Effect of glenoid perforation during total shoulder arthroplasty on glenoid component cement fixation and suprascapular nerve

Background Arthritic glenoids are susceptible to vault perforation during total shoulder arthroplasty. We investigated the effects of glenoid perforation and subsequent cement extrusion on the suprascapular nerve and on the glenoid cement infiltration. Methods Total shoulder arthroplasty using three-pegged glenoid components were performed on 10 cadaveric shoulders assigned to two groups (perforation vs. control). In perforation group, the glenoids were reamed eccentrically and intentionally perforated medially through the central peg hole, whereas control group received perpendicular reaming with no perforation. Bone cement was applied to each peg. Spatial relationship between the extruded cement and the suprascapular nerve, and the amount of cement infiltration into the cancellous bone were evaluated. Results In perforation group, five specimens were perforated anteriorly, and two posteriorly. In the two posteriorly perforated specimens, the suprascapular nerve was in direct contact with extruded cement at the spinoglenoid notch. Perforation group showed significantly less cement infiltration into the cancellous bone than control group (p = 0.008). Conclusions Glenoid perforation decreases the volume of cement infiltration into the cancellous bone potentially compromising glenoid component fixation. Glenoid perforation tends to occur anteriorly rather than posteriorly in arthritic glenoids; however, if perforation occurs posteriorly, the suprascapular nerve is at immediate risk from the extruded cement. Level of evidence: Basic science study.