Surface replacement of the humeral head in the rheumatoid shoulder.

The clinical results obtained an average of 4.2 years after resurfacing of the humeral head in 72 rheumatoid shoulders showed 94% of the patients being pleased regarding pain relief and 82% reporting improved shoulder mobility. Shoulder function was significantly improved. The radiographs were analyzed regarding the position of the humeral head resurfacing cup, proximal migration of the humerus, and glenoid attrition during the follow-up period. Change of the distance between the superior margin of the cup and the greater tuberosity and/or change of inclination of the prosthesis were regarded as signs of prosthetic loosening. With that definition, 25% of the cups were found to be loose at follow-up. Prosthetic loosening, however, had no bearing on the clinical result. Also, no relationship was found between the position of the cup and the clinical outcome. Neither progressive proximal migration of the humerus in 38% of the shoulders nor central attrition of the glenoid in 22% of the shoulders showed any relationship to gain of mobility, pain relief, or functional ability.