title: Effects of the combination of microfracture and self-assembling Peptide filling on the repair of a clinically relevant trochlear defect in an equine model.
abstract: BACKGROUND
  The goal of this study was to test the ability of an injectable self-assembling peptide (KLD) hydrogel, with or without microfracture, to augment articular cartilage defect repair in an equine cartilage defect model involving strenuous exercise.
  
  
  METHODS
  Defects 15 mm in diameter were created on the medial trochlear ridge and debrided down to the subchondral bone. Four treatment groups (n = 8 each) were tested: no treatment (empty defect), only defect filling with KLD, only microfracture, and microfracture followed by filling with KLD. Horses were given strenuous exercise throughout the one-year study. Evaluations included lameness, arthroscopy, radiography, and gross, histologic, immunohistochemical, biochemical, and biomechanical analyses.
  
  
  RESULTS
  Overall, KLD-only treatment of defects provided improvement in clinical symptoms and improved filling compared with no treatment, and KLD-only treatment protected against radiographic changes compared with microfracture treatment. Defect treatment with only microfracture also resulted in improved clinical symptoms compared with no treatment, and microfracture treatment resulted in repair tissue containing greater amounts of aggrecan and type-II collagen compared with KLD-only treatment. Microfracture treatment also protected against synovial fibrosis compared with no treatment and KLD-only treatment. Treatment with the self-assembling KLD peptide in combination with microfracture resulted in no additional improvements over microfracture-only treatment. In general, the nature of the predominant tissue in the defects was a mix of noncartilaginous and fibrocartilage tissue, with no significant differences among the treatments.
  
  
  CONCLUSIONS
  Treatment of defects with only KLD or with only microfracture resulted in an improvement in clinical symptoms compared with no treatment; the improvement likely resulted from different causes depending on the treatment. Whereas microfracture improved the quality of repair tissue, KLD improved the amount of filling and protected against radiographic changes.
  
  
  CONCLUSIONS
  Treatment of defects with only microfracture and with KLD only resulted in clinical improvements compared with untreated defects, despite differing with respect to the structural improvements that they induced.
authors.affiliation: Department of Internal Medicine, Rush University Medical Center, 1735 West Harrison Street, Room 553A, Chicago, IL 60612.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Miller
authors.affiliation: Massachusetts Institute of Technology, 77 Massachusetts Avenue, MIT NE47-377, Cambridge, MA 02139.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Grodzinsky
authors.affiliation: Department of Environmental and Radiological Health Sciences (M.F.B.) and Orthopaedic Research Center, Department of Clinical Sciences (C.W.M. and D.D.F.), College of Veterinary Medicine and Biological Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523. E-mail address for D.D. Frisbie: david.frisbie@colostate.edu.
authors.forename: Myra F
authors.initials: MF
authors.lastname: Barrett
authors.affiliation: Massachusetts Institute of Technology, 77 Massachusetts Avenue, MIT NE47-377, Cambridge, MA 02139.
authors.forename: Han-Hwa
authors.initials: HH
authors.lastname: Hung
authors.affiliation: Massachusetts Institute of Technology, 77 Massachusetts Avenue, MIT NE47-377, Cambridge, MA 02139.
authors.forename: Eliot H
authors.initials: EH
authors.lastname: Frank
authors.affiliation: Department of Radiology, College of Veterinary Medicine, University of Florida, PO Box 100126, Gainesville, FL 32610.
authors.forename: Natasha M
authors.initials: NM
authors.lastname: Werpy
authors.affiliation: Department of Environmental and Radiological Health Sciences (M.F.B.) and Orthopaedic Research Center, Department of Clinical Sciences (C.W.M. and D.D.F.), College of Veterinary Medicine and Biological Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523. E-mail address for D.D. Frisbie: david.frisbie@colostate.edu.
authors.forename: C Wayne
authors.initials: CW
authors.lastname: McIlwraith
authors.affiliation: Department of Environmental and Radiological Health Sciences (M.F.B.) and Orthopaedic Research Center, Department of Clinical Sciences (C.W.M. and D.D.F.), College of Veterinary Medicine and Biological Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523. E-mail address for D.D. Frisbie: david.frisbie@colostate.edu.
authors.forename: David D
authors.initials: DD
authors.lastname: Frisbie
mesh_terms: D000818:Animals; D001182:Arthroscopy; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D004195:Disease Models, Animal; D004285:Dogs; D006736:Horses; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000627:therapeutic use; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D019637:Orthopedic Procedures / Q000379:methods*; D010455:Peptides / Q000627:therapeutic use*; D011859:Radiography; D011897:Random Allocation
chemical_list: D010455:Peptides; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate