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Clinical Information

Degenerative Disc Disease (DDD)

AxiaLIF

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 8,000 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

As of October 2009, more than 8000 AxiaLIF procedures have been performed with a complication rate of approximately 1%. The serious complication rate is .79% and the bowl complication rate is .59%. The overall complication rate (~1%) 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 region.²⁰ Dural tears are still common with lateral approaches (7.6%) in primary procedures and as high as 15.9% in revision surgeries.²¹ 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 8,000 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.
11. Salehi SA, Tawk R, Ganju A, et al: Transforaminal lumbar interbody fusion: surgical technique and results in 24 patients. Neurosurgery 2004 54:368-374.
12. Akesen B, Wu C, Mehbod AA, et al: Biomechanical Evaluation of Paracoccygeal Transsacral Fixation. J Spinal Disord Tech 2008 21:39-44.
13. Okuda S, Miyauchi A, Oda T, Haku T, Yamamoto T, Iwasaki M. Surgical complications of posterior lumbar interbody fusion with total facetectomy in 251 patients. J Neurosurg Spine 2006 4:304-309.
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. 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.

Publications

Clinical Information

Radiculopathy

Radiculopathy is not a condition, but rather a description of when one or more nerves are affected and are not functioning properly. AxiaLIF addresses radiculopathy via indirect decompression. This minimally invasive procedure often relieves patient radiculopathy immediately post-surgery with lower complication rates.

Radiculopathy is compression on the nerve root or nerve bundle can cause pain, weakness, numbness, or difficulty controlling specific muscles. This pain or another symptom, called referred pain, manifests in an extremity while the cause is near the nerve root. For example, nerve compression in lower back can cause numbness in the thigh. Polyradiculopathy results when there is more than one spinal root affected; this commonly causes multiple symptoms.

Causes of radiculopathy include an inflamed or pinched (compressed) nerve, or lack of blood flow causing the nerves to work ineffectively. The use of a straight leg raising test can assist in the diagnosis of lumbar or sacral nerve root radiculopathy. Both surgical and non-surgical treatment options are available. Non-surgical options may include physical therapy, medication, osteopathic manipulation, chiropractic manipulation and acupuncture. In the long run the cause of the radiculopathy is usually solved by a surgical option. A common surgical option involves direct decompression, wherein bone is removed to take pressure off of the exiting nerve root(s).

Instead of removing bone, the AxiaLIF procedure employs a dual pitch rod to push the L5 and S1 vertebral bodies apart. This opens the foramen - the "window" through which the nerve roots exit. By doing so, pressure is taken off the nerves and pain to the lower extremities can be relieved.

Surgeons have found that they are able to consistently relieve patient radiculopathy post AxiaLIF surgery. In addition, AxiaLIF provides additional benefits compared to traditional fusion, such as shorter hospital stays, small incision site, and lower complication rates.

Publications

Clinical Information

Spondylolisthesis

Literature indicates that fusion is the standard of care for spondylolisthesis. But which fusion method is most appropriate?

The surgical goals for Spondylolisthesis include:

• Realignment of the Spine
• Decompression of the Nerves
• Stabilization

AxiaLIF addresses all three of these goals. Realignment can be achieved via distraction, patient positioning and/or reduction with pedicle screws. Decompression is achieved via the AxiaLIF rod's dual-pitch threads, which provide indirect decompression via distraction. Finally, the AxiaLIF trans-sacral approach provides an interbody that is uniquely qualified to resist the shear force inherent in Spondylolisthesis. The axial orientation of the rod also offloads some of the force placed on the pedicle screws.

AxiaLIF allows surgeons to achieve these goals without retracting nerve roots. It also eliminates potential complications such as retrograde ejaculation and various vascular injuries. Finally, unlike the anterior and posterior approaches, it maintains the integrity of the soft tissues.

Clinical Information

Complex Spine

AxiaLIF is the least invasive solution for L4/5 - L5/S1 fusion and is an attractive option for anchoring the base of a long construct in both revision and extension applications.

AxiaLIF has the potential to address the shortcomings of current operative approaches to stabilizing long posterior fixations:

• Technique can be performed quickly with little blood loss.
• Posterior fixation and AxiaLIF interbody can be Implanted during the same operative setting.
• In case of revisions, original posterior fixation can be preserved.
• Fixation can be extended with patient in prone position
• AxiaLIF interbody eliminates the need for patient repositioning and draping

Publications

Clinical Information

Revision

Fusion revisions pose unique challenges to spine surgeons. Indications for revision include:

• Pseudoarthrosis
• Extension of long fusion
• Instrumentation failure

Depending on the access route chosen for the index operation, scarring can be particularly problematic. This challenge may be magnified if posterior instrumentation needs to be removed and/or replaced.

The pre-sacral access route utilized by AxiaLIF eliminates the threats of vascular and neurological damage that would accompany a revision using traditional access routes to the spine. In addition, the 3D Axial Rod provides immediate rigid fixation of the anterior column.

AxiaLIF also provides an attractive alternative to conventional techniques when an existing construct requires extension to an adjacent level. In the example below, a 52 y/o M with prior femoral ring and posterior instrumentation presented with symptomatic progression of degenerative disc at L5-S1. The solution in this case was an AxiaLIF 360 construct with facet screws posteriorly — the L4-L5 construct was left undisturbed.

Photos courtesy William D. Tobler MD, Mayfield Clinic and Spine Surgery Center, Cincinnati, OH

Clinical Information

Obesity

Obese patients pose unique challenges to today's surgeons. They typically suffer from a wide range of co-morbidities (diabetes, heart disease, hypertension, stroke, high blood cholesterol, etc.) and almost always require special planning in the OR setting (e.g. weight limit of the Wilson frame is 300 lbs.).

Traditional anterior and posterior approaches to the spine offer limited visibility of the surgical site, which can significantly delay surgery. Instruments must be long enough to reach the surgical site; once they are in place, their movement is hampered by the depth of the incision.

The AxiaLIF technique is distinguished from other approaches to spinal fusion in that it is virtually indifferent to patient weight. The pre-sacral route utilized to access the spine does not vary in length with increased weight — therefore, it requires no modification in either technique or instrumentation for the obese patient. In addition, the 3D Axial Rod provides immediate rigid fixation of the anterior column.

The AxiaLIF interbody creates indirect decompression of the neural foramen can be combined with minimal access pedicle screw techniques when direct neural decompression is needed.