New approach for quantitative assessment of articular cartilage degeneration in horses with osteoarthritis.

This research paper evaluates a new digital imaging technique for measuring the degree of osteoarthritis in the proximal articular surface of the first phalanx in horses.

Study Objective

• The main objective of the study is to examine a modified digital imaging technique to assess the level of osteoarthritis across the proximal articular surface of the first phalanx in horses quantitatively. The technique involves the use of a grayscale reference calibration with pixel value mean calculation to assess the condition.

Methods

• The study involved 6 metacarpophalangeal joint specimens attained from 6 different horses at various stages of osteoarthritis.
• The joint specimens, along with 4 grayscale reference calibration targets, were submersed in a bath of saline solution (0.9% NaCl).
• Digital images were then obtained from the articular surface before and after being stained with Indian ink for detailed analysis.
• Using a computer, the scientists carried out a gray level analysis of the unstained and ink-stained cartilage surfaces, as well as the grayscale reference calibration targets.
• They based the measurements on a 255 grayscale mean pixel value. An increase in this mean pixel value after staining helped to calculate the Cartilage Degeneration Index (CDI).

Results

• The CDI of the proximal articular cartilage surface of the first phalanx specimens was seen to range from 9.2 +/- 5.7 (representing early stage osteoarthritis) to 41.5 +/- 3.6% (representing late stage osteoarthritis).
• Measurements taken six times and repositioning and restaining the specimens had no significant effect on the results.
• Measurements could be taken up to 10 times on nonstained specimens without having to refresh the bath solution.
• In stained specimens, a significant increase in the mean gray level was observed after the sixth measurement.

Conclusions

• The use of this modified digital imaging technique provides a way to quantitatively assess the level of cartilage degeneration due to osteoarthritis on the cartilage’s articular surface.
• The CDI presents the first measure for osteoarthritis-induced cartilage degeneration over an entire joint surface in horses in a quantitative manner.