No effect of hole geometry in microfracture for talar osteochondral defects

A.C. Kok, G.J.M. Tuijthof, S. den Dunnen, J. van Tiel, M. Siebelt, V. Everts, C.N. van Dijk, G.M.M.J. Kerkhoffs

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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.

Questions/purposes
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.

Clinical Relevance
Bone marrow stimulation technique does not appear to be improved by changing the depth or diameter of the holes.
Original languageEnglish
Pages (from-to)3653-3662
JournalClinical Orthopaedics and Related Research
Volume471
Issue number11
DOIs
Publication statusPublished - 2013

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