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Artrodese Versus Estabilização Interespinhal Para Espondilolistese Lombar

Thomas Scioscia, MD; Corey Wallach, MD; Jeffrey C. Wang, MD


Nesta secção, dois especialistas defendem maneiras distintas de abordar a espondilolistese lombar degenerativa grau I. O método convencional de fusão é confrontado com um método mais novo e menos invasivo (a estabilização dinâmica interespinhal lombar). Veja a seguir as opiniões em relação a um caso de uma mulher de 66 anos com dor nos membros inferiores desencadeada pela marcha e dor lombar crônica moderada e que não tem tido sucesso com as medidas de tratamento conservador.
FONTE: SPINELINE January/February 2008

Case Presentation

A 66-year-old woman presents with a grade I L4-5 spondylolisthesis that moves slightly on flexion/extension radiographs. She has no medical problems and is very healthy. Her symptoms are classic for neurogenic claudication without significant low back pain. She has had some chronic but very tolerable low back pain for over 10 years. She can walk one block, but needs to stop because of leg pain and fatigue. She obtains significant relief of her symptoms with sitting or leaning forward.

What course of treatment would you recommend?

Thomas Scioscia, MD, Responds

There are multiple ways to treat a patient with degenerative spondylolisthesis and stenosis. We must first exhaust nonoperative management such as therapy, exercise and epidural steroid injections. If surgery is needed, I discuss with the patient all of his options including decompression, decompression and fusion, with or without an interbody device, and the most recent option of interspinous spacer devices. I then let the patient make an educated decision on the treatment he or she would like to pursue. Historically, decompression and fusion has been the treatment of choice for stenosis with instability. Recently, interspinous spacers have been developed to treat patients with stenosis symptoms that are relieved by sitting or leaning over. It has been well demonstrated that flexion decreases the amount of stenosis by distracting the soft tissues (ligamentum flavum, posterior annulus and facet capsule), therefore increasing the area of the spinal canal. A correctly placed interspinous spacer mimicks the flexed position at the implanted spinal segment. This usually relieves the neurogenic claudication which improves a patient’s function.  Currently, we have four-year follow-up supporting its efficacy and safety.1 Complications are less common, it can be done under local anesthesia and recovery time is minimal. I have little doubt that our patient would prefer undergoing implantation of an interspinous device rather than jumping to a fusion type of procedure. I personally would rather try the shorter procedure with minimal recovery time than the three-hour procedure with three to six months of recovery. Selection is paramount and fortunately for our patient, she fits the inclusion criteria for this less invasive treatment.

The evidence for an interspinous device in this case is overwhelming. First, she is the perfect candidate. The patient is a healthy 66-year-old with mild to moderate stenosis that produces neurogenic claudication which is fully relieved  by sitting. Her back pain remains insignificant and unchanged for years. Her disease is at L4-L5 only and her slip is relatively stable. Indications for interspinous technologies are exactly these; over 50, up to a stable grade I spondylolisthesis, mild to moderate stenosis, leg pain relief with sitting (classic claudication symptoms), and disease at one or two levels. A well placed interspinous device should alleviate her leg pain by placing the L4-L5 spinal segment in the flexed or sitting position while increasing central canal, lateral recess and foraminal area for the cauda equina and nerve roots.

There is little risk of infection, dural leak, iatrogenic nerve damage, radiculitis, nonunion, bone graft site pain, hardware failure, misplacement of hardware, need for transfusion, adjacent segment disease, peri-operative morbidity and mortality. Those of us who do fusions know these complications all too well. We must remember that our most important duty as physicians and surgeons is to do no harm. The placement of an interspinous device has minimal complications and is a completely revisable procedure. The larger fusion surgery can be done if the interspinous device fails to give the patient enough relief.

