The aim of our study is to investigate whether the combination of hypertonic dextrose injection and shoulder joint hydrodilation, in conjunction with physical therapy, can effectively enhance shoulder joint pain relief, improve range of motion, and enhance daily life functionality in patients with frozen shoulder.

Frozen shoulder (FS), also known as adhesive capsulitis, is a common shoulder ailment, with an annual incidence of approximately 2.4 individuals per 100,000, accounting for about 2% of the total population. The onset of symptoms is predominant in individuals aged forty to sixty years, presenting as persistent restrictions in shoulder joint mobility accompanied by shoulder joint pain.

While the detailed mechanisms underlying frozen shoulder remain unclear, arthroscopic examination of the shoulder joint reveals thickening and contraction of the shoulder joint capsule, adhesion with the humeral head, and a reduction in joint cavity volume, particularly in the folds of the axillary recess of the joint capsule and its surrounding areas. These changes contribute to restricted shoulder joint mobility in individuals with frozen shoulder. Additionally, research suggests that in cases of severe inflammation, certain cytokines and growth factors drive fibroblasts to replace normal tissue through repair and remodeling responses. This excessive fibrosis and the loss of normal collagen remodeling response further contribute to the development of frozen shoulder.

The meta-analysis published in JAMA Network in 2020 highlighted the significance of medium to long-term physical therapy in facilitating subsequent improvements in range of motion and functionality for patients with adhesive capsulitis, also known as frozen shoulder. Moreover, numerous studies suggest that combining intra-articular injections with shoulder joint capsular distension procedures, such as hydrodilatation, can enhance shoulder joint function and mobility.

Prolotherapy is a non-surgical regenerative injection therapy involving the injection of a solution into painful or degenerated areas. The injected proliferants induce a local inflammatory response, triggering the release of growth factors and stimulating fibroblasts and collagen-producing cells. This process mimics the natural healing mechanisms of the body, promoting cellular tissue growth through a beneficial inflammatory response. In clinical practice, the most commonly utilized solution for prolotherapy is the hypertonic dextrose with concentrations ranging from 15% to 25%. Concentrations exceeding 10% are generally considered to induce local inflammation, thereby triggering a cascade of reparative effects.

Although there have been numerous studies on shoulder joint capsular distension procedures in the past, the injected solutions often consisted of corticosteroids and saline. In clinical observations, the use of hypertonic dextrose injection combined with shoulder joint capsular distension appears to offer improved outcomes in terms of pain relief and joint angle progression in patients with adhesive capsulitis. However, there is currently no research investigating the effectiveness of hypertonic dextrose injection combined with shoulder joint capsular distension for treating frozen shoulder. Therefore, this study represents the first exploration of whether the use of hypertonic dextrose injection combined with shoulder joint hydrodilatation and physical therapy is more effective than the conventional approach using saline injection combined with physical therapy in the treatment of frozen shoulder.

Inclusion Criteria:

1. Frozen shoulder is diagnosed by physicians based on the patient's medical history, physical examination, X-ray, and ultrasound reports.
2. The symptoms persist for more than 3 months.
3. There is a reduction of at least 30 degrees in at least two of the affected shoulder joint angles compared to the angles of the healthy side: shoulder flexion, abduction, and external rotation.

Exclusion Criteria:

1. Ultrasound of the shoulder muscles reveals a complete tear or massive tear of the rotator cuff tendon or calcific tendinitis.
2. Systemic rheumatic disease.
3. Previous shoulder fracture or surgical intervention.
4. Recent shoulder joint injections within the last 3 months.
5. Acute cervical nerve root compression.
6. Current pregnancy or breastfeeding.
7. Poorly controlled diabetes (intravenous glucose injection may cause temporary blood sugar elevation).
8. Patients with cancer.
9. Cognitive impairment, inability to follow simple instructions, or inability to cooperate with the study procedures.