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Burst Fracture in a 79-Year-old Male: How would you treat?

Patient History

The patient is a 79-year-old man with a history of hypertension. From ground level, he fell off a curb. He presented one week after the fall with worsening mid back and left flank pain.

Examination

His exam revealed tenderness at the thoracolumbar junction, but no neurological deficits.

Prior Treatment

Despite NSAIDs and narcotic pain medications, his pain worsened.

Images

CT scans showed a L1 compression fracture with a retropulsed fragment causing 40% canal compromise (Figure 1, 2). Osteopenia and other chronic degenerative changes were noted.

Lateral CT scan, L1 burst fracture with retropulsed fragment
Figure 1

Axial CT scan, L1 burst fracture with retropulsed fragment
Figure 2

Diagnosis

The patient has a L1 burst fracture with osteopenia.

Suggest Treatment

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Selected Treatment

The patient underwent a left L1 laminotomy for nerve root compression with placement of pedicle screws above and below the fracture (T12 and L2). Ligamentum taxis then was applied by distracting the pedicle screws. Additional reduction of the fracture was carried out with a bone tamp. We then performed an open, left-sided transpedicular kyphoplasty. Final fusion was performed with placement of allograft and BMP posterlaterally from T12 to L2. (Figures 3, 4)

The procedure obtained modest reduction of the fracture and a good clinical outcome with significant reduction in pain. Even if the patient does not solidly fuse, the methyl methacrylate should provide reasonable stability of the body fracture.

Post-op posterior x-ray shows pedicle screw placement, kyphoplasty
Figure 3

Post-op lateral x-ray shows pedicle screw placement, kyphoplasty
Figure 4

Outcome

The patient's deep back pain was improved immediately post-op. He had the expected post-op pain, but by 6 weeks was no longer taking narcotic pain relievers.

Case Discussion

This case demonstrates an increasingly useful hybrid form of surgical stabilization of an osteoporotic burst fracture including both kyphoplasty and instrumented fusion.

The patient's injury pattern underscores the spectrum between high energy trauma to good quality bone and low energy trauma to poor quality bone. With this continuum in mind, a wide range of responses to these injuries is needed. Clearly, this is not a simple, superior endplate vertebral compression fracture. Nor, on the other hand, is this a markedly unstable fracture dislocation with an incomplete neurological deficit. In either of those cases, treatment options are relatively limited and more clearly defined.

In neurologically intact patients, most thoracolumbar burst fractures are best treated non-operatively. (1) In this patient, in particular, there is no contra-indication to a trial of non-operative management, with or without bracing.

In the clinical context of a fall from ground level, this relatively low energy mechanism implies significant osteoporosis. Recognizing the patient's bone loss has significant implications on the power of spinal instrumentation to achieve and maintain stability. On the other hand, the lower energy mechanism of injury tends to predict for a ligamentously stable spine. There is little risk of late neurologic decline.

Comorbidities
The patient's comorbidities may also affect the suitability of various treatment options. First, in many patients, body habitus or peripheral joint arthritis (in the shoulders or hips, for example), may render bracing very difficult or less effective. Second, older patients may be too medically frail for more aggressive operative techniques, such as anterior-posterior open stabilization.

Vertebral Body Augmentation / PMMA
Radiographic characteristics of the fracture may affect the appropriateness of the intermediate options. Vertebral body augmentation (e.g. vertebroplasty and kyphoplasty) procedures are typically utilized in older, osteoporotic patients with low energy injuries to the vertebral body. Reported outcomes for these procedures have been favorable and complication rates have been low. However, percutaneous injection of polymethylmethacrylate (PMMA) leakage confers a low, but serious risk of leakage with the possibility for iatrogenic neurologic injury. In particular, the risk of leakage increases in burst fractures. Any fracture with more than 50% height loss will have some bowing of the posterior cortex into the canal. In this patient however, a separate fracture fragment is seen. This may increase the risk of leakage further. That said, this patient may have done well with a vertebroplasty or kyphoplasty alone. Having performed a number of these procedures in an open manner in patients with fractures and symptomatic stenosis, I have found that the PMMA rarely leaks back into the canal. (2-5)

In osteoporotic patients in particular, there would be a higher risk of screw loosening and pull-out. The use of PMMA in a vertebral body fracture in conjunction with transpedicular instrumentation has been described as a means of improving anterior column stiffness to decrease the risk of fixation failure of the screws. (4-6) Interestingly, the worse the bone quality, the more effective PMMA becomes in restoring vertebral body strength and stiffness. PMMA confers little benefit in young patients with normal bone. These hybrid procedures are NOT indicated in younger patients with healthy bone. (7)

