Abstract
Charles Neer designed his original prosthesis in 1951. It was made of cast cobalt chrome alloy and was only press-fit. There was not any significant loosening in his original series, but patients complained of easy fatigability. Neer attributed this to glenoid issues and that a glenoid replacement would eliminate this. The Neer II system was introduced with a glenoid component in 1973 and first generation cement fixation was used. Cemented glenoid components have been found to have radiolucencies in 26–100% with progressive radiolucencies in 0–36%. High rates of lucencies raise issues of fixation. Cementless glenoid components have been found to have fewer lucencies but require metal backing leading to higher stress concentrations. Greater bone stock is required and there are the problems of polyethylene dissociation and screw breakage prior to bony ingrowth. Rodosky reported a higher failure rate with a cementless design versus cemented glenoids. With humeral fixation, symptomatic loosening is not a problem with cement or coated press-fit fixation. Neer’s and Cofield’s long-term outcome studies with cemented stems have shown the incidence of humeral loosening to be low (0–2.5%). Cementing provides immediate fixation with the ability to place components in shafts with poor proximal bone stock. A recent literature review noted radiographic evidence of loosening in 12% of uncemented humeral components with only 0.3% of the patients having symptomatic loosening. Fixation of humeral components should be based on bone quality, patient age, prosthetic design and surgeon preference.
The abstracts were prepared by Mrs Dorothy L. Granchi, Course Coordinator. Correspondence should be addressed to her at PMB 295, 8000 Plaza Boulevard, Mentor, Ohio 44060, USA.
