BlueCross and BlueShield of Montana Medical Policy/Codes
Interspinous Distraction Devices (Spacers)
Chapter: Surgery: Procedures
Current Effective Date: August 01, 2012
Original Effective Date: May 01, 2007
Publish Date: May 03, 2012
Revised Dates: March 1, 2010, March 26, 2012

Interspinous spacers are small devices implanted between the vertebral spinous processes. After implantation, the device is opened or expanded to distract (open) the neural foramen and decompress the nerves.

Interspinous spacers are devices implanted between vertebral spinous processes. These interspinous implants aim to restrict painful motion while otherwise enabling normal motion. The devices (spacers) distract the spinous processes and restrict extension. This procedure theoretically enlarges the neural foramen and decompresses the cauda equina in patients with spinal stenosis and neurogenic claudication. Other types of dynamic posterior stabilization devices are pedicle screw/rod-based devices and total facet replacement systems; these are not covered in this policy.

The interspinous implant is inserted between the spinous processes through a small (4–8 cm) incision and acts as a spacer between the spinous processes, maintaining the flexion of that spinal interspace. The supraspinous ligament is maintained and assists in holding the implant in place. The surgery does not include any laminotomy, laminectomy, or foraminotomy at the time of insertion, thus reducing the risk of epidural scarring and cerebrospinal fluid leakage.

Regulatory Status

In November 2005, the X-STOP® Interspinous Process Decompression (IPD®) System (Kyphon-now part of Medtronic Spine LLC) was approved by the U.S. Food and Drug Administration (FDA) for “treatment of patients aged 50 or older suffering from neurogenic intermittent claudication secondary to a confirmed diagnosis of lumbar spinal stenosis.” It is approved for patients with moderately impaired physical function who have had a regimen of at least 6 months of non-operative treatment and who have relief of their pain when in flexion. The device is approved for implantation at 1 or 2 lumbar levels in patients whose condition warrants surgery at no more than 2 levels. The X-STOP PEEK (polyetheretherketone) received approval in 2006 and is a modified version of the X-STOP that includes a PEEK spacer and additional 16-mm spacer size. The indications are the same as for the X-STOP titanium model.

The FDA lists the following contraindications to use of the X-STOP:

  • an allergy to titanium or titanium alloy;
  • spinal anatomy or disease that would prevent implantation of the device or cause the device to be unstable in situ, such as:
    • significant instability of the lumbar spine, e.g., isthmic spondylolisthesis or degenerative spondylolisthesis greater than grade 1.0 (on a scale of I to 4);
    • an ankylosed segment at the affected level(s);
    • acute fracture of the spinous process or pars interarticularis;
    • significant scoliosis (Cobb angle greater than 25 degrees);
  • cauda equina syndrome defined as neural compression causing neurogenic bowel or bladder dysfunction;
  • diagnosis of severe osteoporosis, defined as bone mineral density (from DEXA scan or some comparable study) in the spine or hip that is more than 2.5 [standard deviations] SD below the mean of adult normals in the presence of one or more fragility fractures;
  • active systemic infection or infection localized to the site of implantation.

The Wallis System (originally from Abbott Spine; currently from Zimmer Spine) was introduced in Europe in 1986. The first generation Wallis implant was a titanium block; the second generation device is composed of a plastic-like polymer that is inserted between adjacent processes and held in place with a flat cord that is wrapped around the upper and lower spinous processes. The Wallis System is currently being tested in a FDA-regulated clinical trial. Also in a FDA-regulated clinical trial is the DIAM Spinal Stabilization System (Medtronic Sofamor Danek), which is a soft interspinous spacer with a silicone core. The DIAM system requires removal of the interspinous ligament and is secured with laces around the upper and lower spinous processes. Other clinical trials underway at U.S. centers are studying the In-Space (Synthes), Superion (Vertiflex), and FLEXUS (Globus Medical) devices; the comparator in these trials is the X-STOP device.

