We read with great interest the recent article by Lin et al.
1
The authors examined the efficacy of intra-articular steroid injection and distension
in treating patients with frozen shoulder by performing both pairwise meta-analysis
and network meta-analysis. They found that distension yielded better external rotation
(ER) improvement at medium term and had similar effects on shoulder-function improvement
and pain reduction as intra-articular steroid injection. We appreciate the authors'
great work on this topic, and we have some comments about this study.
- 1.Not only the treatment methods but also the stage of frozen shoulder should be considered. The pathogenesis of frozen shoulder could be divided into freezing, frozen, and thawing stages.2The treatment effects in different stages would possibly be different. Regarding this issue, Lin et al1performed a subgroup analysis stratified by categorizing studies into earlier stage or later stage of frozen shoulder by “mean duration of symptoms” in those studies. However, it should be noted that the symptom duration in these studies are usually in a wide range, such as 2 to 37 months in the study of Sharma et al.3As a result, the findings of this subgroup analysis would be limited. This is a limitation in a meta-analysis, and further studies of different treatments in different stages of frozen shoulder would be needed.
- 2.Does distension with intra-articular injection really works? As summarized in table 1, the amount of the fluid used for distention ranged from 20 to 40mL.1An issue of concern is whether the injected fluid could expand the joint capsule. Although using distension in treating frozen shoulder has been reported in some studies, the possible mechanism of using distension has not been elucidated.3Actually, the anterior capsule in patients with frozen shoulder is extremely thick. Research based on the arthroscopic findings indicated that there is thickened and stiffened joint capsule and the capacity of the joint is reduced.4According to our clinical experience, it is difficult to expand the capacity of the joint during arthroscopy surgery unless capsular release was performed. Therefore, we doubt that intra-articular injection of 20 to 40mL of the fluid could reach the effect of “distension” in frozen shoulder.
- 3.This meta-analysis found that distension yielded better ER improvement at short term and medium term. Accordingly, the authors suggested that early distension could be considered the preferred treatment for patients with predominant ER limitation. However, the interpretation of this finding might not be appropriate, since no definite evidence suggests that early distension is beneficial for patients with predominant ER limitation.
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References
- Comparative efficacy of intra-articular steroid injection and distension in patients with frozen shoulder: a systematic review and network meta-analysis.Arch Phys Med Rehabil. 2017 Sep 9; ([Epub ahead of print])
- Frozen shoulder.BMJ. 2005; 331: 1453-1456
- Adhesive capsulitis of the shoulder, treatment with corticosteroid, corticosteroid with distension or treatment-as-usual: a randomised controlled trial in primary care.BMC Musculoskelet Disord. 2016; 17: 232
- Arthroscopic appearance of frozen shoulder.Arthroscopy. 1991; 7: 138-143
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Disclosures: none.
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© 2017 by the American Congress of Rehabilitation Medicine
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- The Authors RespondArchives of Physical Medicine and RehabilitationVol. 99Issue 2
