title: Nubac disc arthroplasty: preclinical studies and preliminary safety and efficacy evaluations.
abstract: BACKGROUND
  Disc arthroplasty is gaining popularity for treatment of low-back pain caused by degenerative disc disease (DDD). It can involve total disc replacement or partial disc or nucleus replacement (or augmentation). Compared with total disc replacement, nucleus replacement is less invasive, has less surgical risk, has faster postoperative recovery, and doesn't "burn bridges" should further surgery be required. However, nucleus replacement has a high risk of implant expulsion because the device is not fixed to the vertebrae. Nubac is the first polyetheretherketone (PEEK)-on-PEEK articulated disc arthroplasty device designed to optimally restore the lumbar anatomy and biomechanics.
  
  
  METHODS
  ISO 10993 standards were used to evaluate the biocompatibility of the PEEK material. Chemical and thermal-mechanical tests and in vivo study assessed PEEK's biostability after exposure to high g irradiation and harsh oxidative conditions. Biomechanical tests to evaluate kinematic properties and anatomical restoration of the implanted lumbar motion segments and implant expulsion risk assessments were performed with a human cadaveric model. Because of the novelty of PEEK-on-PEEK as a self-mating articulating material, extensive wear tests were conducted with unidirectional and coupled motions. Static and fatigue strength also were tested. Animal study with a baboon model was conducted with gross, radiographic, biomechanical, and histological evaluations at 6 and 12 months postoperatively. Preliminary clinical data were collected through a prospective multicenter cohort study.
  
  
  RESULTS
  PEEK demonstrated exceptional biocompatibility and biodurability. Nubac restored disc height and motion segment range of motion. The unique articulating design of the Nubac demonstrated low risk of implant expulsion in a human cadaveric model. Wear tests showed that the Nubac has minimal wear and compares favorably to other disc arthroplasty materials. The Nubac also had excellent static and fatigue properties for the intended application. The animal study showed that the Nubac caused no adverse local or systematic tissue reaction and there was no detectable wear debris. The preliminary clinical data showed no major intraoperative vascular and neurological complications. There was significant Visual Analog Scale and Oswestry Disability Index score improvement.
  
  
  CONCLUSIONS
  The preclinical data supported the design rationale, and the preliminary clinical data (level II evidence) on safety and efficacy were encouraging.
  
  
  CONCLUSIONS
  The Nubac could be a viable first surgical option for patients with back pain caused by DDD.
authors: Pioneer Surgical Technology, Marquette, Mich.
authors: Qi-Bin
authors: QB
authors: Bao
authors: Pioneer Surgical Technology, Marquette, Mich.
authors: Matthew
authors: M
authors: Songer
authors: Santa Rita Hospital, Sao Paulo, Brazil.
authors: Luis
authors: L
authors: Pimenta
authors: Arkade Privatklinik Niederschmalkalden, Breitungen, Germany.
authors: Dieter
authors: D
authors: Werner
authors: Instituto de Ortopedia, Mexico City, Mexico.
authors: Alejandro
authors: A
authors: Reyes-Sanchez
authors: UO Ortopedia Traumatologia, Thiene, Italy.
authors: Massimo
authors: M
authors: Balsano
authors: Ospedale Sandro Pertini, Rome, Italy.
authors: Umberto
authors: U
authors: Agrillo
authors: Carolina Neurosurgery and Spine Association, Charlotte, NC.
authors: Domagoj
authors: D
authors: Coric
authors: Orthopedic Surgery Association of Marquette, Marquette.
authors: Kenneth
authors: K
authors: Davenport
authors: SUNY Upstate Medical University, Syracuse.
authors: Hansen
authors: H
authors: Yuan
keywords: PEEK-on-PEEK articulation; disc arthroplasty; nucleus replacement