The Coflex implant (Paradigm Spine) is used in Europe but is not currently FDA approved. ExtendSure and CoRoent (both from NuVasive) were launched in Europe in 2005 and 2006. The NL-Prow (Non-Linear Technologies), Aperius (Medtronic Spine) and Falena (Mikai) devices are in trials in Europe.



Blue Cross Blue Shield of Montana (BCBSMT) considers interspinous distraction devices investigational as a treatment of neurogenic intermittent claudication.

Federal Mandate

Federal mandate prohibits denial of any drug, device, or biological product fully approved by the FDA as investigational for the Federal Employee Program (FEP). In these instances coverage of these FDA-approved technologies are reviewed on the basis of medical necessity alone. Call the BCBSMT FEP Customer Service Department at 1-800-634-3569 for benefit information.

Policy Guidelines

Effective January 1, 2007, there are specific CPT category III codes for this procedure:

  • 0171T
  • 0172T

Effective January 1, 2007, there is also a HCPCS “C” Medicare pass-through code for the device:

C1821 Interspinous process distraction device (implantable)

Prior to 2007, the procedure should have been coded using CPT code 22899 (unlisted procedure, spine).


This policy was originally created in 2006 and was updated regularly with searches of the MEDLINE database. The most recent literature search was performed for the period of January 2011 through September 2011. MEDLINE searches have found the literature to be dominated by reports from non-U.S. centers of devices that have not received FDA approval, though a number of them are in trials at U.S. centers. As of September 2011, only the X-STOP device has FDA approval for use in the U.S., and this policy does not address other devices. Following is a summary of the key literature to date.

In 2009, Chou and colleagues presented a review of evidence related to surgical treatments for low back pain for the American Pain Society. (1) They concluded, on the basis of the randomized trial data described below, (2) that the evidence was fair quality and that an interspinous spacer device is superior to nonsurgical therapy for 1- or 2-level spinal stenosis with symptoms relieved with forward flexion but that insufficient evidence exists to judge long-term benefits or harms. Of note, the reviewers considered the Zucherman et al. (2) and Anderson et al. (3) reports as 2 separate studies, while this analysis considers the Anderson et al. to be a subset of the Zucherman et al. study. No trial had compared an interspinous spacer device to standard decompressive surgery.

Kabir et al., in a 2010 systematic review, observed that apart from the 2 randomized controlled trials (RCTs), other studies with X-STOP were not of high methodologic quality. (4) The authors observed that results at 2 years were analyzed using only the Zurich Claudication Questionnaire (ZCQ), while analysis of 1-year results also included the Short-Form 36 (SF-36). They also noted concerns about the trial raised by the FDA: First, the block randomization employed could potentially be used to select patients more likely to respond to the intervention. Second, outcomes in both groups were worse than expected, suggesting that power calculations were invalid. Third, results from one center were clearly superior to those of other centers. Four-year follow-up included only 18 of the original 100 patients, and Oswestry Disability Index (ODI) scores were reported instead of ZCQ scores. Studies of the other devices (DIAM, Coflex, Wallis, DIAM) included in the review showed satisfactory outcomes to varying degrees; however, it was stated that “due to small numbers and poor design of studies, it is difficult to clearly define indications for their use in lumbar degenerative disease”. The authors concluded that X-STOP may improve outcomes compared to nonoperative treatment in a select group of patients 50 years of age or older with radiologically confirmed lumbar canal stenosis and neurogenic claudication who have improvement of symptoms on flexion; however, they suggest that further good quality trials are required to clearly identify indications for the use of the devices.

Controlled Trials

Multiple reports have been published from the single prospective randomized trial, conducted for FDA approval, for the X-STOP device.

