Progression of Erosive Changes of Glenoid Rim After Arthroscopic Bankart Repair

Abstract

To evaluate changes of the glenoid after arthroscopic Bankart repair (ABR) in patients with different preoperative glenoid structures. Patients who underwent ABR for traumatic anterior shoulder instability were retrospectively investigated. They were divided into 3 groups on the basis of preoperative glenoid structure by computed tomography (CT): normal glenoid (group N), glenoid erosion (group E), or glenoid defect associated with a bony Bankart lesion (group B). Shoulders in group B were also stratified according to the postoperative status of the bone fragment (union, nonunion, or resorbed). Postoperative changes of glenoid width (Δ) (increase: Δ ≥5%, stable: Δ >-5% to <5%, decrease: Δ ≤-5%) and the extent of glenoid bone loss were investigated by 3-dimensional CT. A total of 186 shoulders were divided into 3 groups: group N (n= 61), group E (n= 46), and group B (n= 79). At initial postoperative CT, the glenoid width was decreased in 41 shoulders, stable in 20 shoulders, and increased in no shoulders from group N. The respective numbers were 27, 18, and 1 in group E, and 50, 22, and 7 in group B. The glenoid width was reduced in all groups (mean percent change:-8.8%,-5.9%, and-6.1%, respectively). In group B, glenoid width decreased in most of the shoulders without bone union. The glenoid bone loss on the preoperative and postoperative final CT was, respectively, 0% and 8.6% in group N (P < .0001), 9.9% and 12.4% in group E (P= .03), and 10.4% and 7.2% in group B (P= .01). Final glenoid bone loss >13.5% was recognized in 18.2% of group N, 35.7% of group E, and 21.8% of group B. Glenoid width often decreased after ABR because of anterior glenoid rim erosion, and this change was frequent in patients with preoperative normal glenoid, glenoid erosion, or without postoperative union of a bony Bankart lesion. Level 3, Case-control study.