Effectiveness of USG-Guided Shoulder Injections as an Adjunct to a Home Exercise Program in the Conservative Management of Painful Frozen Shoulder and Its Association With Pain Phenotypes

This study will include patients presenting to the Physical Medicine and Rehabilitation outpatient clinics of Konya Beyhekim Training and Research Hospital with chronic shoulder pain and restricted range of motion, who are clinically diagnosed with frozen shoulder following a comprehensive evaluation. A total of 68 consecutive patients aged 18-75 years, with shoulder pain lasting at least three months and diagnosed with frozen shoulder after appropriate differential diagnosis, who consent to participate will be enrolled. All participants will provide written informed consent for study participation. Sociodemographic characteristics and clinical examination findings will be recorded for all participants.

As part of the clinical examination, patients will be evaluated for diagnosis and differential diagnosis based on the results of impingement tests, the drop arm sign, shoulder ultrasonography (e.g., presence of significant effusion, rotator cuff tear, etc.), and plain radiography. Following assessment according to predefined inclusion and exclusion criteria, patients will be randomized (block randomization) to receive either USG-guided suprascapular nerve block alone or a combination of suprascapular nerve block and subacromial injection.

Patients' sociodemographic data, as well as detailed clinical and examination findings and baseline outcomes, will be recorded. Patients will be informed about their condition, and modifications to activities of daily living will be recommended. Patients' pain phenotypes (nociceptive, neuropathic, nociplastic) will be categorized based on clinical history and validated questionnaires, and it will be determined which pain types derive greater benefit from these injections.

As part of an individualized home-based exercise program, patients in both groups will perform range-of-motion exercises, Codman exercises, isometric strengthening, and stretching within their self-limited pain threshold. The home exercise program will be demonstrated in person by a physician or physiotherapist, and written printed materials will be provided to the patients. Exercise adherence will be assessed at the 3rd, 6th, and 20th week follow-up visits, and when necessary, patients will be contacted by telephone to support and monitor adherence to the exercise program. Patients with less than 70% adherence will be excluded from the analysis.

In the first group (USG-guided suprascapular nerve block group), a suprascapular nerve block will be administered under ultrasound guidance in accordance with the literature (triamcinolone 20 mg/1 mL + 1% lidocaine 4 mL). In the second group (combination of suprascapular nerve block and subacromial injection group), patients will receive, in a similar manner under ultrasound guidance, a suprascapular nerve block (triamcinolone 10 mg/0.5 mL + 1% lidocaine 4 mL + 0.5 mL saline), followed by an ultrasound-guided subacromial/deltoid bursa injection (triamcinolone 10 mg/0.5 mL + 1% lidocaine 2.5 mL). Patients will be blinded to the type of these injections administered to them. At the 3-week follow-up after the first injection, for patients in both groups who do not show sufficient reduction in pain (defined as a decrease of less than 3 points on the VAS or less than 50% reduction) and who are willing to proceed, repeat injections will be administered in the same manner based on a joint decision between the patient and the physician.