Using the entire study population of 191 patients in this multicenter trial, Zucherman et al. reported an improvement of 45% over the mean baseline Symptom Severity Score in the treated patients at 2 years compared with 7% improvement in the control group, which had medical (nonoperative) therapy including epidural injection. (2) In a separate paper, Anderson and colleagues, reporting on a subset of 75 randomized patients who had spondylolisthesis (out of the total group of 191 patients with 1- or 2-level lumbar spinal stenosis), found a success rate of 63% in treated patients compared with 13% in controls. (3) Four-year follow-up was reported for 18 of the treated patients in the study. (5) Hsu et al. reported quality-of-life data (SF-36) from the same trial. (6) The patients, who had to meet a number of inclusion/exclusion criteria, were assessed at baseline and at 6 weeks, 6 months, 1 year, and 2 years following the initial treatment. The X-STOP group showed improvements (by single-factor ANOVA or t-test) in both physical and mental component scores compared to both baseline and control subjects. There was a large loss to follow-up (42%) in the medical-treatment group; 6% of the experimental and 26% of the control subjects underwent laminectomy.

Uncontrolled Series

Several large case series of patients implanted with X-STOP devices have been reported.

A series of 175 patients were treated at a German center between February 2003 and June 2007. (7) Mean visual analog scale (VAS) score was reduced from 61.2 to 39 on a 100-point scale at 6 weeks postoperatively and maintained to the 2-year evaluation. Mean ODI scores were 32.6 (range 8-80, SD: 16.0) preoperatively, 22.7 (range 0-85, SD: 15.6) at 6 weeks postoperatively, and 20.3 (range 0-42, SD: 17.5) at 2 years. No complications were associated with use of the device. Eight patients required removal of the device and microsurgical decompression because of unsatisfactory outcome.

In a 2010 paper, Rolfe and colleagues evaluated outcomes of a series of 179 patients with and without scoliosis in order to test a contraindication which limits X-STOP use to patients with a maximum scoliosis of 25 degrees. (8) Patients, who received the device between January 2006 and May 2007, were divided into 3 groups: Group 1 without scoliosis (controls, n=116), Group 2 patients with low scoliosis (11-25 degrees, n=41), and group 3 (high scoliosis, n=22). At 1 year, 56% of Group 1 and Group 2 patients, but only 18% of Group 3 patients, achieved improvement of 15 or more points on ODI. Satisfaction rates were 76% for Group 1, 78% for Group 2, and 59% for Group 3. On average, all 3 groups improved for each outcome: Group 1 (ODI 17.3, VAS 2.0, standing time 39 minutes, and walking time 43 minutes), Group 2 (ODI 20.0, VAS 1.9, standing time 65 minutes, and walking time 64 minutes), Group 3 (ODI 7.2, VAS 0.9, standing time 18 minutes, and walking time 16 minutes). The authors conclude that surgeons and patients must be aware that overall lumbar scoliosis greater than 25 degrees may portend less favorable outcomes

Brussee et al. reviewed pre- and postoperative ZCQ and SF-36 questionnaires completed by 65 patients who received the X-STOP device between 2003 and 2006. (9) A good outcome was achieved by 31% of patients. Good outcome was not related to body-mass index (BMI) or number of implanted devices but was related to the absence of orthopedic co-morbidity or male gender. The authors concluded that X-STOP does improve the clinical situation; however, a good outcome is achieved less often than previously reported.

Siddiqui and colleagues conducted a prospective observational study of 40 of 45 consecutive patients implanted with the X-STOP device. (10) Patients were evaluated at 3, 6, and 12 months using the ZCQ, ODI, and SF-36. Only 24 patients (60%) completed all questionnaires and were analyzed. By 12 months, clinically significant improvement in symptoms and physical function was noted by 54% and 33% of the 24 patients, respectively. Postoperatively, 29% of patients required caudal epidural after 12 months for recurrence of symptoms of neurogenic claudication. The authors concluded that while the device offers significant short-term improvement over a 1-year period, results are less favorable than those reported in the multicenter randomized trial.

