- Department of Neurosurgery, Northwestern University, Chicago, IL, USA
- Division of Neurological Surgery, The Spine Clinic of Los Angeles at Good Samaritan Hospital, An Affiliate of the University of Southern California Medical Center, Los Angeles, CA, USA
Larry T. Khoo
Division of Neurological Surgery, The Spine Clinic of Los Angeles at Good Samaritan Hospital, An Affiliate of the University of Southern California Medical Center, Los Angeles, CA, USA
DOI:10.4103/2152-7806.90026Copyright: © 2011 Smith ZA. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Smith ZA, Armin S, Raphael D, Khoo LT. A minimally invasive technique for percutaneous lumbar facet augmentation: Technical description of a novel device. Surg Neurol Int 19-Nov-2011;2:165
How to cite this URL: Smith ZA, Armin S, Raphael D, Khoo LT. A minimally invasive technique for percutaneous lumbar facet augmentation: Technical description of a novel device. Surg Neurol Int 19-Nov-2011;2:165. Available from: http://sni.wpengine.com/surgicalint_articles/a-minimally-invasive-technique-for-percutaneous-lumbar-facet-augmentation-technical-description-of-a-novel-device/
Background:We describe a new posterior dynamic stabilizing system that can be used to augment the mechanics of the degenerating lumbar segment. The mechanism of this system differs from other previously described surgical techniques that have been designed to augment lumbar biomechanics. The implant and technique we describe is an extension-limiting one, and it is designed to support and cushion the facet complex. Furthermore, it is inserted through an entirely percutaneous technique. The purpose of this technical note is to demonstrate a novel posterior surgical approach for the treatment of lumbar degenerative.
Methods:This report describes a novel, percutaneously placed, posterior dynamic stabilization system as an alternative option to treat lumbar degenerative disk disease with and without lumbar spinal stenosis. The system does not require a midline soft-tissue dissection, nor subperiosteal dissection, and is a truly minimally invasive means for posterior augmentation of the functional facet complex. This system can be implanted as a stand-alone procedure or in conjunction with decompression procedures.
Results:One-year clinical results in nine individual patients, all treated for degenerative disease of the lower lumbar spine, are presented.
Conclusions:This novel technique allows for percutaneous posterior dynamic stabilization of the lumbar facet complex. The use of this procedure may allow a less invasive alternative to traditional approaches to the lumbar spine as well as an alternative to other newly developed posterior dynamic stabilization systems.
Keywords: Interspinous, minimally invasive, posterior dynamic stabilization
In this report, we describe the development and use of a novel, percutaneous posterior dynamic stabilization (PDS) system. We additionally present our initial 1-year clinical results with the use of this system. This device, PercuDyn (Interventional Spine, Inc., Irvine, CA), is delivered percutaneously through a paramedian Wiltse type approach where it is then applied bilaterally through the superior articular facets of the inferior body. This device is currently available for clinical use in both the United States and in foreign markets. Biomechanically, the device serves to augment the posterior elements and stiffen the functional segments. Here it acts as a mechanical stop beneath the inferior articulating facet of the segment. It works to limit extension and therefore prevent further compression of the central canal, spinal foramina, and the lateral recess space. Biomechnically, the device serves to augment the posterior elements and stiffen the functional segments as well. In this report, we provide a technical description of this percutaneous surgical technique, a brief notation of the device biomechanics, as well as the system's clinical application with our initial 1-year clinical results.
