CT scan evaluation of glenoid component fixation: a prospective study of 27 minimally cemented shoulder arthroplasties

BACKGROUND: Glenoid component failure is the most common complication of total shoulder arthroplasty. It can be correlated with failure of the component itself to resist wear and deformation, failure of fixation or failure of the glenoid bone. Anchor Peg Glenoid component (Depuy(®)) seems to have a higher bone fixation in biomechanical canine model: it is a all-polyethylene, concave component with one circumferentially fluted, central, interference-fit peg and three small cemented peripheral pegs. MATERIALS AND METHODS: We realized a prospective study of Anchor Peg total shoulder arthroplasty, included 27 patients suffering from primary arthrosis or arthritis, without rotator cuff tear. A clinical and radiographic evaluation was performed at 3 months, 1 and 2 years; a CT scan was made in postoperative and analyzed central peg’s bone integration 1 year later. RESULTS: Improvement of postoperative Constant score and radiographic good results were correlated with satisfactory subjective results reported by patients. We observed radiolucent lines under glenoid component in 3 cases. Twenty-six CT scans were available at 1 year: it showed complete bone integration around the central peg in 21 cases and partial peripheral bone integration in four cases. Only one patient had any tissue integration around the peg, probably because of his implantation near cortical bone of scapular spine. DISCUSSION/CONCLUSION: Long-term result of arthroplasty is correlated with glenoid durable fixation to underlying bone: this study shows higher fixation of glenoid component with bone integration of central peg. However, these results will have to be confirmed in a later revision.