Medical Policy

This document addresses interspinous, non-pedicle fixation devices attached to the spinous process to achieve rigid spinal fixation and accommodate bone graft material for spinal fusion.

Note: Interspinous process fixation devices in this document differ from interspinous process spacers and dynamic stabilization systems that are motion preserving devices. Please see the following related documents for additional information concerning these devices:

• SURG.00075 Intervertebral Stabilization Devices
• SURG.00092 Implanted Devices for Spinal Stenosis

Investigational and Not Medically Necessary:

Interspinous process fixation devices are considered investigational and not medically necessary for all indications.

The standard surgical procedure for rigid spinal fixation involves the use of pedicle screws, rods and plates. Non-pedicle interspinous process fixation devices (with or without additional instrumentation) were developed as a minimally invasive rigid fixation alternative to standard rigid fixation instrumentation using pedicle screws and rods or interbody cages. According to the U.S. Food and Drug Administration (FDA) 510(k) clearance, interspinous process fixation devices are intended for use with bone graft material and are not intended for stand-alone use.

Available evidence comparing the Aspen^® Spinous Process Fixation System (Zimmer Biomet Spine, Inc, Westminster, Colorado) to standard pedicle fixation includes two articles describing the biomechanical effect of the device on cadaver spines (Kaibara, 2012; Karahalios, 2010) and a small prospective study evaluating individuals with a primary diagnosis of lumbar spinal stenosis (with pain) treated with the Aspen device or an interspinous process spacer (Kim, 2012a). Of the 6 individuals implanted with the Aspen device (as a stand-alone procedure), 2 (33%) had postoperative spinous process fractures observed on computed tomography (CT). Limitations of this study include lack of randomization and small sample size leading to insufficient power to detect risk factors for fracture or differences in patient-centered outcomes.

Kim and colleagues (2012b) retrospectively compared 40 individuals who underwent single level spinal fusion with the CD HORIZON^® SPIRE™ (Medtronic Sofamor Danek, Inc., U.S.A., Memphis, TN) interspinous fusion device (IFD) for lumbar spine disease (n=12, degenerative spondylolisthesis; n=2, intervertebral disc herniation; n=26, spinal stenosis) to 36 individuals with similar lumbar spinal disorders (n=10, degenerative spondylolisthesis; n=7, foraminal stenosis; n=1, intervertebral disc herniation; n=18, spinal stenosis) who underwent spinal fusion with pedicle screw fixation. All individuals in both groups underwent posterior lumbar interbody fusion with a polyetheretherketone cage or a titanium alloy cage. Both groups were evaluated using dynamic lateral radiographs, visual analogue scale (VAS), and a Korean version of the Oswestry Disability Index (K-ODI) scores. The mean follow-up period was 14.2 months in the IFD group and 18.3 months in pedicle screw group. At 1-year follow-up, there was an improvement in the mean preoperative to postoperative VAS scores from 7.16 (± 2.1) to 1.3 (± 2.9) and 8.03 (± 2.3) to 1.2 (± 3.2) (p<0.05) in the IFD and pedicle screw groups, respectively. The K-ODI was reduced significantly in an equal amount in both groups 1 year postoperatively (p<0.05); however, no statistical difference in clinical outcomes was noticed between the 2 groups. Postoperative radiographs in the IFD group showed less improvement of instability at the instrumented level compared with the pedicle screw group. A higher incidence of adjacent segmental degeneration was reported in the pedicle screw group (n=13, 36.1%) than in the IFD group (n=5, 12.5%; p=0.029). In the IFD group, 1 individual had sustained back pain, and lumbar CT revealed fusion failure and inferior articular process fracture. There were no major surgery-related complications such as deep infection, nerve root injury, and cerebral spinal fluid (CSF) leakage in the IFD group; however, in the pedicle screw group, 3 individuals developed deep infection, 2 individuals experienced CSF leakage, and 1 individual required re-operation for a postoperative epidural hematoma. Limitations of this study include the retrospective, nonrandomized design, the heterogeneous population of participants in terms of preoperative diagnoses, and a relatively short-term follow-up period.

