Description
Facet arthroplasty refers to the implantation of a spinal prosthesis to restore posterior element structure and function as an adjunct to neural decompression. This procedure is proposed as an alternative to posterior spinal fusion for patients with facet arthrosis, spinal stenosis and spondylolisthesis.

For individuals who have lumbar spinal stenosis who receive facet arthroplasty, the evidence includes a preliminary report of a randomized controlled trial. Relevant outcomes are symptoms, functional outcomes, quality of life and treatment-related morbidity. Interim results from a pivotal trial of the ACADIA Facet Replacement System were reported in 2012. No additional publications from this trial, which was expected to be completed October 2015, have been identified to date. In addition to the lack of evidence on clinical outcomes with facet arthroplasty, no device has received U.S. Food and Drug Administration approval. The evidence is insufficient to determine the effects of the technology on health outcomes.

Background 
Spinal fusion is a common surgical treatment following surgical decompression when conservative treatment fails. However, spinal fusion alters the normal biomechanics of the back, which may potentially lead to premature disc degeneration at adjacent levels. A variety of implants have been investigated as alternatives to rigid interbody or posterolateral intertransverse spinal fusion. This evidence review addresses the implantation of prostheses intended to replace the facet joints and excised posterior elements, termed facet arthroplasty.

The objective of facet arthroplasty is to stabilize the spine while retaining normal intervertebral motion of the surgically removed segment following neural decompression. It is proposed that facet arthroplasty should also maintain the normal biomechanics of the adjacent vertebrae. If normal motion patterns are achieved by artificial joints in the spine, the risk of adjacent-level degeneration thought to be associated with fusion may be mitigated.  

Regulatory Status 
No facet arthroplasty devices have been approved by the U.S. Food and Drug Administration (FDA). The ACADIA^™ Facet Replacement System (Facet Solutions, Hopkinton, MA, acquired by Globus Medical in 2011) is currently being evaluated as part of an ongoing FDA-regulated investigational device exemption phase 3 trial. A phase 3 trial of the Total Facet Arthroplasty System^® (TFAS^®; Archus Orthopedics) has been discontinued. (Facet Solutions acquired Archus Orthopedics in 2009. In 2011, Globus Medical acquired Facet Solutions.)

Another implant design, the Total Posterior-element System (TOPS^™; Premia Spine), is currently available in Europe.

Related Policies
70187 Artificial Intervertebral Disc: Lumbar Spine 
701107 Interspinous Distraction Devices (Spacers)

Policy:
Total facet arthroplasty is investigational and/or unproven and therefore considered NOT MEDICALLY NECESSARY.

Policy Guidelines
Coding 
See the Codes table for details.

Rationale  
Evidence reviews assess the clinical evidence to determine whether the use of technology improves the net health outcome. Broadly defined, health outcomes are the length of life, quality of life and ability to function, including benefits and harms. Every clinical condition has specific outcomes that are important to patients and to managing the course of that condition. Validated outcome measures are necessary to ascertain whether a condition improves or worsens; and whether the magnitude of that change is clinically significant. The net health outcome is a balance of benefits and harms.

To assess whether the evidence is sufficient to draw conclusions about the net health outcome of technology, two domains are examined: the relevance and the quality and credibility. To be relevant, studies must represent one or more intended clinical uses of the technology in the intended population and compare an effective and appropriate alternative at a comparable intensity. For some conditions, the alternative will be supportive care or surveillance. The quality and credibility of the evidence depend on study design and conduct, minimizing bias and confounding that can generate incorrect findings. The randomized controlled trial is preferred to assess efficacy; however, in some circumstances, nonrandomized studies may be adequate. Randomized controlled trials are rarely large enough or long enough to capture less common adverse events and long-term effects. Other types of studies can be used for these purposes and to assess generalizability to broader clinical populations and settings of clinical practice.

Clinical Context and Therapy Purpose
The purpose of facet arthroplasty in patients who have lumbar spinal stenosis is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The question addressed in this evidence review is: Does facet arthroplasty improve the net health outcome in patients with lumbar spinal stenosis?

The following PICO was used to select literature to inform this review.

Patients
The relevant population of interest is individuals with lumbar spinal stenosis.

Intervention
The therapy being considered is facet arthroplasty. A variety of implants have been investigated as alternatives to rigid interbody or posterolateral intertransverse spinal fusion. This evidence review addresses the implantation of prostheses intended to replace the facet joints and excised posterior elements, termed facet arthroplasty. The objective of facet arthroplasty is to stabilize the spine while retaining normal intervertebral motion of the surgically removed segment following neural decompression. It is proposed that facet arthroplasty should also maintain the normal biomechanics of the adjacent vertebrae. If normal motion patterns are achieved by artificial joints in the spine, the risk of adjacent-level degeneration thought to be associated with fusion may be mitigated. Facet replacement is a surgical procedure requiring inpatient hospitalization.

