1. Introduction

Osteoarthritis (OA) remains the most common form of arthritis despite the presence of aspects that overlap with those of other arthritic conditions, such as persistent pain, stiffness, and loss of mobility, especially among the elderly [1]. The major objective is to understand the pathophysiological differences, one of which is the progressive destruction of the representative, joint surface and cartilage, together with gross changes within the subchondral bone, synovium, and other joint structures. Such changes lead to the development of bone spurs and shrinkage of soft tissue and cartilage, which can be seen as a narrowing of joint spaces during imaging replacement [2]. The end result is ultimately dysfunction regarding the compromised joint as well as excruciating pain. When it comes to causation, much is known about how OA is an effect of a great number of processes, including not only mechanical and biological but also metabolic and genetic factors that explain the complexity of this disease.

The primary goals of traditional OA management put emphasis on symptom control and improving patients’ quality of life [3]. Currently, the most common therapeutic approaches include pharmacological treatments such as analgesics and non-steroidal anti-inflammatory drugs (NSAIDs), physical therapy, and, in worst-case scenarios, surgical interventions like arthroplasty [4]. However, despite these treatment modalities, many patients continue to experience unabated pain and functional restraints. What is calling for, therefore, are other forms of therapy that have less adverse effects, especially on the side of pain management, and which do not involve operating or taking drugs for a long time [5].

In recent years, laser therapy has garnered attention as a promising non-invasive treatment option for OA. Laser therapy utilizes specific wavelengths of light to penetrate soft tissues, with the aim of inducing the natural healing process within our own body, which involves liberating agents of inflammation involved in healing and repair without the collateral damage as is often seen in inflammatory processes. Laser therapy was initially employed in dermatology, dentistry, and ophthalmology, but its mechanisms of action, that being, decreasing inflammatory markers, enhancing cellular repair, and modulating pain, exhibit its potential applicability in musculoskeletal conditions like osteoarthritis.

This study attempts to answer several key questions regarding the use of laser therapy in osteoarthritis mangment. One key investigation is the evaluation of the impact of different laser wavelengths on pain mitigation in patients with osteoarthritis, as variations in wavelength may significantly influence therapeutic outcomes. Additionally, the study aims to comprehend how alterations in the dosage of laser affect the healing of joint function, determining whether higher or lower dosages yield better results in managing osteoarthritic symptoms. Another important consideration is the comparison of outcomes between short-term and long-term laser therapy treatments, which may inform us of the sustainability of symptom relief over extended periods of time; this is important when deciding on the time period for regular treatment. Furthermore, the study investigates whether any significant complications or side effects are linked with the regular use of laser therapy in osteoarthritis management, clarifying its safety profile. Finally, the research will attempt to compare laser therapy with traditional osteoarthritis treatments to find out which of the two holds higher efficacy in the management of symptoms and overall improvement of patient satisfaction. Only from this can we discover viable alternatives to existing therapeutic options.

As interest in non-invasive, non-pharmacological treatments grows, laser therapy has garnered attention, especially for patients who are either unsuitable for surgical intervention or wish to avoid chronic medication use. While several studies have suggested that laser therapy may alleviate OA symptoms, there is still a lack of comprehensive data comparing the effectiveness of different types of laser therapy. Understanding the impact of varying wavelengths, dosages, and treatment durations is critical to establishing optimal treatment protocols, ensuring safety, and verifying clinical efficacy. Thus the primary objective of this study is to assess the efficacy of various forms of laser therapy in mitigation of pain and improvement of joint function in patients with osteoarthritis, with a specific focus on randomized controlled trials (RCTs) conducted in Saudi Arabia. This approach aims to provide insights into local treatment outcomes of the country.

The studywillalsosystematicallysearch for global studies on the subject matter,givinga moreupdatedsystematic reviewtocomplementthe last review conductedsomefew years ago. This will involve the collection and synthesis of data that includes the effects of different laser parameters, such as wavelength, dosage, and treatment duration, on osteoarthritic symptoms. Furthermore, the study will evaluate the safety and side effect profile of laser therapy, using both local and global data to ensure a proper understanding of its application in osteoarthritis treatment.

