title: Percutaneous posterior cervical fusion with the DTRAX Facet System for single-level radiculopathy: results in 60 patients.
abstract: OBJECTIVE
  The authors present 1-year results in 60 patients with cervical radiculopathy due to spondylosis and stenosis that was treated with a bilateral percutaneous facet implant. The implant consists of a screw and washer that distracts and immobilizes the cervical facet for root decompression and fusion. Clinical and radiological results are analyzed.
  
  
  METHODS
  Between 2009 and 2011, 60 patients were treated with the DTRAX Facet System in a multicenter prospective single-arm study. All patients had symptomatic clinical radiculopathy, and conservative management had failed. The majority of patients had multilevel radiographically confirmed disease. Only patients with single-level radiculopathy confirmed by history, physical examination, and in some cases confirmatory nerve blocks were included. Patients were assessed preoperatively with Neck Disability Index, visual analog scale, quality of life questionnaire (Short Form-12 version 2), CT scans, MRI, and dynamic radiographs. Surgery was percutaneous posterior bilateral facet implants consisting of a screw and expandable washer and iliac crest bone aspirate. Patients underwent postoperative assessments at 2 weeks, 6 weeks, 3 months, 6 months, and 1 year with validated outcome questionnaires. Alterations of segmental and overall cervical lordosis, foraminal dimensions, device retention and fusion criteria were assessed for up to 1 year with CT reconstructions and radiographs. Fusion criteria were defined as bridging trabecular bone between the facets, translational motion < 2 mm, and angular motion < 5°.
  
  
  RESULTS
  All patients were followed to 1 year postoperatively. Ages in this cohort ranged from 40 to 75 years, with a mean of 53 years. Forty-two patients were treated at C5-6, 8 at C6-7, 7 at C4-5, and 3 at C3-4. Fifty-six had bilateral implants; 4 had unilateral implants due to intraoperative facet fracture (2 patients) and inability to access the facet (2 patients). The Neck Disability Index, Short Form-12 version 2, and visual analog scale scores were significantly improved at 2 weeks and remained significantly improved up to 1 year. At the treated level, 93% had intrafacet bridging trabecular bone on CT scans, translational motion was < 2 mm in 100% and angular movement was < 5° in 83% at the 1-year follow-up. There was no significant change in overall cervical lordosis. There was a 1.6° loss of segmental lordosis at the treated level at 1 year that was significant. Foraminal width, volume, and posterior disc height was significantly increased at 6 months and returned to baseline levels at 1 year. There was no significant decrease in foraminal width and height at adjacent levels. There were no reoperations or surgery- or device-related complications, including implant failure or retained hardware.
  
  
  CONCLUSIONS
  Results indicate that the DTRAX Facet System is safe and effective for treatment of cervical radiculopathy.
authors: Clinical Faculty, Department of Neurosurgery, University of California San Francisco Medical Center, San Francisco, CA, USA. bruce@neurospine.org
authors: Bruce M
authors: BM
authors: McCormack
authors: Rafael C
authors: RC
authors: Bundoc
authors: Mario R
authors: MR
authors: Ver
authors: Jose Manuel F
authors: JM
authors: Ignacio
authors: Sigurd H
authors: SH
authors: Berven
authors: Edward F
authors: EF
authors: Eyster
mesh_terms: D002574:Cervical Vertebrae / Q000601:surgery*; D003952:Diagnostic Imaging; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants; D011474:Prosthesis Design; D011843:Radiculopathy / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation*; D013130:Spinal Stenosis / Q000601:surgery*; D055009:Spondylosis / Q000601:surgery*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D021801:Zygapophyseal Joint / Q000601:surgery