Glenoid component retroversion is associated with osteolysis.

BACKGROUND: It has been suggested that glenoid component retroversion and eccentric loading are an important mechanism leading to glenoid component loosening, but little clinical data have been published to support this concept.
METHODS: Sixty-six shoulders underwent total shoulder replacement with an all-polyethylene press-fit pegged glenoid component designed for osseous ingrowth for treatment of osteoarthritis. These shoulders were followed clinically and with radiographs for an average (and standard deviation) of 3.8 ± 1.8 years (range, two to seven years). Preclinical radiographic loosening was defined as osteolysis around the central peg of the glenoid component.
RESULTS: Of the sixty-six shoulders, twenty (30%) had osteolysis around the center peg. The length of time after replacement (p = 0.0006), preoperative glenoid retroversion (p = 0.036), and postoperative glenoid component retroversion (p = 0.041) were correlated with osteolysis around the glenoid center peg and an increase in the Lazarus component loosening grade. Postoperative retroversion correlated with preoperative retroversion (Pearson correlation coefficient = 0.44, 95% confidence interval [CI] = 0.19 to 0.64, p = 0.0011). The presence of osteolysis around the center peg was not correlated with a worse clinical outcome defined by shoulder scores or a reoperation due to glenoid loosening. After adjustment for follow-up time, excessive postoperative glenoid retroversion (≥15°) was associated with an increased odds of osteolysis (odds ratio = 5.23, 95% CI = 1.31 to 20.9]), whereas preoperative glenoid retroversion was associated with no change in the odds of osteolysis.
CONCLUSIONS: Osteolysis around the center peg of a glenoid component is correlated with component retroversion of ≥15°. This finding suggests that there should be additional investigation into the effects of correcting preoperative glenoid retroversion to prevent osteolysis around the center peg.