FFX® facet cages have been studied in 8 peer-reviewed publications: 6 clinical studies and 2 biomechanical studies. Each study is summarized below with its design, sample size and key results, with a link to the original article.
fusion rate
on CT scan
operative time
vs Pedicle screws
blood loss
vs Pedicle screws
less metal than
Pedicle screws
89% to 91% of FFX® devices achieve bony fusion of the facet joint on CT scan.
| Study | Population | Follow-up | Fusion rate |
|---|---|---|---|
| Mostofi, 2025 | 100 patients | 12 months | 91% |
| Houari et al., 2024 | 252 devices (56 patients) | 2+ years | 91%with FFX® and its facet screw (45 patients); 89% across all devices |
| Srour et al., 2020 | 205 devices (53 patients) | 12 months | 89%standalone, without concomitant PLIF cages (38 patients); 86% across all devices |
Shorter surgery and less blood loss than Pedicle screws, with similar clinical results at 2 years.
| Outcome | FFX® | Pedicle screws | Study |
|---|---|---|---|
| Mean operative time | 99 min | 153 min | Srour, 202270 patients, p < 0.001 |
| Mean blood loss | 251 mL | 447 mL | Srour, 202270 patients, p < 0.01 |
| Fusion at 2+ years | 91%with facet screw; 89% across all devices | 85% | Houari et al., 2024112 patients |
| Reoperation at 2 years | 3.6% | 10.7% | Houari et al., 2024112 patients, not significant |
Pain and disability are roughly halved after FFX® facet arthrodesis.
| Study | Measure | Before | After | P |
|---|---|---|---|---|
| Mostofi et al., 2026118 patients, positive injection test, 3 months | Oswestry Disability IndexODI | 70.9 | 34.5 | < 0.05 |
| Mostofi, 2025100 patients, 12 months | Oswestry Disability IndexODI VAS pain | 46 7.2 | 18 2.1 | < 0.05 < 0.05 |
| Srour et al., 202053 patients, 12 months; 93% improved in VAS or Oswestry score | Oswestry Disability IndexODI Back pain VAS Leg pain VAS | 44.7% 5.7 5.6 | 24.0% 3.1 2.1 | < 0.001 < 0.001 < 0.001 |
| Houari et al., 202456 FFX® patients, 2+ years; similar to Pedicle screws | Oswestry Disability IndexODI Back pain VAS Leg pain VAS | 52% 6.30 5.73 | 35% 3.45 2.38 | < 0.001 < 0.001 < 0.001 |
All-cause postoperative complications, mostly transient sciatica, similar to Pedicle screws (16.1% vs 19.6%).
Houari et al., 2024; Srour et al., 2020; Mostofi, 2025Mean increase at 2+ years after surgery vs preoperative (P < 0.001).
Houari et al., Clin Spine Surg, 2024in lumbar stenosis patients; their back pain improved more after surgery (4.7 vs 1.8 VAS points).
Houari et al., J Craniovertebr Junction Spine, 2025when FFX® is added to a long construct (L2-S1); -57% in a short construct (L4-L5).
Saddiki et al., Int J Spine Surg, 2025vs Pedicle screws before fusion (L5-S1; -13.5% at L3-L4); equivalent stability after fusion.
Simon et al., Int J Spine Surg, 2022Surgical success was largely independent of injection test and SPECT/CT results; the injection test better predicted functional outcome.
Mostofi et al., J Craniovertebr Junction Spine, 2026Six clinical and two biomechanical studies, most recent first.
Mostofi K, Peyravi M, Shirbacheh A, Shirbache K. J Craniovertebr Junction Spine. 2026;17(3):244-250. DOI: 10.4103/jcvjs.jcvjs_227_25
Key results. Oswestry Disability Index improved from 70.9 to 34.5 at 3 months in patients with a positive injection test. Surgical success was largely independent of preoperative injection test and SPECT/CT results; the injection test predicted functional outcome better than SPECT/CT.
Houari O, Ben Ammar M, Mortada J, Bolognini F, Musacchio M, Lebedenski A, Srour R. J Craniovertebr Junction Spine. 2025;16:343-348. DOI: 10.4103/jcvjs.jcvjs_11_25
Key results. 73% of stenosis patients had a positive medial branch block, confirming facet-generated back pain. Back pain improved more in patients with a positive block than in those with a negative block (4.7 vs 1.8 VAS points); leg pain improved similarly in both groups.
