As always, the diagnosis must be correct before attempting treatment. If the patient has had the problem upwards of 3 months, has lost shoulder internal rotation (hand behind back), has reduced flexion eg less than 90 degrees, and has night pain being unable to lay on the shoulder, glenohumeral hydrodilation is the gold standard procedure. Aggressive physiotherapy will worsen the problem. Asking a worker to wait 12 to 24 months for eventual rsolution of symptoms is cruel and uneconomic, and is likely to result in pain behaviours and very poor return to work / activity outcomes.
Radiologists seem to have taken over the procedure, using guided imaging for the capsule. The most effective method that I have encountered depends upon a Doctor with good surface anatomy skills to perform an in rooms procedure, about 20 minutes, unguided by imaging. (Based upon the original American Orthopaedic article). A local anaesthetic injection is used, then a mixture of saline, anaesthetic, and a small amount of cortisone (celestone), which is injected into the capsule via syringe. The Doctor can feel the capsular resistance, then giveway at points. The maximum volume is 40 millilitres. Repeat procedure is not performed, if necessary, for at least 8 weeks.
Post procedure, as soon as possible, the shoulder is taken through range of movement exercises, with the patient doing the same at home.

Normal cortisone injections into the shoulder should be avoided, as after the second injection it has been reported that tissue tendon rupture can increase to 50%.

Capsular dilatation does not work if there is a capsular tear. If the fluid leaks out, there is no backpressure against the syringe, then the capsule could be torn, or the technique of injection is poor. Normal strengthening exercises can be prescribed post procedure, weith a graduated increment of 10 to 15 %, no more.
Hope this helps
MrPhysio