title: Kinematic analysis following implantation of the PRESTIGE LP.
abstract: BACKGROUND
  The clinical success of cervical arthroplasty hinges on the ability to preserve or improve the biomechanics of the functional spinal unit. The purpose of this study was to conduct a radiologic assessment of kinematic parameters preimplantation and postimplantation of the PRESTIGE LP Cervical Disc System (Medtronic, Memphis, Tennessee).
  
  
  METHODS
  A total of 120 radiographs of 20 patients following single-level implantation of the PRESTIGE LP were retrospectively reviewed. Static and dynamic radiologic assessments were performed before surgery and at 1 year postoperation. Kinematic parameters including range of motion (ROM), horizontal translation, center of rotation (COR X, Y), anterior disc height and posterior disc height, and disc angle and shell angle were assessed for each spinal level using quantitative motion analysis software. Clinical outcomes were assessed using the short form health survey physical component scores and mental component scores.
  
  
  RESULTS
  The mean physical component scores and mental component scores of the short form health survey (SF-36) improved significantly following surgery. At 1 year postoperation, ROM, translation, and COR X were preserved. The COR Y shifted superiorly from 3.17 ± 2.08 mm preoperation to 0.98 ± 2.23 mm postoperation (P < .001). The anterior disc height and posterior disc height were significantly increased following surgery (3.97 ± 1.01 to 4.78 ± 1.11 mm and 3.04 ± 0.69 to 3.66 ± 0.61 mm, respectively; P < .01). The preoperative disc angle was 3.32° ± 2.92° and the postoperative shell angle was 1.11° ± 4.29°, with a mean change of -2.22° ± 4.63° (P < .05).
  
  
  CONCLUSIONS
  The PRESTIGE LP maintained preoperative ROM, translation, and COR X values. The postoperative COR Y value changed significantly by shifting superiorly, accompanied by an increase in DH. There was a loss of lordosis at the level of surgery, with the PRESTIGE LP endplates having an almost parallel endplate configuration.
authors.affiliation: Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada ; Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.
authors.forename: Izabela
authors.initials: I
authors.lastname: Kowalczyk
authors.affiliation: Division of Neurosurgery, London Health Sciences Center, London, Ontario, Canada.
authors.forename: Navjot
authors.initials: N
authors.lastname: Chaudhary
authors.affiliation: Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada ; Division of Neurosurgery, London Health Sciences Center, London, Ontario, Canada.
authors.forename: Neil
authors.initials: N
authors.lastname: Duggal
keywords: Cervical arthroplasty; Cervical disc prosthesis; Kinematics; PRESTIGE LP; Range of motion; Total disc replacement