The findings of this study will help refine treatment protocols for osteoarthritis, providing evidence-based recommendations for the use of laser therapy. This could guide clinicians in selecting optimal laser parameters (wavelength, dosage, treatment duration) and identifying patient populations who would benefit most from this non-invasive therapy. Furthermore, the safety profile outlined in this study will contribute to risk-benefit assessments in clinical settings, potentially expanding the use of laser therapy as a standard option in OA management.

2. Methods

This study was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

2.1 Eligibility Criteria

The study included all published RCTs that investigated the effectiveness of laser therapy on osteoarthritis in any joint, with the language restricted to English. Only adult patients diagnosed with osteoarthritis, based on the American College of Rheumatology (ACR) criteria or expert opinion from orthopedists or rheumatologists, were considered. Studies comparing different forms of laser therapy, with variations in parameters such as wavelength and exposure time, were included. Participants with severe cognitive impairments or other combined joint disorders were excluded.

2.2 Search Strategy

Relevant articles were identified using specific keywords such as “osteoarthritis,” “degenerative arthritis,” “arthrosis,” and “OA,” along with terms like “high-intensity laser therapy” or “low-intensity laser therapy.” The search was conducted using electronic databases, including CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, and PEDro (Physiotherapy Evidence Database). Additionally, a manual search of references from selected studies and relevant reviews was performed.

2.3 Study Selection

All identified studies were screened, initially by reviewing titles and abstracts, followed by a full-text review to determine eligibility. Our search date was June, 2024, for local studies and August 2024 for global studies. Any studies that did not meet the predefined inclusion criteria were excluded, and reasons for exclusion were documented. A forward and backward citation search was also conducted to identify additional relevant RCTs.

2.4 Data Extraction

Data from the eligible studies were extracted, including details such as author, sample size, average age, type of osteoarthritis, laser modality used, therapeutic effects, and adverse effects.

2.5 Data Analysis

Data was analyzed using SPSS software after importing from Microsoft Excel. The data on normality and homogeneity was first tested. While mostly homogenous, the data did not follow normality, and thus, only non-parametric tests were conducted, such as Kruskal-Walis. The chi-square test was conducted between nominal and continuous variables, while the bivariate correlation was conducted between continuous variables only. Qualitative analysis was also carried out to assess the evidence for symptomatic relief from laser therapy, taking into account the clinical heterogeneity and methodological quality of the studies. The interventions were grouped into high, low, or other laser therapies as per Cochrane Collaboration criteria .

3. Results

A total of seven studies conducted locally in Saudi Arabia were identified, alongside 43 randomized controlled trials (RCTs) from global sources (Figure 1).

Figure 1: PRISMA Flowchart.

3.1 Type of Osteoarthritis

All 7 local studies focused exclusively on the knee joint. Globally, the majority of studies (76.7%) involved males with knee osteoarthritis. Meanwhile, 4 studies (9.3%) investigated the temporomandibular joint, 3 (7.0%) focused on hand osteoarthritis, 2 (4.7%) examined cervical spine osteoarthritis, and only 1 (2.3%) study targeted the hip joint (Figure 2).

Figure 2: Subtypes of osteoarthritis found amongst studies.

3.1.1 Temporomandibular Joint

Among the four studies involving the temporomandibular joint (TMJ), two reported significant improvements in pain and function following mid-level laser therapy at a wavelength of 904 nm, administered three times a week for three weeks (p<0.05). Of the remaining two studies, one observed a slight improvement in pain and function after low-level laser therapy, while the other reported no significant changes in any parameter (p>0.05).

3.1.2 Thumb Carpometacarpal Joint

The three studies focusing on hand osteoarthritis each utilized different laser modalities. The study employing high-power laser therapy demonstrated a significant reduction in pain at the end of treatment (p<0.001). In contrast, the study using low-power laser therapy reported improvements in carpometacarpal opposition (p=0.001) and grip strength (p=0.041). Lastly, the study utilizing helium laser therapy documented a slight decrease in tenderness of the metacarpophalangeal and interphalangeal joints (p<0.01 and p<0.05, respectively).

