A Biomechanical Study of Double-row Suture-bridge and Double-screw Fixation Strength in Split-type Greater Tuberosity Fractures of the Humerus

Background: This study aimed to compare the fixation strength of double-row suture-bridge (DR) and double-screw (DS) fixation methods in treating split-type greater tuberosity fracture of the humerus. Methods: : We established 24 fracture models of frozen pig shoulders with reserved supraspinatus, infraspinatus, and teres minor muscles. The specimens were randomly divided into two groups according to the fixation methods of double-row suture-bridge (group A) and double screws (group B). The loads of 3-mm displacement, 5-mm displacement, and fixation failure of each group were measured using a biomechanical device in both traction directions of the supraspinatus muscle (horizontal direction) and infraspinatus-teres minor muscles (vertical backward direction). Results: : In the direction of supraspinatus traction, there was no statistical difference in the mean load values of 3-mm displacement, 5-mm displacement, and fixation failure in both groups ( p > 0.05). In the direction of infraspinatus-teres minor traction, the mean load values of 3-mm displacement, 5-mm displacement, and fixation failure of double-screw fixation were greater than those of double-row suture-bridge fixation ( p = 0.000). Conclusion: The fixation strength of double-screw suture-bridge and double screws were equivalent in the direction of the supraspinatus. However, the fixation strength of double-screw suture-bridge was less than that of double screws, indicating poor anti-rotation property. Double-screw suture-bridge fixation alone is not recommended to treat split-type greater tuberosity fracture with a large fragment.