Lateral Percutaneous Interspinous System for the Treatment of Lumbar Stenosis

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Chapter 34 Lateral Percutaneous Interspinous System for the Treatment of Lumbar Stenosis

Luiz M. Pimenta, MD, PhD, Carlos F. Arias, MD, Leonardo Oliveira, BSc

One of the main problems of degenerative spine disease is a narrowed spinal canal [1]. The pathologic progression begins with degenerative changes within the disc, which eventually lead to a loss of disc height. Resultant instability may worsen the spondylosis by inducing facet joint hypertrophy [2]. Furthermore, hypertrophy and buckling of the ligamentum flavum, particularly during extension, contribute to a reduction in the size of the thecal sac. This reduction limits the space available for the cauda equina, so the patient experiences symptoms of neurogenic claudication. The patient experiences relief in flexion [3].

Traditionally, spinal fusion has been the mainstay of surgical approaches for the management of low back pain or lumbar instability. Furthermore, there is some evidence that fusion may increase the biomechanical stresses imposed on the adjacent segments that could lead to transitional disease, which may occur earlier in patients with instrumented fusion [4].

Dynamic stabilization is a system that favorably alters the movement and load transmission of a spinal motion segment, without fusing the segment [5,6]. In other words, such a system would restrict motion in the direction or plane that produces pain, or painful motion, but would otherwise allow a full range of motion [7–10,12].

An interspinous distraction device was first described by Dr. Fred L. Knowles more than 50 years ago. Dr. Jacques Senegas was one of the first innovators in this area, and since his work [12], many new interspinous devices have been developed for ideal performance and clinical results [13–15].

Currently a variety of interspinous process implants are available [16] with different characteristics in material (allograft, polyetheretherketone [PEEK], titanium, elastomeric compounds, etc), kinematic features (static and dynamic), and surgical technique (open and percutaneous techniques) but share the goal of achieving some distraction between two vertebral bodies in order to accomplish the following goals:

image Augment the foramen size
image Unload both of the facet joints and intervertebral discs
image Reduce back pain
image Block painful extension movement
image Avoid narrowing of the spinal canal diameter

These devices help open the spinal canal diameter to relieve the patient’s neurogenic symptoms. However, upon insertion many interspinous devices require sacrifice of the integrity of the supraspinous ligament, paraspinous muscles, and fascia. These structures are important elements that maintain spinal stability, so their preservation inherently stabilizes the motion segment [7–11,17].

New technology now allows insertion of interspinous process implants via a minimally invasive lateral percutaneous approach that involves shortened surgery time, hospital stay, and rehabilitation and allows a faster return to daily activities. The RENEGADE interspinous implant (Globus Medical, Audubon, PA) is generally barbell shaped with a fluted conical insertion end to facilitate distraction and a central portion that rests on the spinous processes. The unique design allows for percutaneous insertion and simultaneous distraction of the interspinous space (Fig. 34-1).

image

Figure 34–1 RENEGADE interspinous implant (Globus Medical, Audubon, PA).

Indications

The basic indication for inserting a device between the lumbar spinous processes is mild or moderate intermittent neurogenic claudication from spinal stenosis, which is often relieved during flexion and worsened in extension. Other recommendations available in literature for these devices include the following:

image Low back pain resulting from mild to moderate degenerative disc disease (“discogenic pain”)
image Instability
image Herniated discs
image Fusion at an adjacent level
image Scoliosis

Contraindications

Insertion of a lumbar interspinous implant is contraindicated by the following conditions:

image Absence of or damage to the spinous process or interspinous space
image Severe osteoporosis, osteopenia, or other metabolic bone disease
image Tumors
image Active infections
image Allergies to implant materials

Advantages

Advantages of percutaneous interspinous process implantation over open implantation are as follows:

image A lateral percutaneous approach using a small far-lateral incision
image Preservation of the supraspinous ligament
image Preservation of the interspinous ligament in adjacent levels
image Preservation of the integrity of paraspinal muscles
image Unique interspinous device allowing a lateral approach at L5-S1
image Insertion technique allowing simultaneous distraction
image Achievement of a parallel relative position of the vertebral bodies, opening the intervertebral foramen
image Unloading of both facet joint articulations and intervertebral discs, thereby lowering the intradiscal pressure and reducing pain
image Avoidance of narrowing of the spinal canal in extension
image Placement safe for treatment of multilevel pathology
image Alternative for older patients with systemic disease in whom for long and invasive surgery is contraindicated
image Shorter surgical time and less blood loss
image Shorter hospitalization
image More rapid patient return to daily activities
image Ease of removal
image Preservation of anatomy to allow for future operations if necessary

Disadvantages

The disadvantages of an interspinous process implant are as follows:

image Implant interrupts the interspinous ligament at index level.
image Implant may decrease lumbar lordosis.
image Technique requires a short learning curve to achieve the best results.
image Its insertion in older and/or osteoporotic/osteopenic patients could cause intraoperative fracture of the spinous process.
image Implant could increase facet joint articulation at adjacent levels.

