Description
Background: A hook plate is a widely used implant to treat acromioclavicular (AC) joint injuries with effective vertical stiffness and satisfying outcomes. However, the hook plate has some drawbacks, including acromial osteolysis and peri-implant fracture. The hypothesis is that there are some instabilities on the horizontal plane. This study aimed to study the biomechanics of hook plate fixation and hook plate fixation with AC joint suture augmentation.
Study design: Experimental biomechanical Cadaveric study
Methods: Twelve fresh-frozen cadaveric shoulders were included in this study, four males and two females. The mean age was 61 ± 8 years. In sequence, we stimulated acromioclavicular joint dislocation. We evaluated the effectiveness of Hook plate fixation and Acromioclavicular joint augmentation with FiberTape. A 1.5 N/m torque was used to move the clavicle in the anterior and posterior directions, and the displacement was measured. Data was presented in mean and standard deviation.
Results: Hook plate fixation with or without suture augmentation could reduce a vertical displacement comparable to an intact state (3.1 ± 3.4 mm, 3.0 ± 3.3 mm, 3.6 ± 1.5 mm; p > 0.05). Hook plate fixation with or without suture augmentation had an anterior stiffness comparable to the intact state (36.6 ± 19.4 Nm/rad, 38.9 ± 14.8 Nm/rad, 29.6 ± 12.7 Nm/rad; p > 0.05). However, hook plate fixation with or without suture augmentation had a posterior stiffness that was significantly higher than the intact state (42.0 ± 13.2 Nm/rad, 42.0 ± 19.8 Nm/rad, 21.2 ± 15.6 Nm/rad; p < 0.01). Three specimens with hook plate fixation without suture tape augmentation had dislocation during testing.
Conclusion: Hook plate fixation with or without suture augmentation could provide anterior horizontal and vertical stability for high-grade AC joint injury, comparable to the intact condition. However, hook plate fixation had a significantly higher posterior stiffness than intact conditions. Suture augmentation could prevent AC joint dislocation during testing.