Scalfani and colleagues (2014) retrospectively reviewed medical records to evaluate postoperative clinical outcomes in 53 individuals who were implanted with a second generation polyaxial PrimaLOK™ SP Interspinous Fusion System (OsteoMed, Addison, TX). All participants reached the 1-year postoperative time point. Participants had a mean age of 60 years (range, 34-89 years) at the time of surgery. The most common primary surgical indications were degenerative disc disease with stenosis (45.3%), herniated disc (18.9%) and spondylolisthesis (11.3%). A total of 34 participants were implanted with the PrimaLOK SP device, 16 participants received both a polyetheretherketone interbody cage and the PrimaLOK SP device, and 3 participants received pedicle screw instrumentation, a polyetheretherketone interbody cage and the PrimaLOK SP device. Complications included intraoperative dural tear (n=1) and readmission for intractable pain after a post-discharge mechanical fall (n=1). There were no cases of fracture or migration of the device observed at the 6-week postoperative time point; however, there were 4 cases of hardware removal and 2 cases of re-operation for adjacent level disease during the follow-up period. The pain index score improved from 7.17 ± 1.68 to 4.48 ± 2.8 (p=0.0001, 22 months average follow-up) for the overall study group. There was no difference in Macnab classification score between different primary surgical indication groups (χ² p>0.05). Limitations of this review include the retrospective study design and lack of data collection on preoperative VAS scores of low back and leg pain and validated quality of life of life data to distinguish if the postoperative improvement was predominantly in axial low back pain, radicular lower extremity pain or neurogenic claudication.

Lopez and colleagues (2017) systematically evaluated the literature on lumbar spinous process fixation and fusion devices (excluding dynamic fixation and spinous process spacer devices). A total of 15 articles met the inclusion and exclusion criteria, including 4 comparative studies (level III evidence), 2 case series (level IV evidence), and 9 in vitro biomechanics studies (level V evidence). Two of the nonrandomized studies compared interspinous process fixation devices to pedicle screws in individuals undergoing interbody fusion and two other studies included interspinous process fixation devices alone or pedicle screws plus an interspinous process fixation device in individuals undergoing interbody fusion. Use of an interspinous process fixation device was associated with decreased surgical time and blood loss compared to pedicle screw implantation procedures. The authors reported that flawed study designs may have inadequately controlled for biases when reporting outcomes of reduced spinal instability at 1 year, rates of device failure, bony fracture, and complications. No comparative studies exist that report either complication rates of interspinous process fixation devices to other treatment modalities or length of hospital stay for interspinous process fixation devices compared to pedicle screw implantation procedures.

In 2019, Wei and colleagues published the results of a retrospective study that included 95 participants with lumbar disc herniation (LDH). The participants were treated with inter-spinal distraction fusion (ISDF) using the BacFuse^® Spinous Process Fusion Plate (RTI Surgical, Inc., Marquette, MI). Symptoms and imaging were evaluated prior to surgery, immediately following surgery, 6 months post-op, and a single final visit (average was 15.4 ± 3.4 months). Follow-up assessment reported improvements from baseline in VAS from 6.7 ± 1.3 to 2.1 ± 1.4 (p<0.001) at final follow-up, and ODI of 33.3 ± 6.2 to 12.5 ± 5.7 (p<0.001) at final follow-up. Imaging showed the anterior disc height was not statistically different at the post-operative follow-up (p=0.502). The imaging results showed initial improvement in imaging for both posterior disc height (18.3%) and foramina height (9.7%), only to have decreases of 2.4% and 5.1% respectively, at the final follow-up. Only 1 participant suffered a spinous process fracture but this did not cause significant back discomfort and was treated non-operatively. Long-term studies with a robust sample size are needed to show the product is durable and participants experience long-term improvement with use of the BacFuse implant for LDH.

