Anatomic and histologic features and ultrasonographic appearance of the collateral ligaments of the metacarpophalangeal and metatarsophalangeal joints in cadaveric limbs from horses without lameness.

The research focused on understanding the structure and condition of the collateral ligaments in the joints of horse limbs, combining results from histology and ultrasonography. It found inconsistencies between the visual signs from ultrasonography and the detailed tissue structure from histologic examination, suggesting other imaging methods may be necessary for accurate diagnosis of less obvious lesions.

Study Overview

• The study aimed to describe the anatomic and histologic features of the collateral ligaments (CLs) in metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in horse limbs. It also sought to compare these findings with how these ligaments appeared in ultrasonographic images.

Methods

• Cadaveric limbs from non-lame adult horses, euthanized due to other reasons, were used. Specifically, 28 limbs (16 forelimbs and 12 hind limbs) from 9 different horses were involved in the study.
• 26 out of these 28 limbs were examined using ultrasonography immediately after euthanasia, while all 28 limbs underwent postmortem gross and histologic examinations.
• The depth, width, and appearance of the CLs from the ultrasonographic images were then compared with the histologic results.

Findings

• The researchers found that a significant proportion of the CL samples exhibited abnormalities on histologic examination, with varying levels of damage observed. Only 39% of the samples were deemed normal.
• It was observed that the severity of the lesion increased the further distally it was located on the limb, and the lateral CL was more often affected compared to the medial CL.
• The ultrasonographic results did not correlate with the histologic findings, unable to detect the observed abnormalities in the tissue structure.

Conclusions

• Based on the findings, the researchers concluded that horses might have histologic abnormalities within the CLs of MCP and MTP joints due to joint hyperextension and compression. This could, in turn, predispose the horses to desmopathy and ligament failure in case of any trauma.
• The failure of ultrasonography to detect such morphological changes suggests more sensitive imaging techniques (like MRI) are needed for accurate diagnosis of subclinical lesions.