A Biomechanical Analysis of Anchor Placement for Bankart Repair: Effect of Portal Placement

During arthroscopic Bankart repair, penetration of suture anchors through the far cortex can compromise the initial biomechanical characteristics of anchor stability and repair integrity. This study compared the placement of suture anchors through a low anterior-inferior rotator interval portal (AI) vs a trans-subscapularis portal to evaluate the rate of anchor perforation as well as biomechanical strength. Ten matched pairs of cadaveric shoulders were randomized to an AI or a trans-subscapularis portal for placement of suture anchors at the 3 o'clock and 5:30 positions. The following measurements were obtained: (1) distance from the portal to the cephalic vein; (2) presence and length of anchor penetration through the inferior glenoid; and (3) ultimate failure strength of the anchors. The distance from the portal to the cephalic vein was significantly greater with the AI vs the trans-subscapularis portal across all specimens (29.9 vs 11.2 mm, P<.05). The rate of anchor penetration was significantly increased in the AI group vs the trans-subscapularis group at the 5:30 position (60% vs 10%, P=.014) but not at the 3 o'clock position (P=.33). Mean pullout strength of the anchors at the 5:30 position trended higher in the trans-subscapularis group, but the difference was not significant (132.8 vs 112.6 N, P=.18). The cephalic vein is closer to the trans-subscapularis portal than to the AI, but is at a safe distance. Both the rate and the degree of glenoid suture anchor penetration were lower with the trans-subscapularis portal compared with the AI at the 5:30 position. Placing anchors through the trans-subscapularis portal provides a safe alternative method, with improved positioning of the inferiormost anchor compared with the traditional AI.