Decompression, Correction, and Interbody Fusion for Lumbar Burst Fractures Using a Single Posterior Approach

Abstract

Burst fractures of the lumbar spine with instability or severe kyphosis are best served by surgical treatment. The question as to how these fractures should be approached and stabilized (anteriorly, posteriorly, or combined anteroposteriorly) is controversial. We performed decompression, correction, and interbody fusion using a single posterior approach for Denis type B or C lumbar burst fractures with severe kyphosis. The operative technique is as follows: after partial laminectomy, the bone fragment, which had migrated into the spinal canal, is impacted into the posterior wall of the vertebral body. After curetting the injured disk, bone chips and adapted lamina are inserted into the disk space for anterior support. Five Denis type B or C burst fractures demanding >20° kyphosis correction were treated by this procedure. Mean follow-up was 41 months. We evaluated neurologic assessment and localized kyphotic angle.

The neurologic function of all 5 patients improved by at least 1 grade, as measured by the Frankel grading scale. Mean values of localized kyphosis improved from a mean 23.0· before surgery to -3.0° after surgery. At follow-up examination, average regional kyphosis was -2.4°. No implant failure was observed at follow-up. Bony fusion was achieved in all patients.

The advantages of this operative procedure are it is safe for the neural structures and complete spinal canal decompression and kyphosis correction are achieved, while providing anterior support and posterior stabilization.

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Although lumbar burst fractures are common, various therapeutic options are available in terms of conservative treatment and operative treatment. The advantages of surgical treatment for lumbar burst fractures include better correction of kyphotic deformity, greater initial stability, and an opportunity to perform direct decompression.¹ The question as to how these fractures should be approached and stabilized (anteriorly, posteriorly, or combined anteroposteriorly) is controversial. We performed decompression, correction, and interbody fusion using a single posterior approach for Denis type B or C lumbar burst fracture (Figure 1). The goal of this study was to examine the efficacy of the surgical procedure.

Figure 1: Schematic of decompression, correction, and interbody fusion by a single posterior approach.

Surgical Technique

The patient is placed prone over the Relton-Hall 4-poster frame. A straight vertical midline incision is made. The paraspinal muscles are dissected and pedicle screws are inserted 2 levels above and below the fractured vertebra. A partial laminectomy by en-bloc fashion is performed with a diamond burr (Figure 2A). Then, using a specially designed L-shaped impactor, the bone fragment, which had migrated into the spinal canal, is impacted into the posterior wall of the vertebral body (Figure 2B). The spine is transiently corrected and stabilized by placing a rod. After curetting the injured disk, bone chips are impacted into the anterior disk space. Then, en-bloc resected lamina is adapted to the height of the defect and inserted into the disk space for anterior support (Figures 2C, 2D). Finally, slight shortening is performed using instrumentation.

Figure 2: The lamina is resected by en-block fashion (A). Using a specially designed L-shaped impactor, the bone fragment, which had migrated into the spinal canal, is impacted into the posterior wall of the vertebral body (B). The lamina is grafted to the disk space (C). CT shows that bone chips and en-bloc resected lamina are impacted into the anterior disk space (D).

Patients and Methods

Five patients (2 men, 3 women; mean age, 34.6 years; age range, 13-63 years) with Denis type B or C lumbar burst fractures requiring >20° kyphosis correction were treated with decompression, correction, and interbody fusion using a single posterior approach. All of the patients had neurological deficit. Mean follow-up was 41 months (range, 24-92 months). Fracture levels were distributed, with 1 patient at L1, 3 at L2, and 1 at L3. Denis classification² was burst fracture type B in 4 patients and type C in 1.

We evaluated neurologic assessment and localized kyphotic angle. Neurologic assessment was made initially and at follow-up using the Frankel method.³ Localized kyphotic angle was measured using the Cobb method as measured from the superior endplate of the vertebra cephalad to the injured disk to the inferior endplate of the vertebra caudal to the injured disk (Figure 3). The preoperative, postoperative, and follow-up radiographs or computed tomography (CT) scans were evaluated.

Figure 3: Method of measuring radiographic data. Figure 4: Patient with a burst fracture at L2. Preoperative sagital CT scan (A). Postoperative radiograph (B). Radiograph at 3-year follow-up (C).

Results

The mean estimated intraoperative blood loss was 872 mL (range, 400-1160 mL). The mean operative time was 5.7 hours (range, 4.5-7.5 hours). Two patients had dural tears due to the fracture. It was possible to suture the dural tears in these 2 cases. No perioperative complications were observed.

Postoperative neurologic improvement occurred from Frankel grade C to D in 4 patients and from Frankel grade C to E in 1 patient. Mean values of localized kyphosis are given, with negative values implying lordosis and positive values denoting kyphosis. The angle representing the regional sagittal alignment improved from a mean value of 23.0· before surgery to -3.0· after surgery. At follow-up examination, the regional kyphosis was on average -2.4·. No implant failure was observed at follow-up. Bony fusion, shown by plain radiograph or CT at follow-up, was achieved in all patients.

