Review of Interspinous Process Devices
Stephanie Hsu, BA, James Zucherman Md
Interspinous Process Device Introduction
Spinal stenosis is a narrowing of the spinal canal causing compression of neutral structures and/or their blood supply. The underlying pathologies include thickened lamina, hypertrophied ligamentum flavum, spondylolisthesis (slippage of one vertebra forward over the vertebra below), disc bulge, facet arthrosis and congenital narrowing of the spinal canal.
As the disc degenerates and dehydrates, the disc space collapses, leading to annular bulging and infolding of the ligamentum flavum. The facet joints assume a larger load, leading to facet arthrosis, osteophyte formation, and even facet cysts. These degenerative changes reduce the area of the canal for the passage of the nerves.
In the subarticular zone, traversing nerve root is compressed. In the neuroforamen, compression of the exiting nerve root can occur. Spondylolisthesis contributes to further narrowing of the spinal canal and neuroforamen. Neurogenic claudication is a complex of symptoms resulting from lumbar spinal stenosis (narrowing of nerve passageways). The most significant symptoms include leg pain and numbness. Often, these symptoms are relieved by forward flexion of the spine.
Degenerative spine conditions, especially spinal stenosis, are becoming more common with the increasingly aging population.
Treatments include physical therapy and steroid epidural injections. For severe symptoms, surgical decompression include laminotomy, laminectomy, endoscopic decompression, or other minimally invasive decompressive techniques.
Interspinous process devices (IPD) have been developed to achieve indirect decompression by limiting lumbar extension of the abnormal joint and enlarging the spinal canal and neuroforamen. Candidates for IPD are individuals who get relief when they flex (sit and bend forward) and experience worsening of symptoms when their spine is extended (standing and walking).
The advantages of IPD compared to standard surgical decompression include the option of local anesthesia as well as the reduced risks of nerve injury, epidural fibrosis, and spinal fluid leakage. The IPD surgery is minimally invasive, and the bony structures and soft tissues are left intact.
Usually the hospital stay and rehabilitation are shorter. The IPD procedure is also reversible and allows further surgical treatment if necessary. For these reasons, IPD is especially attractive and suitable for patients with multiple comorbidities, though results are better in those under 70. By distracting the spinous processes and restricting extension, the IPD devices unload the facet joints and restore neuroforaminal and central canal size.
In a study, Guehring et al also showed that IPD devices lower intradiscal pressure.
Currently available IPD brands
Increasing number of interspinous process devices (IPD) have been introduced as an alternative to standard lumbar spine surgeries. There are now dynamic or static interspinous process devices, and interspinous process fusion devices.
Interspinous devices include:
X-Stop (Medtronic, US)
DIAM (Medtronic, US)
Superion (Vertiflex, US)
Coflex (Paradigm Spine, US)
Wallis (Zimmer Spine, US)
Viking (Sintea, Italy)
Ellipse (Sintea, Italy)
BacJac (Pioneer, US)
ExtenSure (NuVasive, US)
Promise (Biomech, Taiwan)
Rocker (Biomech, Taiwan)
Biolig (Cousin Biotech, France)
In-Space (Synthes, US) – Terminated
I-MAXX (Maxx Spine, Germany)
Flexus (Globus, US)
Spinos (Privelop, Germany)
Aperius (Medtronic, US)
Helifix (Alphatex Spine, US)
Interspinous fusion devices include:
Aspen (Lanx, Biomet)
BacFuse (Pioneer, US)
Stabilink (Southern Spine, US)
Spire (Medtronic, US)
BridgePoint (Alphatec Spine, US)
SP-Fix (Globus, US)
Posterior Fusion System (Lanx, US)
Axle (X-Spine, Bacterin, US)
Affix (NuVasive, US)
Aileron (Life Spine, US)
coflex-F (Paradigm Spine, US)
Inspan (Spine Frontier, US)
Interbridge Interspinous Posterior Fixation System (LDR Spine, Zimmer Biomet, US)
Minuteman (Spinal Simplicity, US)
PrimaLOK (OsteoMed, US)
Octave (Life Spine, US)
Zip Mis Interspinous Fusion System (Aurora Spine, US)
Neurological and Functional Outcome Measurements
There are different outcome scales to evaluate neurological and functional status of patients with neurogenic claudication. The most commonly used outcome measurements include:
1.) Zurich Claudication Questionnaire (ZCQ), also called the Brigham Spinal Stenosis
Questionnaire or Swiss Spinal Stenosis Questionnaire
The Zurich Claudication Questionnaire (ZCQ) has three subscales: symptom severity with a range of 1 to 5, physical function with a range of 1 to 4, and patient satisfaction with a range of 1 to 4. A satisfied patient has a satisfaction score of less than 2.5
2.) The Modified Roland Disability Questionnaire for Sciatica (MRDQ)
The Modified Roland Disability Questionnaire for sciatica (MRDQ) has 23 points, with higher scores indicating more disability.
