Fractures of the third metacarpal/metatarsal condyles: UK perspective

Fractures of the metacarpal/metatarsal condyles are the most common long bone fracture of Thoroughbred racehorses. The frequency distribution of 174 fractures in 167 horses referred to Newmarket Equine Hospital was evaluated recently by Ben Jacklin [1]. The first part of the presentation will outline the results of this study.
The majority (65%) of fractures involved 2- and 3-year-old horses in flat race training while 18% were horses trained for jump racing. The majority of fractures (78%) occurred between April and October, increasing in frequency through the turf flat racing season and peaking in September. This seasonality was most marked in 2-year-old horses whose skeletons are athletically naïve at the beginning of the year but on which increasing athletic demands are made as the season progressed. One hundred and four fractures (60%) involve forelimbs and 70 (40%) hindlimbs but there was no significant sidedness for any fracture category. One hundred and thirty-nine fractures (80%) occurred laterally and 35 (20%) medially. Combining data from another study published in the UK [2] and comparing this to pooled studies from the USA [3–8] indicated that fractures of the medial condyle are more common in the UK (26%) than in the USA (14%). Additionally 44% of fractures seen in 2-year-olds were of the medial condyle, compared to only 11% of fractures seen in older animals.
In evaluating the origins of the fractures, 5 (7%) lateral fractures arose in the sagittal ridge, 33 (49%) adjacent to this in the region of the condylar groove and 29 (43%) abaxially in the middle one-third of the condyle. In contrast, 92% of medial fractures originated axially in the region of the condylar groove. This is interesting data and questions some concepts with respect to current theories of pathogenesis. It is also important in considering fracture risks as axially located fractures are usually longer than those originating abaxially. In the reported series, 40 (23%) fractures propagated into the diaphysis involving 28 (80%) medial and 12 (9%) lateral condyles. Of these 20 (71%) medial and 11 (92%) lateral fractures had spiral configurations; the remainder were confined to a parasagittal plane. […]