Facet Wedge Spine System
Frank Kandziora and Maarten Spruit
The intended use, indications and contraindications for FW fixation are very similar to TFS fixation.
- Stand-alone (bilateral) in situ facet fusion with or without decompression
- Facet arthritis: fixation and fusion of facet joint
- Supplementary fixation after anterior cage or nonunion of ALIF
- Supplementary contra lateral fixation after MISS TLIF
- Unilateral application, except in combination with pedicle screw fixation on the contralateral side
- Compromised facets due to decompression techniques
- Fracture or other instabilities of the posterior elements
- Acute or chronic systemic or localized spinal infections
Tips for safety and effectiveness
The FW Spine System Risk Assessment identified that incorrect placement of the K-wire for rasp or FW positioning could result in damage to soft tissue, neural structures, or large blood vessels. A second risk involves the use of the facet opener. Excessive force or inappropriate manipulation may also lead to the damage of neural structures. Several control measures are incorporated into the Facet Wedge system to minimize these risks and plans are also in place to conduct a study that will measure their occurrence.
The Facet Wedge spine system includes the following implants and features (Fig 5):
Kirschner wire hole enables guided insertion over K-wire (a)
Rails stop translational motion and generate contact between subchondral bone and implant (a)
Low profile feature decreases muscle irritation (b)
Implant shoulder that controls insertion depth (b)
Teeth keep the implant in the desired position prior to screw insertion (b)
Divergent angular stable locking screws for primary fixation (b)
Various implant sizes to accommodate patient anatomy (b)
Perforations create optimal fusion conditions (c).
Cases provided by Frank Kandziora, Frankfurt, Germany
A 45-year-old healthy male patient experienced load dependent lower back pain (LBP) for 6 years, with no radicular pain and no neurologic deficit.
Multilevel facet pathology is shown in Fig 6. Intraoperative and postoperative images are shown (Fig 7-9).
A 51-year-old female patient experiencing LBP for 3 years (Fig 10).
A healthy 66-year-old female patient had been experiencing LBP for 5 years.
Cases provided by Maarten Spruit, Nijmegen, Netherlands
Case 4 : ALIF L4-L5 non union
A 40-year-old man 5 years after ALIF L4-L5 using SynFix with axial low back pain. The CT scan shows locked pseudarthrosis (Fig 17). Nonoperative treatment failed. The treatment option was bilateral Facet Wedge at L4-L5.
A less invasive approach was used with Insight Retractor using the bilateral Facet Wedge. No bone graft. X-ray follow-up after 3 months and CT assessment after 6 months (Fig 18-19).
Case 5 : Degenerative scoliosis
A female patient 66-years-old with back pain, leg pain, and degenerative deformity. The x-rays show left convex degenerative scoliosis Cobb T12-L3 38. Nonoperative treatment failed. Treatment option was posterior fusion T11-L5, with URS Facet Wedge L2-L3 unilaterally.
A conventional approach for posterior correction was taken, with indirect Foraminal decompression and Facet Wedge fusion (apex curve). Facet Wedge introduction after curve correction with rod in situ. X-ray follow-up initially (Fig 20), with CT assessment of Facet Wedge fusion after 6 months (Fig 21).
Primary stability and permanent fusion through locking of the facet joints.
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