3.) The Visual Analog Scale (VAS)
In VAS, pain is evaluated on a 100 mm scale, ranging from 0 mm of “no pain” to 100 mm of “the worst pain imaginable.”
4.) The Oswestry Disability Index (ODI)
In the Oswestry Disability Index (ODI), 0 points indicates no disability and 100 points indicates the worst possible disability.
5.) Short Form (36) Health Survey (SF-36)
The Short Form (36) Health Survey (SF-36) is a patient reported questionnaire that includes eight scaled scores. Each scale is transformed into a 0-100 scale. The lower the score, the greater the disability: zero indicates maximum disability, while 100 indicates no disability. The eight scaled score sections include: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning, and mental health.
As of July 2016, 560 references regarding interspinous process devices were found through electronic database searches. In this review, 12 studies were chosen for evaluation based on the following criteria: randomized controlled trials and prospective studies. Review and meta-analysis were performed for these studies on treatment of lumbar spinal stenosis using interspinous process devices, standard surgical decompression, and other therapies.
Zucherman et al (2005) compared X-Stop to conservative treatment with epidural steroid injections. Their results from randomized, multicenter trials showed that for patients with neurogenic claudication, X-Stop led to a greater improvement of symptoms and function than epidural steroid blocks and conservative treatment. The ratio of success was almost 5 times greater than non-surgical treatment. Anderson et al (2006) compared X-Stop with conservative treatment in patients with degenerative spondylolisthesis. Both Zucherman et al and Anderson et al studies showed ZCQ improvement by 23.2 (SD 18.5-27.8).
Interspinous process devices have been compared to decompressive laminectomies for lumbar spinal stenosis in randomized studies. In a prospective case control study of 60 patients, Richter et al (2009) compared one group of patients who underwent Coflex interspinous process device procedure with surgical decompression with another group of patients who only underwent surgical decompression. Both cohorts demonstrated clinical improvement in VAS, ODI, and MRDQ. There were no statistically significant differences between the two groups at six weeks and at one year follow-up. Strömqvist et al (2013) compared X-Stop to decompressive laminectomies in one or two level lumbar spinal stenosis.
In their study, 100 patients with neurogenic claudication were relieved by flexion. Evaluation at six, 12, and 24 months showed no significant differences between decompressive laminectomies and X-Stop in ZCQ scores, VAS, and SF-36. However, X-Stop surgeries took less time (62 minutes) than laminectomies (98 minutes). There was also less blood loss with X-Stop surgeries: 54 mL as opposed to 262 mL in laminectomies. Reoperation rate was 26% for X-Stop and 6% for laminectomies. Lønne at al (2015) also compared the X-Stop to decompressive laminectomies. There were no significant differences in ZCQ and patient-reported scores. X-Stop surgery reoperation was 25% as compared to 5% for laminectomies. Prospective cohort studies by Bhadra et al (2008), Brussee et al (2008), Kuchta, et al (2009), and Galarza et al (2010) showed improvement after IPD procedures.
The spinous processes are tension-bearing structures. Placement of interspinous devices can convert the spinous processes to compression-loading structures. Osteoporotic or osteopenic spinous processes are susceptible to fractures or bone erosion. Other complications include device malposition or dislocation. However, there are numerous types of IPD devices manufactured in the world. It is very difficult to compare the rates of clinical success, failures, and complications between different brands.
The Advantages of Interspinous Process Devices (IPD)
One of the most important advantages of IPD is the safety of this minimally invasive procedure compared to surgical bony decompression. Though the results from any procedure are expected to not be as good as in younger healthier patients, IPD, because of its safety, is especially suitable for frail elderly patients with multiple medical comorbidities.
The IPD procedure is reversible and leaves bony structures and soft tissues intact. The device can be removed easily and other surgical treatment can be performed with the original anatomy essentially intact. The IPD procedure significantly reduces risk of nerve injury.
Since the procedure does not involve entering the spinal canal, it does not lead to epidural fibrosis or spinal fluid leakage. With the IPD procedure, iatrogenic instability does not occur as it may following bony decompression. Most IPD surgeries can also be performed under local anesthesia and usually, the hospital stay and rehabilitation are shortened.
Amundsen T, Weber H, Lilleås F, Nordal HJ, Abdelnoor M, Magnaes B. Lumbar spinal stenosis. Clinical and radiologic features. Spine (Phila Pa 1976). 1995 May 15;20(10):1178-86.
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 Jun;4(6):463-71.
Beyer F, Yagdiran A, Neu P, Kaulhausen T, Eysel P, Sobottke R. Percutaneous interspinous spacer versus open decompression: a 2-year follow-up of clinical outcome and quality of life. Eur Spine J. 2013 Sep;22(9):2015-21. Epub 2013 Apr 27.
Bhadra AK, Raman AS, Tucker S, Noordeen HH. Interspinous implant in lumbar spinal stenosis: a prospective cohort. ArgoSpine News J (2009) 21: 142.
Bono CM, Vaccaro AR. Interspinous process devices in the lumbar spine. J Spinal Disord Tech. 2007 May;20(3):255-61.
Brodke DS, Annis P, Lawrence BD, Woodbury AM, Daubs MD. Reoperation and revision rates of 3 surgical treatment methods for lumbar stenosis associated with degenerative scoliosis and spondylolisthesis. Spine (Phila Pa 1976). 2013 Dec 15;38(26):2287-94.
Brussee P, Hauth J, Donk RD, Verbeek AL, Bartels RH. Self-rated evaluation of outcome of the implantation of interspinous process distraction (X-Stop) for neurogenic claudication. Eur Spine J. 2008 Feb;17(2):200-3. Epub 2007 Oct 31.
Carlsson AM. Assessment of chronic pain. I. Aspects of the reliability and validity of the visual analogue scale. Pain. 1983 May;16(1):87-101.
Cinotti G, De Santis P, Nofroni I, Postacchini F.Stenosis of lumbar intervertebral foramen: anatomic study on predisposing factors. Spine (Phila Pa 1976). 2002 Feb 1;27(3):223-9.
Fairbank JC, Couper J, Davies JB, O’Brien JP. The Oswestry low back pain disability questionnaire. Physiotherapy. 1980 Aug;66(8):271-3.
Galarza M, Fabrizi AP, Maina R, Gazzeri R, Martínez-Lage JF. Degenerative lumbar spinal stenosis with neurogenic intermittent claudication and treatment with the Aperius PercLID System: a preliminary report. Neurosurg Focus. 2010 Jun;28(6):E3.
Galarza M, Gazzeri R, De la Rosa P, Martínez-Lage JF. Microdiscectomy with and without insertion of interspinous device for herniated disc at the L5-S1 level. J Clin Neurosci. 2014 Nov;21(11):1934-9. Epub 2014 Oct 3.
