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EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2017
a)
b)
c)
Fig 6: Propagating fractures of the third metacarpal bone; (a) diagrammatic representation of distracting forces; (b) counter action by a splinted Robert Jones bandage extending to the level of the distal row of carpal bones; (c) bandage cast used to immobilise a propagating fracture of the medial condyle of the third metacarpal bone.
et al. 1998). The most common combination involving the metacarpal condyles is for fracture to occur in conjunction with breakdown of the suspensory apparatus, usually due to biaxial fracture or dehiscence of the proximal sesamoid bones. The priority in these circumstances is preservation of
the distal limb vasculature and therefore immobilisation in flexion is necessary. Affected animals usually will make little effort to load the limb. The support of choice is a dorsal splint applied with fibreglass casting material to increase mediolateral stability. This is aided further by a heel wedge to maximise foot ground contact. However, in moving the horse from the racetrack to an onsite clinical facility, use of a leg saver brace is appropriate.
Fractures of the forelimb proximal sesamoid bones Fractures of proximal sesamoid bones in the forelimb are the most common catastrophic (resulting in death) injury in training and racing in the USA (Johnson et al. 1994) where most races are on dirt tracks. They are less common in the UK (Parkin et al. 2004) where an increased risk in flat racing on all weather surfaces has been identified (Parkin et al. 2004; Kristofferson et al. 2010). Biaxial mid body fractures of the proximal sesamoid bones disrupt entirely the suspensory apparatus and thus palmar support of the metacarpophalangeal joint. In addition to stretching and tearing of the palmar vessels and nerves, this results in marked displacement of sharp fracture fragments that can lacerate the neurovascular bundle. Emergency support of the distal limb in a flexed position is therefore critical to maintaining viability (Figs 7 and 8). Arthrodesis of the metacarpophalangeal joint is the only treatment option available to afflicted horses and requires substantial financial commitment from owners. Similar flexed support is appropriate, although less critical, for uniaxial fractures and should be applied if, following clinical examination, this is the principal differential (Fig 9).
© 2016 EVJ Ltd a) b)
Fig 7: a) Diagrammatic representation of the principal distracting forces for mid body fractures of the proximal sesamoid bones; (b) diagrammatic representation of the effect of a Leg Saver Splint.
Dorsal splints, Leg Saver Splints1 or board splints all are
appropriate for removal from the racetrack to the onsite clinical facility and for onward transport to a referral hospital.
Luxation of the metacarpophalangeal joint Luxation or subluxation of the metacarpophalangeal joint can accompany fractures of the distal metacarpal condyles and/or palmar process of the proximal phalanx. Additionally,
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