3.1.3 Cervical Joint

Of the two studies examining cervical spine osteoarthritis, one reported a significant reduction in muscle spasms following low-power laser therapy at a wavelength of 830 nm, delivered over 10 sessions (p<0.05). However, the other study found no significant improvement when comparing laser therapy to the Saunders method of physiotherapy (p>0.05).

3.1.4 Hip Joint

The single study focusing on the hip joint reported significant improvements in pain and inflammatory markers after photobiomodulation therapy using low-level laser therapy and low-emission diodes (LED) (p<0.05).

3.2 Type of Intervention & placebo

There was a notable lack of studies directly comparing high-power and low-power laser therapies. Instead, most research focused on low-power laser therapy, either as a standalone treatment or in combination with other modalities such as exercise or pharmacological agents.

For the local studies, 3 (42.9%) investigated low-power laser therapy alone, while 2 (28.6%) examined low-power laser therapy combined with another modality. One study (14.3%) explored high-power laser therapy in combination with another modality, and only one made a direct comparison between low-power and high-power laser therapy.

Globally, 9 studies (20.9%) evaluated low-power laser therapy alone, while 12 (27.9%) investigated low-power laser therapy combined with another modality. There were 7 studies (16.3%) that focused on high-power laser therapy, and only 1 study (2.3%) assessed high-power laser combined with another modality. Additionally, 5 studies (11.6%) evaluated moxibustion laser therapy, 4 (9.3%) examined acupuncture laser therapy, and 3 (7.0%) explored combinations of photobiomodulation (Figure 3).

Figure 3: Different types of laser intervention amongst studies.

The most common comparator in these studies was a sham or placebo laser, used in 27 studies (62.8%). Of these, 9 (20.9%) used a sham laser in combination with other interventions. Only one study (2.3%) directly compared interventions without a placebo, while 6 studies (14.0%) did not include any comparator.

3.3 Outcomes

3.3.1 Laser versus Placebo

In terms of the superiority of intervention, all 7 local studies reported laser therapy as superior to placebo. Globally, 27 studies also found laser therapy to be more effective than placebo, while 5 studies reported no significant improvement when compared to placebo (Figure 4). Among studies comparing multiple laser modalities, 8 reported differences in efficacy between lasers, whereas 3 found no significant differences in performance.

Figure 4: Different outcomes recorded from global studies.

3.3.2 Pain and Function Scales

Among the local studies, one study reported a significant improvement in the Visual Analog Scale (VAS) score after 4 weeks of laser therapy (p<0.05). Another local study demonstrated a significant improvement in VAS score after 6 weeks of treatment (p=0.0014), while three studies observed very significant improvements in VAS scores after 6 weeks (p<0.0001).

Globally, despite variations in pain assessment scales across studies, 9 out of 43 studies reported significant changes in VAS pain scores after laser therapy (p<0.05), while 3 studies reported very significant changes (p<0.0001). Additionally, 9 studies documented significant improvements in the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score (p<0.05), while 4 studies reported very significant improvements (p<0.01) after laser therapy.

3.3.3 Modality Used in Combination

For studies combining laser therapy with other modalities, 3 local studies showed significant improvements in pain and movement when exercise was performed concurrently with laser therapy (p<0.05). Globally, 6 studies similarly reported significant improvements in pain and movement when exercise was combined with laser therapy (p<0.05). Furthermore, one global study highlighted several significant outcomes, including improvements in cadence (p<0.009), reductions in the duration of right limb support (p<0.035), and enhancements in gait speed (p<0.005).

3.4 Laser properties (Wavelength & sessions per weak)

The most commonly used wavelength range was between 800-1000nm, the average sessions done per week was 3 and the average duration was 5 weeks. A trend was noticed where a longer duration of therapy was matched with shorter sessions (Figure 5). Of the global studies that administered laser therapy at 3 sessions per week, 22 reported a positive outcome on at least one scale. The degree of watts used was highly variable and did not contribute to the significance of outcomes, despite the statistical analysis showing a significant change in watts with the choice of intervention (p=0.025). The same was true for change in wavelength with choice of intervention (p=0.007). Additionally, statistical analysis showed a significant correlation between the condition and mean age (p=0.046), condition, and sessions per week (p=0.046).