Gazzeri R, Galarza M, Alfieri A. Controversies about interspinous process devices in the treatment of degenerative lumbar spine diseases: past, present, and future. Biomed Res Int. 2014;2014:975052. Epub 2014 Apr 13.
Gibson JN, Grant IC, Waddell G. The Cochrane review of surgery for lumbar disc prolapse and degenerative lumbar spondylosis. Spine (Phila Pa 1976). 1999 Sep 1;24(17):1820-32.
Gibson JN, Waddell G. Surgery for degenerative lumbar spondylosis: updated Cochrane Review. Spine (Phila Pa 1976). 2005 Oct 15;30(20):2312-20.
Guehring T, Omlor GW, Lorenz H, et al. Disc distraction shows evidence of regenerative potential in degenerated intervertebral discs as evaluated by protein expression, magnetic resonance imaging, and messenger ribonucleic acid expression analysis. Spine (Phila Pa 1976). 2006 Jul 1;31(15):1658-65.
Guehring T, Omlor GW, Lorenz H, et al. Stimulation of gene expression and loss of anular architecture caused by experimental disc degeneration–an in vivo animal study. Spine (Phila Pa 1976). 2005 Nov 15;30(22):2510-5.
Guehring T, Unglaub F, Lorenz H, Omlor G, Wilke HJ, Kroeber MW. 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 May;15(5):597-604. Epub 2005 Aug 13.
Hicks GE, Morone N, Weiner DK. Degenerative lumbar disc and facet disease in older adults: prevalence and clinical correlates. Spine (Phila Pa 1976). 2009 May 20;34(12):1301-6.
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 Dec;5(6):500-7.
Johnsson KE, Udén A, Rosén I. The effect of decompression on the natural course of spinal stenosis. A comparison of surgically treated and untreated patients. Spine (Phila Pa 1976). 1991 Jun;16(6):615-9.
Kim KA, McDonald M, Pik JH, Khoueir P, Wang MY. Dynamic intraspinous spacer technology for posterior stabilization: case-control study on the safety, sagittal angulation, and pain outcome at 1-year follow-up evaluation. Neurosurg Focus. 2007 Jan 15;22(1):E7.
Kondrashov DG, Hannibal M, Hsu KY, Zucherman JF. Interspinous process decompression with the X-STOP device for lumbar spinal stenosis: a 4-year follow-up study. J Spinal Disord Tech. 2006 Jul;19(5):323-7.
Kuchta J, Sobottke R, Eysel P, Simons P. 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 Jun;18(6):823-9. Epub 2009 Apr 22.
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 Feb;17(1):72-7; discussion 78.
Lønne G, Johnsen LG, Rossvoll I, et al. Minimally invasive decompression versus x-stop in lumbar spinal stenosis: a randomized controlled multicenter study. Spine (Phila Pa 1976). 2015 Jan 15;40(2):77-85.
Marsh GD, Mahir S, Leyte A. A prospective randomised controlled trial to assess the efficacy of dynamic stabilisation of the lumbar spine with the Wallis ligament. Eur Spine J. 2014 Oct;23(10):2156-60. Epub 2014 Jul 30.
McHorney CA, Ware JE Jr, Lu JF, Sherbourne CD. The MOS 36-item Short-Form Health Survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care. 1994 Jan;32(1):40-66.
Moojen WA, Arts MP, Jacobs WC, et al. IPD without bony decompression versus conventional surgical decompression for lumbar spinal stenosis: 2-year results of a double-blind randomized controlled trial. Eur Spine J. 2015 Oct;24(10):2295-305. Epub 2015 Jan 14.
Patil CG, Sarmiento JM, Ugiliweneza B, et al. Interspinous device versus laminectomy for lumbar spinal stenosis: a comparative effectiveness study. Spine J. 2014 Aug 1;14(8):1484-92. Epub 2013 Oct 4.
Patrick DL, Deyo RA, Atlas SJ, Singer DE, Chapin A, Keller RB. Assessing health-related quality of life in patients with sciatica. Spine (Phila Pa 1976). 1995 Sep 1;20(17):1899-908; discussion 1909.
