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Case Studies
Unstable Fractures of the Lumbar Spine
Philippe Gillet, MD
University Hospital, Sart-Tilman Liège, Belgium

Case Histories
Case 1:
F.F. aged 27, was involved in a car accident and was admitted with an unstable fracture of L2, without neurologic compromise. Lateral plain films revealed a burst-type fracture with a 22° kyphosis measured between L1 and L3, a 60% crushing of the anterior column of L2, and an anterior L1-L2 subluxation (Fig 1). The CT scan showed severe canal compromise (80%) with global retropulsion of the intermediate column as well as fractures of both posterior articular processes and the left lamina of L2 (Fig 2).

Case 2:
M.D. aged 35, fell from a height and sustained an unstable fracture of L3, also without neurologic compromise. Lateral plain films revealed a 10° kyphosis between L2 and L4, and a 50% crushing of the anterior column of L3. AP plain films showed a sagittal fracture of the vertebral body and a slight traumatic scoliosis (Fig 3). The CT scan showed a severe canal compromise (80%) with a central distribution of bone fragments in the neural canal and fractures of the left L2-L3 articular processes and L3 lamina (Fig 4).

Treatment options include:

  • Posterior realignment and fixation by short or long instrumentation, and bone grafting.
  • Anterior vertebrectomy and strut grafting with anterior instrumentation.
  • Combined or staged anterior and posterior approach (e.g. anterior strut grafting and posterior instrumentation).

Fig. 1

Fig. 2

Fig. 3

Fig.4

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Unstable Fractures of the Lumbar Spine: Discussion
Jean-Pierre C. Farcy, MD
Maimonides Medical Center, New York, NY

Case 1:
This patient has sustained a burst-type fracture with disruption of all three columns of the spine. Essential to planning a treatment approach to these injuries is consideration of three elements: neurologic status/stability, spinal deformity, and spinal stability. The latter two are frequently closely interrelated but not necessarily so. In this case neurologic compromise has not occurred; furthermore, the level of injury may not involve the conus medularis although sagittal reconstructions to visualize the cord anatomy would be desirable. In view of the above consideration, the degree of canal obstruction does not play a significant role in a treatment plan.

The next consideration is the degree of local spinal deformity. Although several classification and measuring systems have been proposed to evaluate traumatic deformity, my choice has been to consider the local deformity in reference to normal values and thus obtain a sense of relative spinal deformity. The latter measure has been termed the Sagittal Index (SI) which in this case would be approximately 42° (measured kypho (32) - normal segmental kyphus (-10) = 42).

The third consideration in this injury is the degree of stability. As an offspring of the Denis classification, an instability grade (IG) has been proposed which closely examines not only the bony but also the ligamentous components of each column to obtain an overall score. Each column is given two points for injury to bone or ligaments in each; the most unstable injury pattern is thus an IG of 6. In this case the IG is 5.

In order to address the instability and deformity of this injury, a posterior pedicle screw/rod construct should be applied to reconstruct the normal sagittal contour and height. Although instrumentation from L1 to L3 is sufficient, the augmentation with hooks weakens both interspinous and flavum ligaments rostrally and impinges upon the caudal facet joints. A simultaneous anterior/posterior approach is preferable, accomplishing both decompression and supplementation of the posterior fixation without requiring hook augmentation. It also increases the chance for successful fusion. Careful reduction intraoperatively should not place risk on nerve roots; however, potential for dural leak is present due to the posterior element fracture. Intraoperative monitoring with MEP and SSEP is recommended.

Case 2:
The same initial approach should be applied with this case. The patient is neurologically intact despite significant canal space narrowing below the conus. The SI is 27 and the IG is 6. Although a posterior approach alone will permit frontal and sagittal plane realignment, it does not ensure solid fusion or permit decompression. A shattered vertebral body with interspersed disc material has little chance of leading to a reliably solid fusion. Furthermore, placement of hooks to support screws posteriorly will, as mentioned above, lead to weakening of interspinous ligaments and impingement against the facet joints leading to junctional problems. A simultaneous anterior/posterior approach with an anterior strut graft is recommended.

Our current approach to spine fractures without neurologic deficit is based upon a prospective study from which the following was concluded: for S1<15 and IG<2, treatment is with a brace; for 15<SI<25 and 1<IG<3, treatment is by reduction and casting; for 25<SI<35 and/or 3<IG<5, posterior reduction and instrumentation is performed; for SI greater than 35 and/or an IG greater than 5, a simultaneous anterior/posterior approach is performed.

This reduction and placement of the graft as well as the instrumentation were performed well. I would have suggested, however, that the anterior and posterior approaches be performed simultaneously.

