Primary frozen shoulder: brief review of pathology and imaging abnormalities

Abstract

Background: Primary frozen shoulder (FS) is a painful contracture of the glenohumeral joint that arises spontaneously without an obvious preceding event. Investigation of the intra-articular and periarticular pathology would contribute to the treatment of primary FS.

Review of literature: Many studies indicate that the main pathology is an inflammatory contracture of the shoulder joint capsule. This is associated with an increased amount of collagen, fibrotic growth factors such as transforming growth factor-beta, and inflammatory cytokines such as tumor necrosis factor-alpha and interleukins. Immune system cells such as B-lymphocytes, T-lymphocytes and macrophages are also noted. Active fibroblastic proliferation similar to that of Dupuytren's contracture is documented. Presence of inflammation in the FS synovium is supported by the synovial enhancement with dynamic magnetic resonance study in the clinical setting.

Conclusion: Primary FS shows fibrosis of the joint capsule, associated with preceding synovitis. The initiator of synovitis, however, still remains unclear. Future studies should be directed to give light to the pathogenesis of inflammation to better treat or prevent primary FS.

Fig. 1

Arthroscopic view of the right shoulder in a 57-year-old man with primary frozen shoulder. The arthroscope is inserted through the standard posterior portal. Inflamed synovium is noted in the anterosuperior region (a). Using an electric cautery, the anterior capsule is being divided (b). Note the thickened joint capsule. G glenoid fossa, LHB long head of biceps

Fig. 2

Dynamic magnetic resonance imaging of primary frozen shoulder. Serial gradient echo images (TR 45 ms; TE 10 ms; flip angle 40°) were obtained in an oblique coronal plane through the center of the humeral head before (a), and 55 s (b) and 121 s (c) following a bolus intravenous administration of Gd-DTPA. Note the marked enhancement in the glenohumeral joint and, to a lesser degree, in the subacromial region. Reproduced from Reference [24] with permission

Fig. 3

Pathology and pathogenesis of primary frozen shoulder. In the left of the scheme, the pathological findings documented in the literature are listed. In the right, the possible concept of the pathogenesis of primary FS is shown