A 2023 prospective study by Skoblar and colleagues evaluated radiographic fusion outcomes of individuals who received a minimally invasive interspinous fixation device. This was a single-center, single-physician study in which 43 individuals returned to the surgeon’s office for a follow-up computed tomography (CT) scan to assess the fusion. Follow-up was done at a mean of 459 days following surgery. Of the levels assessed, 92.8% were considered fused by CT scan. CT imaging identified four spinous process fractures which were asymptomatic and healed without intervention. In this study, there were no clinical outcomes provided, nor was there comparison to a control group.

In 2024, Baranidharan reported the two-year results of a multi-center, prospective, randomized controlled trial (RCT) which compared the efficacy of an implanted interspinous fixation device (the Minuteman^® interspinous fixation device) to open direct surgical decompression for treatment of lumbar spinal stenosis. Efficacy was assessed using the VAS for leg and back pain, ODI for pain-related disability, the physical function component of the Zurich Claudication Questionnaire (ZCQ) for lumbar spinal stenosis physical function, the functional status questionnaire for activities of daily living (ADL), analgesic and concomitant medication use and employment status. Physical function was also assessed using a walking distance test (distance walked in five minutes) and a sitting-to- standing test (number of repetitions completed from sitting to standing in one minute). Participants were randomized in a 1:1 fashion between interspinous fixation (n=20) and decompression (n=23). Prior to surgery, there were 2 participants who instead of receiving interspinous fixation had decompression surgery instead. At 24 months, there were 15 (75%) fixation device participants available for follow-up and 19 (83%) decompression participants available. Clinical success was defined as a greater than or equal to 30% improvement in leg pain (as measured by VAS), back pain (as measured by VAS), pain-related disability (as measured by ODI), and greater than 0.5-point improvement in lumbar spinal stenosis function (as measured by ZCQ). There were three decompression cases and one interspinous fixation case which did not have a favorable outcome throughout the 24-month post-surgical period. There were an additional five participants who showed a loss of clinical benefit at the 24-month follow-up (three cases were interspinous fixation and 2 cases were decompression surgery). At the 24-month visit, the clinical success rate for leg pain in the interspinous fixation device group was noted in 72% of participants and for back pain success was noted in 56% of participants. The clinical success rates for leg pain for those in the decompression group at 24 weeks was 76% and for back pain was also 76%. The clinical success rates for ODI disability for those who had interspinous fixation device were 56% at 24 months and was 80% for those who had decompression surgery. There were 50% of participants who had clinical success rates after interspinous fixation device surgery for the ZCQ and 80% in the decompression group. The mean increase in walking distance varied between 66% and 94% in the interspinous fixation device cohort and varied between 34% and 53% for those in the decompression group. For the sitting-to-standing repetitions, the mean increase was larger in the interspinous fixation device group compared to the decompression group but was not statistically significant (0.105<0.972). The authors noted at least two study investigators deviated from the randomization assignments which lowered the sample size in the interspinous fixation device group which failed to establish noninferiority of the interspinous fixation device relative to decompression surgery.

In 2025, the North American Spine Society (NASS) issued coverage recommendations for interspinous fixation devices noting:

There has been an increasing body of published literature on outcomes related to interspinous devices which affix to the spinous processes for the purposes of augmenting fusion. There is still limited evidence published about outcomes of such devices that are used for stabilization of a motion segment, but the evidence has improved with regards to the quality of studies that support this technique. There are published prospective studies that support the use of this technology for stabilization of single-level degenerative spondylolisthesis when combined with a direct decompression and fusion. Trials comparing interspinous fixation (ISF) to PS are limited due to small sample size and methodological uncertainties but suggest similar clinical outcomes when either is performed as a supplement to interbody fusion. However, there is some evidence that interspinous devices which affix to the spinous processes may be less mechanically stabilizing than PS constructs. Overall, there are insufficient prospective randomized trials with sufficient follow-up to determine the relative effectiveness and safety of this class of devices in comparison to PS fixation.

