title: Two-year observation of artificial intervertebral disc replacement: results after supplemental ultra-high strength bioresorbable spinal stabilization.
abstract: OBJECTIVE
  This 2-year experimental study was conducted to investigate the efficacy of a bioactive three-dimensional (3D) fabric disc for lumbar intervertebral disc replacement. The authors used a bioresorbable spinal fixation rod consisting of a forged composite of particulate unsintered hydroxyapatite/poly-L-lactide acid (HA/PLLA) for stability augmentation. The biomechanical and histological alterations as well as possible device-related loosening were examined at 2 years postoperatively.
  
  
  METHODS
  Two lumbar intervertebral discs (L2-3 and L4-5) were replaced with the 3D fabric discs, which were augmented by two titanium screws and a spanning bioresorbable rod (HA/PLLA). The segmental biomechanics and interface bone ingrowth were investigated at 6, 15, and 24 months postoperatively, and results were compared with the other two surgical groups (3D fabric disc alone; 3D fabric disc with additional anterior instrumentation stabilization). The 3D fabric disc and HA/PLLA-spinal segments demonstrated segmental mobility at 15 and 24 months; however, the range of motion (ROM) in flexion-extension decreased to 49 and 40%, respectively, despite statistically equivalent preserved torsional ROM. Histologically there was excellent osseous fusion at the 3D fabric disc surface-vertebral body interface. At 2 years posttreatment, no adverse tissue reaction nor aseptic loosening of the device was observed.
  
  
  CONCLUSIONS
  Intervertebral disc replacement with the 3D fabric disc was viable and when used in conjunction with the bioresorbable HA/PLLA spinal augmentation. Further refinements of device design to create a stand-alone type are necessary to obviate the need for additional spinal stabilization.
authors.affiliation: Department of Orthopaedic Surgery, Hokkaido University Graduate School of Medicine, Kitaku, Sapporo, Japan. y-kotani@med.hokudai.ac.jp
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Kotani
authors.forename: Kuniyoshi
authors.initials: K
authors.lastname: Abumi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Shikinami
authors.forename: Masahiko
authors.initials: M
authors.lastname: Takahata
authors.forename: Ken
authors.initials: K
authors.lastname: Kadoya
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kadosawa
authors.forename: Akio
authors.initials: A
authors.lastname: Minami
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kaneda
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D017886:Durapatite; D005500:Follow-Up Studies; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology / Q000601:surgery*; D019344:Lactic Acid; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery; D008422:Materials Testing; D008567:Membranes, Artificial; D011091:Polyesters; D011108:Polymers; D019736:Prostheses and Implants; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012756:Sheep; D013122:Spinal Diseases / Q000601:surgery; D013123:Spinal Fusion / Q000295:instrumentation
chemical_list: D001672:Biocompatible Materials; D008567:Membranes, Artificial; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D017886:Durapatite