Enlargement of Drill Holes After Use of a Biodegradable Suture Anchor: Quantitative Study on Consecutive Postoperative Radiographs

Abstract

Osteolysis around a biodegradable device has been warned of in several reports. We investigated variations of drill holes of polylactic acid (PLA) suture anchors in consecutive radiographs after arthroscopic capsulolabral repair to assess the influence of enlargement of the drill holes on clinical outcome. Twenty patients who underwent arthroscopic capsulolabral repair using 3 Panalok suture anchors for traumatic anterior shoulder instability were included in the study. The mean follow-up period was 25.8 months. From radiographs taken on postoperative day 1, at 3 and 12 months, and at the latest follow-up, the diameter of each drill hole was measured. The diameter enlargement ratio was calculated for each drill hole by dividing each diameter by the corresponding day-1 diameter. The patients were divided into 2 groups based on the degree of enlargement of drill holes (greater or less than the mean + 1 standard deviation [SD]) and the clinical outcome of each group was evaluated according to the Rowe score and range of motion. Diameter enlargement ratios tended to increase with time (P = .0152 for 3 v 12 months postoperatively, and P = .0049 for 3 v latest follow-up). Three drill holes out of 53, 17 out of 60, and 11 out of 47 showed enlargement over the mean + 1 SD, at 3 and 12 months postoperatively and at latest follow-up, respectively. Eleven patients had such enlarged drill holes, and had significantly poor Rowe score (70.9 v 95.6 points; P = .0267) at latest follow-up. A drill hole filled with a PLA anchor tended to enlarge over time. We found that 55% of patients had at least 1 drill hole that enlarged beyond the mean + 1 SD. These patients had significantly less favorable results in function and stability. The present study raises concern about the use of PLA suture anchors for the fixation of detached glenoid labrum. Level IV, therapeutic case series.