In osteoporotic patients, I would add PMMA to the screw tracts at the levels above and below the fracture. If the kyphoplasty system is used, a single bone void filler (1.5 cc) can be injected into the body on each side. This will markedly improve screw pull-out strength. Consider adding short screws to the fracture level. These screws create a 3-point bending force and may improve sagittal balance at the injured segment. (12)

Along the same lines, for short segment posterior instrumentation, monoaxial screws will have greater rigidity against the rods and allow more complete reduction and maintenance of that reduction. In this case, screw-based reduction has to be tempered by the osteoporosis. Excessive pre-loading of the screws will inevitably lead to screw loosening and construct failure. Burst fractures are unstable in torsion as well as flexion-extension. Adding a cross-link to this construct would improve torsional stiffness. (4, 13-14)

Short segment, transpedicular stabilization is one of the more common forms of operative stabilization for thoracolumbar burst fractures. Several series have shown significant loss of reduction after open reduction with internal fixation with short-segment posterior fixation due to the loss of the spine's anterior weight-bearing capacity.

While anterior procedures are more reliable in canal decompression in burst fractures, the osteoporosis that challenges other aspects of this patient's care makes decompression easier. Tamping the bone from the canal into the vertebral body is more effective in osteoporotic than in healthy bone burst fractures. In the latter circumstance, disc material within the fracture often works as a spring gradually pushing bone back into the canal.

Corpectomy
Anterior corpectomy procedures are similarly effective in restoring anterior load bearing. Unfortunately, anterior column instrumentation requires fixation into the cancellous bone which is typically affected earlier and more significantly than the cortical pedicles posteriorly. That is, anterior column instrumentation is not recommended in osteoporotic patients. Anterior corpectomy with pedicle screw fixation, or a front-back procedure is another option. In older patients, the morbidity of this, larger procedure may overwhelm its biomechanical benefits.

Timing
Having selected an appropriate treatment strategy, the next question is: when to offer surgery? Is there any down side to bracing the patient and offering surgery only if bracing fails? In the absence of neurologic deficits, is one week enough of a trial of non-operative management? In my practice, I often see "worsening" pain in patients attempting increased activity level. Adjusting pain level for a given activity level, the pain is really about the same. It usually takes 2 to 4 weeks for symptoms to abate.

Some authors state that waiting a couple of week's results in lower extravasation rates for PMMA in burst fractures. On the other hand, if operative fixation seems inevitable, it is better to do the surgery as soon as the patient has been medically cleared. The surgeon must consider the likelihood of successful healing.

Case Related Comments

Kummel's Cleft
This patient has a nitrogen cleft under the superior endplate. This so-called Kummel's cleft has been reported to represent AVN of the subcortical cancellous bone. While that concept is controversial, these radiographic phenomena are certainly more common in patients with secondary osteoporosis, such as those on steroids. They are less likely in pathologic fractures from metastatic disease or infection. These clefts also predict for a likely failure of medical management no matter how long the patient is observed or braced. Thus, a nitrogen cleft is one reason to offer earlier vertebral augmentation. (2, 8-11)

Role of Nonsteroidals
The author mentions use of nonsteroidals in this patient. There is some evidence to suggest that NSAIDs delay healing, increase pseudarthrosis rates, and are best avoided in the early post-fracture and post-fusion period. I am not sure I agree with the statement that a fusion is not needed here. While the fracture is likely adequately stabilized by the PMMA, the operative procedure has rendered the segment less stable. Failure of fusion will lead to screw loosening and, possibly, post-decompression deformity/spondylolisthesis. (15-16)

Summary
In older patients, the extent of any recommended surgery must be commensurate with nature of the patient's problem, functional limitations, and comorbidities. Development of a treatment strategy, the thought process should not be one of dichotomy (screws versus cement). Rather, a list of the patient's deficits/mechanical issues is generated. Each of the individual problems may require a different operative response. In this case: anterior column instability to axial loading, i.e. loss of weight bearing potential, leads to PMMA augmentation of the vertebral body (kyphoplasty in this case). Performance of a laminectomy in this case is controversial in the absence of neurologic compromise. After decompression, however, or in any patient with posterior ligamentous injury, a posterolateral fusion with transpedicular instrumentation is required. With an increasingly active and sizable elderly population, hybrid procedures such as this will become more frequently performed.

