This randomized controlled trial evaluates the clinical efficacy of ultrasound-guided intra-articular hyaluronic acid injection combined with rehabilitation in patients with adhesive capsulitis (frozen shoulder).

Participants were randomly assigned to either an injection plus rehabilitation group or a rehabilitation-only group. The injection group received ultrasound-guided intra-articular hyaluronic acid once weekly for three weeks, along with a standardized rehabilitation program for six weeks. The control group received the same rehabilitation program without injection.

Clinical outcomes were assessed at multiple time points, including baseline, 4, 6, 8, and 12 weeks. The primary outcome was the change in the Shoulder Pain and Disability Index (SPADI) total score. Secondary outcomes included SPADI pain and disability subscales, as well as shoulder range of motion.

The trial was registered retrospectively at ClinicalTrials.gov (NCT07570095) after study completion due to administrative oversight.

The study was conducted in accordance with the protocol approved by the Tri-Service General Hospital Institutional Review Board (approval no. C202205160) prior to enrollment. The IRB-approved protocol specified the eligibility criteria and outcome measures reported in this record; discrepancies in the initial registry entry have been corrected in this amendment.

Adhesive capsulitis is a common musculoskeletal disorder characterized by progressive pain and restricted range of motion of the shoulder joint, leading to significant functional impairment. Although rehabilitation remains the cornerstone of treatment, the additional benefit of intra-articular hyaluronic acid injection remains controversial.

This randomized controlled trial aimed to evaluate the clinical efficacy of ultrasound-guided intra-articular injection of non-cross-linked hyaluronic acid combined with a structured rehabilitation program in patients with adhesive capsulitis.

Participants were randomly assigned to two groups: an injection plus rehabilitation group and a rehabilitation-only group. The injection group received ultrasound-guided intra-articular hyaluronic acid injections once weekly for three consecutive weeks. Both groups underwent a standardized rehabilitation program twice weekly for six weeks, including range of motion exercises, stretching, and strengthening under the supervision of a physical therapist.

Clinical outcomes were assessed at multiple time points, including baseline, 4, 6, 8, and 12 weeks. The primary outcome measure was the change in the Shoulder Pain and Disability Index (SPADI) total score over time. Secondary outcomes included SPADI pain and disability subscales, as well as shoulder external rotation range of motion.

The trial was registered retrospectively at ClinicalTrials.gov (NCT07570095) after study completion due to administrative oversight.

The study was conducted in accordance with the protocol approved by the Tri-Service General Hospital Institutional Review Board (approval no. C202205160) prior to enrollment. The IRB-approved protocol specified the eligibility criteria and outcome measures reported in this record; discrepancies in the initial registry entry have been corrected in this amendment.

Inclusion Criteria:

• Adults aged 40 to 70 years.
• Clinical diagnosis of frozen-phase primary adhesive capsulitis characterized by predominant stiffness as the chief complaint, with symptom duration of at least 3 months, minimal resting pain, and absence of nocturnal pain.
• Limitation of both active and passive shoulder range of motion, particularly in external rotation.
• Ability to understand the study procedures and provide informed consent.

Exclusion Criteria:

• Prior shoulder surgery or fracture on the affected side.
• Rotator cuff tear confirmed by imaging.
• Glenohumeral osteoarthritis or inflammatory joint disease.
• Neurological disorders affecting shoulder function.
• Previous intra-articular injection within the past 3 months.
• Contraindications to hyaluronic acid injection.