Mostofi K. Eur J Orthop Surg Traumatol. 2025;35(1):299. DOI: 10.1007/s00590-025-04425-y
Key results. 91% fusion rate at 12 months; mean VAS pain from 7.2 to 2.1 and Oswestry Disability Index from 46 to 18 at 12 months; low complication rate.
Houari O, Douanla A, Ben Ammar M, et al. Clin Spine Surg. 2024. DOI: 10.1097/BSD.0000000000001704
Key results. Bony fusion at 2+ years in 91% of patients treated with FFX® and its facet screw (45 patients); 89% across all 252 FFX® devices implanted vs 85% with Pedicle screws. Mean foraminal height increased by 3.7 mm. Reoperation 3.6% with FFX® vs 10.7% with Pedicle screws (not statistically significant). VAS and Oswestry scores improved significantly in both groups, with no difference between groups.
Srour R. Cureus. 2022;14(3):e22931. DOI: 10.7759/cureus.22931
Key results. Mean operative time 99 min vs 153 min (p < 0.001); mean blood loss 251 mL vs 447 mL (p < 0.01).
Srour R, Gdoura Y, Delaitre M, et al. Int J Spine Surg. 2020;14(6):996-1002. DOI: 10.14444/7149
Key results. 86.3% of implanted devices showed facet fusion at 12 months (88.7% in patients without concomitant PLIF cages). Leg pain VAS from 5.6 to 2.1, back pain VAS from 5.7 to 3.1, Oswestry Disability Index from 44.7% to 24.0% (all p < 0.001); 93% of patients improved in VAS or Oswestry score. No surgical complication and no revision surgery.
Saddiki R, Dhenin A, Montron L, et al. Int J Spine Surg. 2025. DOI: 10.14444/8826
Key results. Adding FFX® to Pedicle screws reduced the stress on the screws by 57% in a short construct (L4-L5) and by 62% in a long construct (L2-S1).
Simon L, Millot F, Hoarau X, et al. Int J Spine Surg. 2022;16(5):935-943. DOI: 10.14444/8355
Key results. Before fusion, stress on the facets of the adjacent levels was up to 15.7% lower with FFX® (13.5% lower at L3-L4, 15.7% lower at L5-S1), and adjacent disc stress at L5-S1 was 7.7% higher with Pedicle screws. After fusion, both constructs provided equivalent stability.
Randomized controlled trial
Decompression plus FFX® vs decompression alone, 1 to 3 levels (L1 to S1). Primary endpoint: composite clinical success at 2 years (back pain reduction of more than 20 mm on the VAS, no reoperation at the index level, no additional lumbar treatment).
Sponsor: SC MEDICA. ClinicalTrials.gov: NCT06106061
Schmoelz W, et al. Clin Biomech. 2025;124:106491.
Key results. Compared with discectomy alone, smaller increase in range of motion in all three planes and less disc height loss; no subsidence or migration of the device.
Srour R, et al. J Orthop. 2021;25:173-178.
Key results. Reoperation for same-level reherniation 0.9% with DIVA® vs 9.8% with discectomy alone (P = 0.0032); all-cause reoperation 4.5% vs 11.3% (P = 0.055); pain and disability improved similarly in both groups.
In published studies, most patients treated with FFX® facet arthrodesis report clearly less pain and better function one year after surgery, and most implants achieve bony fusion of the facet joint.
In a prospective multicenter study, 93% of patients improved on pain or disability scores at 12 months, and disability (Oswestry score) fell by almost half, from 44.7% to 24.0%. In a series of 100 patients, average pain fell from 7.2 to 2.1 out of 10.
Fusion of the facet joints was confirmed on CT scan in 89% to 91% of devices, depending on the study.
Srour et al., Int J Spine Surg, 2020; Mostofi, Eur J Orthop Surg Traumatol, 2025; Houari et al., Clin Spine Surg, 2024.
With the FFX® facet cage, published fusion rates range from 89% to 91%, assessed on CT scan from 12 months to more than 2 years after surgery.
In the first prospective multicenter study, 89% of devices were fused at 12 months when FFX® was used standalone, without interbody (PLIF) cages, and 86% across all 205 devices. In a comparative study, 91% were fused at 2+ years when FFX® was used with its facet screw, and 89% across all 252 devices. A series of 100 patients reported a 91% fusion rate at 12 months.
