title: Computer-assisted mosaic arthroplasty using patient-specific instrument guides.
abstract: OBJECTIVE
  Success of mosaic arthroplasty requires that the transplanted plugs be positioned to reconstruct the curvature and height of the original articular surface. This case report demonstrates how to achieve correct plug positioning using patient-specific instrument guides manufactured on a 3D printer.
  
  
  METHODS
  Using a 3D computer model of bone and cartilage, the harvesting of plugs and their placement at the defect site was planned on the computer. Instrument guides were manufactured in thermoplastic on a 3D printer; the bottom surface of the guides fit to the contour of the knee and the top surface contained holes to precisely position the surgical instruments. The instrument guides were used on a young female patient to repair a large articular cartilage defect in the left knee.
  
  
  RESULTS
  The patient showed an increased range of motion in the knee and also a decrease in pain and discomfort at her 2-year follow-up. A CT arthrogram at 2 years postoperative showed a smooth and appropriate contour of the reconstructed cartilage over the defect.
  
  
  CONCLUSIONS
  Image-based preoperative planning and the use of patient-specific instrument guides can yield a good patient outcome without requiring optically tracked intraoperative guidance.
authors.affiliation: Department of Surgery, Kingston General Hospital, Queen's University, Kingston, ON, K7L 3N6, Canada.
authors.forename: Manuela
authors.initials: M
authors.lastname: Kunz
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Waldman
authors.forename: John F
authors.initials: JF
authors.lastname: Rudan
authors.forename: Davide D
authors.initials: DD
authors.lastname: Bardana
authors.forename: A James
authors.initials: AJ
authors.lastname: Stewart
mesh_terms: D000328:Adult; D001178:Arthroplasty / Q000379:methods*; D002358:Cartilage, Articular / Q000473:pathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D007718:Knee Injuries / Q000601:surgery*; D007719:Knee Joint / Q000473:pathology / Q000601:surgery*; D016059:Range of Motion, Articular; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome