Anterior interbody fusion in fractures and fracture-dislocations of the spine

Instrumented ligamentotaxis and stabilization of compression and burst fractures of dorsolumbar and mid-lumbar spines

BACKGROUND

Controversy continues regarding the best treatment for compression and burst fractures. The axial distraction reduction utilizing the technique employing the long straight rod or curved short rod without derotation to reduce fracture are practised together with short segment posterolateral fusion (PLF). Effects of the early postoperative mobilization without posterolateral fusion on reduction maintenance and fracture consolidation were not evaluated so far. The present prospective study is designed to assess the effectiveness of i) reduction and restoration of sagittal alignment, ii) no posterolateral fusion on the reduced, fractured vertebral body and injured disc, iii) fracture consolidation and iv) the fate of the unfused cephalad and caudal injured motion segments of the fractured vertebra.

MATERIALS AND METHODS

The study includes 15 Denis burst and two Denis type D compression fractures between T(12) and L(3). The lordotic distraction technique was used for ligamentotaxis utilizing the contoured short rods and pedicle screw fixator. Three vertebrae including the fractured one were fixed. The patients after surgery were braced for ten weeks with activity restriction for 2-4 weeks. The patients were evaluated for change in vertebral body height, sagittal curve, reduction of retropulsion, improvement in neural deficit. The unfused motion segments, residual postoperative pain and bone and metal failure were also evaluated.

RESULTS

The preoperative and postreduction percentile vertebral heights at, zero (immediate postoperative), at three, six and 12 months followup were 62.4, 94.8, 94.6, 94.5 and 94.5%, respectively. The percentages of the intracanal fragment retropulsion at preoperative, and postoperative at zero, 3, 6 and 12 months followup were 59.0, 36.2,, 36.0, 32.3, and 13.6% respectively. The preoperative and postreduction percentile loss of the canal dimension and at zero, three, six and 12 months were 52.1, 45.0, 44.0, 41.0 and 29% respectively suggesting that the under-reduced fragment was being resorbed gradually by a remodeling process. The mean initial kyphosis of 33° became mean 2° immediately after reduction and mean 3° at the final followup. The fractured vertebral bodies consolidated in an average period of ten weeks (range 8-14 weeks). The restored disc heights were relatively well maintained throughout the observation period. All paraparetic patients recovered neurologically. There were no postoperative complications.

CONCLUSION

Instrument-aided ligamentotaxis for compression and burst fractures utilizing the short contoured rod derotation technique and the instrumented stabilization of the fractured spine are found to be effective procedures which contribute to the fractured vertebral body consolidation without recollapse and maintain the motion segment function.

Morphological adaptation of the bone graft and fused bodies after non-instrumented anterior interbody fusion of the lower cervical spine

PURPOSE

To assess the remodelling process of the bone graft and fused bodies after non-instrumented anterior interbody fusion with autogenous iliac graft in patients with spondylosis, infections, fractures, or disorders of the cervical spine.

METHODS

68 patients aged 18 to 58 years who underwent non-plated anterior lower cervical interbody fusion with an iliac graft were retrospectively studied. Diagnoses of the patients were degenerative disc diseases (n=32), disc herniation (n=15), fractures (n=13), and tuberculosis (n=8). The Robinson and Smith technique was used to treat degenerative disc diseases and protruded disc, and the Bailey and Badgley procedure for fractures or tuberculosis of the cervical spine. 34, 25, and 9 patients underwent one-, 2-, and 3-segment fusions, respectively. 18 of the 25 patients underwent two-segment fusion with a single large bone block, and 7 with 2 separate bone blocks for each segment. Four of the 9 patients underwent three-segment fusion with a single large bone block, and 5 used separate grafts for each segment independently. Plain and stress radiography was primarily used to assess the fusion. Computed tomography and magnetic resonance imaging were also used in some patients. Some anterior graft extrusion (amounting to less than 10% of corresponding anteroposterior body width) was used to observe the remodelling during graft-take and thereafter. Postoperative cervical traction for 2 to 4 weeks, then cervical collar immobilisation for 4 to 12 weeks were strictly followed according to the numbers of fused segments. A halo vest was applied in 4 patients with fracture undergoing 3-segment fusion as they could not tolerate the prolonged bed rest or rigid cervical brace.

RESULTS

The mean time for the graft to fuse was 8.6 (range, 7-14) weeks in patients who underwent each segment fusion with independent free grafts, and 10 and 14 weeks in those who underwent 2- and 3-segment single large graft fusion, respectively. The final loss of disc height and joint angle were negligible, regardless of the extent of fusion. Bony absorption of the anteriorly protruded part of the graft began at postoperative week 10 (range, 6-28), which coincided with the time of graft-take and initiation of remodelling.

CONCLUSION

The earliest sign of bony absorption of the anteriorly protruded part of the graft indicated the initiation of the graft-take and the graft remodelling. The inwaisting sign of the surgically fused block of vertebral bodies was a morphological adaptation. Despite the altered biomechanics of the spine in the fused area, the inwaisting sign indicated maintenance of normal function at the parafusion motion segments.

Stabilisation of fractured thoracic and lumbar spine with Cotrel-Dubousset instrument

OBJECTIVE

To evaluate the effectiveness of 2 different types of Cotrel-Dubousset instrument systems in stabilising thoracolumbar and lumbar spine fractures.

METHODS

Between January 1989 and December 1993, 45 fractures in 42 patients with unstable fracture or fracture dislocation of the thoracolumbar and lumbar spines were randomly assigned to 2 surgical treatments with Cotrel-Dubousset instrumentation-using either a long segment (Group 1) or a short segment (Group 2)-and short posterolateral fusion.

RESULTS

Consolidation of the fractured vertebral body and posterolateral fusion were achieved at a mean time of 4.5 months; fusion rates were 75% in Group 1 and 83% in Group 2. The average collapses of anterior vertebral body height in Group 1, in the immediate postoperative period and at the final follow-up, were 15% and 17%, respectively; and in Group 2, the figures were 16% and 24%, respectively. The correction of vertebral height and kyphosis at the last follow-up were lost more in Group 2 (5.7 degrees ) than in Group 1 (4.4 degrees ). There were neurological recoveries in 6 of the 9 cases of incomplete paraplegics, including complete recovery in 5, and one-Frankel grade increase in one. There were 15 instrument failures in 12 patients, including screw breakage in 3 Group 1 cases and 6 Group 2 cases. The plug dislodged in 3 Group 1 cases, and the hook dislodged in 3 Group 2 cases. In other words, instrument failures were more common in Group 2.

CONCLUSION

Cotrel-Dubousset stabilisation of the fractured spine achieves fracture consolidation, but does not maintain the restored height and sagittal curve completely until fusion. The long rod and short fusion construct was more effective for all fracture types than was the short rod and fusion construct, although it leads to wider immobilisation of normal segments.