Double-Sling Augmentation vs Bankart: Superior? How?

A double-sling augmentation strategy could prevent anterorinferior translation in shoulders with 20% glenoid bone defects when compared with the Bankart repair or the single-sling augmentation technique, according to a new study.

In the study, “Dynamic Double-Sling Augmentation Prevents Anteroinferior Translation for Recurrent Anteroinferior Shoulder Dislocation with 20% Glenoid Bone Loss: A Cadaveric Biomechanical Study,” the researchers wanted to compare the dynamic double-sling with single-sling augmentation using the conjoined tendon with 20% of an anteroinferior glenoid bone defect. The study was published online on November 24, 2021, in the journal Arthroscopy.

The researchers tested the stability of 12 shoulders in 60˚of glenohumeral abduction and 60˚of external rotation in 5 conditions: intact, 20% glenoid bone loss, Bankart repair, single-sling augmentation with the conjoined tendon, and double-sling augmentation with both the conjoined tendon and long head of the biceps tendon.

They determined shoulder stability using anteroinferior humeral head translation force of 20N, 30N, 40N, 50N, or 60N.

The tests showed a significant increase in anteroinferior humeral head translation after the creation of 20% glenoid bone defect under the 20N translational force (10.52 ± 0.71 mm). Structural failure occurred following the Bankart repair and the single-sling augmentation under the 30N (9.84 ±1.25 mm) and 40N (9.59 ± 0.66 mm) translational forces.

Overall, the double-sling augmentation prevented the anteroinferior humeral head translation under the translational force of less than 40N. Only half of the augmentation structure (8.25 ±1.66 mm) had failed under the 50N translational forces.

“In the absence of any Hill-Sachs lesion and when tested at 60˚abduction and external rotation in shoulders with 20% glenoid bone defects, at time-zero, the double-sling augmentation strategy could effectively prevent anteroinferior translation when compared with the Bankart repair or the single-sling augmentation technique under all magnitudes of the translational force in biomechanical simulation. Nevertheless, none of the constructs restored the humeral head translation to the normal intact state,” the researchers wrote.

The study authors included Liren Wang, Yuhao Kang, Yufeng Li, M.D., Chenliang Wu, M.D., Jia Jiang, Jinzhong Zhao and Guoming Xie of Shanghai Jiao Tong University Affiliated Sixth People’s Hospital and Suiran Yu of Shanghai Jiao Tong University.