Bony integration of a hybrid glenoid component in anatomical shoulder arthroplasty : short-term CT scan analysis

Loosening of the glenoid component in the long term remains an important complication of the anatomical total shoulder arthroplasty (aTSA). The aim of this study was to explore the bony integration of a hybrid glenoid component based on an analysis of CT scans.

In a prospective multicentre study, patients who underwent primary aTSA, whose hybrid design of glenoid component included a fully-polyethylene flanged upper peg and a porous-coated titanium lower peg, and who were reviewed with CT scans between 12 and 24 months postoperatively, were included. Two independent observers reviewed the scans. Bony integration of the upper peg was scored as described by Arnold et al, and integration of the lower peg was scored as described by Gulotta et al. Perforation of the glenoid vault in any plane was also assessed.

From an initial group of 120 aTSAs in 116 patients, 104 CT scans were analyzed in 100 patients (four bilateral shoulders, mean age 66 years (SD 11), 62 female and 38 male). Osteolysis around the upper peg was found in 32 patients (32 aTSAs; 31%). Of the remaining patients, 72 had a mean Arnold score of 5.6 points (SD 0.9), and 70 (67%) had perfect integration. The lower peg had a mean Gulotta score of 6.5 points (SD 1.4). There was perfect integration of the lower peg in 70 patients (70 aTSAs; 67%). A total of nine patients (nine aTSAs; 9%) had no bony integration at either peg. There was perforation of the glenoid in an anterior or posterior direction at the level of the upper peg in three and 28 patients, respectively. This occurred at the level of the lower peg in 11 and 18 patients, respectively. The inter- and intraobserver reliability was good (k = 0.782 and 0.86, respectively). No implant breakage occurred at a mean follow-up of 16 months (12 to 24). The clinical outcome was satisfactory at a mean follow-up of 32 months (24 to 35), as assessed by a visual analogue scale score for pain, the Constant-Murley score, Subjective Shoulder Value, and American Shoulder and Elbow Surgeons score.

Short-term CT scan analysis of a new hybrid anatomical glenoid component found perfect bony integration around the lower porous coated titanium peg in 90% of patients. The upper polyethylene flanged peg had bony integration in 70 patients (70 aTSAs; 67%). Longer follow-up is needed to analyze the rate of survival of this component. The short-term clinical outcome was satisfactory.