A case-control study of bone density patterns in the metacarpophalangeal joint between non-racehorses and thoroughbred racehorses with and without fractures of the metacarpophalangeal joint

Abstract

Reason for performing study The metacarpophalangeal joint carries high loads and is one of the most common sites of overload arthroses and joint failure. Racing seems to be a risk factor for fractures and fractures occur mostly on the forelimbs.

Objective The objective of this study was to utilize computed tomography from clinical cases to establish subchondral bone density patterns of the articular surface in limbs with third metacarpal condylar fractures, proximal phalanx fractures and proximal sesamoid bone fractures and to look at the differences and agreements with non-fractured limbs and between non-racehorses and racehorses.

Material and methods An experimental group of clinical CT scans of 22 forelimbs of thoroughbred racehorses with fractures in the third metacarpal, proximal phalanx or proximal sesamoid bones was compared to a control group of 24 non-fractured limbs of Quarter horses. Also, 18 racehorses from the fractured group were used as controls for other bones than their fractured bone. An image analysis program generated color-coded clinical-CT images and the different bones were analyzed at different denser or less dense areas of the bone. The Fisher’s exact test was used to establish the statistical significance of differences.

Results In this study, differences in subchondral bone density patterns of the third metacarpal, the proximal phalanx and the proximal sesamoid bones were found between the racehorses and non-racehorses. Significant differences in subchondral bone density patterns were found on the sagittal groove, in the middle and at the lateral and medial side of the third metacarpal bone, in the middle and at the lateroproximal side of the proximal phalanx and at the side where the proximal sesamoid bones are facing each other. Also, significant differences in subchondral bone density patterns were found between fractured and non-fractured limbs in the proximal phalanx and the proximal sesamoid bones. These differences were found in the middle of the proximal phalanx and the side where the proximal sesamoid bones are facing each other.

Conclusion and Clinical Relevance There was a significant difference between the fractured and non-fractured limb and the non-racehorses and racehorses in this paper. However, due to the limitations of this study more research regarding this subject is still necessary.