In addition, the spacers have proven to do what they are suppose to do biomechanically: decompress the stenotic segment and not affect adjacent levels. Richards showed in an MRI cadaver study that the canal area, subarticular diameter and foraminal area all substantially increased postimplantation (18%, 50% and 25% respectively).2 Siddiqui had similar findings in an in-vivo positional MRI study.3 Swanson showed that the implant favorably affected the disc by decreasing nucleus and posterior annulus pressure without affecting the anterior annulus or adjacent segment discs. Wiseman found that facets are also unloaded by the device decreasing the mean force by 67% with no affect at adjacent facets. Lindsey found the only motion that was substantially changed was extension, while not affecting adjacent segment kinematics. In summary, the prosthesis studied decreases stenosis in all areas of the spinal unit while decreasing facet and disc pressure without affect on adjacent levels.

Finally, it works, especially on the patient selected in this discussion. Zucherman, Hsu, Anderson and Kondrashov have shown good clinical outcomes with implantion of an interspinous device.4 Anderson showed that the subset of patients with spondylolisthesis had the most benefit from implantation compared to controls or other patient subsets. The recent study by Kondrashov studied patients at four-year follow-up observing 17 out of 18 patients had improved function and improvement in Oswestry Disability Index (ODI) scores.

Currently, interspinous technology is the fastest growing sub-market in the business of spinal implants. This technology is very successful on the patients who are appropriately selected. Fortunately for this patient, she is a great candidate for this technology. She should respond well to this intervention, with a substantial decrease in leg pain and improved everyday function. A fusion may not be needed in this patient and thus should not be the first line of surgical treatment. Interspinous spacer implanation versus fusion is comparable to a knee scope versus knee replacement for a painful knee. If the less invasive procedure has a good chance at helping, it should be the first line of treatment.

In summary, interspinous technology is not a cure-all. It is a step in the continuum of surgical treatment for  degenerative spinal disorders. Each day I see very happy patients who have avoided fusion and their lives have been substantially changed. I urge you to place it in your surgical armamentarium and use it when indicated. I also urge you not to overuse it for severe stenosis, herniated discs, back pain, radiculitis when sitting or trying to correct deformity. The technology will improve over time which may expand its indications. Because other indications have not been studied or approved, stick to the perfect indication, such as the patient in this discussion.


Kondrashov DG, Hannibal M, Hsu KY, Zucherman JF. Interspinous process decompression with the X-STOP device for lumbar spinal stenosis: a 4-year follow-up study. J Spinal Disord. 2006;19(5):323-327.

2. Richards JC, Majumdar S, Lindsey DP, Beaupre GS, Yerby SA. The treatment mechanism of an interspinous process implant for lumbar neurogenic intermittent claudication. Spine. 2005;30(7):744-749.

3. Siddiqui M, Karadinas E, Nicol M, et al. Effects of X-STOP device on sagittal lumbar spine kinematics in spinal stenosis. J Spinal Disord. 2006 July; 19(5) 328-333.

4. Zucherman JF, Hsu KY, Mehalic TF, et al. A multicenter, prospective, randomized trial evaluating the X STOP interspinous process decompression system for the treatment of neurogenic intermittent claudication: two-year follow-up results. Spine. 2005;30(12):1351-1358.

Corey Wallach, MD, Responds

The development and availability of interspinous spacers has gained significant enthusiasm within the spine community. However, like all new technologies, they are certainly not without limitations, and the appropriate use and indications for these devices remains to be clarified. Although the patient in the above scenario does describe symptoms of classic neurogenic claudication—symptoms that may be amenable to treatment with an interspinous device—I believe she would be better served by a traditional decompression and fusion.

A brief review of the clinical data leading to the FDA’s approval of the first interspinous process device available in the United States, the X STOP, may temper some of the swelling enthusiasm for their use. In the initial FDA analysis of clinical outcomes following implantation of the X STOP device, the overall success rate at two years was a mere 59%.1 Even more concerning was the fact that the clinical success rates at the testing site where the device was initially designed and the patents for the device were held, were significantly better than at the other sites involved in the study. Interestingly, when this site was removed from the initial analysis, the two-year clinical success rate dropped to a rather poor 33%.1 Although there are several reasonable explanations for this, such as the inventors’ familiarity with the device, their technical expertise with its use, etc, the disparity is concerning nonetheless.

