Comparison of the effect of high-power laser and conventional physiotherapy in the treatment of supraspinatus tendonitis

Tendonitis is the most common musculoskeletal disorder of the shoulder joint. The positive effects of low-power laser such as increasing range of motion and reducing pain in shoulder tendonitis treatment have been confirmed. The aim of this study is to evaluate the effect of a high-power laser, compared with conventional physiotherapy.

Tendonitis is the most prevalent musculoskeletal problem affecting the shoulder joint, accounting for one-third of all joint problems. Tendinitis is an inflammation or irritation of the thick fibrous cords that connect the muscle with the bone. Pain and tenderness are felt immediately outside a joint in this disease. Various therapies for shoulder tendonitis have been suggested, including no steroidal anti-inflammatory medication injections, glucocorticoids injections, exercise therapy, ultrasound therapy, cold therapy, and laser therapy. With minimal energy and a single wavelength, this laser belongs to the class III laser treatment. The laser's method is based on enhancing cellular activity, anti-inflammatory components, and collagen formation, according to laboratory research. Baxter has connected enhanced serotonin, prostaglandin inhibition, and fibroblast activity to the physiological mechanism of laser pain alleviation and tissue regeneration. However, the use of lasers in the treatment of shoulder tendonitis has been documented in multiple papers to have good results such as greater range of motion and decreased discomfort. Haslerud et al. verified the impact of a low-power laser in the treatment of shoulder tendonitis at the right dosage in a systematic study published in 2014. The failure of laser therapy owing to faulty technique and inadequate dosage is examined in this research. The high-power laser, which is classified as a class IV laser and generally consists of many wavelengths with a combined power of more than 1000 mW, has just lately entered the area of laser treatment. It is believed to offer deeper penetration depth and more effective therapy than low power lasers because to the presence of numerous simultaneous wavelengths that are absorbed at various levels of tissue and higher output energy than low power lasers. Limited research on the clinical assessment of high-power lasers have been conducted so far, but they have proven the favorable therapeutic impact of this laser as a low-power laser. The goal of this research was to compare the effects of high-power laser treatment to traditional physiotherapy and to explain how high-power lasers work.

The patients in this study were a randomized single-blind controlled trial. Patients were diagnosed with supraspinatus muscle tendonitis by an orthopedic physician. Being at least positive on at least three of the five clinical tests including arc painful syndrome, impingement test, supraspinatus test, palpation sensitivity test, and Hawkins-ken test were inclusion criteria.

Any of the cervical radiculopathies, joint acromioclavicular dysfunction, frozen shoulder, systemic inflammatory diseases, complete rupture of the tendon and scapula, and injection of thyroid corticosteroids in the past month were the criteria for exclusion from the study. All participants first filled out the consent form to participate in the study approved by the School of Rehabilitation of Tehran University of Medical Sciences and the procedures were explained to them. Then, using a questionnaire, patients' personal information, weight and height were measured and recorded. 40 patients (23 females and 17 males) were randomly divided into two groups including: 20 patients (12 females and 8 males) (HPL), and 20 patients (11 females and 9 males) as the control group. All patients were right-handed and were treated for at least 6 sessions for two weeks.

Method of measurement; All patients completed the Visual Scale Analogue questionnaire before and after the treatment period to determine the amount of pain. The questionnaire was given to the patient as a non-scaled 100 mm line showing zero as a painless condition and 100 as a maximum pain. The patient was asked to mark the line using a pen, based on the extent of his shoulder pain. It was then measured and recorded using a graduated ruler. This questionnaire consists of 30 patient-centered questions that assess the functional activity of the shoulder joint and social activities and psychological conditions of the patient. This questionnaire has been validated in several studies and its validity and reliability have been confirmed. All patients completed this questionnaire before and after the treatment period.

Better technical conditions for the treatment of musculoskeletal issues have been offered by a high-power laser with a power of more than 1 watt and the ability to simultaneously emit numerous wavelengths. Three elements influence the therapeutic dosage of a laser: output power, wavelength, and treatment time. More energy density in the tissue may be achieved by using higher output power and a diversity of wavelengths, as well as a longer treatment period. Wavelength variation, on the other hand, may absorb energy at various tissue levels. At the same time, laser photon penetration depth rises, allowing for stronger biochemical effects in deep tissues. Conforti et al. treated 135 patients with Whiplash Cervical Injury using a high-power laser (12 watts) and traditional physiotherapy for 5 days in 2013. According to the findings, a high-power laser had a 50% larger impact on pain reduction than the control group. A high-power laser (10 watts) demonstrated a substantial reduction in pain score in 69.9% of participants in another Morinoto research.

Conclusion: It seems that laser therapy as a complementary modality along with other physiotherapy methods is useful and its combination with other non-invasive physiotherapy methods can improve the quality of treatment. The anti-inflammatory mechanism of the laser may have improved joint function by accelerating pain relief. On the other hand, high-power laser as a new method has more therapeutic effects than conventional physiotherapy in the short term, but more studies are needed to prove this claim.