Surgical treatment of nonconstrained glenoid component failure

Total shoulder replacement for pathological conditions of the glenohumeral joint has proven to be a very durable procedure with a low complication rate and a high rate of patient satisfaction. Glenoid component revision rates reported in the literature are generally less than 4% (range, 0 to 12.5%) for nonconstrained total shoulder replacements at 3- to 5-year follow-up. Glenoid component failure occurs as a result of loosening, breakage, or damage of the glenoid component. The causes for glenoid component failure include infection, trauma, eccentric loading after a rotator cuff tear, and technical errors. Technical factors include inadequate glenoid bone contouring allowing rocking of the platform, excessive cement buildup with noncontained cement that may break free and allow toggling of the platform, and component malalignment or poor soft tissue balancing leading to dislocations with associated loosening or breakage. The patients experience pain and loss of motion, and diagnostic radiographs often reveal a progressive increase in radiolucencies around the glenoid component. Treatment consists of glenoid component replacement when bone stock allows or glenoid component removal with upsizing of the humeral head when bone stock is insufficient to support a new component. In the case of infection, removal of both components is advocated. Results of glenoid component revision surgery are satsifactory in the majority of cases, with patients who have intact and normally functioning deltoid and rotator cuff muscles faring better than those who have some form of compromise.     

Fixation of glenoid component: Keel versus pegs

Glenoid component fixation and long-term stability is determined by a multitude of anatomic and biomechanical factors. Recent advances in total shoulder arthroplasty have emphasized glenoid fossa preparation, glenoid component design, and implant fixation in an effort to decrease the incidence of glenoid component loosening, but there remains a paucity of information addressing the influence of these factors on implant stability.     

Pegged or keeled glenoid component use: Which is it?

With variation in glenoid design focused mainly on the backside interface of the component with the glenoid bone, keeled and pegged glenoid components have become the basis for most implants. Keeled implants offer a single, deep anchor for the component, while pegged implants offer stability with less bone removal. There is a trend in multiple studies for decreased radiolucent lines, decreased loosening, and decreased revision rates with pegged components. In-line pegs confer several advantages over out-of-line pegs. Advancements in cementing techniques and glenoid preparation have improved longevity for all types of glenoid implants.