Natural history of frozen shoulder: fact or fiction? A systematic review

BackgroundIn 1940s, it was proposed that frozen shoulder progresses through a self-limiting natural history of painful, stiff and recovery phases, leading to full recovery without treatment. However, clinical evidence of persistent limitations lasting for years contradicts this assumption.ObjectivesTo assess evidence for the natural history theory of frozen shoulder by examining: (1) progression through recovery phases, and (2) full resolution without treatment.Data sourcesMEDLINE, PubMed, EBSCO CINAHL and PEDro database searches augmented by hand searching.Study selectionCohort or randomised controlled trials with no-treatment comparison groups including adults with frozen shoulder who received no treatment and reporting range of motion, pain or function for ≥6 months.Data extractionReviewers assessed study eligibility and quality, and extracted data before reaching consensus. Limited early range-of-motion improvements and greater late improvements defined progression through recovery phases. Restoration of normal range of motion and previous function defined full resolution.ResultsOf 508 citations, 13 articles were reviewed and seven were included in this review. Low-quality evidence suggested that no treatment yielded some, but not complete, improvement in range of motion after 1 to 4 years of follow-up. No evidence supported the theory of progression through recovery phases to full resolution without treatment. On the contrary, moderate-quality evidence from three randomised controlled trials with longitudinal data demonstrated that most improvement occurred early, not late.LimitationsLow-quality evidence revealed the weakness of longstanding assumptions about frozen shoulder.ConclusionContradictory evidence and a lack of supporting evidence shows that the theory of recovery phases leading to complete resolution without treatment for frozen shoulder is unfounded.