Surgical technique

The procedure for implantation of the RENEGADE lumbar interspinous device is as follows:

1. The patient’s written informed consent is obtained.
2. The patient is positioned prone and in flexion, such that the end plates are parallel to each other (Fig. 34-2A).
3. A 2- to 3-cm incision is made about 15 to 20 cm from the midline at the indicated level (Fig. 34-2B).
4. A small cannula is inserted into the lateral incision and is positioned on the interspinous ligament, between the superior and inferior spinous processes (Fig 34-2C and D).
5. A Kirschner wire is inserted into the cannula and advanced through the interspinous ligament (Fig. 34-2E and F).
6. The surrounding tissue is dilated with a series of larger cannulas (Fig. 34-2G to J).The largest cannula and the Kirschner wire are kept in place, and the remaining cannulas are removed (Fig. 34-2K).
7. A trial implant is then inserted over the Kirschner wire to size the interspinous space and determine the amount of distraction required at the index level (Fig. 34-3A and B).
8. The RENEGADE implant is inserted into the interspinous space over the Kirschner wire, and placement is checked with fluoroscopy (Fig. 34-3C).
9. Distraction occurs as the implant is advanced until the implant’s central recess lies in the interspinous space (Fig. 34-3D and E).
10. Once the implant is properly positioned and distraction is achieved, the implant holder, Kirschner wire, and cannula are removed (Fig. 34-3 F to H).
image

Figure 34–2 Surgical technique for implantation of a lumbar interspinous device: (A) Patient positioned prone and in flexion. (B) Small lateral incision. (C) Locating the 4-mm cannula between spinous processes. (D) Fluoroscopic AP view showing Kirschner wire inserted into cannula and located between spinous processes. (E) Intraoperative picture showing Kirschner wire inserted into cannula and located between spinous processes. (F) Kirschner wire with Mini Quick Connect Handle (RENEGADE implant set) inserted into cannula and located between the spinous processes. (G) The 9-mm cannula inserted over the 4-mm cannula. (H) The 14-mm radiolucent cannula inserted over the 9-mm cannula. (I) Internal cannula removed. Kirschner wire shown in place with radiolucent cannula. (J) All cannulas shown inserted in place. (K) Internal cannula removed. Wire shown in place with 24-mm radiolucent cannula.

image

Figure 34–3 Surgical technique for implantation of a lumbar interspinous device: (A) Trial implant in place within cannula. (B) To size for overall length, determine the correct groove on the trial implant while it is in place. The first distal groove on the trial implant indicates a 25-mm overall implant length. Each groove indicates another 5 mm of length. (C) Implant over Kirschner wire. (D) Implant at the interspinous space. (E) Implant inserted into the interspinous space. (F) Implant in place. (G) Cannula and Kirschner wire removed. (H) Incision after removal of cannula and Kirschner wire.

The technique allows insertion of the implant as far anterior as possible, to allow ideal distraction and a more stable motion segment.

Postoperative care

No special postoperative care is needed. Patients are encouraged to walk the same day as surgery and may be discharged within 24 hours. Analgesic drugs such as nonsteroidal anti-inflammatory drugs may be prescribed.

Clinical series

Methods

Patients diagnosed with lumbar foraminal and/or central canal stenosis with neurogenic claudication were included. Operative time, blood loss, and hospitalization time were recorded. Subjects were evaluated preoperatively and then postoperatively at 1 and 6 weeks, and 3, 6, and 12 months. Analysis consisted of clinical outcomes and radiologic assessment of disc and foraminal height through radiographic and computed tomographic evaluation by an independent radiologist. The following evaluation instruments were used: pain assessment by means of Visual Analog Scale responses and functional assessment by means of Oswestry Disability Index responses. The Short Form 36 Health Status Survey (SF-36) was also used to assess patients’ overall health.

Results

In this initial series, 14 patients (9 men, 5 women) with a median age of 69.6 years (range 48 to 82) and central stenosis with neurogenic claudication were enrolled. The operated levels were L2-L3, L3-L4, L4-L5, and L5-S1. Nine patients were treated at one level, and 5 patients at two levels, for a total of 19 levels treated. The mean surgical time was 34.3 minutes; mean blood loss was less than 50 mL. The mean hospital stay was 23.4 hours.

