to 68 WOMAC subscale) was 18.2 points in the exercise group and 2.83 points better (1.62 points better to 4.04 points better) in the adjunctive therapy plus exercise group; relative improvement 9% (5% better to 13% better) (45 studies; 3323 participants). These results are not clinically important. Mean QOL in the exercise group was 56.1 points and 1.04 points worse in the adjunctive therapies plus exercise therapy group (1.04 points worse to 3.12 points better); relative improvement 2% (2% worse to 5% better) (11 studies; 1483 participants), indicating no benefit (low-certainty evidence). Moderate-certainty evidence indicates that adjunctive therapies plus exercise probably result in a slight increase in participant-reported global assessment (short-term), with success reported by 45% in the exercise therapy group and 17% more individuals receiving adjunctive therapies and exercise (RR 1.37, 95% CI 1.15 to 1.62) (5 studies; 840 participants). One study (156 participants) showed little difference in radiographic joint structural changes (0.25 mm less, 95% CI -0.32 to -0.18 mm); 12% relative improvement (6% better to 18% better). Low-certainty evidence (8 trials; 1542 participants) indicates that adjunctive therapies plus exercise may not increase adverse events compared with exercise only (8.6% versus 6.5%; RR 1.33, 95% CI 0.78 to 2.27).

AUTHORS' CONCLUSIONS

Moderate- to low-certainty evidence showed no difference in pain, physical function or QOL between adjunctive therapies and placebo adjunctive therapies, or in pain, physical function, QOL or joint structural changes, compared to exercise only. Participant-reported global assessment was not reported for placebo comparisons, but there is probably a slight clinical benefit for adjunctive therapies plus exercise compared with exercise, based on a small number of studies. This may be explained by additional constructs captured in global measures compared with specific measures. Although results indicate no increased adverse events for adjunctive therapies used with exercise, these were poorly reported. Most studies evaluated short-term effects, with limited medium- or long-term evaluation. Due to a preponderance of knee osteoarthritis trials, we urge caution in extrapolating the findings to populations with hip osteoarthritis.

Application of high-intensity laser in pain treatment of patients with knee osteoarthritis

Osteoarthritis is a rheumatic disease characterized by degeneration and decay of cartilage in the joints. As the disease worsens, the joint space narrows causing numbness and pain, which often impairs movement. In addition to pharmacological therapy, low-intensity laser (LILT), high-intensity laser (HILT) and exercise are used to treat osteoarthritis (OA) of the knee. HILT is a new modality in our country and the experience from its application is small, especially in the treatment of OA of the knee. Aim of the paper was to compare the effect of HILT with LILT in the treatment of OA of the knee. Material and methods: This was a randomized comparative unilateral blind study involving 72 patients divided into two groups. The first group was treated with HILT, the second group treated with LILT. Outcome measure was the visual analogue scale (VAS) for pain, which was made on the first and tenth day of treatment. Statistical significance was defined as p <0.05. Results: We found a significant difference between the two groups in terms of VAS score after 10 therapies  in favor to a significantly lower score, that is, less pain in the HILT group (p = 0.0035). The comparison of the VAS score between the two times in the two groups separately showed that in both, the HILT and the LILT groups, the VAS score after 10 days of therapy was significantly lower compared to thatat 0 time, for consequently p = 0.00001vsp = 0.00001. Conclusion: Treatment with HILT and LILT significantly reduces pain and stiffness in patients with OA. Patients treated with HILT had better results, i.e., had a significant reduction in pain than patients treated with LILT. HILT was more effective than LILT.

Guidelines versus evidence: what we can learn from the Australian guideline for low-level laser therapy in knee osteoarthritis? A narrative review