A 2011 study assessed implant survival in a retrospective analysis of 46 consecutive patients (61 devices) with a minimum follow-up of 24 months. (11) Inclusion criteria were the same as in the pivotal randomized trial by Zucherman et al. (2) At a mean follow-up of 34 months (range, 24-70 months), 14 patients (30.4%) had undergone revision surgery to remove the implant. Most revisions occurred within the first 12 months. Revisions were due to lack of improvement (n=6), worsening of low back pain (n=1), recurrence of symptoms after initial good outcome (n=4), implant dislocation (n=2), and fracture of a spinous process (n=1). Two additional patients were lost to follow-up, and one patient was unhappy with the result and did not complete the questionnaires. Kaplan-Meier analysis predicted an implant survival of 34% at 53 months. The mean time until implant removal was 15.4 months. In the remaining 29 patients who did not undergo revision surgery, clinical outcomes improved significantly. VAS for lumbar pain decreased from 4.8 to 3.2 and VAS for leg pain decreased from 5.4 to 2.0. The ODI improved from 39.9 to 24.7 and the SF-36 physical component score improved from 30.2 to 38.4. The overall clinical success rate was 36%, defined as an improvement of the ODI by at least 15 points or a patient’s satisfaction rating of “very satisfied”. The authors concluded that clinical outcomes after X-STOP implantation might be considerably less favorable than what has been previously published and that further research is needed to improve patient selection.

Adverse Events

A number of papers focus on complications with the X-STOP device.

Barbagallo et al. analyzed complications in a series of 69 patients and proposed an anatomic scoring system for patient selection. (12) At a mean follow-up of 23 months, 8 complications (11.5%) were recorded: 4 device dislocations and 4 spinous process fractures.

Bowers et al. reviewed records of 13 patients implanted with the X-STOP device at one U.S. center. (13) Nine patients had severe and 4 had moderate stenosis. Average follow-up was 42.9 months (range, 3-48 months). Initially, pain improved an average of 72%; however, preoperative pain returned in 77% of the patients. The overall complication rate was 38%, including 3 spinous process fractures and 2 instances of new onset radiculopathy. Eleven of the 13 patients required additional spinal surgery.

A prospective observational study found a high rate of spinous process fractures in 38 patients (50 implants, 97.4% follow-up) after implantation of the X-STOP titanium (n=34), X-STOP PEEK (n = 8), or Aspen (n=8) devices. (14) Although no fracture was identifiable on plain radiographs, postoperative computed tomography (CT) identified nondisplaced spinous process factures in 11 patients (28.9% of patients, 22% of levels). Direct interview of patients and review of medical records indicated that 5 fractures were associated with mild to moderate lumbar back pain, and 6 fractures were asymptomatic. Three of the 11 patients underwent device removal and laminectomy for persistent pain. Fractures in 3 other patients had healed by 1 year.

Verhoof et al. reported that, in a cohort of 12 consecutive patients with symptomatic lumbar spinal stenosis caused by degenerative spondylolisthesis who were treated with X-STOP and followed up for a mean of 30.3 months, 8 patients had complete relief of symptoms postoperatively while 4 had no relief. (15) Recurrence of pain, neurogenic claudication, and worsening of neurologic symptoms were observed in 3 patients within 24 months. Postoperative radiographs and magnetic resonance imaging (MRI) did not show changes in percentage of slip or spinal dimensions. Seven patients had posterior fusion within 24 months. The authors did not recommend the device for treatment of spinal stenosis complicating degenerative spondylolisthesis.

Clinical Input Received through Physician Specialty Societies and Academic Medical Centers

While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted.


In response to requests, input was received from 1 physician specialty society and 3 academic medical centers while this policy was under review in 2009. Differing input was received; several reviewers felt data were sufficient to demonstrate improved outcomes.


In response to requests, input was received from 2 physician specialty societies and 2 academic medical centers while this policy was under review in March 2011. Two of those providing input agreed this technology is investigational due to the limited high-quality data on long-term outcomes including durability. Two reviewers did not consider this investigational but felt the technology had a role in the treatment of selected patients with neurogenic intermittent claudication.