In summary, there is insufficient evidence in the peer-reviewed published medical literature to support the long-term clinical benefit of interspinous process fixation devices. Randomized controlled trials are needed to demonstrate the clinical utility of interspinous process fixation devices compared with established standard surgical approaches involving pedicle screw-rod fixation with lumbar fusion procedures.

The pedicle is a small area of bone that is the first to extend out from both sides of the back of the vertebral body and joins with broad flat plates of bone (laminae) to form a hollow archway that protects the spinal cord. One type of fixation involves pedicle screws that are inserted as anchors for rods that provide fixation. Another type of fixation is the interbody cage placed in the disc space. Both of these fixation devices support fusion when used with bone graft material.

Interspinous process fixation devices attach to a vertebral spinous process and are intended for use as an adjunct to instrumented vertebral fixation procedures, as well as a compartment for bone graft material for fusion. Interspinous process fixation devices have been proposed for use after failed spinal fusion procedures and for treatment of degenerative disc disease, pseudoarthrosis, spondylolisthesis, trauma (dislocation or fracture), and tumors.

Lamina: Part of the vertebra located behind the vertebral body. A flat area of bone between the superior process forming the facet joint and the spinous process, helping to form the central canal through which the spinal cord passes.

Pedicles: Two short, rounded processes made of thick cortical bone that extend posteriorly from the lateral margin of the dorsal surface of the vertebral body.

Spinal fusion: A surgical procedure to stabilize the spine by fusing together two or more vertebrae.

Spinous process: The small, bony protuberances located along the back of the spinal column that act as attachment sites for muscles and ligaments.

Spondylolisthesis: A condition that occurs when one vertebra slips out of the proper position onto the bone below it.

The following codes for treatments and procedures applicable to this document are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

When services are Investigational and Not Medically Necessary:
When the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

Peer Reviewed Publications:

1. Baranidharan G, Bretherton B, Feltbower RG, et al. 24-month outcomes of indirect decompression using a minimally invasive interspinous fixation device versus standard open direct decompression for lumbar spinal stenosis: a prospective comparison. J Pain Res. 2024; 17:2079-2097.
2. Huang WM, Yu XM, Xu XD, et al. Posterior lumbar interbody fusion with interspinous fastener provides comparable clinical outcome and fusion rate to pedicle screws. Orthop Surg. 2017; 9(2):198-205.
3. Kaibara T, Karahalios DG, Porter RW, et al. Biomechanics of a lumbar interspinous anchor with transforaminal lumbar interbody fixation. World Neurosurg. 2010; 73(5):572-577.
4. Karahalios DG, Kaibara T, Porter RW, et al. Biomechanics of a lumbar interspinous anchor with anterior lumbar interbody fusion. J Neurosurg Spine. 2010; 12(4):372-380.
5. Kim DH, Shanti N, Tantorski ME, et al. Association between degenerative spondylolisthesis and spinous process fracture after interspinous process spacer surgery. Spine J. 2012a; 12(6):466-472.
6. Kim HJ, Bak KH, Chun HJ, et al. Posterior interspinous fusion device for one-level fusion in degenerative lumbar spine disease: comparison with pedicle screw fixation - preliminary report of at least one year follow up. J Korean Neurosurg Soc. 2012b; 52(4):359-364.
7. Lopez AJ, Scheer JK, Dahdaleh NS, et al. Lumbar spinous process fixation and fusion: a systematic review and critical analysis of an emerging spinal technology. Clin Spine Surg. 2017; 30(9):E1279-E1288.
8. Moojen WA, Arts MP, Bartels RH, et al. Effectiveness of interspinous implant surgery in patients with intermittent neurogenic claudication: a systematic review and meta-analysis. Eur Spine J. 2011; 20(10):1596-1606.
9. Panchal R, Denhaese R, Hill C, et al. Anterior and lateral lumbar interbody fusion with supplemental interspinous process fixation: outcomes from a multicenter, prospective, randomized, controlled study. Int J Spine Surg. 2018; 12(2):172-184.
10. Sclafani JA, Liang K, Ohnmeiss DD, Gordon C. Clinical outcomes of a polyaxial interspinous fusion system. Int J Spine Surg. 2014; 8:35.
11. Skoblar M, Hedman T, Rogers AJ, et al. Instrumented posterior arthrodesis of the lumbar spine: prospective study evaluating fusion outcomes in patients receiving an interspinous fixation device for the treatment of degenerative spine diseases. J Pain Res. 2023; 16:2909-2918.
12. Tram J, Srinivas S, Wali AR, et al. Decompression surgery versus interspinous devices for lumbar spinal stenosis: a systematic review of the literature. Asian Spine J. 2020; 14(4):526-542.
13. Wei H, Tang H, Zhang T, et al. Preliminary efficacy of inter-spinal distraction fusion which is a new technique for lumbar disc herniation. Int Orthop. 2019; 43(4):899-907.

