Degenerative Disc Disease (DDD)

AxiaLIF (axial lumbar interbody fusion) is an access variation of the current standard of care fusion procedures. AxiaLIF is a proven anterior stabilization and interbody fusion technique via a retroperitoneal access. It is axial (caudal to cephalad) approach to the lumbar spine can potentially improve the biomechanical mechanism of fusion. With the addition of posterior fusion and instrumentation, a robust axial construct is placed which restores disc height, sagittal balance and lordosis with minimal muscle dissection, blood loss and postoperative pain. Furthermore, the axial access mitigates spinal nerve manipulation, injuries and simplifies endplate preparation for fusion by reducing the challenges associated with accessing a collapsed disc space.

When fusion and stabilization of the anterior spine is needed, an approach and construct that spares the annulus and supporting tissues may provide significant advantages over both traditional open approaches as well as other MIS techniques. AxiaLIF has safely been performed more than 6,500 times across the United States, in a variety of settings-including large academic medical centers, community hospitals, and on occasion, the outpatient setting. Positive, expedient, reproducible pain relief and consistent functional results continue to be reported in the literature have been achieved across practice settings.

To date, AxiaLIF is the most studied and validated MIS lumbar fusion technique available, with 17 peer reviewed original articles, scientific journal and textbook publications. This body of peer reviewed literature demonstrates that AxiaLIF provides comparable or improved fusion rates to other procedures with fewer iatrogenic complications, shorter hospital lengths of stay, and application to patient populations contra-indicated for other procedures. In addition, the literature also addresses key topic areas like anatomy, spinal access, biomechanics, functional outcomes, arthrodesis rates, complications for degenerative disc disease, instability and adult degenerative scoliosis that are positively impacted by the AxiaLIF procedure.

AxiaLIF is contraindicated in patients with previous bowel surgery, irritable bowel surgery, pelvic disease, or peri-rectal abscesses. AxiaLIF is also contraindicated in pregnancy and for those with severe spondylolisthesis (grades III or IV). An MRI to the tip of the coccyx should be performed prior to surgery to rule out any sacral abnormalities that would rule out safe access to the L5/S1 disc space.

Overall, the radiographically assessed fusion rate for AxiaLIF (via plain films or CT) is well aligned with conventional interbody fusion techniques, is superior to those performed with allograft bone dowels, and is equivalent to fusions enhanced with bone morphogenic proteins.^3,9-10 While fusion results for transforaminal lumbar interbody fusion (TLIF) with BMP demonstrated fusion rate of 92%, these procedures require the removal of surrounding ligamentous structures or the facet joint. As a result, implant migration and reduction in biomechanical stability are potential risks for TLIF.¹¹

Posterior implant migration is not a risk or complication of the AxiaLIF procedure since it does not disrupt the facet joint or remove surrounding ligamentous tissue that would allow for expulsion or migration to occur. The axial rod traverses the intervertebral space, resists sheer forces and is anchored in the superior and inferior vertebral bodies surrounding the disc space. This creates even greater resistance to migration and expulsion. When annular tissue is compromised for the surgical implantation of a conventional interbody fusion device, these procedures further destabilize the spinal segment. By maintaining these structures, the improved stability and immobility to the spinal segment allow for bone incorporation during the fusion process with reduced risk of excessive motion and instability during the healing process.¹²

Complications

Since 2005, more than 6,500 AxiaLIF procedures have been performed with a known complication rate of 1.08% (as reported to the FDA MDR database). The serious complication rate is .79% and the bowl complication rate is .59%. The overall complication rate (1.08%) includes costly complications such as post-operative infection, which is greatly reduced by AxiaLIF's minimally invasive access. (Company Data)

When compared to PLIF, the complication rate of AxiaLIF is superior. While PLIF provides for discectomy, interbody placement, direct decompression, and fixation through one incision, the associated complication rate is quite high. The most commonly reported complications include dural tears (7.6%), pedicle screw malposition (2.8%), increased leg pain (.8%), motor complications (6%), and permanent motor loss (1.6%).13 Another study reported an overall complication rate for PLIF of 9.1%.¹⁴

