Shockwave therapy and manipulation may give short term relief for frozen shoulder, but longer term effects still uncertain

Extracorporeal shockwave therapy probably reduces short term pain linked to frozen shoulder, while manipulation under anaesthesia - with or without steroid injections - probably improves short term flexion (raising the arm forward and overhead) compared with usual care, finds a review of the latest trial evidence published by The BMJ today.

Most other treatment effects remain uncertain due to low certainty evidence and inconsistent data, and comparative safety and longer term effects are not well established.

Frozen shoulder (adhesive capsulitis) occurs when the strong connective tissue surrounding the shoulder joint becomes thick, stiff and inflamed, causing pain and restricted movement. It’s more common in people aged 40-60 years, and among women than men.

Many treatments are available, including drugs, steroid injections, and surgery, but their comparative benefits and harms remain uncertain.

To address this, researchers analysed the results of 189 randomised controlled trials involving 12,988 adults (average age 54 years) with adhesive capsulitis comparing active treatments with another intervention, placebo, or usual care on pain, function, range of motion, and adverse events. 

Moderate certainty evidence showed that extracorporeal shockwave therapy (low energy sound waves delivered to damaged tissue to stimulate blood flow and healing) probably reduced short term pain compared with usual care (mean difference -1.97 on a 0-10 scale).

There was some indication that extracorporeal shockwave therapy may also improve short term function, flexion, and abduction, but the researchers say these apparent benefits are less certain because they are based on low certainty evidence and inconsistencies in the data.

Moderate certainty evidence also suggested that manipulation by a clinician under anaesthesia combined with a steroid injection probably improved short term flexion (mean difference 33.29 degrees), as did manipulation under anaesthesia alone (26.16 degrees), compared with usual care.

Evidence for most other treatments, outcomes beyond three months, and comparative safety is substantially less certain because adverse events were incompletely and inconsistently reported.

While this was a comprehensive synthesis of randomised evidence, the researchers acknowledge that most trials were at high risk of bias, factors such as disease duration, clinical stage, and previous treatment, were incompletely or inconsistently reported, and the findings may be limited to patients with primary adhesive capsulitis. 

As such, they say these findings might be useful for informing specific treatment decisions within the first six months and do not establish longer term comparative effectiveness or overall benefit-harm profiles.

Treatment decisions should also consider invasiveness, costs, patient preferences, clinical expertise, and uncertainty about longer term benefits and harms, they conclude.