Figure 5: Total duration of therapy matched with sessions per week.

3.5 Adverse effects & Long-term outcomes

Studies did not explicitly report adverse effects, and of those that did, only mentioned warmness and irritation but these were not significant (p>0.05). Despite a few patients needing re-therapy, long-term outcomes were not given focus amongst the majority of studies.

3.6 Statistical analysis

Normality testing using Sharpiro-wilk for both local and global studies showed that the data was not normally distributed (p<0.05). In comparison, homogeneity testing was significant (p<0.05) for a few factors but not overall.

Figure 6: Independent sample Kruskal Walis test for global studies. a) Distribution of sessions per week across condition; b) Distribution of mean age (years) across condition.

Amongst global studies, independent samples of Kruskal walis showed significance in the distribution of mean age (p=0.46) and the distribution of sessions per week (p=0.46) across all categories of condition (Figure 6). Similarly, it also showed significance in the distribution of sample size (p=0.48), Watts (p=0.25), and wavelength (p=0.007) across all categories of intervention.

The chi-square between outcomes and intervention amongst global and local studies did not show any significance (p=0.744). Amongst local studies, Pearson’s correlation was significant between the duration of therapy, number of males, and sessions per week used (p<0.01) (Table 1). Amongst global studies, Pearson’s correlation was significant between sample sizes, number of males, and wavelength used (p<0.01) (Table 2). The entire synthesis of local and global studies is shown in Tables 3 and 4.

Table 1: Pearson’s correlation for local studies.

Table 2: Pearson’s correlation for global studies.

Table 3: Synthesis of data from local studies.

Table 4: Synthesis of data from global studies

3.7. Risk of bias

Amongst local studies, only 3 studies raised concerns, despite the overall low risk of bias (Figure 7,8). The issue was mostly with what outcomes were considered and how they were recorded. Furthermore, a few weaknesses in the methodology lowered the overall robustness of the studies, leading to further suspicion of bias towards certain outcomes.

Figure 7: Risk of bias of local studies as percentage of intention-to-treat.

Figure 8: Risk of bias of local studies according to 5 domains.

4. Discussion

This review primarily aimed to assess the efficacy of laser therapy for osteoarthritis, focusing on local studies conducted in Saudi Arabia (SA) while also taking a snapshot of the findings from global research. The studies from SA were limited in number; as such, they provided minimal insights into treatment outcomes. Statistical analysis revealed no significant results due to the small dataset; however, based on the qualitative evaluation, certain trends were appreciated. Primarily, low-level laser therapy (LLLT) and high-level laser therapy (HLLT), when combined with exercise, offered a greater benefit to patients with knee osteoarthritis than placebo. But this is the extent to which inferences can be made. Although it is acknowledged that knee osteoarthritis remains the more prevalent and comparatively more morbid condition [56], which explains why all local studies focused on it as the exclusive indication, It is unknown how laser therapy can affect patients with osteoarthritis of different joints within this same demographic. Overall, while the outcomes slightly differ from those of global studies, the latter reports the sufficiency of LLLT to bring about significant outcomes. Nonetheless, it is not enough to warrant the inclusion of therapy into regular clinical practice. The disproportionate representation of local studies compared to global ones underscores the need for more extensive and methodologically robust research.

In comparison, the global studies reviewed in this paper offer valuable insights into the efficacy of laser therapy in osteoarthritis management. Several noteworthy patterns were appreciated. Firstly, the majority of studies reported LLLT as superior to placebo, though improvements in VAS and WOMAC were more substantial when LLLT was combined with another modality like exercise. It should be noted that this conclusion on the superiority of LLLT is not made on the merit of the changes seen in VAS and WOMAC as compared to HLLLT but rather due to the fact that the majority of studies only studied LLLT against a placebo. This may be due to LLLT being more accessible or cheaper. Conversely, it can be recognized as a limitation since there were few direct one-to-one comparisons between LLLT and HLLT. Nevertheless, the significant outcomes in patient symptoms still lend credence to LLLT as a treatment modality. However, a review paper by Ahmed et al. [57], which acknowledged how laser therapy is effective but only when used as an adjunct to rehabilitative exercise, found that HLLT was more efficacious with regards to symptom improvement, at least as far as knee osteoarthritis was concerned. The authors Wu et al. [58] go as far as reporting how high-intensity laser therapy is even better than conventional modalities. However, after reviewing the literature, exercise should be given the spotlight as it is mentioned as a tried and tested method of non-invasive treatment according to multiple review papers [2,5]. So, while it is understood how laser therapy has yet to establish itself as a dependable treatment option, it does beg the question of whether the positive outcomes obtained from the majority of studies were mostly, if not entirely, due to the effects of exercise instead of the laser.

