[Reliability of load-sharing classification in indications for anterior vertebral body replacement in thoracolumbar spine fractures].

INTRODUCTION

So far, the Load-Sharing Classification (LSC) has been the commonest method employed to identify indication for anterior replacement of vertebral bodies in thoracolumbar spine fractures. The aim of this study was to verify reliability of the LSC method in indications for anterior replacement surgery.

METHODS

Fractures were examined using x-ray, CT and MRI methods. The prospective study included only patients with type A3 comminuted fractures (AO classification) of the thoracolumbar vertebrae (Th11-L2), with MRI confirmed grade 3 or 4 intervertebral disc injuries (according to Oner) and with no concomitant nerve injuries. All fractures were treated using isolated posterior transpedicular (TP) fixation. 18 months after the procedure, angulation of the regional kyphosis, screw rupturing, Visual Analogue Scale (VAS) scores at rest and under loading, Pain Scale (PS) scores and Work Scale (WS) scores were assessed. The study group included 42 patients aged 27-72 years (the mean age was 51.55 y.o.a.), 28 subjects were males and 14 females. Using the LSC classification system, the study group was divided into two subgroups, one including patients with LSC up to grade 6 - Group A (18 subjects) and the other one including patients with LSC 7 to 9 - Group B (24 subjects).

RESULTS

Statistical assessment of clinical (PS, WS, VAS at rest and VAS after loading) and radiological findings (the degree of kyphotic changes) at month 18 identified no statistically significant correlations between the two subgroups. TP fixation failures (srews rupturing) occured only in Group A in two subjects.

DISCUSSION: Based on the LSC, Group B was expected to have inferior outcomes, however, this was not the case in our study group. Therefore, it can be concluded that LSC is not a reliable predictor of the final clinical and radiological findings in the type A3 fractures with grade 3 or 4 TH-L intervertebral disc injuries. The defined LSC 6- point threshold for indications for anterior vertebral body and disc replacements is arguable.

CONCLUSION

The authors do not consider the LSC method sufficiently reliable for determining indications for anterior replacements.