Short-term results of a hybrid ingrowth glenoid in anatomic total shoulder arthroplasty: a radiographic analysis for radiolucent lines and osteointegration using tomosynthesis

Background

Loosening of the glenoid component is the most common cause of implant failure in total shoulder arthroplasty. Recently, a hybrid glenoid component with polyethylene peripheral pegs and an ingrowth central peg was developed. This study aimed to evaluate radiolucent lines (RLLs) around the pegs and osteointegration around the central metal peg in the hybrid glenoid component using tomosynthesis.

Methods

Nineteen patients with a hybrid glenoid and 18 with a cemented all-polyethylene glenoid were included. Radiographic lucency around the glenoid components was graded (Grade 0-5). To investigate the accuracy of RLL detection on plain radiographs, tomosynthesis images and plain radiographs were compared 2 years postoperatively. The zone of spot welds (a sign of osteointegration) and RLL in the hybrid glenoids were evaluated.

Results

The incidence of RLL was 15.8% (Grade 1, 3/19 cases) in the hybrid glenoid component and 33.3% (Grades 1 and 3: three cases each, 6/18 cases) in the cemented all-polyethylene glenoid component; however, the difference was not statistically significant. All 19 patients achieved osteointegration around the central metal peg 8 months postoperatively, and no progression of the RLL was observed. The concordance in the detection of RLL between tomosynthesis and plain radiography was 89.4% (17/19 cases) in the hybrid glenoid group and 72.2% (13/18 cases) in the cemented all-polyethylene group. However, plain radiography tended to underestimate RLL in both groups.

Conclusion

The hybrid glenoid component may be a viable alternative to the cemented all-polyethylene glenoid. Tomosynthesis may be a new and effective modality for evaluating glenoid loosening.