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Background: The pathophysiological mechanisms behind proliferation of fibroblasts and deposition of dense collagen matrix in idiopathic frozen shoulder remain unclear. Alarmins (also known as danger signals) are endogenous molecules that are released into the extracellular milieu after infection or tissue injury and that signal cell and tissue damage. Purpose: To investigate whether the presence of alarmins is higher in patients with idiopathic frozen shoulder than in control subjects. Study Design: Controlled laboratory study. Methods: Shoulder capsule samples were collected from 10 patients with idiopathic frozen shoulder and 10 patients with unstable shoulders (control). The samples were stained with hematoxylin and eosin (H&E) and analyzed by immunohistochemistry using antibodies against alarmin molecules including high-mobility group protein B1 (HMGB1), interleukin 33, S100A8, S100A9, and the peripheral nerve marker PGP9.5. Immunoreactivities were rated in a blinded fashion from “none” to “strong.” Immunohistochemical distribution within the capsule was noted. Before surgery, patient-ranked pain frequency, severity, stiffness, and the range of passive shoulder motion were recorded and statistically analyzed. Results: Compared with control patients, patients with frozen shoulder had greater frequency and severity of self-reported pain (P = .02) and more restricted range of motion in all planes (P < .05). H&E-stained capsular tissue from frozen shoulder showed fibroblastic hypercellularity and increased subsynovial vascularity. Immunoreactivity of alarmins was significantly stronger in frozen shoulder capsules compared with control capsules (P < .05). Furthermore, the expression of the alarmin molecule HMGB1 significantly correlated (r > 0.9, P < .05) with the severity of patient-reported pain. Conclusion: This study demonstrates a potential role for key molecular danger signals in frozen shoulder and suggests an association between the expression of danger molecules and the pain experienced by patients. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate patients clinically diagnosed with early stage primary/idiopathic adhesive capsulitis to determine the existence of any pattern of movement loss and associated pain that may facilitate early recognition., Design: Cross-sectional study., Setting: Private upper limb specialty clinic, Newcastle, Australia., Participants: Fifty-two patients clinically diagnosed with early stage adhesive capsulitis by a medical practitioner or physiotherapist., Main Outcome Measures: Percentage loss of active and passive ranges of eight shoulder movements and the pain level at the end of each movement. The reason for limitation of movement was also recorded., Results: Factor analysis clearly identified two groups for percentage loss of active range of movement. Notably external rotation movements grouped separately from other movements. A single group emerged for percentage loss of passive range of movement suggesting a non-specific global loss. For both pain at the end of active range of movement and passive range of movement two groups emerged, however the delineation between the groups was less clear than for percentage loss of active range of movement suggesting a pattern of end range pain may be less useful in identifying patients in this stage., Conclusions: External rotation movements in neutral and abduction generally group together and behave differently to other shoulder movements in patients clinically diagnosed with early stage primary/idiopathic adhesive capsulitis. In particular external rotation in abduction has emerged as the most painfully limited movement in this sample. This study provides preliminary evidence of patterns of range of movement and end range pain that require testing in a population of mixed shoulder diagnoses to determine their diagnostic utility for early stage adhesive capsulitis., (Copyright © 2014 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.)