Medical Policy

Subject:Interspinous Fixation Devices
Policy #:  SURG.00134Current Effective Date:  10/08/2013
Status:ReviewedLast Review Date:  08/08/2013


Rigid spinal fixation instrumentation generally includes pedicle screws with rods and anterior or posterior interbody cages. Non-pedicle fixation devices have been developed and have U.S. Food and Drug Administration (FDA) 510(k) clearance. These devices are affixed to the spinous process to achieve fixation. They also accommodate bone graft material for fusion and are not intended to be used for stand-alone use per the FDA 510(k) clearance.

Note: Interspinous fixation devices in this document differ from interspinous process spacers (for example, X STOP®, Medtronic Inc., Minneapolis, MN) and dynamic stabilization systems (for example, Dynesys®, Zimmer Inc., Minneapolis, MN) that are motion preserving devices. Please see the following related documents for additional information concerning these devices:

Position Statement

Investigational and Not Medically Necessary:

Interspinous 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; however, the pedicle may not support fixation due to osteoporosis, trauma, or previous pedicle fixation failure. Non-pedicle interspinous spinal fixation devices were developed as an alternative. Examples of these devices include, but are not limited to, the Aspen™ Spinous Process Fixation System (Lanx Inc., Broomfield, Colorado), CD HORIZON® SPIRE Plate (Medtronic Inc., Memphis, TN), SP-FixTM Spinous Process Fixation Plate (Globus Medical Inc., Audubon, PA), and PrimaLOKTMSP (OsteoMed, Addison, TX).

The interspinous fixation devices (with or without additional instrumentation) are marketed as a minimally invasive rigid fixation alternative to standard rigid fixation instrumentation using pedicle screws and rods or interbody cages. The FDA 510(k) clearance does not require clinical trials, but requires a predicate device for the applicant device prior to marketing. The available evidence in the peer-reviewed published medical literature comparing interspinous fixation devices to standard pedicle fixation consists of two articles describing the biomechanical effect of the Aspen device on cadaver spines (Kaibara, 2012; Karahalios, 2010).

A randomized, single blind (participant) industry-sponsored clinical trial, A Multi-Center Prospective Randomized Study Comparing Supplemental Posterior Instrumentation, Aspen™ Spinous Process System Versus Pedicle Screw Fixation, in Lateral Lumbar Interbody Fusion (LLIF) or Anterior Lumbar Interbody Fusion (ALIF), is currently recruiting participants. Study completion is anticipated in March 2014.


Vertebral Anatomy and Interspinous Fixation Devices

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. This is a titanium cylinder that is placed in the disc space. Both of these fixation devices support fusion when used with bone graft material.

The interspinous fixation device is attached to a vertebral spinous process. Interspinous fixation devices are designed for use as an adjunct to instrumented vertebral fixation providing additional fixation as well as a compartment for bone graft material for fusion.

Interspinous fixation devices have been used for the treatment of the following conditions:

  1. Degenerative disc disease (DDD);
  2. Spondylolisthesis;
  3. Trauma (fracture or dislocation);
  4. Tumors;
  5. Pseudarthrosis;
  6. Failed previous fusion.

Some interspinous fixation devices have been used as an adjunct to the following surgical procedures:

  1. Supplemental fixation for ALIF procedures;
  2. Supplemental fixation for TLIF procedures;
  3. Supplemental fixation lateral interbody fusion procedures;
  4. Posterior interlaminar fusion;
  5. Posterolateral fusion;
  6. Revision option in failed fusion/hybrid constructs.

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.

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

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

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.  A draft of future ICD-10 Coding (effective 10/01/2014) related to this document, as it might look today, is included below for your reference.  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.

22899Unlisted procedure, spine [when specified as insertion of a non-pedicle interspinous fixation device]
ICD-9 Diagnosis 
 All diagnoses
ICD-10 ProcedureICD-10-PCS draft codes; effective 10/01/2014:
 For the following procedures when specified insertion of a non-pedicle interspinous fixation device:
0RH40BZInsertion of interspinous process spinal stabilization device into cervicothoracic vertebral joint, open approach
0RH60BZInsertion of interspinous process spinal stabilization device into thoracic vertebral joint, open approach
0SH00BZInsertion of interspinous process spinal stabilization device into lumbar vertebral joint, open approach
0SH30BZInsertion of interspinous process spinal stabilization device into lumbosacral joint, open approach
ICD-10 DiagnosisICD-10-CM draft codes; effective 10/01/2014:
 All diagnoses

Peer Reviewed Publications:

  1. 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.
  2. 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.

Government Agency, Medical Society, and Other Authoritative Publications: 

  1. U.S. Food and Drug Administration 510(k) Premarket Notification Database. Aspen™ Spinous Process Fixation System. Summary of Safety and Effectiveness. No. K071877. Rockville, MD: FDA. September 17, 2007. Available at: Accessed on July 8, 2013.
  2. U.S. Food and Drug Administration 510(k) Premarket Notification Database. PrimaLOK™ SP. Summary of Safety and Effectiveness. No. K100354. Rockville, MD: FDA. August 17, 2010. Available at: Accessed on July 8, 2013.
  3. U.S. National Institutes of Health. A multi-center prospective randomized study comparing supplemental posterior instrumentation, Aspen™ Spinous Process System versus pedicle screw fixation, in lateral lumbar interbody fusion (LLIF) or anterior lumbar interbody fusion (ALIF). NLM Identifier: NCT01549366. Last updated on May 11, 2012. Available at: Accessed on July 8, 2013.
Web Sites for Additional Information
  1. U.S. National Library of Medicine. Medline Plus. Spinal fusion. Available at: Accessed on July 8, 2013.

Aileron® Interspinous Fixation System
Aspen Spinous Process Fixation System
Coflex-F® Implant
SP-Fix Spinous Process Fixation Plate
StabiLink™ MIS Spinal Fixation System
VertiFlex® Spinous Process Fixation Plate 

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.

Document History
Reviewed08/08/2013Medical Policy and Technology Assessment Committee (MPTAC) review. Updated Description, Rationale, and Background sections. Index updated with the StabiLink MIS Spinal Fixation System and VertiFlex Spinous Process Fixation Plate devices.
 04/19/2013Updated Index section with the Aileron Interspinous Fixation System.
 12/11/2012Updated Index section with the coflex-F implant device.
New08/09/2012MPTAC review. Initial document development.