Shoulder pain is the most common musculoskeletal problem after low back and neck pain. It has negative socioeconomic effects on patient's daily life (1). Subacromial impingement syndrome is one of the most common diseases of the shoulder and seen in 44-65% of patients who consult a doctor with shoulder pain. This syndrome spectrum includes supraspinatus tendon partial tears, supraspinatus tendinitis, calcific tendinitis and subacromial bursitis. Many treatments are used to reduce pain and accelerate functional rehabilitation in patients with shoulder pain. These treatments include analgesic physical therapy agents (superficial hot and cold applications, deep heaters, diadynamic currents, transcutaneous electrical stimulation, interferential current, short wave diathermy), therapeutic exercises, massage, functional electrical stimulation, acupuncture, analgesics, non-steroid anti-inflammatory drugs, oral steroids and steroid injections. Transcutaneous pulse radiofrequency therapy (TCPRF) is a painless and outpatient physiotherapy modality that does not require any anesthesia or sedation. TCRPF can also be used in some other painful conditions of the chin, neck, lower back, wrist, knee, elbow and ankle regions. Ultrasound measurement of acromio-humeral distance and supraspinatus tendon thickness are reliable and effective methods for demonstrating subacromial impingement syndrome. Although there have been previous studies investigating the effectiveness of TCPRF treatment in patients with shoulder pain, the number of these studies are insufficient. In addition, there are no studies evaluating the effectiveness of treatment by ultrasound examination. In this study, the investigators aimed to evaluate the effect of TCPRF treatment on pain, range of motion and functional status in subacromial impingement syndrome patients by means of clinical and ultrasound findings.

The study will be conducted between January 2020 and January 2021 at Gazi University Faculty of Medicine, Department of Physical Medicine and Rehabilitation. Fifty patients with subacromial impingement syndrome are planned to be recruited for the study.

The patients included in the study will be randomized into two groups with a computer program. In order to comply with the double-blind study protocol, the researcher performing the randomization of the patients will not participate in the treatment and evaluation processes. Demographic data of patients will be recorded at the beginning of the study. Therapeutic exercises and nonsteroidal anti-inflammatory drug therapy will be initiated to all patients. Detailed shoulder joint range of motion examination, visual analog scale, shoulder pain and disability index, quality of life scale (SF-36), shoulder ultrasound examination for acromio-humeral distance and supraspinatus tendon thickness measurements will be performed before and after treatment (Basal, 1st, 4th and 12th weeks). A pair of TCPRF electrodes will be applied to the painful shoulder at six standardized sites for 2 minutes each (approximately a total of 15 minutes). The device is not going to be activated in the control group. It will be activated in the study group. In the study group device will be set at 80 V, every pulse will continue for 10 milliseconds and 5 pulses per second. In the control group the device will be set at 0 V. TCPRF treatment is going to be applied for one session in both groups. During the three-month follow-up period, therapeutic exercises and as long as it is considered necessary nonsteroidal anti-inflammatory drugs will be continued in both groups.