Interspinous implants (spacers) distract the spinous processes and restrict extension in order to reduce pain in patients with lumbar spinal stenosis and neurogenic claudication. Although the single randomized study of the X-STOP device reports short-term improvements in symptoms and functional status when compared to non-operative therapy, a number of questions remain. Overall, high-quality comparative data are limited. There is a need for longer-term (more than 2 years) outcome data on symptom relief, the need for repeat procedures, and implant survival. Future studies need to better control for potential biases and avoid other methodologic issues, including follow-up of patients in the control group and consistent use of outcome measurements. There are also questions about patient section criteria; for instance, should patients with any degree of spondylolisthesis be excluded from this treatment? In addition, comparisons with decompressive surgery are lacking, and recent case series indicate that outcomes may be less favorable than those reported in the multi-center randomized trial. Because the impact of this technology on net health outcome is not known, this device is considered investigational.

Practice Guidelines and Position Statements

The United Kingdom’s National Institute for Health and Clinical Excellence (NICE) published guidance in November 2010 stating that “Current evidence on interspinous distraction procedures for lumbar spinal stenosis causing neurogenic claudication shows that these procedures are efficacious for carefully selected patients in the short and medium term, although failure may occur and further surgery may be needed. The evidence reviewed consisted mainly of reports on X-STOP. (16)

2009 guidelines from the American Pain Society indicate that interspinous spacer devices, based on fair evidence, have a B recommendation (panel recommends that clinicians consider offering the intervention). (1, 17) The net benefit was considered moderate through 2 years, with insufficient evidence to estimate the net benefit for long-term outcomes.

In 2007, the North American Spine Society published new guidelines on the diagnosis and treatment of degenerative lumbar spinal stenosis. (18) They concluded that with a single Level 1 study on the X-STOP, “there remains insufficient evidence to make a recommendation.” These guidelines remain current in January 2011.

Medicare National Coverage

There is no national coverage decision.

The Centers for Medicare and Medicaid Services (CMS) approved a special add-on payment for hospitals that offer surgery using the patented X STOP(R) Interspinous Process Decompression (IPD(R)) System ("X STOP") in 2007. (19)

Rationale for Benefit Administration

This medical policy was developed through consideration of peer reviewed medical literature, FDA approval status, accepted standards of medical practice in Montana, Technology Evaluation Center evaluations, and the concept of medical necessity. BCBSMT reserves the right to make exceptions to policy that benefit the member when advances in technology or new medical information become available.

The purpose of medical policy is to guide coverage decisions and is not intended to influence treatment decisions. Providers are expected to make treatment decisions based on their medical judgment. Blue Cross and Blue Shield of Montana recognizes the rapidly changing nature of technological development and welcomes provider feedback on all medical policies.

When using this policy to determine whether a service, supply, drug or device will be covered, please note that member contract language will take precedence over medical policy when there is a conflict.