Anterior lumbar interbody fusion (ALIF) provides for the most optimally sized interbody device and does not require dissection of spinal muscles or the removal of facet joints; however its use is best limited to patients without prior abdominal surgeries. Furthermore, revisions can be extremely challenging with vascular complications exceeding 50%.¹⁵ Overall, the risk of vascular injury during ALIF is approximately 10% and the risk of retrograde ejaculation is in the range of 1.1%.¹⁶

TLIF also allows for direct decompression (on one side) and requires less retraction of the neural elements than PLIF to gain access to the disc space. However, access to the L5-S1 disc space is difficult in TLIF and there is significant risk of injury to nerve roots (27%).¹⁷ Additional complications include radiculopathy (4%),¹⁸ lower fusion rates than other interbody fusion techniques,¹⁸ and poorly prepared endplates.¹⁹

Lateral approaches are growing in popularity but little information is available regarding these procedures (extreme lateral and direct lateral interbody fusion). While these approaches avoid the spinal muscle dissection of posterior approaches, and reduce the risk of vascular injury, these approaches are not feasible at L5-S1 due to the iliac crest, and on occasion the L4-5 level is not accessible either due to iliac crest. The most common complications include post-operative paresthesias in the thigh and groin region²⁰ and in the neurapraxia in the psoas muscle at a rate of nearly 80%.²¹ Dural tears are still common with lateral approaches (7.6%) in primary procedures and as high as 15.9% in revision surgeries.²² L4-L5 provides the biggest challenge for the lateral approaches and a greater risk of transient or prolonged nerve involvement than any of the other levels accessible by these approaches.

Conclusion

AxiaLIF is a proven anterior stabilization and interbody fusion technique with a growing compendium of published outcomes data. The procedure is widely performed in a variety of settings with a consistently low complication rate. When compared to standard fusion procedures, AxiaLIF has fewer iatrogenic complications, results in less blood loss than other MIS procedures such as TLIF, reduces hospital stays, and has a lower risk of post-operative infection.

From a cost-perspective, AxiaLIF provides a lower cost interbody fusion with improved patient outcomes. Current standard of care fusion procedures have a documented reoperation rate of approximately 4% while AxiaLIF's reoperation rates are less than one percent. Futhermore, AxiaLIF patients report more rapid pain relief, including equal or superior fusion rates at 12 months with similar VAS and ODI scores respectively.

With more than 6,500 procedures performed over the last 3 years and a documented complication rate (including major complications) of approximately 1%, AxiaLIF has shown its safety across treatment settings. With more surgeons and patients requesting MIS options for treating a variety of conditions including adult degenerative scoliosis, spondylolisthesis, and degenerative disc disease, it is imperative that surgeons have access to the safest, most effective, and least costly procedures available. Furthermore, as the United States enters a period of unprecedented healthcare reform, AxiaLIF is well positioned with its established and growing compendium of evidence to be a leader in the treatment of lumbar disorders.

