Injection decisions in frozen shoulder should be framed around likely benefit, timing, risk and what the procedure enables next. Corticosteroid injection has its clearest role in short-term pain relief; the additional value of capsular distension remains less certain.
Intra-articular corticosteroid injection can improve pain and function in the short term, particularly when pain is prominent. Benefits tend to narrow over longer follow-up. Hydrodilatation may improve disability and external rotation for some patients, but protocols and comparative results vary.
Corticosteroid injection
Reviews of randomised trials commonly report faster early improvement after corticosteroid injection than placebo or some conservative comparators. This makes clinical sense when pain and synovial inflammation dominate. It should not be described as a guaranteed cure or as physically removing the capsular restriction.
Evidence does not establish one universally best steroid, dose or injection site. Glenohumeral injection is commonly used. Accuracy may improve with image guidance, although evidence that guidance consistently produces better patient outcomes is less definitive than evidence that it improves needle placement.
Hydrodilatation
Hydrodilatation introduces fluid into the glenohumeral joint, usually with local anaesthetic and often corticosteroid, to distend the capsule. Studies vary in injected volume, whether capsular rupture is intended, imaging method and accompanying rehabilitation. These differences make a single effect estimate difficult to apply to every service.
Some analyses find transient improvements in disability or external rotation compared with steroid injection alone; others find little clinically important advantage. Because corticosteroid is often included in both arms, it can be difficult to isolate the effect of distension itself.
Selection and shared decision-making
Discussion should include symptom duration and irritability, prior treatment, diabetes, medicines, infection risk and patient preferences. People with diabetes should be warned that glucose may rise temporarily after steroid injection and should follow an appropriate monitoring plan. Consent should also cover post-injection flare, bleeding, infection, skin or fat changes and the limits of expected benefit.
Connecting procedure and rehabilitation
An injection may create a period in which sleep, movement and participation are easier. The follow-up plan should specify what activity or rehabilitation will be attempted, what reaction is acceptable and when outcomes will be reviewed. Aggressive stretching immediately after a procedure is not automatically indicated.
Key uncertainties
- Which patients gain a clinically important additional benefit from hydrodilatation?
- What volume and technique are optimal?
- How much does image guidance change outcomes rather than accuracy?
- What is the best timing and rehabilitation dose after intervention?