| Objective To analyze the trauma mechanism of the lamina fractures and dural tears and cauda equina entrapment in L2-L5 burst fractures, and to explore the relationship between the two.To determine the incidence of dural tears and cauda equina entrapment in lumbar burst fractures with lamina fracture and to find out if any specific clinical and radiographic factors are predictive of dural tears and cauda equine entrapment. To determine if the Sequence of reduction maneuver and laminectomy influence the recovery of neurological function.Methods 36 consecutive patients who had L2–L5 fresh burst fractures with lamina fractures were retrospectively analyzed. Age, sex, etiology, segments distribution and classification of the spine fractures , complications of the fractures and all the radiologic parameters were statistically analyzed .Percentage increase of interpedicular distance was measured on posterior-anterior X-ray of lumbar spine . Middle column height loss,kyphotic angle was measured on lateral lumbar spine X-ray.Spinal canal stenosis was measured on cross-sectional images of CT. Modified Frankel neurologic functional grades was record preoperatively and on postoperative follow-up at the end of times. Parameter above of patients with DT and/or CEE(Group A1) and of others without DT and/or CEE (Group B1) were analyzed with Student's t test or rank-sum test. Reduction maneuver in the first reset again laminectomy (Group A2) and the first reset laminectomy (Group B2) were compared with the degree of improvement in neurological function after operation.Results Damage concentrated in L2 and L3 , which together account for 91.7%. Fall from height accounted for 72% of Causes of injury. Injury in nine cases of calcaneal fractures (25%). Distribution of fracture types, Denis D-type accounted for 52.8%. In 36 cases, concurrent DT and/or CEE were 44.4%. The difference between Group A1 and Group B1 was significant when compared with percentage increase of interpedicular distance by t test (t = 4.246, P <0.01),and were not significant when compared with age, sex, etiology, kyphotic angle middle column height loss,spina cannal stenosis.By the Mann-Whitney U rank sum test, A1, B1 two preoperative neurological score was significant different (Z = 3.976, P <0.01). All patients with neurological improvement of varying degrees.Group B2, compared to Group A2,although the sequence of reduction and laminectomy was different, but the improvement degree of neurological function at postoperation of the two ,by the Mann-Whitney U rank sum test,were not different statistically significantly (P> 0.05 ).Conclusion At the effect of axial load, L2-L5 burst fractures are often accompanied by lamina fractures and DT and CEE . Often the cause of the neurologic deficit in lower lumbar burst fractures may be the displacement of nerve roots through the vertical laminar fracture rather than from direct anteroposterior compression from retropulsed bony fragments.In patients with Lamina fractures, particularly in patients with greenstick fractures , it is difficult to determine whether there is a clear DT and CEE by preoperative clinical and imaging findings. Therefore, if there is any suspicion of such an occurrence, it should be the rule to begin with posterior approach and use the open book technique to expose the dura safely. The present results showed that the sequence of reduction and laminectomy did not affect the improvement degree of neurological function at postoperation, but a limited number of cases such as the impact of confounding factors, we believe that reduction maneuver should be done after laminectomy at appropriate. |
