[The Facet Wedge: a minimally invasive technique for posterior segmental intra-articular fusion].

OBJECTIVE

Minimally invasive posterior segmental instrumentation and intra-articular fusion with the Facet Wedge device.

INDICATIONS: All fusion indications in degenerative disc disease without significant translational instability, postnucleotomy syndrome, spondylarthrosis, discitis.

CONTRAINDICATIONS: Translatory instabilities, status after decompression with partial facet joint resection, spondylolysis in the affected segment.

SURGICAL TECHNIQUE: Through a 3 cm skin incision, blunt transmuscular approach to the corresponding facet joint L1/2 to L5/S1. Opening of the joint capsule and visualisation of the intra-articular space. Cartilage removal and intra-articular implantation of the Facet Wedge device. Fixation of the implant by means of two angle-stable screws inserted in the corresponding facet joint parts.

POSTOPERATIVE MANAGEMENT: Early mobilisation under thomboprophylaxis. Wearing a trunk-stabilizing brace for up to 12 weeks, depending on the type and extent of the procedure. No restrictions regarding walking distance, standing and sitting immediately postoperatively after pain.

RESULTS

In all, 27 patients (mean age 51.2 years, range 30-76 years) were enrolled in the prospective nonrandomized study from 02/2015 to 9/2017 with a total of 31 treated segments. In 23 cases a ventrodorsal surgical technique was used, in 4 cases a purely dorsal procedure with interposition of an intervertebral cage. Follow-up was 2 years. The Oswestry Score (ODI) improved from an average of 40.6% preoperatively to 16.6% postoperatively. The visual analog scale (VAS) for back pain improved from an average of 6.7 points preoperatively to 2.1 points 2 years postoperatively. During this observation period, 2 implant-specific complications were observed. One Facet Wedge had to be revised due to misplacement with early loosening. In another case, loss of correction occurred in a preoperatively existing first-degree spondylolisthesis with revision to a dorsal screw-rod system.