This narrative review analyses the Australian Guideline (2018) for the treatment of knee osteoarthritis (KOA) developed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. The Guideline recommended against the use low-level laser therapy (LLLT). Why this conclusion was reached is discussed in this review in the context of evidence provided in other systematic reviews, the latest of which was published in 2019 and which provided strong support for LLLT for knee OA. We evaluated the reference list cited for the recommendation “against” LLLT and compared this with reference lists of systematic reviews and studies published before and after the publication date of the Guideline. Eight randomised controlled trials (RCTs) of LLLT were cited in the Guideline the latest of which was published in 2012. There were seventeen additional RCTs, five of which together with one systematic review were located in the year of publication, 2018. The most recent systematic review in 2019 included 22 RCTs in its analysis. Discordance with the levels of evidence and recommendations was identified. Although GRADE methodology is said to be robust for systematically evaluating evidence and developing recommendations, many studies were not identified in the Guideline. In contrast, the latest systematic review and meta-analysis provides robust evidence for supporting the use of LLLT in knee OA. The conflict between guidelines based on opinion and evidence based on meta-analysis is highlighted. Given the totality of the evidence, we recommend that the Australian Guideline should be updated immediately to reflect a “for” recommendation.

Low Level Laser Therapy in Knee Osteoarthritis: A Narrative Review

Knee osteoarthritis (KOA) is the most common musculoskeletal disorder, especially in middle up to old age. KOA also results in many complications like changes in gait. Nowadays, changes in lifestyle and the reduced physical activity make people more vulnerable to KOA. Therefore, considering the increasing prevalence of KOA in many societies and the costs imposed on the afflicted people and their governments, providing conservative management approaches with a view to saving time and money is important. There are an assortment of conservative strategies in the management of KOA including low level laser therapy (LLLT). Since the introduction of lasers in the medical field in 1960, various types of lasers with widespread administration programs are used for medical conditions from cosmetics to surgery. However, there are conflicting findings on the application of lasers in osteoarthritis. To discuss the basis of the highest level of evidence, only systematic reviews with or without meta-analyses published up to January 2019 were included in the present work. In this regard, Scopus, PEDro, Medline, ISI Web of Science, Cochrane, PubMed, Irandoc, Iran Medex, Magiran, and SID were searched to retrieve articles in English or Persian. A total of 22 systematic reviews and meta-analyses were found, 14 of which were included in this study. The accepted articles were published between 1991 and up to 2019. The purpose of this narrative review was to investigate the effect of LLLT on pain and function in subjects with KOA. The result of the present review may help clinicians in making evidence-based decisions on optimal care in relation to administering LLLT.

Work-related outcomes in randomized, double blind, placebo-controlled trials in osteoarthritis - are they adequately reported in journal publications? A systematic review

Background

Osteoarthritis (OA) has a high prevalence in Western societies and can affect an individual's life in a number of domains, including work. In our experience, treatment trials on OA, however, rarely report work-related outcomes. Here we conducted a systematic review to assess the reporting of work-related outcomes in randomized, double blind, placebo-controlled trials in OA. Our systematic review also compared two search strategies for identifying eligible publications, one where work-related terms were included in the database search string (A) and one where this was not the case and work-related outcomes were identified by searches of full text Portable Document Formats (PDFs) (B). Search strategy A would conventionally be used and would only identify publications where work-related terms were mentioned in the title or abstract. Search strategy B presents the innovation of full text PDF searching and would identify publications were work-related terms were reported in the full text, regardless of whether they are mentioned in the title and abstract or not. We hypothesize that search strategy B identifies more relevant publications than search strategy A.

Methods

Electronic database searching was performed in Medline (Pubmed) from database inception to February 23, 2017 to identify peer-reviewed articles of randomized, double blind, placebo-controlled treatment trials in OA of the hand, hip, or knee, available as full-text PDFs. For search strategy A, search terms to identify work-related outcomes were included in the database search string, while search strategy B did not have these terms included in the database search string, but instead involved full text PDF searching. We included English language articles only and only those articles where searchable PDFs were available, to enable a comparison between search strategies A and B. Additionally, included studies also needed to report on pain intensity in relation to the work-related outcomes.

Results

Search strategy A yielded 50 hits combined for hand, hip or knee OA that mentioned some work-related concept in the title or abstract; 12 articles had to be excluded because they were not available as searchable PDFs. Screening of the remaining 38 articles resulted in only two articles that satisfied our inclusion criteria. Search strategy B yielded 986 hits, out of which 201 articles were excluded because searchable full text PDFs were not available. PDF full text searching and further screening resulted in 10 articles that were considered eligible for our review.

Conclusions

Work-related outcomes are rarely reported in journal publication on randomized, double blind, placebo-controlled trials of hand, hip or knee OA. Searching full text PDFs yields more eligible articles than searching titles and abstracts only.