Case Report

A 13-year-old girl had a burst fracture at L2 with severe kyphosis and a bone fragment in the spinal canal. Radiographic examination showed kyphotic deformity, and the kyphotic angle was 27°. Decompression, correction, and interbody fusion were performed using a single posterior approach. The patient had a dural tear due to the fracture. It was possible to suture the dural tear. Localized kyphosis improved to 3· after surgery. Postoperative neurologic improvement occurred from Frankel grade C to E. She had no problems in activities of daily living, and no correction loss or instrument failure was seen at 3-year follow-up (Figure 4).

Discussion

The goal of surgical treatment for lumbar burst fractures includes decompression of the neural elements to facilitate neurological recovery, correction of spinal deformity, fusion with rigid stabilization to prevent delayed neural injuries, and maintenance of anatomic alignment. However, the selection of the approach (anteriorly, posteriorly, or combined anteroposteriorly) for decompression and stabilization of lumbar burst fracture is controversial.¹

The anterior approach with corpectomy, structural bone graft, and a lateral plate or rod fixation has been used to directly reconstruct the weight-bearing anterior column. Long-term loss of correction of 1° to 4° after the anterior approach is reportedly less than that for the posterior approach.^4-6 However, the anterior approach has only at best been able to correct two-thirds of the kyphotic deformity in cases with severe kyphosis.^4-6 Because only 2 columns can be accessed (anterior and middle column) through the anterior approach, the ability to perform corrections is limited.⁷ Furthermore, the anterior approach enables direct access to posterior wall fragment(s). However, corpectomy performed within the 24 hours, or even the first few days after the accident, usually causes a great amount of blood loss.⁴

The posterior procedure is well established. The advantages include safe exploration of the surgical site without violating the pulmonary, visceral, and vascular structures. The posterior approach has the advantage of alignment correction. Pedicle screw-rod systems provide rigid segmental fixation along all 3 columns of the spine and allow a combination of forces (distraction, compression, or rotation) to be selectively applied to the spinal segments. Thus, pedicle screw fixation improves the ability to correct a spinal deformity.^7-9 The great advantage of the posterior approach is that it gives a clear view of the neural structures; this allows the removal of possibly dangerous structures around neural structures. Using the posterior approach, all processes, such as decompression, correction of alignment with instrumentation, and posterior stabilization, are performed safely under direct view. Furthermore, dural tears occur frequently in lumbar burst fractures with posterior element fractures.¹⁰ It is possible to suture a dural tear when using the posterior approach. Therefore, posterior short-segment fixation without anterior support is the most common and most simple treatment of burst fractures.¹¹

However, instrumentation failure and recurrence of kyphosis have been reported when surgery is performed without anterior support.^12-15 A 20% to 50% incidence of implant failure and a 7° to 9° loss in reduction of kyphosis have been reported.^12-15 The high rate of implant failure may be due to loss of anterior support. The injured disk and fractured vertebral body may easily collapse with short-segment instrument fixation.¹ Posteromedial or posterolateral fusion or transpedicular bone grafting have not been able to prevent the loss of kyphosis correction.^16-18 These facts suggest that it is important to not only stabilize posteriorly but also support anteriorly.

The method described here allows complete decompression and correction with both anterior support and posterior stabilization for Denis type B or C burst fracture. After partial laminectomy, the bone fragment which migrated into the spinal canal is impacted into the posterior wall of the vertebral body. As a result, circumferential decompression is achieved. Furthermore, by using resected lamina as an anterior strut bone graft, it is possible to achieve both anterior support and posterior stabilization with instrumentation. Finally, compression of the pedicle screw extension tips enables complete kyphosis correction. As a result, improvement of paralysis, appropriate alignment, minimum correction loss, and no perioperative complications were observed. Additionally, only 1 motion segment is fused when instrumentation is removed after bone fusion is completed.

The combined anteroposterior approach is able to correct kyphosis and reconstruct anterior support. However, combined surgery required a long total operative time and is associated with a great amount of intraoperative blood loss.¹⁹ Denis type A burst fracture with severe kyphosis should be treated by the combined anteroposterior approach for demanding kyphosis correction and long anterior support. However, our procedure enables kyphosis correction and reconstruction of anterior support for Denis type B and C burst fracture with shorter operating time and less amount of intraoperative blood loss than the combined anteroposterior approach. Furthermore, our procedure is free of complication associated with the anterior approach.

Conclusion

In the surgical treatment of Denis type B or C lumbar burst fractures, decompression, correction, and interbody fusion by a single posterior approach is a safe surgical treatment for the neural structures. The advantages of this operative procedure are it is safe for the neural structures and complete spinal canal decompression and kyphosis correction are achieved, while providing anterior support and posterior stabilization.

References

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Authors

Drs Sasagawa, Kawahara, Murakami, Demura, and Tomita are from the Department of Orthopedic Surgery, Kanazawa University, Kanazawa, Japan.

Drs Sasagawa, Kawahara, Murakami, Demura, and Tomita have no relevant financial relationships to disclose.

Correspondence should be addressed to: Takeshi Sasagawa, MD, Department of Orthopedic Surgery, Kanazawa University, 13-1 Takaramachi, Kanazawa, 920-8641, Japan.

doi: 10.3928/01477447-20090818-28