References
1.Farcy JP, Weidenbaum M, Glassman SD. Sagittal index in management of thoracolumbar burst fractures. Spine. 1990; Sep.15 1990;9: 958-65.
2.McLain, Sparling A., Benson D. Early failure of short segment pedicle instrumentation for thoracolumbar fractures. J Bone Joint Surg. 1993;75:162-167.
3. Gertzbein SD, Courtney Brown CM, Jacobs RR, et al. Decompression and circumferential stabilization of unstable spinal fractures. Spine. Aug.13 1988; 8:892-5.
4.Weidenbaum M, Farcy JP. Surgical management of thoracic and lumbar spine fractures. In: The Textbook of Spinal Surgery. Bridwell, KH; DeWald, RL. J.B. Lippincott Co. Philadelphia,PA;1991:911-957.
5.J.P. Farcy. Simultaneous anterior and posterior procedures for short segment spine pathology. Video tape 23112, American Academy of Orthopaedic Surgeons. 1993.

Unstable Fractures of the Lumbar Spine: Discussion
Roger Robert, MD
CHU Nantes, France

Case 1:
Faced with this burst and dislocated fracture, with no neurologic indications, we would carry out a reduction using CCD instrumentation with pedicle fixation at L1 and L3, infrapedicle hooks at L3, de Peretti hooks at L1, and a double DLT. As the fracture is dislocated, we would also make a posterolateral graft. As there are no neurologic indications we would not perform a laminectomy.

We congratulate Dr. Gillet on the quality of the reduction he obtained and on the strong construct which is still in place two years later. However, we would note that, in our experience, it is necessary to protect the screws by placing supra and infra-laminar hooks at each end of the construct, as recommended by Dr. Claude Argenson.

Case 2:
For this type of injury (i.e. a burst fracture at L3 with no neurologic complications) we make a short construct with pedicle fixation at L2 and L4, and protect the rods with infralaminar hooks at L2. A frame construct with two DLTs is necessary. We would not carry out a laminectomy if there are no neurologic indications, despite the extent of the posterior displacement. We would not use a graft, either, as a well-reduced fracture usually consolidates well with good osterosynthetic instrumentation.

Regarding the actual treatment, we note that the posterior approach with laminectomy largely contributed to the destabilization of the fractures. Ther fact that the igrate fragments were pushed intra-canal is not significant so long as there are no neurologic complications, although it is not a technique without danger. Ther posterior destabilization requires further anterior arthrodesis resulting in heavy management. We would have kept the anterior approach only for the very unlikely case of pseudoarthrosis.

We believe that the posterior displacement would correct itself over time even if not reduced, and that a correctly stabilized fracture not presenting neurologic complications initially is not likely to do so at a later stage.

References
1. Findley JM, Grace MG, Saboe LA, Davis LA. A survey of vertebral burst-fracture management in Canada. Can J Surg.;Aug. 1992;35(4):407-13.

2. DePeretti F, Cambas PM, Puch JM, Nasr ZG, Lovet J, Argenson C. Modular construction using CD universal instumentation for comminuted fractures of the thoracolumbar junction. Rev Chir Ortho Reparatrice Mot.1994;80(3):205-16.

Unstable Fractures of the Lumbar Spine:
Treatment and Follow-Up
Though very similar at presentation, the two cases were treated differently:

Case 1 was treated using our usual method of posterior approach, short segmental pedicle fixation (L1-L3) with our original CCD frame, (in which the DLT is bent and purchases against the spinous process to protect the implants from bending) and with in situ contouring of the rods allowing restoration of the sagiftal profile of the spine and canal decompression by ligamentotaxis, posterior bone fusion. An anatomic reduction was obtained (Fig 5) and whereas the comminution of the vertebral body was easily recognizable on the immediate postoperative plain films, there was no loss of correction at 2 years follow-up (Fig 6). The patient regained his normal lifestyle.

In the second case, a posterior approach was used to fix the instrumentation and realign the spine but because of the particular distribution of the bone fragments in the canal, it was suspected that ligamantotaxis would fail. After a left laminofacetectomy allowing a posterolateral approach of the spinal canal, the retropulsed bone fragments were driven back into the vertebral body with a bone pusher. The laminofacetectomy weakened the posterior column, and moreover, intraoperative films showed a large bone gap in the vertebral body (Fig 7). A secondary anterior strut grafting procedure was felt necessary to avoid late post-traumatic kyphosis (Fig 8).

Fig. 5

Fig. 6

Fig.7

Fig. 8

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Your Comments
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