Radiologic, mechanical, and histologic evaluation of 2 glenoid prosthesis designs in a canine model

Aseptic loosening of glenoid components is a common problem associated with total shoulder arthroplasty. A new glenoid design aimed at improving fixat ion outcomes was compared with conventional keeled glenoids in weight-beari ng canine shoulders. Radiographic, histologic, and mechanical tests were pe rformed at 3 postoperative intervals (0, 3, and 6 months). The uncemented p egged glenoid achieved bone ingrowth around the peg flanges in each case. T his result was confirmed histologically and radiographically. Mechanical re sults indicated that mean fixation strength increases significantly between 0 and 3 months after surgery and remains strong through 6 months. In contr ast, conventional keeled glenoids were found to have partial or complete ra diolucent lines around the keel in each instance, and mechanical testing de monstrated that mean fixation strength weakens significantly between 0 and 3 months after surgery and remains weak through 6 months. These results sho w that stem design changes can improve implant fixation. A cementless flute d peg stem was superior to a conventional cemented keel design in achieving osseous integration and fixation in a weight-bearing animal model.