Resection interposition arthroplasty of the shoulder affected by inflammatory arthritis

To determine the therapeutic value of resection-interposition arthroplasty (RIAP) of shoulders in rheumatoid or other inflammatory arthritis, 53 patie nts were reviewed clinically and radiographically after a mean follow-up pe riod of 8.2 +/- 4.3 years (3.5 to 17.5 years). The Constant Score averaged 42.33 +/- 16.2 (12 to 76). Patients with a follow-up period of more than 10 years performed significantly worse than those with shorter follow-up peri ods. In most cases, radiographs showed a progressive medial displacement an d loss of size of the humeral head as well as a decrease of the joint space with time. Abduction proved to be highly dependent on the degree of medial displacement of the humeral head, whereas the Constant Scores correlated w ith the width of the joint space. Despite initially acceptable postoperativ e results, outcome at longer follow-up periods worsened as the result of we ar of the glenoidal cartilage and osseous resorption of the humeral head, r esulting in a progressive medialization of the center of rotation.