Effects of immobilization on the capsule of the canine glenohumeral joint. A structural functional study.

The effects of immobilization on the function of the glenohumeral joint and its capsule were investigated in eight beagle dogs. One foreleg of each animal was immobilized in a spica cast, and the dogs were euthanized after 4, 8, 12, and 16 weeks of immobilization in groups of two. The contralateral limb and the forelegs of two normal beagles were used as controls. At the time of euthanasia, the range of motion, intraarticular filling volume during passive movements of the joint, and intraarticular filling volume to rupture the capsule were measured. The synovium, including the capsule and the subscapular bursa, were examined histologically. In the immobilized limb, there was progressive restriction in the range of motion with increases in intraarticular pressure, and the filling volume that was required to cause a rupture of the capsule diminished. Morphologically, the capsule and the subscapular bursa showed focal adhesions. Thus, it appeared that immobilization of these canine forelimbs produced changes in the glenohumeral joint that resembled those of frozen shoulder in humans.