Total shoulder replacement using a bone ingrowth central peg polyethylene glenoid component: a prospective clinical and computed tomography study with short- to mid-term follow-up.

AIM OF THE STUDY: To assess the clinical and computed tomography (CT) outcomes of shoulder replacement with a novel bone ingrowth all-polyethylene glenoid component (APGC).

METHODS: Twenty-eight patients (30 shoulders) with osteoarthritis, mean age 62.3 years (range, 45-75), were implanted with the novel component between 2011 and 2013. Patients were evaluated by active range of motion (ROM), Constant-Murley score (CMS), simple shoulder test (SST), X-rays, and multidetector CT at two months and at a mean follow-up of 31 months (range, 24-39). Early and late follow-up CT scans were available for 21/30 shoulders.

RESULTS: Median ROM increased from 105 to 160° for anterior elevation, from 100 to 160° for lateral elevation, from 20 to 40° for external rotation, and from 2 to 10 points for internal rotation (all p < 0.001). CMS rose from 30 to 80.5 points and SST from 2.5 to 11 (both p < 0.0001). None of the glenoid components migrated. Progressive radiolucency was seen in 28/30 shoulders. There was a strong correlation between greater bone ingrowth (median Arnold score: 7) and lower radiolucency score (median Yian score: 2) at the last follow-up (p < 0.001). Osteolysis around the central peg was seen in two shoulders. There was no correlation between clinical scores and CT findings (p >0.05).

DISCUSSION: The partially cemented glenoid component for TSR assessed in this study resulted in satisfactory shoulder function at an early follow-up. The glenoid prosthesis was stable, with few radiolucent lines and good central peg bone ingrowth.

CONCLUSIONS: The satisfactory bone ingrowth documented on CT is encouraging and supports the use of the new prosthesis. Long-term follow-up studies can confirm if this device represents a rational alternative to fully cemented polyethylene glenoids.