Ultrasound plus low-level laser therapy for knee osteoarthritis rehabilitation: a randomized, placebo-controlled trial

This study evaluated the synergistic effects of ultrasound (US) and low-level laser therapy (LLLT) with or without therapeutic exercises (TE) in women with knee osteoarthritis. Forty-two Caucasian women with knee osteoarthritis were allocated into three groups: (1) the placebo group who did not perform TE, but the prototype without emitting light or ultrasonic waves was applied, (2) the US + LLLT group in which only the prototype was applied and (3) the TE + US + LLLT group that performed TE before the prototype was applied. However, 35 women completed the full clinical trial. Pressure pain thresholds (PPT) using an algometer and functional performance during the sit-to-stand test were carried out. The average PPT levels increased for US + LLLT (41 ± 9 to 54 ± 15 N, p < 0.01) and TE + US + LLLT (32 ± 8 to 45 ± 9 N, p < 0.01) groups. The number of sit-to-stands was significantly higher for all groups. However, the change between pre-treatment and post-treatment (delta value) was greater for the US + LLLT (4 ± 1) and TE + US + LLLT groups (5 ± 1) than for the placebo group (2 ± 1) with a significant intergroup difference (p < 0.05). This study showed reduced pain and increased physical functionality after 3 months of US + LLLT with and without TE.

Therapeutic modalities and postural balance of patients with knee osteoarthritis: systematic review

AbstractObjective The objective of this review was to evaluate the evidence of the influence of therapeutic modalities on postural balance in patients with knee osteoarthritis (OA).Methods A search for published papers on therapeutic modalities was conducted using the Pubmed, Medline, Lilacs and SciELO databases. The keywords “knee” and “balance” in combination with “osteoarthritis” were used as the search strategy. Randomized controlled clinical trials published in the last 10 years in either English or Portuguese were selected. The PEDro scale was applied to assess the quality of the selected clinical trials.Results A total of 46 studies of patients with knee OA were found, of which seven were analyzed in full and 39 were excluded because they did not meet the inclusion criteria. Of the seven studies reviewed, six were considered to have a high methodological quality on the PEDro scale. Several therapeutic modalities were found (physical exercise, hydrotherapy, electrotherapy and manual therapy), and postural balance improved in only three studies.Conclusion The studies included in this systematic review had a high methodological quality, so it can be concluded that the therapeutic modalities used in those studies improved postural balance in patients with knee OA.

Laboratory-based measurement of standing balance in individuals with knee osteoarthritis: a systematic review

BACKGROUND

Laboratory-based measurement of standing balance is used to assess postural control in people with and without pathology, including knee osteoarthritis. However, no summary of available data has been reported in this patient population. This study aimed to summarize available data and testing methods for individuals with knee osteoarthritis.

METHODS

Medline (OvidSP and PubMed), Embase, CINAHL, and Web of Science were searched from 1994 to October 25, 2014 to identify studies containing a quantifiable measure of standing balance. Methodological quality was assessed using a modified 17-item Downs & Black quality index. Studies scoring <50% were eliminated.

FINDINGS

The search strategy initially yielded 1523 unique papers; 21 met all inclusion and quality assessment criteria. The variables measured in three or more of the 21 papers were anteroposterior centre of pressure (COP) velocity, mediolateral COP velocity, mean COP velocity, anteroposterior range of COP, mediolateral range of COP, anteroposterior COP standard deviation, mediolateral COP standard deviation, COP path length, COP area, Biodex anteroposterior score, Biodex mediolateral score, and overall Biodex score. In general, people with knee osteoarthritis exhibited worse standing balance compared to healthy controls. However, there remained much discrepancy in testing procedures across studies.

INTERPRETATION

These findings indicate that people with knee osteoarthritis exhibit altered postural control. However, no conclusions could be made on the differences between radiographic severities. That said, these findings provide an opportunity for future researchers and clinicians to compare their findings with the currently published data.

Physical therapies for improving balance and reducing falls risk in osteoarthritis of the knee: a systematic review

INTRODUCTION

osteoarthritis (OA) of knee has been reported as a risk factor for falls and reduced balance in the elderly. This systematic review evaluated the effectiveness of physical therapies in improving balance and reducing falls risk among patients with knee OA.