Comparators
The following therapies/tools/rules/practices are currently being used to make decisions about facet arthroplasty.

Spinal fusion is a common surgical treatment following surgical decompression when conservative treatment fails. However, spinal fusion alters the normal biomechanics of the back, which may potentially lead to premature disc degeneration at adjacent levels. Facet arthropathy may also be treated with nerve ablation techniques.

Outcomes
The general outcomes of interest are pain, function, quality of life, and adverse events related to the surgical procedure. These outcomes should be measured over months to years.

A report by Palmer et al. (2011) indicated the U.S. Food and Drug Administration regulated multicenter investigational device exemption trial (NCT00418197) of the Total Facet Arthroplasty System was discontinued due to financial reasons.¹ Two of 10 Total Facet Arthroplasty System implants performed at the authors’ institution experienced stem fracture after total facet replacement.

A phase 3 multicenter randomized trial of the ACADIA^® Facet Replacement System (NCT00401518) was completed in October 2017 but results have not yet been fully published.The trial enrolled 390 subjects with lumbar spinal stenosis, and compared facet arthroplasty with the ACADIA^® system to spinal fusion. An abstract reported by Myer et al. (2014) in conference proceedings provided interim 2- and 4-year results for 243 patients.² According to a 2018 case report, 2 of 5 patients at one institution who received the ACADIA^® Facet Replacement System as part of the trial experienced a return of neurological symptoms, local tissue reaction and development of cobalt allergy.³

TOPS™ device, Smorgick et al. (2020) reported 11-year outcomes of 10 individuals from a single center in Israel who received the TOPS™ device as an adjunct to decompression to treat neurogenic claudication of at least 12 weeks' duration due to spinal stenosis with single-level grade 1 L4-5 degenerative spondylolisthesis.⁴ In this study, 6-week improvements in leg pain, back pain, disability and quality of life were generally maintained at 11 years. In terms of adverse events, there was one case of implant failure at 12 weeks that involved damaged polycarbonate urethane component that led to internal locking of the device. But, no other instances of screw loosenings or breakages, spontaneous fusion, or progression of the spondylolisthesis were observed. Although these findings are encouraging, more rigorous evaluation of the TOPS™ device in large randomized controlled trials is still needed to determine its effects on health outcomes.

Summary of Evidence
For individuals who have lumbar spinal stenosis who receive spinal decompression with facet arthroplasty, the evidence includes a preliminary report of a randomized controlled trial and a few case series studies. Relevant outcomes are symptoms, functional outcomes, quality of life, and treatment-related morbidity. Interim results from a pivotal trial of the ACADIA^® Facet Replacement System were reported in 2012. No additional publications from this trial, which was expected to be completed October 2015, have been identified to date. In addition to the lack of evidence on clinical outcomes with facet arthroplasty, no device has received U.S. Food and Drug Administration approval. The evidence is insufficient to determine the effects of the technology on health outcomes.

Practice Guidelines and Position Statements
No guidelines or statements were identified.

U.S. PREVENTIVE SERVICES TASK FORCE RECOMMENDATIONS
Not applicable 

ONGOING AND UNPUBLISHED CLINICAL TRIALS
Some currently unpublished trials that might influence this policy are listed in Table 1.

Table 1. Summary of Key Trials  

NCT: national clinical trial.
^a Denotes industry-sponsored or cosponsored trial.

References 

1. Palmer DK, Inceoglu S, Cheng WK. Stem fracture after total facet replacement in the lumbar spine: a report of two cases and review of the literature. Spine J. Jul 2011;11(7):e15-19. PMID 21703940
2. Myer J, Youssef JA, Rahn KA, et al. ACADIA facet replacement system IDE clinical trial: Preliminary outcomes at two-and four-years postoperative [abstract]. Spine J. 2014;11(Suppl. 1):S160-161.
3. Goodwin, MM, Spiker, WW, Brodke, DD, Lawrence, BB. Failure of facet replacement system with metal-on-metal bearing surface and subsequent discovery of cobalt allergy: report of 2 cases.. J Neurosurg Spine, 2018 Apr 14;29(1). PMID 29652237
4. Smorgick Y, Mirovsky Y, Floman Y et al. Long-term results for total lumbar facet joint replacement in the management of lumbar degenerative spondylolisthesis. J Neurosurg Spine. 2019 Oct;1-6:1-6. PMID 31585417

Coding Section

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.  

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross Blue Shield Association technology assessment program (TEC) and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

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