title: No effect of hole geometry in microfracture for talar osteochondral defects.
abstract: BACKGROUND
  Débridement and bone marrow stimulation is an effective treatment option for patients with talar osteochondral defects. However, whether surgical factors affect the success of microfracture treatment of talar osteochondral defects is not well characterized.
  
  
  OBJECTIVE
  We hypothesized (1) holes that reach deeper into the bone marrow-filled trabecular bone allow for more hyaline-like repair; and (2) a larger number of holes with a smaller diameter result in more solid integration of the repair tissue, less need for new bone formation, and higher fill of the defect.
  
  
  METHODS
  Talar osteochondral defects that were 6 mm in diameter were drilled bilaterally in 16 goats (32 samples). In eight goats, one defect was treated by drilling six 0.45-mm diameter holes in the defect 2 mm deep; in the remaining eight goats, six 0.45-mm diameter holes were punctured to a depth of 4 mm. All contralateral defects were treated with three 1.1-mm diameter holes 3 mm deep, mimicking the clinical situation, as internal controls. After 24 weeks, histologic analyses were performed using Masson-Goldner/Safranin-O sections scored using a modified O'Driscoll histologic score (scale, 0-22) and analyzed for osteoid deposition. Before histology, repair tissue quality and defect fill were assessed by calculating the mean attenuation repair/healthy cartilage ratio on Equilibrium Partitioning of an Ionic Contrast agent (EPIC) micro-CT (μCT) scans. Differences were analyzed by paired comparison and Mann-Whitney U tests.
  
  
  RESULTS
  Significant differences were not present between the 2-mm and 4-mm deep hole groups for the median O'Driscoll score (p = 0.31) and the median of the μCT attenuation repair/healthy cartilage ratios (p = 0.61), nor between the 0.45-mm diameter and the 1.1-mm diameter holes in defect fill (p = 0.33), osteoid (p = 0.89), or structural integrity (p = 0.80).
  
  
  CONCLUSIONS
  The results indicate that the geometry of microfracture holes does not influence cartilage healing in the caprine talus.
  
  
  CONCLUSIONS
  Bone marrow stimulation technique does not appear to be improved by changing the depth or diameter of the holes.
authors.affiliation: Department of Orthopedic Surgery, Orthopedic Research Center Amsterdam, Academic Medical Center, G4-262 Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands, a.kok@amc.uva.nl.
authors.forename: Aimee Claire
authors.initials: AC
authors.lastname: Kok
authors.forename: Gabrielle J M
authors.initials: GJ
authors.lastname: Tuijthof
authors.forename: Steven
authors.initials: S
authors.lastname: den Dunnen
authors.forename: Jasper
authors.initials: J
authors.lastname: van Tiel
authors.forename: Michiel
authors.initials: M
authors.lastname: Siebelt
authors.forename: Vincent
authors.initials: V
authors.lastname: Everts
authors.forename: C Niek
authors.initials: CN
authors.lastname: van Dijk
authors.forename: Gino M M J
authors.initials: GM
authors.lastname: Kerkhoffs
mesh_terms: D000818:Animals; D001861:Bone Regeneration; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D020219:Chondrogenesis; D003646:Debridement; D005260:Female; D006041:Goats; D019637:Orthopedic Procedures / Q000379:methods*; D012038:Regeneration; D013628:Talus / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D013997:Time Factors; D055114:X-Ray Microtomography
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