METHODS

a computerised search was performed to identify relevant studies up to November 2013. Two investigators identified eligible studies and extracted data independently. The quality of the included studies was assessed by the PeDro score.

RESULTS

a total of 15 randomised controlled trials involving 1482 patients were identified. The mean PeDro score was 7. The pooled standardised mean difference in balance outcome for strength training = 0.3346 (95% CI: 0.3207-0.60, P = 0.01 < 0.00001, P for heterogeneity = 0.85, I(2) = 0%). Tai Chi = 0.7597 (95% CI: 0.5130-1.2043, P<=0.0014, P for heterogeneity = 0.26, I(2) = 0%) and aerobic exercises = 0.6880 (95% CI: 0.5704-1.302, P < 0.00001, P for heterogeneity = 0.71, I(2) = 0%). While pooled results for falls risk outcomes in, strength training, Tai chi and aerobics also showed a significant reduction in reduced risk of falls significantly with pooled result 0.55 (95% CI: 0.41-0.68, P < 0.00001, P for heterogeneity = 0.39, I(2) = 6%).

CONCLUSION

strength training, Tai Chi and aerobics exercises improved balance and falls risk in older individuals with knee OA, while water-based exercises and light treatment did not significantly improve balance outcomes. Strength training, Tai Chi and aerobics exercises can therefore be recommended as falls prevention strategies for individuals with OA. However, a large randomised controlled study using actual falls outcomes is recommended to determine the appropriate dosage and to measure the potential benefits in falls reduction.

Osteoarthritis year in review: outcome of rehabilitation

PURPOSE

This review highlights seminal publications of rehabilitation interventions for osteoarthritis (OA) since April 2012.

METHODS

Medline in process, Embase, CINAHL and Cochrane databases were searched from April 2012 through February 2013 for English language publications using key words osteoarthritis, rehabilitation, physiotherapy, physical therapy, and exercise. Rehabilitation intervention studies included randomized trials or systematic reviews/meta-analyses or pre-post studies. Pilot randomized trials, feasibility studies and studies of surgical interventions unless they included evaluation of a rehabilitation intervention were excluded.

RESULTS

Twenty-five studies were identified for inclusion and grouped thematically. The short-term benefits (i.e., to 3 months) of variable types and dosages of exercise were demonstrated for a number of outcomes including pain, stiffness, function, balance, biomarkers, and executive function and dual task performance (related to falling) in people with knee OA. Modalities such as 890-nm radiation, interferential current, short wave diathermy, ultrasound and neuromuscular functional electrical stimulation did not demonstrate benefit over sham controls in those with knee OA. Spa therapy improved pain over the period of treatment in those with knee and hand OA. Supervised self-management based on cognitive therapy principles resulted in improved outcomes for people with knee OA. Shock absorbing insoles compared to normal footwear minimally improved knee pain and but not function and did not decrease knee load. Neuromuscular and motor training improved function in those with total hip replacement. Accelerated weight-bearing and rehabilitation (8 versus 11 weeks) was demonstrated to be safe and effective at 5 years following matrix autologous chondrocyte implantation for cartilage defects in the knee.

CONCLUSIONS

Exercise remains a mainstay of conservative management although most studies report only short-term outcomes. Self-management strategies also are beneficial in knee OA. There seems to be a placebo effect with most trials of physical modalities although spa therapy demonstrated very short-term effects.

Effect of low-level laser therapy in patients with chronic knee osteoarthritis: a single-blinded randomized clinical study

The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on pain relief and functional performance in patients with chronic knee osteoarthritis (OA). Forty patients with knee OA were randomly assigned into active laser group (n = 20) and placebo laser group (n = 20). The LLLT device used was a Ga-As diode laser with a power output of 50 mW, a wavelength of 850 nm, and a diameter beam of 1 mm. Eight points were irradiated and received dosage of 6 J/point for 60 s, with a total dosage of 48 J/cm(2) in each session. The placebo group was identical but treated without emission of energy. LLLT was applied two times per week over the period of 4 weeks. Outcome measurements included pain intensity at rest and at movement on visual analog scale, knee function using Western Ontario McMaster Universities Osteoarthritis Index scale, and ambulation duration. These measurements were collected at baseline and post-intervention. The results showed significant improvements in all assessment parameters in both groups compared to baseline. Active laser group showed significant differences in pain intensity at rest and movement, knee function, and ambulation duration when compared with the placebo group. Therefore, LLLT seemed to be an effective modality for short-term pain relief and function improvement in patients with chronic knee OA.