The mean follow-up time was 12 months. The posterior disc height increased by 38% after 12 months, whereas foraminal height increased by 27% during the same period. The mean preoperative Visual Analog Scale score was 8.8 with standard deviation (SD) 1.21; the mean score obtained 12 months after surgery was 2.2, with SD 1.29. The mean preoperative Oswestry Disability Index value was 57.8 with TD 11.59; the value had decreased to 18.7 with SD 12.12 at 12 months’ follow up. All improvements from preoperative to postoperative values were statistically significant (P ≤ 0.05).

Key Points

image The unique lateral percutaneous insertion method minimizes tissue disruption, reducing surgical time, blood loss, and hospital stay.
image Patient Visual Analog Scale and Oswestry Disability Index scores significantly improved after surgery.

Conclusion

The use of a lateral interspinous device is a safe and effective strategy for the treatment of neurologic claudication due to central stenosis. This novel percutaneous approach offers a less invasive surgical option, maintaining the supraspinous ligament and preserving the interspinous ligament at adjacent levels, with minimal management of the interspinous ligament at the index level. This procedure allows for short operative time, minimal blood loss, and reduced hospitalization time. The lateral interspinous device is an excellent option to maintain motion while improving disc and foraminal height and ultimately reducing the painful symptoms of lumbar stenosis. Careful and appropriate patient selection is essential to ensuring optimal outcomes.

CASE STUDY 34.1

A 76-year-old man presented with a history of progressive low back pain and bilateral neurogenic claudication. His symptoms were relieved on flexion. The decision was made to implant a lumbar interspinous device. Preoperative radiographic and magnetic resonance imaging evaluations are shown in Figure 34-4.

image

Figure 34–4 Case Study 34.1: Preoperative radiographs (top) and magnetic resonance images with computed tomographic images (bottom) from 76-year-old man with neurogenic claudication. (A) multiple degenerative spur changes in vertebral bodies on AP fluoroscopic view; (B) The arrows and lines demonstrate a loss of posterior intervertebral disc height on lateral view; (C and D) The dynamic x-ray view shows that the circle indicates narrowing of the L4 foramen in extension; (E) The sagittal MRI also shows that the circle indicates narrowing of the L4 foramen in extension; (F) The axial views show spinal canal stenosis; (G and H) The CT scan demonstrates degenerative facet joints which are hypertrophied. AP, anteroposterior; EXT, extension; FLEX, flexion.

The interspinous implant was positioned in the interspinous space at L4-L5. The patient experienced a significant reduction in pain immediately postoperatively. Increased posterior disc height was demonstrated at the 6-week follow-up evaluation (Fig. 34-5). The L4 neural foramen was opened in extension, similar to the neutral position (Fig. 34-6). Postoperative computed tomography showed the implant centrally placed at the base of the spinous process (Fig. 34-7). The vertebral end plates remained parallel in extension and flexion (Fig. 34-8), and the foraminal height was maintained.

image

Figure 34–5 Case Study 34.1: Radiographs obtained 6 weeks postoperatively. Left, Anteroposterior view shows central positioning of the device at L4-L5 (circle). Right, Lateral view demonstrate the implant lying at the base of the spinous processes (circle).

image

Figure 34–6 Case Study 34.1: Neutral and extension lateral radiographs obtained 6 weeks postoperatively show the L4 neural foramen opened in extension, similar to the neutral position.

image

Figure 34–7 Case Study 34.1: Postoperative computed tomography scans demonstrate central positioning at the base of the spinous process.

image

Figure 34–8 Case Study 34.1: Lateral radiographs show the device in neutral, flexion, and extension positions. Note that the vertebral end plates remain parallel in extension and flexion and that the foraminal height is maintained.

CASE STUDY 34.2

An 82-year-old woman presented with low back pain and weakness in both legs when walking a distance of 100 meters. Her symptoms decreased in flexion. Preoperative radiographs and computed tomography scans are shown in Figure 34-9. Interspinous implants were placed at L3-L4 and L4-L5. The patient’s claudication symptoms resolved postoperatively. Radiographs demonstrated opening of the foramen (Fig. 34-10). Postoperative computed tomography scans showed correct device positioning, which allowed an increase in spinal canal diameter (Fig. 34-11). Three-dimensional computed tomography scans also showed correct device positioning, widened foraminal openings, and the preserved supraspinous ligament (Fig. 34-12).

image

Figure 34–9 Case Study 34.2: Preoperative radiographs (top) and computed tomography scans (bottom) from an 82-year-old woman show foraminal and central stenosis. Her symptoms improved upon flexion.

