[On the etiology of the loose shoulder--biochemical studies on collagen from joint capsules]

In order to investigate the etiology of loose shoulder, biochemical characteristics of collagens from four major joint capsules of extremities and from joint capsules of loose shoulder have been investigated. Joint capsules of normal shoulder were found to synthesize less collagen fibers comparing to those of other major joints. Furthermore formation of inter-molecular cross-links of collagen from shoulder joint capsule was relatively lower than that of collagens from other major joints. Noteworthy was the fact that collagen fibers from joint capsules of loose shoulder were more soluble and contain less amount of the reducible cross-links than those from joint capsules of the normal shoulder. These data suggest that collagen synthesis and formation of collagen fibers vary with the differences in joint structures, functions and movements. It may also be implied that the joint capsules of loose shoulder produce immature collagen fibers which may reflect the clinical feature of the disease.