Objective. To develop a new diagnostic technology to evaluate articular cartilage quantitatively
by introducing an ultrasonic probe into the knee joint under arthroscopy and analyzing
the A-mode echogram by means of wavelet transformation.
Design. Quantitative evaluation using comparison of two indices on the wavelet map and macroscopic
evaluation using the Outerbridge classification. As the quantitative indices on the
wavelet map, the maximum magnitude and the echo duration which was defined as the
length of time that included 95% of echo signal were selected.
Background. Quantitative evaluation of articular cartilage in situ is required for new tissue-engineered
cartilage but an evaluation system that fully meets this requirement has yet to be
established for clinical use.
Methods. Human articular cartilage specimens were analyzed using an ultrasonic probe after
macroscopic evaluation and the cartilage characteristics on the echo duration–maximum
magnitude graph were examined.
Results. There were significant differences between grade 1 and 3, and grade 2 and 3 in the
echo duration and maximum magnitude. The cartilage specimens had a L-shaped distribution
in echo duration–maximum magnitude graph.
Conclusions. The present study is the new quantitative evaluation system of the articular cartilage
in situ and a clinical trial under arthroscopy is presently underway. The ultrasonic
measurement is highly reproducible, so we can expect this system to be suitable for
in situ reliable examination under arthroscopy.Relevance
Precise evaluation of articular cartilage is of particular importance for longitudinal
clinical trials for determination of best surgical option or effect of new chondroprotective
drugs in arthritic disease and rheumatoid arthritis.