In situ and ex vivo evaluation of an arthroscopic indentation instrument to estimate the health status of articular cartilage in the equine metacarpophalangeal joint

Objective - To evaluate an arthroscopic indentation instrument (Artscan 200) for assessment of the health status of equine articular cartilage. Study Design - In vitro experiment using equine isolated proximal phalanx (P1) specimens. Sample Population - P1 specimens from 39 horses (aged 1.5-22 years). Methods - Reproducibility was tested by determination of the coefficient of variation (CV). Dynamic modulus and cartilage degeneration index (CDI) values were measured at 2 predefined sites (site 1, joint margin; site 2, joint center) to assess the accuracy and to evaluate the relation with surface integrity. Results - CV was 9.0%. A significant decrease in indenter force was identified when dynamic modulus values decreased to < 2.5 MPa (range of tested samples 0.9-8.1 MPa) and when CDI values at site 1 increased to > 50% (range 5.4-72.8%). Conclusions - Technique reproducibility was adequate but accuracy was limited. The device identified degeneration-associated decreases in cartilage stiffness only when the mechanical properties of the cartilage were considerably changed. Clinical Relevance - Usefulness of this indentation instrument during arthroscopic surgery would be limited in the initial phase of OA-like cartilage degeneration, but may yield important information in more advanced OA. (C) Copyright 2006 by The American College of Veterinary Surgeons.