Advances in Research and Frozen Shoulder

Frozen shoulder, also known as adhesive capsulitis, is a painful condition that limits shoulder mobility due to inflammation and thickening of the shoulder joint capsule. Though it’s generally self-limiting—often resolving within one to three years—many patients experience persistent pain and limitations. Over the past few decades, extensive research has sought to uncover effective treatments, highlighting both conservative and advanced therapies while also revealing gaps in knowledge about the condition’s origins and best practices for management.

Conservative Treatments and Initial Approaches

The primary and most widely recommended approaches for frozen shoulder focus on conservative treatments. Physical therapy is considered essential for maintaining and gradually restoring mobility. Physical therapists typically guide patients through structured, progressive exercises tailored to reduce stiffness and pain. Numerous studies from the late 1990s onward reinforce physical therapy’s effectiveness, especially when used in combination with corticosteroid injections. These injections, introduced into the shoulder capsule, offer temporary pain relief and can reduce inflammation, making physical therapy more tolerable during the “freezing” phase.

Hydrodilatation, a technique that injects a high volume of saline into the shoulder capsule to stretch and expand it, emerged in the early 2000s as a promising adjunct to corticosteroids and physical therapy. Recent studies show that hydrodilatation, when combined with steroid injections, can help alleviate symptoms in some patients, especially in the condition’s initial stages. However, results vary, and its long-term benefits over physical therapy alone remain debated in current research.

Insights from the UK FROST Trial

The UK FROST trial, conducted in 2020, is one of the largest randomized controlled studies examining treatments for frozen shoulder. This trial compared three major interventions: manipulation under anesthesia (MUA), arthroscopic capsular release, and structured physiotherapy paired with corticosteroid injections. Surprisingly, the study found no significant long-term clinical superiority among the three interventions, challenging the assumption that surgical options or MUA provide better outcomes than physical therapy with steroid injections alone. This finding has driven a shift toward emphasizing physiotherapy as a safe and cost-effective primary approach, reserving surgery and MUA for cases resistant to conservative treatments.

Emerging Techniques and Experimental Therapies

In recent years, experimental therapies have become a focal point for patients unresponsive to conservative measures. Transarterial embolization (TAE), a minimally invasive procedure that reduces blood flow to specific areas in the shoulder to manage pain, has been explored in preliminary studies. While TAE has shown potential for symptom relief in patients with severe pain unresponsive to other treatments, it remains experimental and is not widely available. Early results suggest it could offer benefits for managing persistent pain, but more extensive trials are needed to validate its safety and efficacy.

Another promising therapy is short-wave diathermy, a form of heat therapy applied directly to the shoulder to improve tissue relaxation and blood flow. Studies suggest that short-wave diathermy, when combined with physical therapy, can improve range of motion and reduce pain, but it is often considered an adjunct rather than a primary treatment. Similar benefits have been observed with extracorporeal shockwave therapy (ESWT), which uses sound waves to target areas of thickened tissue and scarred regions within the capsule. Though results for ESWT are still mixed, ongoing research is hopeful about its potential as a non-invasive way to disrupt adhesions in the shoulder.

Revisiting Surgical Interventions

For patients unresponsive to conservative care, surgical interventions are sometimes recommended. Arthroscopic capsular release, a minimally invasive procedure where a surgeon releases the tightened shoulder capsule, has been a common approach since the 1990s. It generally shows positive outcomes, particularly in restoring mobility and reducing pain, but it carries risks and requires substantial post-operative rehabilitation. MUA, an older technique, involves forcibly moving the shoulder while under anesthesia to break adhesions. Although effective in certain cases, MUA is not without risks, including the possibility of fracturing or damaging tissues if not performed carefully.

Historical studies in the 2000s explored the effectiveness of these surgical methods, and while both MUA and arthroscopic release are associated with improved outcomes, recent trials, including the UK FROST trial, suggest they may not be superior to less invasive options like physical therapy when corticosteroid injections are included.

A Closer Look at Pathophysiology and Risk Factors

Understanding frozen shoulder’s pathophysiology has been another area of research over the past three decades. It is recognized as a disorder often associated with systemic conditions like diabetes and hypothyroidism, which can increase a patient’s likelihood of developing the condition and potentially lead to bilateral shoulder involvement. Research from the BMJ and studies in endocrinology indicate that patients with diabetes are significantly more likely to develop frozen shoulder, and those with thyroid disorders may also be at higher risk due to hormonal imbalances that affect connective tissues.

Looking Forward: Individualized and Cost-Effective Care

Current research is trending toward cost-effective, individualized treatment plans. Findings from recent studies, including those presented at the American Academy of Orthopaedic Surgeons (AAOS) Annual Meeting in 2024, underscore that “watchful waiting” could be an acceptable approach for many patients with mild cases. This approach may minimize costs without compromising long-term outcomes compared to active physical therapy for patients with lower pain and disability levels.

The collective findings over the past 20-30 years emphasize a nuanced approach to managing frozen shoulder. While traditional physical therapy and corticosteroid injections are highly effective for most cases, surgical and experimental interventions remain essential for patients whose symptoms persist or worsen. Researchers continue to seek optimal treatment protocols tailored to individual needs, balancing cost, effectiveness, and invasiveness to improve patient outcomes in both the short and long term.