Amongst the significant statistical findings, a strong relationship was observed between condition and mean age (p = 0.046). This is explainable, as the finding is consistent with demographic trends; for example, knee osteoarthritis is more prevalent among elderly populations due to degenerative changes, whereas hand osteoarthritis may affect younger, active individuals who engage in repetitive manual tasks. It is interesting to note that, according to a report by Peat et al. [59], in the English population, hand osteoarthritis is actually more common than knee osteoarthritis among females. This may partially explain why we did not see this subtype within the current review, as most global studies have a greater percentage of male participants. Similarly, a significant association was noted between condition and sessions per week (p = 0.046), and this may reflect the differences in therapeutic requirements among various joint types. Larger, weight-bearing joints such as the knee might demand more frequent therapy sessions compared to smaller joints like the hand, which could benefit from fewer sessions. However, without further evidence, all of this remains speculative since none of the studies specifically focused on these parameters.

The collected studies had a number of limitations. First and foremost was the lack of standardization. Multiple studies lacked protocols for inclusion, exclusion criteria, laser dosages, duration, application methods, etc. This led to a lack of true homogeneity that made comparisons across studies difficult and made it impossible to conduct a more robust statistical analysis. Additionally, there was heterogeneity in the comparators, with some studies making a comparison with a sham laser while others made a direct comparison between two lasers. Furthermore, there were also a couple of studies that had limited participants, so this added to the reduced statistical power and the generalizability of findings. Coupled with some studies reporting a high dropout rate, a few not blinding participants, and the fact the majority of osteoarthritis subtypes were knee-related, this introduced a significant bias in the reported results.

The second most important limitation was that of gender imbalance; most studies were male-dominated, and this was also reflected in the statistical analysis. Due to this, we cannot comment on whether laser therapy is as efficacious for female patients with osteoarthritis. Regarding other data items, the majority of studies also only provided short-term outcomes (no more than 12 months), and thus, we can’t comment on how effective or safe laser therapy is for long-term management. Also, while most studies mentioned no significant side-effect of laser therapy, there was no systematic documentation or reporting of this. This leaves a gap in the risk-benefit assessment, and thus, we cannot make concrete recommendations that can be utilized by clinical guidelines.

Thirdly, there was a dearth of local studies; since the prime focus of this review was to determine the effects of laser therapy on osteoarthritic patients from SA, we are left with little insight specific to this regional population. Moreover, a lot of the studies combined laser therapy with other modalities. This concurrent use of exercise, kinesiology tape, or other modalities makes it difficult to isolate the effects of laser therapy. This is why our recommendation is to employ a combination of laser therapy with other modalities until further understanding is achieved through prospective research.

5. Conclusions

Generally, low-power laser therapy is a valid non-invasive treatment option for osteoarthritis, particularly in alleviating pain and improving joint function, but only if used in combination with other modalities, with exercise being preferable. While tailoring the laser parameters such as wavelength, dosage, and duration to the specific needs of patients may have a role in influencing outcomes, more studies are needed to explicitly specify the values; for now, the wavelength and duration associated with low-power laser therapy remain safe and effective. It is stressed that future studies need greater standardization in treatment protocols to enhance comparability and reproducibility across studies. Until then, the integration of laser therapy as part of management into clinical practice should be put on hold, or at least the treatment should be offered to those patients not willing to try other options or who have exhausted all other forms of treatment. Further high-quality evidence is essential to establish optimal treatment guidelines.

6. Disclosure of interest

The authors declare no conflicts of interest with respect to the research, authorship, and/or publication of this article.

7. Funding

No funding was received.

