Lumbar Facet Resurfacing: First Experience With the FENIX Implant.

Abstract

This is a feasibility study to confirm the design, patient population, and the surgical technique for FENIX implants. This study evaluated the safety and the clinical and radiologic performance of bilaterally implanted FENIX facet resurfacing device. Facet joint osteoarthritis is responsible for up to 30% of chronic low back pain. Arthroplasty is a surgical treatment option that aims to relieve pain while maintaining or restoring motion. A total of 8 consecutive patients with proven single segmental bilateral lumbar facet joint osteoarthritis as unique pain generator received a bilateral implantation of the FENIX device. Correct device placement and mobility preservation were assessed on x-ray at 6 weeks and at 6, 12, and 24 months after implantation. Magnetic resonance imaging at 12 and 24 months after surgery assessed the bony ingrowth and computed tomography-single photon emision computed tomography was repeated at 6 months to assess evolution of the preoperative inflamed facet joints. The Oswestry disability index, pain visual analogue scale, and the need for analgesic medication were the parameters used for clinical assessment. At 24 months after surgery, 7 of the 8 patients were found to have all implants in place and all assessed parameters were found to be normal. Patients experienced significant pain relief and functionality improvement. Mobility was maintained and no Modic changes were noted, either at the index or at the adjacent levels. No "hot" lesions at the implanted levels were observed on computed tomography-single photon emision computed tomography. One of the 48 (2%) implants was found to be dislocated at 6 months follow-up. The FENIX facet resurfacing technique might be considered in the future as a surgical treatment of well-selected patients suffering from chronic low back pain because of facet joint osteoarthritis. A modification of the superior implant should provide an initial firm fixation preventing implant dislocation.