Government Agency, Medical Society, and Other Authoritative Publications:

1. North American Spine Society (NASS). NASS coverage recommendations. Interspinous devices for fusion. March 2025. Available at: https://www.spine.org/PolicyPractice/CoverageRecommendations/AboutCoverageRecommendations.  Accessed on April 7, 2025.
2. U.S. Food and Drug Administration. 510(k) Premarket Notification Database. Product Codes: KWP, KWQ, MNH, MNI, and PEK. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm. Accessed on April 7, 2025.

1. National Library of Medicine. Medline Plus. Medical Encyclopedia. Spinal fusion. Last Reviewed August 8, 2023. Available at: https://medlineplus.gov/ency/article/002968.htm. Accessed on February 21, 2025.

Aileron^® Interspinous Fixation System
Aurora Spine ZIP™ MIS Interspinous Fusion System
Axle™ Interspinous Fusion System
BridgePoint™ Spinous Process Fixation System
CD HORIZON™ Spinal Fixation System
coflex-F^® Implant System
inuteman G3 Interspinous Interlaminar Fusion Device
PrimaLOK SP Interspinous Fusion System
SP-Fix^® Spinous Process Fixation Plate
StabiLink^® MIS Interspinous Fixation System

The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.

Federal and State law, as well as contract language, including definitions and specific contract provisions/exclusions, take precedence over Medical Policy and must be considered first in determining eligibility for coverage.  The member’s contract benefits in effect on the date that services are rendered must be used.  Medical Policy, which addresses medical efficacy, should be considered before utilizing medical opinion in adjudication.  Medical technology is constantly evolving, and we reserve the right to review and update Medical Policy periodically.
 
No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, or otherwise, without permission from the health plan.
 
© CPT Only – American Medical Association

The requirements below are specific to the Florida Medicaid Managed Care Plan and are not a part of the Medical Policy or Clinical UM guideline approved by Elevance Health's Medical Policy and Technology Assessment Committee.
 
If the Florida Medicaid Managed Care Plan intends to deny coverage on the basis that a diagnostic test, therapeutic procedure, or medical device or technology is experimental or investigational, the Managed Care Plan shall submit a request for coverage determination to the Agency in accordance with rule 59G-1.035, F.A.C and Core SMMC Contract, Attachment II, Section VI.G.4.d.
 
Below is a list of the materials the plans are required to submit when they deny coverage as experimental/investigational: 

1. Include the CPT or HCPCS code(s)  
2. Include a list of other state Medicaid agencies and private insurers who cover the service  
3. Include information about the health service from the U.S. Food and Drug Administration  
4. Include known risks of the service and health outcomes of others who have received it  
5. Include a list of covered alternative services, if any, that could be used to treat the condition  
6. Identify a specific recipient needing the service  
7. Include the recipient’s health history  
8. Include the disease information necessitating the requested service  
9. Include a rationale for the immediacy of the review  

1. Submit the rationale used to preliminarily indicate the service is experimental/investigational
   1. Include peer-reviewed journal articles in PDF format with links to the online articles  
   2. Include evidence-based clinical guidelines reviewed by the plan  
2. Submit direct contact information (name, phone number, & email address) for the Medical Director