Spinal surgery has long sought the optimal strategy for achieving stable fusion between adjacent vertebrae. Traditionally, posterior fixation has relied on pedicle screws, rods, and interbody cages. However, stabilization of the facet joint—until recently an underutilized site for direct fusion—has attracted growing attention as technology and biomechanics have evolved.
Recently, devices known as facet cages—implants that combine cage-like geometry with fixation elements for facet arthrodesis—have received FDA clearance in the United States, marking a new chapter in spinal innovation. Yesterday, the FDA cleared the FFX® Facet Cage from SC Medica, the first facet fusion device approved for stand-alone lumbar use—a milestone that could redefine posterior spinal instrumentation.
What is a Facet Cage?
Facet joints, located on the posterior aspect of the spine, play a critical role in controlling motion and maintaining segmental stability. When degenerated or unstable, they often become a primary source of axial pain and dysfunction.
A facet cage is a small implant inserted within the articular joint space. It replaces the degenerated cartilage with bone graft material, promoting direct osseous fusion between the articular surfaces. This eliminates pathological motion and stabilizes the segment biomechanically.
Historically, facet fusion was performed only as an adjunct to other stabilization techniques—most commonly alongside pedicle screws or interbody cages. Devices like the FFX® now allow the facet joint itself to serve as the primary fusion site, enabling a more direct and minimally invasive approach.
Which FDA-cleared facet fusion systems are currently available, and how do they differ?
1.FFX® Facet Cage (SC Medica): The First Stand-Alone Approval
The FDA granted clearance to the FFX® Facet Cage, developed by SC Medica, making it the first and only facet device approved for stand-alone lumbar fusion. Unlike earlier systems intended merely as supplemental fixation, the FFX® provides bilateral stability and complete facet fusion independently. The device is implanted minimally invasively within the facet joints, which are packed with bone graft to achieve controlled compression and immediate segmental stability.This clearance represents a paradigm shift in posterior spinal surgery, validating facet fusion as a viable primary alternative to traditional pedicle-based constructs.
Potential Benefits
- Reduced surgical invasiveness and operative time
- Decreased blood loss and paraspinal muscle disruption
- Elimination of pedicle screws or interbody cages in select cases
- Simplified instrumentation and lower overall metal burden
2.CAVUX® FFS and FFS-LX (Providence Medical Technology): Adjunctive Facet Fixation
Prior to the FFX®, Providence Medical Technology (PMT) pioneered facet-based systems for adjunctive fixation: the CAVUX® FFS and CAVUX® FFS-LX.
- CAVUX® FFS received FDA clearance in 2022 for the treatment of cervical pseudarthrosis (failed fusion following ACDF).
- CAVUX® FFS-LX, approved in 2024, extended the concept to lumbar fusion at one to two levels.
These devices combine a small facet spacer with an integrated screw, providing rigid intra-articular fixation. Multicenter studies have reported fusion rates near 96% and significant improvement in pain and function at 30-month follow-up. However, both systems are cleared only as supplemental devices, requiring use alongside pedicle screws or other posterior constructs.
Other FDA-Cleared Facet Fusion Systems
While the FFX® remains the only stand-alone facet cage, several other facet fixation systems have received FDA clearance for adjunctive indications:
3.-zLOCK (ZygoFix) :It represents a next-generation facet fixation solution designed to provide supplemental stabilization during lumbar fusion procedures. Cleared by the FDA under 510(k) K242650, the system is indicated for use as an adjunct to single-level interbody fusion in skeletally mature patients. It achieves bilateral fixation of the facet joints through a minimally invasive approach, offering immediate mechanical stability without the need for extensive instrumentation. The system employs a unique, screwless, self-locking implant geometry that preserves surrounding bone integrity while reducing operative time. Its FDA clearance underscores the growing recognition of facet-based fixation as a complementary modality within the broader context of lumbar arthrodesis.
4.-AERO™ Facet Fusion System (Aurora Spine)
The AERO™ Facet Fusion System, developed by Aurora Spine, received FDA 510(k) clearance in early 2025 as a minimally invasive solution for facet joint fusion from C2 to S1. The system features a patented implant design intended to treat patients suffering from chronic axial pain or instability originating from degenerative or arthritic facet joints. The AERO™ system enables intra-articular placement through a small percutaneous access, allowing for targeted joint preparation and graft placement while minimizing tissue disruption. It can be used as a stand-alone facet fusion device or as an adjunct to larger spinal fusion procedures, expanding its clinical versatility across cervical, thoracic, and lumbar applications. This clearance highlights Aurora Spine’s focus on motion-preserving and tissue-sparing spinal technologies.
Expectations and Ongoing Research
The rise of facet fusion systems reflects a broader trend toward minimally invasive, biomechanically aligned procedures. For carefully selected patients—such as those with isolated facet degeneration, localized axial pain, or revision scenarios—facet cages may reduce the need for extensive exposure and minimize complications.
Ongoing research is focused on:
- Optimizing implant materials, including porous titanium, advanced PEEK, and bioactive coatings
- Integrating navigation and robotic guidance
- Generating long-term comparative data versus traditional pedicle-based fusion
Despite their promise, facet cages face several challenges. Current clinical evidence is limited, with most studies reporting follow-up periods under three years. Careful patient selection is critical, as isolated facet fusion may be insufficient in cases of advanced instability, deformity, or multilevel pathology.
Broader adoption will depend on surgeon familiarity, access to intraoperative imaging or navigation, and the development of robust long-term outcome data.
Although long-term data are still emerging, the potential impact of these devices on spinal practice is undeniable. Spinal surgery appears to be moving toward simpler, less invasive, and biomechanically faithful solutions that more closely emulate the natural stability of the spine.
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