Many factors are supposed to concern the instability of the shoulder, such as malformation of the glenoid cavity, capsular disturbance and the scapular incoordination.
We investigated the relationship between general joint laxi t y and instability of the shoulder in 77 cases (35 cases with instability and 42 cases without instability). They were all high school athletes.
We compare d the two groups and found a high incidence of general joint laxity in those with instability. The clinical features of instability of the shoulder appeared to have been caused by general joint laxity, especially in the male.
In most cases (in 80%), we found inferior inst a bility improved by scapular fixation. This result suggests that pectoralis major transfer is an advantageous treatment of unstable shoulders. Other treatments should be considered but our results showed that neither glenoid insufficiency nor joint laxity were significant.
We found a high incidence of m ultidirectional instability in the cases with instability of the shoulder. We should examine multidirectional instability in those patients with inferior instability.
It is important to clarify the pathogenesis of the instability in the management of shoulder disorders.