ICD-9 Codes

Investigational for all codes

ICD-10 Codes
M48.00-M48.0, 0RH008Z, 0RH038Z, 0RH048Z, 0RH108Z, 0RH138Z, 0RH148Z, 0RH408Z, 0RH438Z, 0RH448Z, 0RH608Z, 0RH638Z, 0RH648Z, 0RHA08Z, 0RHA38Z, 0RHA48Z, 0SH008Z, 0SH038Z, 0SH048Z, 0SH308Z, 0SH338Z, 0SH348Z, 0RP008Z, 0RP038Z, 0RP048Z, 0RP108Z, 0RP138Z, 0RP148Z, 0RP408Z, 0RP438Z, 0RP448Z, 0RP608Z, 0RP638Z, 0RP648Z, 0RPA08Z, 0RPA38Z, 0RPA48Z, 0SP008Z, 0SP038Z, 0SP048Z, 0SP308Z, 0SP338Z, 0SP348Z
Procedural Codes: 22899, 0171T, 0172T, C1821
  1. Chou R, Baisden J, Carragee EJ et al. Surgery for low back pain: a review of the evidence for an American Pain Society Clinical Practice Guideline. Spine (Phila Pa 1976) 2009; 34(10):1094-109.
  2. Zucherman JF, Hsu KY, Hartjen 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 (Phila Pa 1976) 2005; 30(12):1351-8.
  3. 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 2006; 4(6):463-71.
  4. Kabir SM, Gupta SR, Casey AT. Lumbar interspinous spacers: a systematic review of clinical and biomechanical evidence. Spine (Phila Pa 1976) 2010; 35(25):E1499-506.
  5. Kondrashov DG, Hannibal M, Hsu KY et al. 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):323-7.
  6. Hsu KY, Zucherman JF, Hartjen CA et al. Quality of life of lumbar stenosis-treated patients in whom the X STOP interspinous device was implanted. J Neurosurg Spine 2006; 5(6):500-7.
  7. Kuchta J, Sobottke R, Eysel P et al. Two-year results of interspinous spacer (X-Stop) implantation in 175 patients with neurologic intermittent claudication due to lumbar spinal stenosis. Eur Spine J 2009; 18(6):823-9.
  8. Rolfe KW, Zucherman JF, Kondrashov DG et al. Scoliosis and interspinous decompression with the X-STOP: prospective minimum 1-year outcomes in lumbar spinal stenosis. Spine J 2010; 10(11):972-8.
  9. Brussee P, Hauth J, Donk RD et al. Self-rated evaluation of outcome of the implantation of interspinous process distraction (X-Stop) for neurogenic claudication. Eur Spine J 2008; 17(2):200-3.
  10. Siddiqui M, Smith FW, Wardlaw D. One-year results of X Stop interspinous implant for the treatment of lumbar spinal stenosis. Spine (Phila Pa 1976) 2007; 32(12):1345-8.
  11. Tuschel A, Chavanne A, Eder C et al. Implant survival analysis and failure modes of the X STOP interspinous distraction device. Spine (Phila Pa 1976) 2011.
  12. Barbagallo GM, Olindo G, Corbino L et al. Analysis of complications in patients treated with the X-Stop Interspinous Process Decompression System: proposal for a novel anatomic scoring system for patient selection and review of the literature. Neurosurgery 2009; 65(1):111-19; discussion 19-20.
  13. Bowers C, Amini A, Dailey AT et al. Dynamic interspinous process stabilization: review of complications associated with the X-Stop device. Neurosurg Focus 2010; 28(6):E8.
  14. Kim DH, Tantorski M, Shaw J et al. Occult spinous process fractures associated with interspinous process spacers. Spine (Phila Pa 1976) 2011; 36(16):E1080-5.
  15. Verhoof OJ, Bron JL, Wapstra FH et al. High failure rate of the interspinous distraction device (X-Stop) for the treatment of lumbar spinal stenosis caused by degenerative spondylolisthesis. Eur Spine J 2008; 17(2):188-92.
  16. National Institute for Health and Clinical Excellence. Interspinous distraction procedures for lumbar spinal stenosis causing neurogenic claudication. 2010. Available online at:  Last accessed October 2011.
  17. Chou R, Loeser JD, Owens DK et al. Interventional therapies, surgery, and interdisciplinary rehabilitation for low back pain: an evidence-based clinical practice guideline from the American Pain Society. Spine (Phila Pa 1976) 2009; 34(10):1066-77.
  18. North American Spine Society. Evidence-based clinical guidelines for multidisciplinary spine care: Diagnosis and treatment of degenerative lumbar spinal stenosis. 2007. Available online at:  Last accessed October 2011.
  19. Medicare Matters. Number MM5276. 2006. Available online at:  Last accessed October 2011.
March 2012 Reviewed policy: updated description, rationale, and references; changed policy statement from medically/not medically necessary to investigational; Name change to Interspinous Distraction Devices (Spacers) from XStop.
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Interspinous Distraction Devices (Spacers)