Abstract
Purpose: The purpose of this study was to analyse the factors affecting outcome after prosthesis implantation for osteonecrosis of the humerus in order to ascertain details concerning the indications for humerus or total prostheses in this condition.
Material and methods: Forty-seven women and 27 men, mean age 57 years with osteonecrosis of the humerus underwent surgery for implantation of 80 shoulder prostheses. According to the Arlet and Ficat classification as modified by Cruess there were five grade II, fifteen grade III, 41 grade IV and fourteen grade V shoulders, with five unclassifiable shoulders. there were 14 supraspinatus tears and five infraspinatus tears. The 26 total shoulder prostheses and 54 humeral prostheses were reviewed at a mean 47 months follow-up. Pre-operative x-rays were available for 65 shoulders and postoperative x-rays for 58.
Results: The subjective outcome was considered good irrespective of the grade (very satisfied 60%, satisfied 30%, dissatisfied 4%). The mean postoperative Constant score was 70 ± 15. The preoperative score was lower for more advanced disease but the difference was not significant at postoperative assessment. The total prosthesis provided better results in grade V shoulders and the hemiprosthesis in grade II and III shoulders.
The result of the humeral prostheses depended on the grade of necrosis. The postoperative Constant score was lower for advanced necrosis with lower scores for motion, force and pain (which was not influenced by age). At last follow-up, 31% of the x-rays revealed a significant narrowing of the glenoid-head space. The clinical outcome was significantly less satisfactory for all Constant scores. Rotator cuff tears, preoperative stiffness favoured glenoid wear. Tears of both cuff tendons led to poor outcome. Bone collapse with impaction of the head into the glenoid and medialisation of the humerus was a significant factor predictive of less satisfactory outcome.
Discussion: The grade of necrosis is a determining factor for indications for humerus or total shoulder arthroplasty for the treatment of osteonecrosis. Our objective results lead us to recommend a humeral prosthesis for grade II and III patients and a total shoulder arthroplasty for grade V patients. For grade IV patients, the choice depends on patient age, shoulder stiffness, the status of the cuff, and most importantly, collapsus of the head of the humerus with impaction-medialisation of the humerus.
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.