References

1. Pimenta L, Bellera F, Carl A, Ledet E, Cragg A: New Percutaneous Access Method and Implant for L4-S1 Spinal Fusion Surgery. Presented at AANS 2004, Session 118 New & Evolving MIS Techniques: Drs. Fessler, Pimenta, Smith & Isaacs,1-6 May 2004, Orlando.
2. Pimenta L, Guerrero L, Cragg A, Diaz R: Minimal Invasive Percutaneous Presacral Axial Lumbar Fusion (AxiaLIF). Prospective clinical and radiographic results after 30 months follow-up. Section on Disorders of the Spine and Peripheral Nerves, Congress of Neurosurgeons, Chicago, IL, October 7-12, 2006.
3. Aryan HE, Newman CB, Gold JJ, Acosta FL Jr, Coover C, Ames CP. Percutaneous Axial Lumbar Interbody Fusion (AxiaLIF) of the L5-S1 Segment: Initial Clinical and Radiographic Experience. J Spinal Disord Tech 2008 Aug, 51(4):225-30.
4. Bradley W, Roush T, Hisey M, Ohnmeiss D, Minimially Invasive Trans-sacral Approach to L5-S1 Interbody Fusion: Technique and Clinical Results, SAS Global Symposium on Motion Preservation Technology, (8th Annual Meeting), Miami, Florida 2008.
5. Tobler, W; Bohinski, R: Experience in 150 Cases with the TranS1 Minimally Invasive Fusion Technique at L5-S1. Global Symposium on Motion Preservation Technology 8th Annual Meeting from May 6-9, 2008, Miami, Florida.
6. Kuslich, SD et al. The Bagby and Kuslich Method of Lumbar Interbody Fusion: History, Techniques, and 2-Year Follow-up Results of a United States Prospective, Multicenter Trial. Spine 1998, 23(11):1267-1278.
7. Anand, N; Baron, E; Thayanithan, G; Khalsa, K; Goldstein, T. Minimally Invasive Multilevel Percutaneous Correction and Fusion for Adult Lumbar Degenerative Scoliosis, J Spinal Disord Tech 2008; 21:459-467.
8. Rodgers, WB, Cox CS, Gerber EJ. Single Level Lumbar Fusion For a Grade I and Grade II Spondylolisthesis Correction Using the Axial Rod System. Accepted for Presentation at Spine Arthroplasty Society, April/May 2009.
9. Burkus JK: Bone morphogenetic proteins in anterior lumbar interbody fusion: old techniques and new technologies. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004. J Neurosurg Spine 2004 1:254-260.
10. Burkus JK, Dorchak JD, Sanders DL: Radiographic assessment of interbody fusion using recombinant human bone morphogenetic protein type 2. Spine 2003 28:372-377.
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14. Park, JS, Kim, YB, Hong, Hyun J, Hwang, SN. Comparison between Posterior and Transforaminal Approaches for Lumbar Interbody Fusion. Journal of Korean Neurosurgical Society Volume 37, Issue 5, May 2005, pp.340-344.
15. Nyguyen, H, et al. Anterior exposure of the spine for removal of lumbar interbody devices and implants. Spine 2006;31:2449-2453.
16. Hynes, R., et al. Complications of the lumbar anterior surgical approach for artificial disc replacement of the lumbar spine. Spine 2005;5(4):S64-S65.
17. Eckman, W, McMillen, M, Hester, L. Incidence and Etiology of Transient Nerve Root Injury with Lumbar Transforaminal Surgery. Spine 2007 7(5);126S-127S.
18. Poh, S, et al. Clinical and Radiological Evaluation of Transforaminal Lumbar Interbody Fusion at 2 Years Follow-up. Spine 2007 IS-163S:25S.
19. Kuklo, T, et al. Transforaminal lumbar interbody fusion: unilateral versus bilateral disk removal-an in vivo study. Am J Orthop. 2003;32:344-348.
20. Bergey, Darren L, Villavicencio, A, Goldstein, T, Regan, J: Endoscopic Lateral Transpsoas Approach to the Lumbar Spine. Spine 2004 29(15); 1681-1688.
21. Bertagnoli R, The AnteroLateral transPsoatic Approach (ALPA): A New Technique for Implanting Prosthetic Disc-Nucleus Devices, J Spinal Disord Tech. 2003 Aug;16(4):398-404.
22. Khan, MH, Rihn, J, Steele, G, Davis, R, Donaldson, WF, Kang, JD, Lee, JY. MD: Postoperative Management Protocol for Incidental Dural Tears During Degenerative Lumbar Spine Surgery: A Review of 3,183 Consecutive Degenerative Lumbar Cases. Spine 2006; 31(22):2609-261.

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