References:

1. Knight RQ, Stornelli DP, Chan DPK, et al. Comparison of Operative versus Nonoperative Treatment of Lumbar Burst Fractures. Clinical Orthopaedics & Related Research. 293:112-121, August 1993.

2. Peh, W.C., L.A. Gilula, and D.D. Peck, Percutaneous vertebroplasty for severe osteoporotic vertebral body compression fractures. Radiology, 2002. 223(1): p. 121-6.

3. Truumees, E., A. Hilibrand, and A.R. Vaccaro, Percutaneous vertebral augmentation. Spine J, 2004. 4(2): p. 218-29.

4. Verlaan, J.J., et al., Balloon vertebroplasty in combination with pedicle screw instrumentation: a novel technique to treat thoracic and lumbar burst fractures. Spine, 2005. 30(3): p. E73-9.

5. Singh, K., et al., Open Vertebral Cement Augmentation Combined With Lumbar Decompression for the Operative Management of Thoracolumbar Stenosis Secondary to Osteoporotic Burst Fractures. J Spinal Disord Tech, 2005. 18(5): p. 413-419.

6. Mermelstein, L.E., R.F. McLain, and S.A. Yerby, Reinforcement of thoracolumbar burst fractures with calcium phosphate cement. A biomechanical study. Spine, 1998. 23(6): p. 664-70; discussion 670-1.

7. Heini, P.F., et al., Augmentation of mechanical properties in osteoporotic vertebral bones--a biomechanical investigation of vertebroplasty efficacy with different bone cements. Eur Spine J, 2001. 10(2): p. 164-71.

8. Hasegawa, K., et al., Vertebral pseudarthrosis in the osteoporotic spine. Spine, 1998. 23(20): p. 2201-6.

9. Kim, D.Y., et al., Intravertebral vacuum phenomenon in osteoporotic compression fracture: report of 67 cases with quantitative evaluation of intravertebral instability. J Neurosurg, 2004. 100(1 Suppl Spine): p. 24-31.

10. McKiernan, F. and T. Faciszewski, Intravertebral clefts in osteoporotic vertebral compression fractures. Arthritis Rheum, 2003. 48(5): p. 1414-9.

11. Lane, J.I., et al., Intravertebral clefts opacified during vertebroplasty: pathogenesis, technical implications, and prognostic significance. Am J Neuroradiol, 2002. 23(10): p. 1642-6.

12. Mahar A, Kim C, Wedemeyer M, et al. Short-Segment Fixation of Lumbar Burst Fractures Using Pedicle Fixation at the Level of the Fracture. Spine. 32(14):1503-1507, June 15, 2007.

13. Slosar PJ, Patwardhan AG, Lorenz M, et al. Instability of the Lumbar Burst Fracture and Limitations of Transpedicular Instrumentation. Spine. 20(13):1452-1461, July 1995.

14. Benson DR, Burkus JK, Montesano PX, et al. Unstable Thoracolumbar and Lumbar Burst Fractures Treated with the AO Fixateur Interne. Journal of Spinal Disorders. 5(3):335-343, September 1992.

15. Burd TA, Hughes MS, Anglen JO. Heterotopic ossification prophylaxis with indomethacin increases the risk of long-bone nonunion. JBJS 85-B(5):700-705, July 2003.

16. Martin GJ, Boden SD, Titus L. Recombinant Human Bone Morphogenetic Protein-2 Overcomes the Inhibitory Effect of Ketorolac, a Nonsteroidal Anti-inflammatory Drug (NSAID), on Posterolateral Lumbar Intertransverse Process Spine Fusion. Spine. 24(21):2188, November 1, 1999.

Author's Response

Doctor Truumees provides a nicely documented rationale for the hybrid procedure performed. The discussion of Kummel's cleft is particularly insightful. I would disagree with the statement that most of these fractures are best treated non-operatively. There have been several papers including meta-analyses written since the Knight et al., 1993 paper that cite no superiority of conservative (non-operative) treatment over operative treatment. Regardless, this patient clearly failed non-operative management in terms of pain tolerance. His activity and ambulation were markedly hindered by progressive pain. In my practice, this impairment exposes him to far greater risks than a short operation and post-operative stay.

Regarding the procedure itself, certainly a number of techniques can be incorporated to increase strength of the construct. The addition of pedicle screws to the fracture level, addition of a crosslink and the use of PMMA to augment pedicle screw fixation are all worthy of consideration. Whether an ultra-rigid titanium construct is the best treatment for an osteoporotic fracture in patients with poor bone quality remains to be proven, especially in terms of stress shielding and load sharing.

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