Abstract
Purpose: The purpose of this work was to compare outcome after hemiarthroplasty and after inverted arthroplasty for the treatment of excentred degeneration of the shoulder joint.
Material and methods: This multicentric study inclued 136 patients, 110 women and 26 men, mean age 72.4 years (range 55 – 86 years) with 142 shoulder prostheses. Among the 142 shoulders operated on, 62 underwent Aequalis hemiarthroplasty and 80 inverted arthroplasty. The preoperative handicap was more severe in the hemiarthroplasty group (Constant score 26) than in the inverted arthroplasty group (Constant score 23).
Results: Clinical and radiological follow-up data were collected at a mean follow-up of 44 months for the Aequalis prostheses and at 45 months for the inverted prostheses. There were seven failures requiring five revision procedures: three in the hemiarthroplasty group and four in the inverted arthroplasty group.
The differences between the hemi- and inverted arthroplasty groups concerned the Constant score, which was significantly better in the inverted prostheses (65.5) than in the hemiarthroplasties (46.1), for all subscores. Active elevation was 138° for the inverted prostheses and 97° for the Aequalis prostheses (p < 0.01). Mean external rotation in position 1 was 22° for the Aequalis prostheses and 11° for the inverted prostheses (p < 0.01) with no difference in elevation rotation. These results remained equivalent and significant over time, even beyond five years.
Radiographically, there was one case with an anomalous humeral component (impaction) in the inverted group. For the inverted prostheses, there were three migrations that have not been revised to date and three partial screw loosenings. The main problem was the development of notches in the scapular column observed in 50% of the cases including 20% which reached the lower screw. For the Aequalis prostheses, the main problem was deterioration of the acromial vault observed in 50% of the cases leading to altered function.
Discussion: Inverted prostheses provide clearly better mid-term results, even after five years. With hemiarthroplasty there is a long-term risk of vault wear. The long-term course of the inverted prostheses is worrisome due to the notches in the scapular column and the stress on the fixation. These prostheses should be used preferably for old persons with a deteriorated vault.
The abstracts were prepared by Docteur Jean Barthas. Correspondence should be addressed to him at Secrétariat de la Société S.O.F.C.O.T., 56 rue Boissonade, 75014 Paris.