Phan K, Mobbs RJ. Minimally Invasive Versus Open Laminectomy for Lumbar Stenosis: A Systematic Review and Meta-Analysis. Spine (Phila Pa 1976). 2016 Jan;41(2):E91-E100.
Postacchini R, Ferrari E, Cinotti G, Menchetti PP, Postacchini F. Aperius interspinous implant versus open surgical decompression in lumbar spinal stenosis. Spine J. 2011 Oct;11(10):933-9.
Pratt RK, Fairbank JC, Virr A. The reliability of the Shuttle Walking Test, the Swiss Spinal Stenosis Questionnaire, the Oxford Spinal Stenosis Score, and the Oswestry Disability Index in the assessment of patients with lumbar spinal stenosis. Spine (Phila Pa 1976). 2002 Jan 1;27(1):84-91.
Richards JC, Majumdar S, Lindsey DP, Beaupré GS, Yerby SA. The treatment mechanism of an interspinous process implant for lumbar neurogenic intermittent claudication. Spine (Phila Pa 1976). 2005 Apr 1;30(7):744-9.
Richter A, Halm HF, Hauck M, Quante M. Two-year follow-up after decompressive surgery with and without implantation of an interspinous device for lumbar spinal stenosis: a prospective controlled study. J Spinal Disord Tech. 2014 Aug;27(6):336-41.
Richter A, Schütz C, Hauck M, Halm H. Does an interspinous device (Coflex) improve the outcome of decompressive surgery in lumbar spinal stenosis? One-year follow up of a prospective case control study of 60 patients. Eur Spine J. 2010 Feb;19(2):283-9. Epub 2009 Dec 5.
Roland M, Morris R. A study of the natural history of low-back pain. Part II: development of guidelines for trials of treatment in primary care. Spine (Phila Pa 1976). 1983 Mar;8(2):145-50.
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 May 20;32(12):1345-8.
Strömqvist BH, Berg S, Gerdhem P, et al. X-stop versus decompressive surgery for lumbar neurogenic intermittent claudication: randomized controlled trial with 2-year follow-up. Spine (Phila Pa 1976). 2013 Aug 1;38(17):1436-42.
Stucki G, Daltroy L, Liang MH, Lipson SJ, Fossel AH, Katz JN. Measurement properties of a self-administered outcome measure in lumbar spinal stenosis. Spine (Phila Pa 1976). 1996 Apr 1;21(7):796-803.
Stucki G, Liang MH, Fossel AH, Katz JN. Relative responsiveness of condition-specific and generic health status measures in degenerative lumbar spinal stenosis. J Clin Epidemiol. 1995 Nov;48(11):1369-78.
Talwar V, Lindsey DP, Fredrick A, Hsu KY, Zucherman JF, Yerby SA. Insertion loads of the X STOP interspinous process distraction system designed to treat neurogenic intermittent claudication. Eur Spine J. 2006 Jun;15(6):908-12. Epub 2005 May 31.
Tsai KJ, Murakami H, Lowery GL, Hutton WC. A biomechanical evaluation of an interspinous device (Coflex) used to stabilize the lumbar spine. J Surg Orthop Adv. 2006 Fall;15(3):167-72.
Urban JP, Roberts S. Degeneration of the intervertebral disc. Arthritis Res Ther. 2003;5(3):120-30. Epub 2003 Mar 11.
Vaccaro AR, Lee JY, Schweitzer KM Jr, et al. Assessment of injury to the posterior ligamentous complex in thoracolumbar spine trauma. Spine J. 2006 Sep-Oct;6(5):524-8. Epub 2006 Jul 11.
Ware JE, Sherbourne CD. The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care. 1992 Jun;30(6):473-83.
Ware JE, Snow KK, Kosinski M, Gandek B. SF-36 Health Survey Manual and Interpretation Guide. Boston, MA: New England Medical Centre, The Health Institute, 1993.
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 Jun 15;30(12):1351-8.