Motion preservation for hyperextension injuries of the cervical spine-an alternative to spondylodesis? A biomechanical cadaver study.

INTRODUCTION

Currently, the gold standard for the treatment of AO type B3 cervical spine injuries is anterior cervical discectomy and fusion (ACDF), leading to an iatrogenic spondylodesis of the affected segment and ultimately bearing the risk of long-term morbidity. This study evaluates the biomechanical properties of a combination of a cervical total disc replacement (CTDR) with anterior fiber tape augmentation for the treatment of AO type B3 injuries in comparison to ACDF.

METHODS

14 human cadaveric cervical spine specimens (C5/6) were biomechanically tested under four different conditions: native, after simulation of an AO type B3 injury, after ACDF and CTDR + FiberTape®. All conditions were tested in the sagittal, frontal, and transversal plane with a load of 2.25Nm and the dislocation recorded. The mean value of range of motion (ROM) was calculated and analysed to identify differences in ROM and the neutral zone.

RESULTS

In flexion/extension, native testing showed a mean deflection of 11.2° ± 3.3°, the AO type B3 injury of 13.7° ± 2.9°, the ACDF of 6.7° ± 3.8° and the CTDR + tape of 9.3° ± 2.9°. Comparing both the injured specimens to the ACDF group (p < 0.001) and the injured to the tape group (p = 0.005) as well as the native to the ACDF group (p = 0.004), the mean values revealed to be significant. Lateral bending revealed a ROM of 6.8° ± 2.7° in the native, 7.7° ± 2.4° in the injured group, 4.7° ± 2.8° after ACDF, and 5.6° ± 2.4° after CTDR + tape, whereby the injured group values were significantly higher than those after ACDF (p = 0.018). The rotation showed a mean ROM of 5.6° ± 2.8° in the native and 5.8° ± 2.6° in the injured group, 4.0° ± 2.1° after ACDF and 6.3° ± 2.8° after CTDR + tape, without significant differences.

CONCLUSION

The combination of a CTDR + FiberTape proved to stabilize AO type B3 cervical spine injury adequately in the most compromised sagittal plane while maintaining micro-mobility and approaching physiological segment mobility.