Abstract
Background context: Stable thoracolumbar spinal fracture is a common injury, yet there remains a relative lack of evidence that would allow reliable prediction of outcome. Variation in outcome in stable thoracolumbar spine fracture without neurological deficit could not be explained by the assessment made from x-rays and CT imaging alone, which measures mainly the bony injury severity. So far, no good classification system has been developed to assess the severity of soft tissue injury (disc).
Objectives: To measure short-term outcome of stable thoracolumbar fracture and analyse aspects of injury severity for their ability to predict outcome. To develop a new disc injury severity grading system in thoracolumbar spine fractures.
Study design: Prospective observational.
Patient sample: 44 patients with stable fractures between T11 and L5 vertebra with no neurological deficit and treated conservatively were selected.
Methods: All had plain x-rays, CT and MRI scans post-injury and at one year post-injury (except CT). Bony injury severity was scored on a seven-point ordinal scale based on (a) communication, (b) apposition and (c) kyphosis. Disc injury severity was scored by the newly developed six-point ordinal scale (none to severe) based on the following variables: (a) Herniation of the disc, (b) Indentation of the end plate, (c) Change in height and (d) Change in signal. Outcome was assessed at one to two years from injury. The following outcome measures were collected: (A) Five domains of pain symptoms – intensity, duration, bothersome, interference and satisfaction. (B) Five domains of function – Physical Component Summary (PSC) measure, Mental Component Summary (MSC) measure, Oswestry disability score, return to pre-injury level of overall activities and return to employment. Non-parametric correlation coefficients were calculated between outcome variables and other variables to look for the predictors of outcome. Stepwise linear regression analysis was performed to compare the predictive values and to look at what proportion of outcome is predicted by different predictors.
Results: According to AO classification, the fractures were A1, A2, A3 and B1. The Spearman correlation coefficients between outcome and injury severity were consistently higher with disc injury severity than bony. For the outcome of pain intensity, the correlation coefficients for disc and bone injury severity respectively were:.63 (p < .0001) and.28 (NS-not significant). Similarly for SF36 PSC were: .41 (p < .01) and.25 (NS). The predictive value of pain at F < .01 was 29% for disc injury severity and all other variable were not significant and excluded. At F < .05, the predictive value of disc injury severity (29%) increased further by 9%, 8% and 6% by addition of variable “Patient’s pre-injury SF36 MSC”, “Legal and Compensation issues pending” and “Physical demand of job” respectively. The predictive value of function at F < .01 was 16% for disc injury severity and it increased to 31% by the addition of “physical demand of the job” variable. At F < 0.05 the predictive value further increased by 5% by addition of variable “Legal and Compensation issues pending”. All other variables were not significant.
Conclusions: A new grading system of disc injury severity was developed and it showed good predictive value for pain and functional outcome. Disc injury severity has a better predictive value for short term outcome than bony injury severity in stable thoracolumbar fractures. In the spectrum of injuries studies, the AO classification and the degree of kyphosis provided no prediction of outcome.
The abstracts were prepared by Emer Agnew, Secretary to the IOA. Correspondence should be addressed to him at Irish Orthopaedic Association Secretariat, c/o Cappagh National Orthopaedic Hospital, Finglas, Dublin 11, Ireland.
