title: The use of polyurethane materials in the surgery of the spine: a review.
abstract: BACKGROUND
  The spine contains intervertebral discs and the interspinous and longitudinal ligaments. These structures are elastomeric or viscoelastic in their mechanical properties and serve to allow and control the movement of the bony elements of the spine. The use of metallic or hard polymeric devices to replace the intervertebral discs and the creation of fusion masses to replace discs and/or vertebral bodies changes the load transfer characteristics of the spine and the range of motion of segments of the spine.
  
  
  OBJECTIVE
  The purpose of the study was to survey the literature, regulatory information available on the Web, and industry-reported device development found on the Web to ascertain the usage and outcomes of the use of polyurethane polymers in the design and clinical use of devices for spine surgery.
  
  
  METHODS
  A systematic review of the available information from all sources concerning the subject materials' usage in spinal devices was conducted.
  
  
  METHODS
  A search of the peer-reviewed literature combining spinal surgery with polyurethane or specific types and trade names of medical polyurethanes was performed. Additionally, information available on the Food and Drug Administration Web site and for corporate Web sites was reviewed in an attempt to identify pertinent information.
  
  
  RESULTS
  The review captured devices that are in testing or have entered clinical practice that use elastomeric polyurethane polymers as disc replacements, dynamic stabilization of spinal movement, or motion limitation to relieve nerve root compression and pain and as complete a listing as possible of such devices that have been designed or tested but appear to no longer be pursued. This review summarizes the available information about the uses to which polyurethanes have been tested or are being used in spinal surgery.
  
  
  CONCLUSIONS
  The use of polyurethanes in medicine has expanded as modifications to the stability of the polymers in the physiological environment have been improved. The potential for the use of elastomeric materials to more closely match the mechanical properties of the structures being replaced and to maintain motion between spinal segments appears to hold promise. The published results from the use of the devices that are discussed show early success with these applications of elastomeric materials.
authors.affiliation: Department of Biomedical Materials Science, University of Mississippi Medical Center, 2500 N State St, Jackson, MS 39216-4505, USA. Electronic address: kstjohn@umc.edu.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: St John
mesh_terms: D006801:Humans; D011140:Polyurethanes / Q000627:therapeutic use*; D013131:Spine / Q000601:surgery*; D059145:Total Disc Replacement / Q000295:instrumentation / Q000379:methods*
chemical_list: D011140:Polyurethanes
keywords: Disc replacement; Dynamic stabilization; Motion sparing; Polyurethane; Review; Spinal surgery