Houari et al., Clin Spine Surg, 2024; Mostofi, Eur J Orthop Surg Traumatol, 2025; Srour et al., Int J Spine Surg, 2020.
Yes. FFX® is authorized for use on its own, without Pedicle screws, including in patients with moderate instability up to grade I spondylolisthesis. It is also the first facet cage FDA cleared for standalone use. The instructions for use give the full indications and contraindications.
This matters because Pedicle screws are the most invasive part of a conventional fusion. In the published comparative studies, patients with lumbar spinal stenosis were treated with decompression and FFX® instead of Pedicle screws, with shorter surgery, less blood loss and similar clinical improvement at 2 years.
It also means much less hardware: a single-level FFX® construct contains about 19 times less implant metal than a single-level Pedicle screw construct (SC MEDICA calculation based on the most frequently implanted sizes).
Pedicle screw fixation remains the option for higher-grade spondylolisthesis, gross instability or deformity.
Srour, Cureus, 2022; Houari et al., Clin Spine Surg, 2024.
Facet arthrodesis with FFX® stabilizes the spine with far less hardware than Pedicle screw fusion, and comparative studies show a shorter, less bloody operation with similar results at 2 years.
A single-level FFX® construct (2 facet cages and 2 facet screws) contains about 19 times less implant metal than a single-level Pedicle screw construct (4 screws, 4 locking caps and 2 rods), according to SC MEDICA’s calculation based on the most frequently implanted sizes. This is the MiNVI principle: the minimum instrumentation needed to reach fusion.
In a cohort of 70 patients, surgery took 99 minutes on average with FFX® vs 153 minutes with Pedicle screws, and blood loss was 251 mL vs 447 mL. In a cohort of 112 patients, clinical improvement at 2 years was similar in both groups; reoperation was 3.6% with FFX® vs 10.7% with Pedicle screws, a difference that was not statistically significant.
Srour, Cureus, 2022; Houari et al., Clin Spine Surg, 2024.
Yes. Most published studies with FFX® were conducted in patients undergoing decompression for lumbar spinal stenosis. In the U.S., FFX® is FDA cleared for lumbar degenerative disc disease and/or degenerative facet disease with instability, from L3 to S1.
Srour et al., Int J Spine Surg, 2020; Houari et al., Clin Spine Surg, 2024; Houari et al., J Craniovertebr Junction Spine, 2025.
A positive block helps, but it is not a gate. Patients with a positive block recover best functionally, yet patients with a negative block can also benefit from facet arthrodesis when the clinical diagnosis of facet syndrome is clear.
In a study of 118 patients, all were first selected on clinical grounds: pain on hyperextension, pain on palpation of the facet joints and imaging signs of facet disease. The injection test and SPECT/CT came afterwards. Pain and disability improved significantly in all patient groups, including patients with negative tests, while a positive injection test was associated with greater functional recovery (P = 0.049). A negative test therefore did not identify patients who failed to benefit from surgery. One possible explanation, not tested in the study, is the known limited sensitivity of these tests.
In practice, these results suggest that facet blocks are useful in the workup but should not, on their own, exclude a patient with a clear clinical diagnosis of facet syndrome. Larger studies are needed to confirm this.
Mostofi et al., J Craniovertebr Junction Spine, 2026; Houari et al., J Craniovertebr Junction Spine, 2025.
It can be, depending on what the workup finds. When facet pain keeps coming back despite injections and radiofrequency ablation, the next step is to look for an underlying segmental instability, for example on flexion-extension radiographs.
Radiofrequency ablation gives temporary relief because the medial branch nerves regenerate, and it does not treat instability. When instability is confirmed, FFX® can be considered to treat degenerative facet disease with instability by fusing the facet joints.
A randomized trial is under way. It tests whether adding FFX® to decompression is superior to decompression alone in 320 patients with lumbar spinal stenosis (ClinicalTrials.gov NCT06106061).
Published evidence to date includes a prospective multicenter study, comparative cohorts and biomechanical studies.
As with all medical devices, there are risks and considerations to device use. Please refer to the device labeling for a full discussion of potential risks, contraindications, warnings, precautions, and instructions for use. The information presented on this website is intended only as a brief summary for visitor convenience. Not all products or indications are cleared in every country and may be subject to further local variations. For specific product information, you should always consult the local product documentation. For advice on medical issues, you should always consult your local medical practitioner.
