title: Chondral defect repair after the microfracture procedure: a nonhuman primate model.
abstract: BACKGROUND
  The extent and time course of chondral defect healing after microfracture in humans are not well described. Although most physicians recommend a period of activity and weightbearing restriction to protect the healing cartilage, there are limited data on which to base decisions regarding the duration of such restrictions.
  
  
  OBJECTIVE
  Evaluation of the status of chondral defect repair at different time points after microfracture in a primate model may provide a rationale for postoperative activity recommendations.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Full-thickness chondral defects created on the femoral condyles and trochlea of 12 cynomolgus macaques were treated with microfracture and evaluated by gross and histologic examination at 6 and 12 weeks.
  
  
  RESULTS
  At 6 weeks, there was limited chondral repair and ongoing resorption of subchondral bone. By 12 weeks, the defects were completely filled and showed more mature cartilage and bone repair.
  
  
  CONCLUSIONS
  In the primate animal model, significant improvements in the extent and quality of cartilage repair were observed from the 6- to 12-week time points after microfracture.
  
  
  CONCLUSIONS
  The poor status of the defect repair at 6 weeks and the ongoing healing observed from the 6- to 12-week time points may indicate that the repair is vulnerable during this initial postoperative period. Assuming the goal of postoperative weightbearing and activity restriction in patients after microfracture is to protect immature repair tissue, this study lends support to extending such recommendations longer than 6 weeks.
authors.affiliation: Massachusetts General Hospital, WACC 508, 15 Parkman Street, Boston, MA 02114, USA. tgill@partners.org
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Gill
authors.forename: Patrick C
authors.initials: PC
authors.lastname: McCulloch
authors.forename: Sonya S
authors.initials: SS
authors.lastname: Glasson
authors.forename: Tracey
authors.initials: T
authors.lastname: Blanchet
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Morris
mesh_terms: D000818:Animals; D001861:Bone Regeneration; D002357:Cartilage Diseases / Q000473:pathology* / Q000601:surgery*; D002358:Cartilage, Articular / Q000473:pathology* / Q000601:surgery*; D004195:Disease Models, Animal; D005269:Femur / Q000293:injuries / Q000473:pathology; D017102:Fracture Healing; D007718:Knee Injuries / Q000473:pathology* / Q000601:surgery*; D008252:Macaca fascicularis; D019637:Orthopedic Procedures / Q000379:methods; D016896:Treatment Outcome