[Hemi-arthroplasty of the shoulder: radiological, functional and dynamic studies]

From September 1973 to October 1992, forty-three shoulder arthroplasties were performed in forty-one patients with complicated fractures or degenerative disease. Radiological and functional assessment with a mean follow-up time of forty-five months permitted us to review twenty patients with fifteen Neer II prosthesis, three isoelastic prosthesis and two total shoulder replacements. Of these, eleven presented with traumatic injuries and four with degenerative disease. The mean age at operative time was 61 years. Radiological evaluation showed that all cases had a retroversion of about 30 degrees. Normal humeral length and lateral shifting were not achieved in most patients; in fact only one had a restored length and lateral shifting. The mean scapulothoracic range of motion was found to be half that of a normal gliding shoulder (angle 30 degrees instead of 60 degrees). The subacromial space was diminished by one third in all cases. Relief of shoulder pain was the most significant finding. Mobility was restored to a level of about 75% of normal according to Constant's Scale. Dynamometric measures showed an important loss of force (47% of normal) despite a normal external rotation force. Recent improvements in implant conception (modular prosthesis) and a better understanding of physiological shoulder mechanisms should improve the functional results of this arthroplasty in the future.