Abstract
Shoulder instability following shoulder arthroplasty may be classified as posterior, anterior, superior or inferior. The basic causes include, malposition of the components, incorrect version of the glenoid or humeral cuts, soft tissue contractures or laxity, and cuff deficiency. These may be present and isolated as combined deficiencies.
As always, avoidance is best, but it is the most common complication of shoulder arthroplasty and this must be dealt with correctly. Recognition of the anatomic aetiology is critical. The proper evaluation with x-ray, CT and MRI will be critical to either avoid the problem or treat it correctly. Normally the glenoid is nearly perpendicular to the scapular while the humeral version is about 30° retroverted.
After defining the anatomic problem, proper component positioning, elimination of contractures, plication of capsular laxity and cuff repair or, replacement, will ensure the best opportunity for a stable shoulder.
The abstracts were prepared by Mrs Dorothy L. Granchi, Course Coordinator. Correspondence should be addressed to her at PMB 295, 8000 Plaza Boulevard, Mentor, Ohio 44060, USA.
