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The study by Buchbinder et al1 suffers from a major drawback to any study dealing with frozen shoulder when the pathophysiology has passed the acute phase. In their study the mean duration of symptoms was 25.5 weeks in the active group with a standard deviation of 13.3 weeks, the mean therefore being approximately 6 months. This is well over the time course one would expect in the inflammatory phase of frozen shoulder, and therefore it is not surprising that prednisolone provided some benefit. I suspect the benefit provided related to improvement in myalgia and wellbeing that occurred with the prescription of prednisolone, but which was quickly lost when prednisolone was reduced and stopped.
Although the authors quote a study co-authored by Buchbinder on a standardised protocol for the measurement of shoulder movement,2 I have concerns that the definition of frozen shoulder, as restricted passive movement by <30° in two or more planes measured at the onset of pain with a gravity inclinometer, may not be appropriate, given that frozen shoulder restricts all movements. There may also be other diseases present. In particular, it would be prudent to consider magnetic resonance imaging scans of the shoulder to confirm the degree, or not, of the adhesions within the shoulder capsule, and also to identify other subtle changes which may not be clinically apparent, such as rotator cuff tears unidentified on ultrasound.
The study, therefore, provides no insight or treatment options for prednisolone in frozen shoulder. It failed to recruit patients into the classical acute phase of a frozen shoulder within the first several months. Until such treatment is examined in an appropriate clinical trial, this study by Buchbinder provides no further evidence of the usefulness or otherwise of prednisolone in frozen shoulder. The study, not surprisingly, failed to show any longlasting benefit of prednisolone because the shoulder, by its natural history, had entered the stiff phase.
We thank Dr Champion for his interest and observations about our trial.
Our study clearly demonstrated a significant short term benefit of prednisolone in all outcomes measured at 3 weeks, including pain, disability, range of active motion, and participant rated improvement. Similarly, at 6 weeks the analysis still favoured the prednisolone group for most outcomes measured. Therefore Dr Champion’s concern that we may have missed an effect of prednisolone because we did not recruit participants early enough in the course of their illness is unfounded. Furthermore, all participants in the study had significant night pain at baseline (mean (SD) scores 7.5 (2.3) and 6.8 (2.1) in the prednisolone and placebo groups, respectively), generally indicative of acute symptoms and therefore likely to be responsive to steroids.
He highlights, though, an important concern for researchers who wish to study people in the early phase of a self limiting condition such as adhesive capsulitis when there may be delays in both seeking medical care and specialist advice. As outlined in our discussion, various strategies were used to recruit patients early in the course of the condition, including fast track referral.1 Previous trials of both prednisolone and intra-articular steroids have included participants with a similar duration of symptoms,2–4 suggesting that the difficulties of early recruitment are universal.
We agree with Dr Champion that patients with frozen shoulder typically exhibit global restriction of both active and passive glenohumeral movements. Our inclusion criteria specifically included a requirement that there be restriction of passive motion of greater than 30° in two or more planes of movement. This was derived from a systematic review of previous inclusion criteria used in trials of adhesive capsulitis.5
In general, the diagnosis of adhesive capsulitis is easily made by clinical assessment alone. Although it would have been of interest to perform magnetic resonance imaging (MRI) on all patients in this trial, this was not essential to our purpose. We have previously reported the variable presence of enhancing fibrovascular scar tissue in the rotator cuff interval, soft tissue thickening around the biceps anchor, and thickening of the axillary pouch in patients with adhesive capsulitis confirmed at surgery.6 However, the utility of MRI for discriminating adhesive capsulitis from other causes of shoulder pain is currently unknown and further studies are needed.
We stand by our conclusion that a short course of prednisolone for adhesive capsulitis is highly efficacious in the short term. Further research should be directed towards determining ways of prolonging its effect by either lengthening the duration of treatment and/or tapering the dose (without concomitantly increasing the risk of toxicity), and/or considering combination or sequential treatment for adhesive capsulitis.
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