title: Evaluation of the biological response of wear debris.
abstract: METHODS
  An animal study was conducted to evaluate the biological response to titanium particles from an artificial intervertebral disc in terms of serology and histologic changes.
  
  
  OBJECTIVE
  To determine the biological response to wear debris in the retroperitoneal and epidural space.
  
  
  BACKGROUND
  Few wear studies exist about mechanical artificial discs.
  
  
  METHODS
  Twenty-three New Zealand white rabbits were used for two approaches of the lumbar spine. In a retroperitoneal group (10 rabbits), lateral flank approach at the L2-L3 area was used. In an epidural group (13 rabbits), a dorsal laminotomy of L2 was performed. The wear debris was obtained from mechanical test cycling of the implantable intervertebral disc. At 4 and 12 weeks postoperatively, five or six animals from each group were killed. The tissues, including deposition site, regional lymph nodes and major organs, were evaluated with hematoxylin and eosin staining.
  
  
  RESULTS
  At death all rabbits were found to be healthy. Blood results from the predeath samples were found to be consistent with the preoperative blood work values. Scar tissue was minimal with good healing. All organs were found to be normal in appearance. On histopathology sections, adverse reactions such as fibrosis, granuloma formation or necrosis were not found in any tissues. Free particles were found sparingly in all tissue sections with minimal cellular response. No remarkable difference was found according to groups or time intervals. Smaller particles were found to be engulfed in macrophages without adverse biological consequences.
  
  
  CONCLUSIONS
  Titanium particles traveled from the sites of deposition but elicited no to minimal biological response.
authors.affiliation: Department of Orthopaedic Surgery, Johns Hopkins Medicine, 601 North Caroline Street, Baltimore, MD 21287, USA.
authors.forename: Bong-Soon
authors.initials: BS
authors.lastname: Chang
authors.forename: Phillip Rand
authors.initials: PR
authors.lastname: Brown
authors.forename: Ann
authors.initials: A
authors.lastname: Sieber
authors.forename: Antonio
authors.initials: A
authors.lastname: Valdevit
authors.forename: Kei
authors.initials: K
authors.lastname: Tateno
authors.forename: John Philip
authors.initials: JP
authors.lastname: Kostuik
mesh_terms: D000818:Animals; D019643:Arthroplasty, Replacement / Q000295:instrumentation*; D001672:Biocompatible Materials / Q000009:adverse effects; D007403:Intervertebral Disc; D007595:Joint Prosthesis / Q000009:adverse effects; D008159:Lumbar Vertebrae; D008297:Male; D023421:Models, Animal; D010003:Osteoarthritis / Q000601:surgery; D011475:Prosthesis Failure; D011817:Rabbits; D014025:Titanium
chemical_list: D001672:Biocompatible Materials; D014025:Titanium