Postural stability in patients with knee osteoarthritis: comparison with controls and evaluation of relationships between postural stability scores and International Classification of Functioning, Disability and Health components

OBJECTIVES

To assess the differences in postural stability between patients with knee osteoarthritis and controls without knee osteoarthritis, and to evaluate possible relations between postural stability scores and International Classification of Functioning, Disability and Health (ICF) components.

DESIGN

An age-matched, case-controlled trial with a cross-sectional design.

SETTING

A teaching hospital.

PARTICIPANTS

Patients with knee osteoarthritis (n=73) and age-matched controls (n=60).

INTERVENTIONS

Data on patients' postural stability and additional health-related variables were collected using various instruments. These included the Hospital Anxiety and Depression Scale, the Multidimensional Fatigue Inventory, the World Health Organization Quality of Life Brief Version, the physical function test (chair-rising time), the Chinese version of the Western Ontario and McMaster Universities Osteoarthritis Index, the Chinese version of the Knee Injury and Osteoarthritis Outcome Score, and the Biodex Stability System.

MAIN OUTCOME MEASURES

A comparison of postural stability in patients with knee osteoarthritis versus that of controls was performed. The relation between postural stability scores for patients with knee osteoarthritis and ICF components was evaluated. Pearson correlation tests were used to determine the variables that correlated with postural stability among these patients.

RESULTS

Patients with knee osteoarthritis displayed lower overall postural stability than controls (scores of 0.7 vs. 0.5, P=.006) and scored lower on the environmental domain of the World Health Organization Quality of Life Brief Version (62.2 vs 66.8, P=.014). For patients with knee osteoarthritis, postural stability was weakly associated with the ICF components of body functions and structures, including pain (r=.33-.34, P=.004), physical fatigue (r=.28, P=.016), and reduced motivation (r=.30, P=.011). Weak to moderate associations between postural stability and the ICF components of activities and participation were found; the relevant ICF variables included reduced activity (r=.38, P=.001), physical domain and function (r=.34-.48, P=.001 to P<.004), activities of daily living (r=.51, P<.001), and sports and recreation (r=.35, P=.003). A moderate association between postural stability and the ICF components of personal and environmental factors was observed, including age (r=.52, P<.001) and quality of life (r=0.4, P=.001).

CONCLUSIONS

Patients with knee osteoarthritis displayed lower postural stability and achieved lower scores in the environmental domain of quality-of-life measures than did controls. The postural stability of patients with knee osteoarthritis was weakly to moderately associated with the following ICF components: body functions and structures, activities and participation, and personal and environmental factors.

Local and systemic cardiovascular effects from monochromatic infrared therapy in patients with knee osteoarthritis: a double-blind, randomized, placebo-controlled study

Infrared (IR) therapy is used for pain relief in patients with knee osteoarthritis (OA). However, IR's effects on the cardiovascular system remain uncertain. Therefore, we investigated the local and systemic cardiovascular effects of monochromatic IR therapy on patients with knee OA in a double-blind, randomized, placebo-controlled study. Seventy-one subjects with knee OA received one session of 40 min of active or placebo monochromatic IR treatment (with power output of 6.24 W, wavelength of 890 nm, power density of 34.7 mW/cm² for 40 min, total energy of 41.6 J/cm² per knee per session) over the knee joints. Heart rate, blood pressure, and knee arterial blood flow velocity were periodically assessed at the baseline, during, and after treatment. Data were analyzed by repeated-measure analysis of covariance. Compared to baseline, there were no statistically significant group x time interaction effects between the 2 groups for heart rate (P = 0.160), blood pressure (systolic blood pressure: P = 0.861; diastolic blood pressure: P = 0.757), or mean arterial blood flow velocity (P = 0.769) in follow-up assessments. The present study revealed that although there was no increase of knee arterial blood flow velocity, monochromatic IR therapy produced no detrimental systemic cardiovascular effects.