Bursa: There were varying degrees of inflammation of the bursa in seven of the ten cases examined.
Capsule: The synovial lining in the ten cases examined (Table 1) did not present a for table continuous layer of cells in all sections. In four instances the cells which were present
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appeared normal; in one instance they showed evidences of proliferation; and in the five remaining cases no synovial cells were found. In these five cases it is probable that the synovial cells, which were originally present, had been destroyed in the formative stages Of the process or during manipulation at the time of operation.
In the subsynovial layer there was fibrosis and degeneration of the collagen in two instances, calcification in two, and chronic inflammation characterized by fibrosis and perivascular infiltration in six instances.
The blood vessels were essentially normal.
Elastic-tissue stains were also made of all sections, but they did not reveal any significant change in the collagen.
Hyaline Cartilage: There was a moderate amount of degeneration in three or four cases examined. These changes might well be within normal limits.
In all ten cases there were changes demonstrated in either the capsule or the bursa or both. The microscopic sections revealed a nearly consistent pathological picture of reparative inflammatory changes, which consisted of degeneration, vascular repair, cuffing of the blood vessels, and mononuclear cells to a lesser or greater degree.