[The frozen shoulder. Arthroscopy, histological findings and transmission electron microscopy imaging]

During a period of 17 months (February 1998 to July 1999) arthroscopy was performed in 172 patients because of pathologic changes of the shoulderjoint.

From the history and clinical examination, only eleven patients fulfilled the criteria for primary frozen shoulder set up by Lundberg in 1969. Further investigations such as X-ray examination, ultrasonography and MRI scanning showed no changes that could explain the clinical picture of shoulder stiffness. Of the eleven patients with frozen shoulder. additionally in two cases hyperthyroidism, in five cases diabetes type II and in a further five cases a Dupuytren's contracture could be found. Based on the operative procedure, recently published by Habermeyer, Ogilvie and Warner we carried out an arthroscopic arthrolysis of the stiff shoulder.

Diagnostic arthroscopy demonstrated synovialitis in the upper and ventral areas of the joint in over 50% of the patients. Interestingly, intraarticular adhesions were not found in any of our patients; in particular, no obliteration of the axillary recess could be seen. Altogether, in seven of the eleven patients with frozen shoulder, a notably contracted biceps tendon was found which obviously applied increased the force on the humeral head, as in corresponding areas cartilage damage could be demonstrated arthroscopically. A significant increase in fibroblast cells next to loose areas of connective tissue could be shown in histological examinations of biopsies of the capsule in the rotatorer interval. We noted thickened vessel walls and an augmentation of the synovial surface, whereas typical inflammation could not be demonstrated in any of the histological specimens. In the transmission-electron microscope examination (TEM) of samples taken from the capsule in the rotatorer interval, structural changes in collagenous tissue were discernible. Typically, a loss of fibril order and a twisting of collagen fibrils were seen. This twirling led to an up to fourfold diameter of the collagenous fibrils, whereby thin, elastin-like filaments could be seen between the thickened bundles of collagen fibrils.

In stage of the primary frozen shoulder exclusive fibrosis of the joint capsule was found. Electronmicroscopic twists of collagen fibrills were marked.