image

Figure 34–10 Case Study 34.2: Postoperative radiographs. Proper position of implants on fluoroscopic AP view (A) and lateral views (B, C and D), A zoomed-in view of the open foramen (E, right upper). The patient’s claudication symptoms have resolved.

image

Figure 34–11 Case Study 34.2: Postoperative computed tomography scans show correct positioning of the device, allowing an increase in spinal canal diameter on sagittal (left) and axial view (right).

image

Figure 34–12 Case Study 34.2: Postoperative three-dimensional computed tomography scans demonstrate correct positioning and widening of the foramen on AP (left) and lateral view (right). These views also highlights the preserved supraspinous ligament. Red circle, implants.

References

1 Zucherman J.F., Hsu K.Y., Hartjen C.A., Mehalic T.F., Implicito D.A., Martin M.J., 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 (Phila Pa 1976. 2005;30(12):1351-1358.

2 Fuchs P.D., Lindsey D.P., Hsu K.Y., Zucherman JF., Yerby SA. The use of an interspinous implant in conjunction with a graded facetectomy procedure. Spine. 2005;30:1266-1272.

3 Lee J., Hida K., Seki T., Iwasaki Y., Minoru A. An interspinous process distractor (X STOP) for lumbar spinal stenosis in elderly patients: preliminary experiences in 10 consecutive cases. J Spinal Disord Tech. 2004;17:72-77.

4 Swanson K.E., Lindsey D.P., Hsu K.Y., Zucherman J.F., Yerby S.A. The effects of an interspinous implant on intervertebral disc pressures. Spine. 2003;28:26-32.

5 Wiseman C.M., Lindsey D.P., Fredrick A.D., Yerby S.A. The effect of an interspinous process implant on facet loading during extension. Spine. 2005;30:903-907.

6 Lindsey D.P., Swanson K.E., Fuchs P., Hsu K.Y., Zucherman J.F., Yerby S.A. The effects of an interspinous implant on the kinematics of the instrumented and adjacent levels in the lumbar spine. Spine. 2003;28:2192-2197.

7 Richards J.C., Majumdar S., Lindsey D.P., Beaupré G.S., Yerby S.A. The treatment mechanism of an interspinous process implant for lumbar neurogenic intermittent claudication. Spine. 2005;30:744-749.

8 Neumann P., Wang Y., Kärrholm J., Malchau H., Nordwall A. Determination of inter-spinous process distance in the lumbar spine. Evaluation of reference population to facilitate detection of severe trauma. Eur Spine J. 1999;8:272-278.

9 Dickey J.P., Bednar D.A., Dumas G.A. New insight into the mechanics of the lumbar interspinous ligament. Spine. 1996;23:2720-2727.

10 Shepherd D.E., Leahy J.C., Mathias K.J., Wilkinson S.J., Hukins D.W. Spinous process strength. Spine. 2000;25:319-323.

11 Kroeber M., Unglaub F., Guehring T., Nerlich A., Hadi T., Lotz J., et al. Effects of controlled dynamic disc distraction on degenerated intervertebral discs: an in vivo study on the rabbit lumbar spine model. Spine. 2005;30:181-187.

12 Senegas J., Etchevers J.P., Vital J.M., Baulny D., Grenier F. Recalibration of the lumbar canal, an alternative to laminectomy in the treatment of lumbar canal stenosis. Rev Chir Orthop Reparatrice Appar Mot. 1988;74(1):15-22.

13 Anderson P.A., Tribus C.B., Kitchel S.H. Treatment of neurogenic claudication by interspinous decompression: application of the X STOP device in patients with lumbar degenerative spondylolisthesis. J Neurosurg Spine. 2006;4(6):463-471.

14 Guizzardi G., Petrini P., Fabrizi A.P., et al. The use of DIAM (interspinous stress-breaker device) in the DDD: Italian multicenter clinical experience. New York, New York: Spinal Arthroplasty Society, 2005.

15 Bono C.M., Vaccaro A.R. Interspinous process devices in the lumbar spine. J Spinal Disord Tech. 2007;20:255-261.

16 Christie S.D., Song J.K., Fessler R.G. Dynamic interspinous process technology. Spine. 2005;30:S73-S78.

17 Guehring T., Unglaub F., Lorenz H., Omlor G., Wilke H.J., Kroeber M.W. Intradiscal pressure measurements in normal discs, compressed discs and compressed discs treated with axial posterior disc distraction: An experimental study on the rabbit lumbar spine model. Eur Spine J. 2006;15:597-604.

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