Despite this rather underwhelming success in its FDA trial, recent studies have shown more significant and sustained improvements in patient outcomes with the X STOP’s use. Two– and four–year follow up studies2,3 have shown statistical improvement when compared to medical/interventional treatment, with patient satisfaction rates of 73% and clinical success in 78% respectively. Only one study specifically looked at the use of interspinous devices in patients with degenerative spondylolisthesis exclusively, and again, at two years, significant improvements were seen in those receiving the device, ie, 63% versus 13% for those undergoing conservative treatment.4

Anecdotal reports of improvement have been even higher. Patients are very pleased with the relative low risks  associated with the procedure, as well as with the rapid postoperative recovery period. Certainly, the potential for a same day surgical procedure to adequately address neurogenic claudication has appeal to patients and physicians alike. Additionally, the fact that we are not “burning any bridges” or limiting our future treatment options for patients with the use of interspinous process devices is frequently cited as a rationale to proceed with this “less invasive” approach, knowing that traditional surgical decompression and fusion will still be available as options if needed.

Lastly, one of the most significant advantages of using an interspinous device is its potential to be inserted with local
anesthetics and sedation alone, and not require a general anesthesia. This enables the benefits of indirect decompression and the documented expansion of the area within the spinal canal and neuroforamen5 to be available to patients who are not medically stable and who could not tolerate a standard decompressive procedure. Several patients with medical comorbidities, such as coronary artery disease and aortic stenosis, who would otherwise be high risk surgical candidates, are now able to have the potential benefits of this indirect decompression
and improvement in their neurological complaints.

However, the patient in this case is without such comorbidities, and would therefore, I believe, be better served by a traditional decompression and fusion.

The clinical improvement with surgical treatment of degenerative spondylolisthesis has been well touted, although there are relatively few studies clearly demonstrating significant clinical improvement when compared to conservative care.6 However, with the recent release of a large prospective randomized trial comparing surgical to nonoperative treatment of degenerative spondylolisthesis, its success has been reinforced.7 This study clearly demonstrated improvements in patients’ pain and function throughout the two-year study. Previous reports have also shown a clear advantage with decompression and fusion over decompression alone in patients with degenerative spondylolisthesis.8 Previous studies also show significant improvement in fusion rates in patients receiving fusions with posterior instrumentation, as opposed to those undergoing uninstrumented fusions.9-11 Surprisingly, data confirming improved clinical outcomes with instrumented fusions is still relatively sparse.10,12-14

Nonetheless, prior to the release of the interspinous spacer, the standard and accepted treatment for this patient would have been a decompression and fusion. However, even with the availability of the interspinous spacers, I believe the most compelling argument for surgical decompression and fusion pertains to a particular characteristic described in our case report, and one that was not addressed or discussed in any of the trials with the interspinous devices. The movement appreciated on flexion and extension films characterizes this patient’s pathology as unstable, and in my mind, one that is best addressed with traditional decompression and fusion. None of the studies describing the role of interspinous devices addressed instability, or movement within the intervertebral segment being “decompressed,” and as such, theoretical complications exist. Would the interspinous device limit the movement of the superior vertebral body, or would the movement put undue stress on the device? Could this movement increase the potential for failure, dislodgement or for spinous process fractures? In contrast however, the above cited studies in defense of decompression and fusion have shown improved clinical outcomes with solid arthrodesis.10,12,14

Lastly, though there is no clear indication in this scenario that her currently “tolerable” back pain is attributable to her spondylolisthesis and the movement appreciated on flexion and extension films, there is the potential for decompression and fusion to address this component of his complaint as well. Recent advances in surgical techniques and devices, such as interbody fusions and minimally invasive approaches, have also led to improved outcomes,15,16 more rapid recovery, and decreased complications,17 though certainly, prospective randomized trials are required to clarify and justify their use.

