MiNVI Minimum Necessary Volume of Instrumentation.

MiNVI stands for Minimum Necessary Volume of Instrumentation. It is SC MEDICA's design philosophy: use the least invasiveness and the least hardware needed to achieve the intended clinical result.

In practice, MiNVI places instrumentation only where fusion is sought. FFX® facet arthrodesis applies this principle to spinal fusion: the facet joints are stabilized and fused from the inside, without Pedicle screws or rods.

Yes, for degenerative conditions with up to moderate instability (grade I spondylolisthesis). Facet arthrodesis is a fusion, but a targeted one: instead of locking the segment from the outside with Pedicle screws and rods, FFX® fuses the facet joints from the inside.

In fact, a Pedicle screw fusion also aims for a bony bridge across the facet joints. FFX® goes straight to that goal, without Pedicle screws or rods.

In comparative studies, surgery was shorter (99 vs 153 minutes) and blood loss lower (251 vs 447 mL) than with Pedicle screws, with 91% fusion on CT scan at 2+ years (with the FFX® locking screw) and similar clinical improvement.

Pedicle screw fusion also increases the load on the adjacent levels, a recognized factor of adjacent segment disease (ASD). In a comparative study, most reoperations in the Pedicle screw group were for ASD. In a finite element study, stress on the adjacent facets was up to 15.7% lower with FFX® than with Pedicle screws before fusion, and adjacent disc stress was 7.7% higher with Pedicle screws.

Srour, Cureus, 2022; Houari et al., Clin Spine Surg, 2024; Simon et al., Int J Spine Surg, 2022.

Yes. Arthrodesis is the medical term for the surgical fusion of a joint: the two bones grow together into a single block of bone.

In the spine, "fusion" usually refers to fusing two vertebrae, either through the disc space (when an interbody cage is used) or between the transverse processes and facet joints, with Pedicle screws and rods holding the segment. Facet arthrodesis fuses the facet joints alone. With FFX®, the fusion is obtained directly where the motion comes from, inside the facet joint.

Both stabilize the facet joint, but in different ways. A traditional transfacet screw crosses the joint to hold it still, but does not fill the gap inside the joint. FFX® is a facet cage: it is placed inside the joint, filling the intra-facet gap, after the facet surfaces have been prepared with a rasp, and is secured with an FFX® locking screw. This design brings three advantages:

Better load distribution. In a finite element study, stress concentrated around the transfacet screw, whereas FFX® spread the load across the joint, which suggests a lower risk of loosening.

Facet preparation for bony fusion. Rasping the facet surfaces before placing the cage promotes bone growth across the joint.

Restoration of foraminal height. The cage gently opens the joint: mean foraminal height increased by 3.7 mm at 2+ years.

Simon et al., Int J Spine Surg, 2022; Houari et al., Clin Spine Surg, 2024.

A single-level FFX® construct (2 FFX® cages and 2 FFX® locking screws, 4 components) contains about 18 times less implanted metal than a single-level Pedicle screw construct (4 Pedicle screws, 4 locking caps and 2 rods, 10 components). And this calculation does not even include the interbody cage that is often added to a Pedicle screw fusion.

This is an SC MEDICA calculation based on the most frequently implanted sizes.

Yes. FFX® can be placed through an open, mini-invasive (tubular), endoscopic or fully percutaneous tubeless approach. The choice depends on the patient's anatomy, the associated decompression and the surgeon's training.

Higher-grade spondylolisthesis (grade II or more), gross instability and deformity still call for Pedicle screw fixation.

In these cases, adding FFX® to the Pedicle screw construct reduces the mechanical stress on the screws: by 57% in a short construct (L4-L5) and by 62% in a long construct (L2-S1), in a finite element study.

And FFX® does not prevent a subsequent Pedicle screw fixation, if one becomes necessary.

Saddiki et al., Int J Spine Surg, 2025.