Abstract
Study Design: Prospective observational study.
Objectives: To score the severity of injury to (a) vertebrae and (b) intervertebral discs following thoraco-lumbar fracture, and compare the two in their ability to predict clinical outcome at 1–2 years.
Methods: 44 patients with fractures between T11 and L5 without neurological deficit were treated conservatively. All had plain X-rays and MRI scans immediately and at one year post-injury. Bony injury severity was scored on a seven-point ordinal scale based on a) comminution, b) apposition and c) kyphosis. Disc injury severity was scored on a six-point ordinal scale based on a) change in signal, b) change in height, c) indentation /herniation. Outcome was assessed at one to two years from injury (av. 18.1 + 5.6 months) Non-parametric correlation coefficients were calculated between injury severity variables and outcome variables.
Outcome measures: Modified Oswestry disability questionnaires, SF-36 questionnaires (physical and mental component summary scores – PCS and MCS), verbal and numeric rating scale of ability to perform pre-morbid activities/work. Detailed analysis of a.) pain (intensity, duration, character, distribution, etc.), b.) early morning stiffness (severity, frequency, and duration).
Results: According to the AO classification, 25% of the fractures were A1 (wedge), 9% were A2 (split), 45% were A3 (burst) and 20% were B1 (flexion-distraction with posterior ligament injury). Disc injuries scored as: grade 3 (mild) in 14%, grade 4 in 36%, grade 5 in 36% and grade 6 (very severe) in 14%. The spearman correlation coefficients between injury severity and outcome were consistently higher with disc injury severity than bony. For the Oswestry disability score the correlation coefficients for disc and bone injury severity respectively were 0.50 (p< .0001) and 0.40 (p< .05), for SF36-PCS: 0.43 (p< .005) and 0.32 (p< .05), for SF36-MCS: 0.43 (p< .005) and 0.06 (NS), for return to pre-morbid activities and work: 0.32 (p< .05) and 0.25 (p< .5), for pain intensity by numeric rating scale: 0.69 (p< .0001) and 0.41 (p< .01), and for pain intensity by verbal rating scale: 0.65 (p< .0001) and 0.28 (p< 0.1).
Conclusion: In all clinical outcomes assessed, there was consistently better prediction by measures of injury severity to the disc than the bone. This study offers possible explanation for previously low or conflicting evidence of correlation between clinical outcome and bony injury in thoraco-lumbar spine fractures uncomplicated by neurological injury. It implies that in selected patients with severe disc injury, treatment focused on eliminating the effects of the disc injury may result in better clinical outcome.
These abstracts were prepared by Mr. Brian J C Freeman FRCS (Tr & Orth). Correspondence should be addressed to him at The Centre for Spinal Studies and Surgery, University Hospital, Queens Medical Centre, Nottingham NG7 2UH.