Following induction of general anesthesia or light anesthesia with sedation, the patient is positioned prone in a lordogenic position on a Jackson table or some other compatible radiolucent operative table. We have found that a Jackson table, with its relatively unencumbered area below the table platform, is ideal particularly when targeting the S1 pedicle since the gantry of the C-arm may require it to be positioned at a significant coronal angle with respect to the table. The bilateral paramedian incision sites are localized with anterior--posterior fluoroscopy with the image at the level to the top of pedicle where the device will be implanted. Two approximately 15-mm incisions are opened through skin and fascia, and an access needle is introduced and under fluoroscopy it is placed over the pedicle, ensuring that its tip is exactly positioned at the bottom of the facet [Figures
Graphics demonstrating the sequential operative procedure for the placement of access needle and K-wire. (a) Trajectory of access needle: anterior-posterior view. (b) Trajectory of access needle: lateral view. (c) The access needle is advanced through the pedicle. (d) The central obturator of the access needle was withdrew and replaced with a K-wire
Soft tissue dilatation, drill, tapping, and countersink shaving of the bone. (a) Soft tissue dilatation is achieved by introducing a teleport dilator. (b) Drilling of the bone through a K-wire. (c) Tapping of the bone through a K-wire. (d) Countersink shaving of the inferior portion of the facet and the pedicle
Diagrams showing final anatomy of the device following placement. As shown in (a) the stabilizers are placed inferior to the inferior articulating facets from the level above (*) and superior to the superior articulating facet from the level below (**). In parts (b) and (c), arrows demonstrate the forces that impact the stabilizer in biomechanical testing. The stabilizer serves to off-load the facet joints and decrease dorsal disk pressure. This increases foraminal area, especially in extension
Nine consecutive patients, aged 26--75 years of age (mean 49.3 years), including eight males and one female, were treated with the described device. All patients presented with symptomatic disease of the lower lumbar segments (one patient at L3/L4, two patients at L4/L5, and six patients at L5/S1). Operative patients had all failed previous attempts at conservative care. Patients were followed prospectively, with preoperative visual analog scale (VAS) and oswestry disability index (ODI) scores as well as 1-year follow-up pain and disability scores. No patient was lost to clinical follow-up.
Clinical 1-year outcome data are reported in
In this report, we describe a novel instrumentation system that can be surgically inserted in a truly minimally invasive fashion bilaterally through two paramedian muscle-splitting 15-mm incisions. Unlike other interspinous stabilization systems, which require a 4–5-cm midline incision and muscle dissection to expose the laminae and facet joints to ensure proper placement of implant, these stabilizers can be percutaneously alone or combined with other decompression procedures.[
It should be noted that the concept of semirigid stabilization has led the development of multiple systems to employ ‘dynamic stabilization’ of the lumbar segments. Many of these devices are meant to hold the degenerative segment in a semiflexed position. This flexion indirectly increases foraminal height and also improves the dimensions of the canal. One important limitation of the current device is that it does not hold the degenerative segment in flexion. Rather, the stabilizers are placed between the inferior articulating facets of the upper vertebral body and the superior articulating facets of the inferior vertebral body. This is done to ‘off-load’ the facet joints, thus acting as a ‘bumper’ that dissipates energy. This is particularly helpful in preserving foraminal height in extension.
While the exact indications for this device may change with further study, we believe that the ideal candidate is a patient who has had minimal response to conservative therapy and early signs of symptomatic lumbar degenerative disc disease. More exactly, this patient would have a borderline canal diameter and would be symptomatic primarily at the extremes of motion (particularly extension). In these patients, a larger surgery, such as transforaminal lumbar interbody fusion, may be avoided. However, patients with severe stenosis of the central canal or the neural foramen are not candidates for this surgery as only direct decompression will alleviate their symptoms. Of two patients with minimal change in VAS and ODI in our series, one had moderate to severe central stenosis. More traditional techniques of direct decompression via laminectomy or laminotomy are likely more appropriate for these individuals. Furthermore, patients with segmental instability, including those with pars defects or spondylolisthesis, are not candidates for this technique. These patients need more formal instrumented fusions to address their anatomical instability.
In addition, it should be noted that the current device can be easily used at L5/S1 as well as other lumbar segments. In fact, at L5/S1, the device may be easier to apply given the orientation of the facet joint at this level is almost perpendicular to the trajectory of device application. At the L4/L5 level and higher, the facet joints are oriented in a more parallel fashion, necessitating a more difficult trajectory angle. In addition, it should be noted that many interspinous stabilization devices cannot be used at L5/S1, given an often small or poorly developed S1 spinous process. Unlike these devices, the current system can be applied at the L5/S1 level.
Although there are many methods available in the treatment of degenerative disease of the lumbar spine, the development of new techniques adds only to the options available to the modern spine surgeon. In this report, we describe a novel, minimally invasive technique that may be appropriate as an alternative to traditional approaches lumbar stabilization as well as other emerging techniques in posterior dynamic stabilization. This technique is fully minimally invasive and the system's attributes have been demonstrated by both our initial biomechanical and clinical experience. Further long-term outcome studies will be needed to further understand the attributes of this surgical technique and the role of this technique in the modern management of symptomatic degenerative disease of the lumbar spine.
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