A novel anchor-loop internal fixation system in coracoclavicular ligament reconstruction for acromioclavicular dislocation: a biomechanical study / 中华创伤骨科杂志

ABSTRACT

Objective:To explore the biomechanical stability of a novel anchor-loop internal fixation system in the treatment of acromioclavicular joint dislocation using cadaveric specimens.Methods:The acromioclavicular ligaments were severed in 12 complete shoulder joint specimens, in which the quasi-static non-destructive cycle experiment was performed until the coracoclavicular ligaments failed. The failure intensities of the coracoclavicular ligaments were recorded. Next, the 12 specimens were randomly divided into groups A, B, C and D ( n=3), in which 4 different internal fixation materials were used respectively to reduce and fix the acromioclavicular joint. Group A was subjected to 3.5 mm clavicular hook locking compression plate, group B to 5 mm soft tissue with wire anchor, group C to 10 mm Endobutton steel plate, and group D to the novel anchor-loop internal fixation system (5 mm soft tissue with wire anchor + 10 mm Endobutton steel plate). An X-ray machine was used to evaluate the reduction and internal fixation of the acromioclavicular joint. After the shoulder specimens were securely fastened by a homemade fixation jig to a 100 KN electronic universal mechanical testing machine, each experimental specimen was subjected to a destructive static tensile mechanic determination in the vertical direction at a loading speed of 100 mm/min. The load-displacement curves were recorded and drawn by a computer connected with the biomechanical testing machine. The failure strength and failure causes were recorded for each internal fixation. Results:The fracture strength of the coracoclavicular ligament in 12 cadaver specimens was (374.6±0.8) N. The mechanical load of internal fixation failure was (409.5±2.6) N in group A, (297.8±3.4) N in group B, (375.2±3.1) N in group C and (376.2±3.1) N in group D. The internal fixation failure was due to clavicular fracture in 2 specimens and to acromial fracture in 1 specimen in group A, to anchor protrusion in all the 3 specimens in group B, to coracoid base fracture in all the 3 specimens in group C, and to anchor protrusion in all the 3 specimens in group D. The mechanical loads of internal fixation failure were significantly different among the 4 experimental groups ( P<0.05). The mechanical load of internal fixation failure in group D was significantly different from that in groups A and B ( P<0.05). Conclusions:Our self-developed novel anchor-loop internal fixation system can effectively reposit the acromioclavicular joint to treat acromioclavicular joint dislocation, because it conforms to the biomechanical characteristics of the acromioclavicular joint, and is easy to handle. Therefore, its feasibility is high.