Aim of Study: (A) To study what causes Anterior Column Deficiency in Burst Fracture of Dorso Lumbar Spine in the acute and later phase. (B) To analyse radiologically, the significance of adjacent disc injuries in burst fracture of dorso lumbar spine. (C) To look into the effectiveness of posterior short segment stabilisation by pedicle screw fixation and fusion in these injuries, in relation to deformity and anterior column deficiency.
Methods and Materials: Twenty consecutive cases of Superior Burst-split fracture of Dorsolumbar spine were studied prospectively. All cases underwent reduction, posterior short segment stabilisation by Steffee type pedicle screw fixation and two level posterolateral fusion. The average follow-up duration was 30.2 months. Standardised AP and lateral radiograph were taken pre-operatively and post-operatively at regular intervals (every three months). Radiological assessment using seven parameters (Vertebral body angle, Upper disc angle, Lower disc angle, Kyphotic angle, etc) were done from these radiographs.
Result and Significance: The total average correction of kyphosis (in degree) at surgery was 21.5°, and the proportion of correction during surgery was – Upper disc 29% (6.3°), Vertebral body 68% (14.6°) and Lower disc 3% (0.6°). So 68% of the correction was at the vertebral body level and 32% at the adjacent discs levels. At follow-up, the total average loss of correction was 16.5°, and the proportion of loss at follow-up was – Upper disc 44% (7.2°), Vertebral body 14% (2.3°) and Lower disc 42% (7.0°). There was loss of 14.2° at the disc levels compared to 2.3° only at the vertebral body level. So 86% of the loss was at the adjacent disc levels.
Conclusion: Distraction at the adjacent disc levels occurred at surgery while contouring the vertebral body using dorsal instrumentation. The distraction at the upper disc level was significant. Distraction at adjacent disc levels resulted in more anterior column deficiency.
At follow-up, the loss in the vertebral body was minimal and most of the loss occurred at the adjacent disc levels. The anterior column deficiency caused by the injury to the adjacent disc is very major cause for failure of dorsal instrumentation than the deficiency caused by the vertebral body. The upper disc is more severely injured than the lower disc in the superior burst split fracture and so the degeneration is rapid in the upper disc and gradual in the lower disc. The CT cuts at the end plate levels of the vertebral body can help to judge roughly the extent of injury to the adjacent disc.
Posterolateral fusion and late disc degeneration after consolidation of fusion result in collapse of the disc in kyphotic angulation, as it prevents collapse of posterior disc height.