References

1. Lin JC, Weintraub N, Aragaki DR. Nonsurgical treatment for rotator cuff injury in the elderly. J AmMed Dir Assoc 9 (2006): 626-632.
2. Fukuda H, Mikasa M, Yamanaka K. Incomplete thickness rotator cuff tears diagnosed by subacromial bursography. Clin Orthop Relat Res 223 (1987): 51-58.
3. Payne LZ, Altchek DW, Craig EV. Arthroscopic treatment of partial rotator cuff tears in young athletes: a preliminary report. Am J Sports Med 25 (1997): 299-305
4. Ellman H. Partial Thickness rotator cuff tears: Arthroscopic classification. CORR 254 (1990): 64-74,
5. Itoi E, Tabata S. Incomplete rotator cuff tears: results of operative treatment. Clin Orthop Relat Res 284 (1992): 128-135.
6. Walch G, Boileau P, Noel E. et al. Impingement of the deep surface of the supraspinatus tendon on the posterior glenoid rim: an arthroscopic study. J Shoulder Elbow Surg 1 (1992): 238-245.
7. Parker RD, Seitz WH Jr. Shoulder impingement/instability overlap syndrome. J South Orthop Association Fall 6 (1997): 197-203.
8. Wiener SN, Seitz WH. Sonography of the shoulder in patients with tears of the rotator cuff, accuracy and value for selecting surgical option. AJRAm J Rroentgenol 160 (1993): 103-107.
9. Boudreault J, Desmeules F, Roy JS, et al. The efficacy of oral non-steroidal antiinflammatory drugs for rotator cuff tendinopathy: a systematic review and meta-analysis. J Rehabil Med 46 (2014): 294-306.
10. Khan KM, Cook JL, Bonar F, et al. Histopathology of common tendinopathies. Update and implication for clinical management. SportsMed 27 (1999): 393-408.
11. Van der Dolder PA, Roberts DL. A trial into the effectiveness of soft tissue massage in the treatment of shoulder pain. Aust J Physiother 49 (2003.): 183-188.
12. Hains G, Descarreaux M, Hains F. Chronic shoulder pain and myofascial origin: a randomized clinical trial using ischemic compression therapy. JManip Physiol Ther 33 (2010.): 362-369.
13. Solem-Bertoft E, Thuomas KA, Westerberg CE, et al. The influence of the scapula retraction and protraction on the width of the subacromial space. An MRI study. Clin Orthop Relat Res 296 (1993): 99-103.
14. Reinold MM, Wilk KE, Fleisig GS, et al. Electromyographic analysis of the rotator cuff and deltoid musculature during common shoulder external rotation exercises. J Orthop Sports Phys Ther 34 (2004): 385-394.
15. Conway JE. Arthroscopic repair of partial thickness rotator cuff tears and SLAP lesions in professional baseball players. Orthop Clin North Am 32 (2001): 443-456.
16. Fukada H. The management of partial-thickness tears of the rotator cuff. Bone Joint J 85 (2003): 3-11.
17. Fleega BA. Arthroscopic transhumeral rotator cuff repair. Giant needle technique. Arthroscopy 18 (2002): 218-23.
18. Fleega BA. Arthroscopic reinforced capsular shift of anterior shoulder instability. Arthroscopy 20 (2004): 543-546.
19. Fleega BA. Postoperative Krankengymnastisches Rehabilitationsprogramm nach Schulteroperationen. Manuelle Medizin 37 (1999): 96-100.
20. Dhillon KS. Subacromial impingement syndrome of the shoulder: a musculoskeletal disorder or a medical myth? Malays Orthop J 13 (2019): 1-7.
21. Koester MC, George MS, Kuhn JE. Shoulder impingement syndrome.Am J Med 118 (2005): 452-455.
22. Garving C, Jakob S, Bauer I, et al. Impingement syndrome of the shoulder. Dtsch Arztebl Int 114 (2017): 765-776.
23. Mackenzie TA, Herrington L, Horlsey I, et al. An evidence-based review of current perceptions with regard to the subacromial space in shoulder impingement syndromes: is it important and what influences it? Clin Biomech 30 (2015): 641-648.