Obviously, the debate over preferred treatment in this scenario boils down to a discussion with one’s patient, a clear explanation of the risks and benefits of each of the above surgical options, as well as an explanation of the prognosis with continued conservative care, so that she is capable of making a well-informed decision. Though an interspinous device may provide adequate temporary relief of her symptoms of claudication, her documented instability and complaints of tolerable back pain suggest that she may ultimately be best served by decompression and fusion.


Food and Drug Administration: Summary Minutes: Meeting of the Orthopaedic and Rehabilitation Devices Advisory Panel. 2004: Gaithersburg, MD. Available at: Accessed: December 15th, 2007.

2. Zucherman JF, Hsu KY, Jartjen CA, et al. A multicenter, prospective, randomized trial evaluating the X STOP interspinous process decompression system for the treatment of neurogenic intermittent claudication: two-year follow-up results. Spine. 2005;30(12):1351-1358.

3. Kondrashov DG, Hannibal M, Hsu KY, Zucherman JF. Interspinous process decompression with the X-STOP device for lumbar spinal stenosis: a 4-year follow-up study. J Spinal Disord Tech. 2006;19(5):323-327.

4. Anderson PA, Tribus CB, Kitchel SH. Treatment of neurogenic claudication by interspinous decompression: application of the X STOP device in patients with lumbar degenerative spondylolisthesis. J Neurosurg Spine. 2007;4(6):463-471.

5. Siddiqui M, Karadimas E, Nicol M, Smith FW, Wardlaw D. Influence of X STOP on neural foramina and spinal canal area in spinal stenosis. Spine. 2006;31(25):2958-2962.

6. Bono CM, Lee CK. Critical analysis of trends in fusion for degenerative disc disease over the past 20 years: influence of technique on fusion rate and clinical outcome. Spine. 2004;29(4):455-463; discussion Z5.

7. Weinstein JN, Lurie JD, Tosteson TD, et al. Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis. N Engl J Med. 2007;356(22):2257-2270.

8. Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg Am. 1991;73(6):802-808.

9. Booth KC, Bridwell KH, Eisenberg BA, Baldus CR, Lenke LG. Minimum 5-year results of degenerative spondylolisthesis treated with decompression and instrumented posterior fusion. Spine. 1999;24(16):1721-1727.

10. Zdeblick TA. A prospective, randomized study of lumbar fusion. Preliminary results. Spine. 1993;18(8):983-991.

11. Bridwell KH, Sedgewick TA, O’Brien MF, Lenke LG, Baldus C. The role of fusion and instrumentation in the treatment of degenerative spondylolisthesis with spinal stenosis. J Spinal Disord. 1993;6(6):461-472.

12. Yuan HA, et al., A historical cohort study of pedicle screw fixation in thoracic, lumbar, and sacral spinal fusions. Spine. 1994;19(20 Suppl):2279S-2296S.

13. Nork SE, Hu SS, Workman KL, Glazer PA, Bradford DS. Patient outcomes after decompression and instrumented posterior spinal fusion for degenerative spondylolisthesis. Spine. 1999;24(6):561-569.

14. Fischgrund JS. The argument for instrumented decompressive posterolateral fusion for patients with degenerative spondylolisthesis and spinal stenosis. Spine. 2004;29(2):173-174.

15. Swan J, Hurwitz E, Malek F, et al. Surgical treatment for unstable low-grade isthmic spondylolisthesis in adults: a prospective controlled study of posterior instrumented fusion compared with combined anterior-posterior fusion. Spine J. 2006;6(6):606-614.

McAfee PC, DeVine JG, Chaput DC, et al. The indications for interbody fusion cages in the treatment of spondylolisthesis: analysis of 120 cases. Spine. 2005;30(6 Suppl):S60-65.

17. Hee HT, Castro FP Jr, Majd ME, Holt RT, Myers L. Anterior/posterior lumbar fusion versus transforaminal lumbar interbody fusion: analysis of complications and predictive factors. J Spinal Disord. 2001;14(6):533-540.

· T Scioscia: a-2, Sea Spine. c-2, Medtronic, Blackstone Medical.
· C Wallach: nothing to disclose.

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