The primary goal of this clinical trial is to compare the effects of High Intensity Laser Therapy (HILT) on tears of tendons of shoulder girdle muscles with those of Ultrasound (US) therapy. It will also learn about the effects of HILT on pain and range of motion of injured shoulder. The main questions it aims to answer are:

Does HILT decrease the debilitating pain? Does HILT increase the range of motion of the sholuder joint? How long does the effect of HILT continue?

Researchers will compare the effects of HILT to a control group (ultrasound therapy group, an established method of treatment in shoulder girdle tendon tears) to see if HILT works better to treat shoulder girdle tendon tears.

Participants will:

receive HILT or US therapy 3 sessions per week for 3 weeks in addition to the therapeutic exercise program.

Visit the clinic at the beginning, at the 4th week and at the 12th week to determine the level of pain and disability via application of surveys.

Tendon thickness of participants will also be measured at the beginning, at the 4th week and at the 12th week to see if the treatment works to heal the tear.

Shoulder disorders are one of the most common musculoskeletal problems worldwide. After low back pain and knee pain, shoulder pain has been estimated to be the third most common musculoskeletal presentation in primary care. Shoulder joint is surrounded by rotator cuff muscles and rotator cuff tendinopathy is the most common cause of shoulder pain. Shoulder pain caused by partial supraspinatus tendon tear (STT) is a complex and challenging issue for clinicians. The choice of the most appropriate treatment management for these tears is controversial.

For Ellman grade I and II tears which comprise STTs of less than 50% or tears which are below 6 mm in thickness, strengthening exercises, ultrasound (US) therapy, physical therapy, injection treatment and medical treatment can provide improvement in patients. However, in grade III tears which involve STTs of more than 50% of the muscle or tears above 6 mm in thickness surgical treatment may be required.

Recently, high-intensity laser therapy (HILT) has been introduced and used in treatment of musculoskeletal disorders. There is no universally accepted theory that explains the exact mechanism of the postulated laser effects, yet. Nd:YAG laser which has a wavelength of 1064 nm is used in HILT. It works in a therapeutic window that has a low absorbability rate in superficial tissue layers, so it penetrates more deeply than other types of lasers. In addition to having a higher power than low-intensity lasers, lasers used in HILT have a shorter laser emission time and a longer laser emission interval. Therefore, a large amount of laser irradiation can be delivered to deep tissues. The utilization of HILT has been expanding, and patients have reported significant improvement in function and reduction of pain.

To our knowledge, no studies to date have been conducted on the effects of HILT on partial STT. The aim of the present study was to evaluate the long-term effectiveness of HILT on pain, disability, and range of motion in patients with shoulder pain caused by STT and to compare its effects to those of US therapy.

The current study was designed as a prospective randomized controlled clinical trial and conducted after approval from the local ethics committee of our medical center. The study was conducted in accordance with the principles of Declaration of Helsinki and registered in the government database. The patients were recruited from the Ankara Bilkent City Hospital, physical medicine and rehabilitation outpatient clinic

Inclusion Criteria:

• to be between 18-75 years old,
• the presence of shoulder pain for more than 3 months
• shoulder pain level of at least 3 on a 10-point Visual Analog Scale
• diagnosis of partial STT's which are below 6 mm in thickness
• no response to conservative treatments such as ice, soft tissue massage, stretching and nonsteroidal anti-inflammatory (NSAID) drugs after 6 weeks.

STT was detected with musculoskeletal system ultrasound by the same physician in outpatient clinic.

Exclusion Criteria:

• inflammatory rheumatic disease,
• cervical radiculopathy
• pregnancy,
• thyroid disease,
• history of cardiac pacemaker placement,
• epilepsy and/or any progressive neurological disease,
• history of shoulder surgery
• shoulder injection within the last 3 months

We can share our Study Protocol, Statistical Analysis plan and patients' informed Consent Forms.

The IPD will become available starting 6 months after publication.

The doctors who are specialized in Physical Medicine and Rehabilitation will be able to access upon contact with the principal investigators via email.