An in vitro biomechanical comparison of a locking compression plate fixation and kerf cut cylinder fixation for ventral arthrodesis of the fourth and the fifth equine cervical vertebrae.

This study tests the effectiveness of two methods for stabilizing the joint between the fourth and fifth cervical vertebrae in horses: a kerf cut cylinder (KCC) technique and a ventrally placed locking compression plate (LCP) method. The researchers found that the LCP technique displayed stronger biomechanical properties than the KCC method in a cadaver model, indicating it may be a more effective stabilization method in a clinical setting.

Research Methodology

The researchers conducted an in vitro biomechanical investigation using the cervical vertebral columns from adult equine cadavers (n=54). The cadavers were divided into three age groups based on horse dentition and vertebral size from radiographs. They were then randomly assigned to one of three groups:

• The KCC group, in which the cadavers received a KCC treatment.
• The KCC-implanted LCP group, where an 8-hole, 4.5mm LCP was implanted along with KCC treatments.
• The intact group, where no implants or treatments were applied.

The specimens within each of these groups were then randomly assigned to one of three loading conditions and tested under 4-point bending until failure. The researchers recorded several measures, including stiffness, bending moment at yield and at failure, and mode of failure.

Results

The research found that all specimens failed at the interface between the fourth and fifth cervical vertebral (C4-C5) articulation.

• The cervical vertebrae stabilized with the LCP construct demonstrated greater stiffness, yield bending moment, and failure bending moment compared to the KCC implanted cervical vertebrae.
• Failure modes varied between groups and depended on the direction of loading. In the KCC group, fractures of C5 associated with the KCC were common. In the LCP group, screw pullouts or fractures of C4 and C5 bodies, especially during extension and on the left side during lateral bending, were common. In the intact group, subluxations, or partial dislocations, were most common.

Conclusion

The study concluded that the LCP construct exhibited superior biomechanical properties as a stabilization technique compared to the KCC construct within this model. However, further research is recommended to investigate the cumulative effects of repetitive loading on this stabilization technique.