Racetrack Fracture Support Equipment - coming to North America this summer

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Words - Ian Wright

Over the last six months, British racecourses have taken a major step forward in racehorse welfare by being provided with fracture support systems (Figure 1). These consist of two sizes of compression boots and flexion splints, both for use in the forelimbs; and a set of modular adjustable splints. Together, these provide appropriate rigid external support for the vast majority of limb fractures that occur during racing. The general principles are that management of all fractures is optimized by applying rapid and appropriate support to provide stability, reduce pain and relieve anxiety. 

Figure 1

The fracture support systems are about to make their debut in North America with trials due to take place this summer and fall with the support of the National HBPA.

The fracture support system is provided in two mobile impact resistant carrying boxes that protect the equipment and allow it to be checked before racing. All boots and splints are permanently labeled with individual racecourse identification to ensure return of equipment if it leaves the racetrack. 

In the last 25 years there have been major improvements in fracture treatment due to significant advances in surgical techniques (particularly with internal fixation), minimally invasive approaches (arthroscopy) and the use of computed tomography (CT). Arthroscopy and CT allow accurate mapping and alignment of fractures, which is important for all and critical for athletic soundness. All have contributed to improvements in survival rates; and it is now safe to say that with correct care, the vast majority of horses that sustain fractures in racing can be saved. Equally importantly, many can also return to full athletic function including racing. 

Fracture incidences and locations vary geographically and are influenced by race types, track surfaces and conditions. There is good evidence that the majority of non-fall related fractures, i.e. those occurring in flat racing and between obstacles in jump racing, are caused by bone fatigue. This is determined by the absolute loads applied to a bone, their speed/frequency and the direction of force application. As seen with stress or fatigue failure in other high-performance working materials in which applied forces are relatively consistent, fractures in racehorse bones occur at common sites, in particular configurations, and follow similar courses. Once the fracture location has been identified, means of counteracting forces which distract (separate) the bone parts can therefore be reliably predicted and countered. 

Worldwide, the single most common racing fracture is that of the metacarpal/metatarsal condyles (condylar fracture). In Europe, the second most common fracture is a sagittal/parasagittal fracture of the proximal phalanx (split pastern). Both are most frequent in the forelimbs. 

In the United States, particularly when racing on dirt, mid-body fractures of both proximal sesamoid bones, which destabilize the fetlock (almost always in the forelimbs), are the most common reason for on-course euthanasia. They occur less frequently when racing on turf. 

There is no specific data documenting outcomes of horses that have sustained fractures on racecourses. However, there is solid data for the two most common racing injuries. The figures below are a meta-analysis of published data worldwide.

CONDYLAR FRACTURES

  • Repaired incomplete fractures: 80% returned to racing

  • Complete non-displaced fractures: 66% of repaired fractures returned to racing

  • Displaced fractures: 51% raced following repair

  • Propagating fractures: 40% raced following repair

SPLIT PASTERN

  • Short incomplete fractures: 65% returned to racing

  • Long incomplete fractures: 61% returned to racing

  • Complete fractures: 51% returned to racing

  • Comminuted fractures in most circumstances end racing careers but with appropriate support and surgical repair, many horses can be saved. There is only one comprehensive series of 64 cases in the literature of which 45 (70%) of treated cases survived.

MID BODY SESAMOID FRACTURES

  • Uni-axial (single) fractures: 53% raced following screw repair

  • Bi-axial (both) fractures are career ending but can be salvaged with appropriate emergency support and arthrodesis (fusion) of the fetlock joint. Results of a single series of 52 cases are available in which 65% of horses were able to have unrestricted activity post-operatively primarily as breeding animals

The science behind the development of the fracture support systems comes from two directions. The first is data collected from racecourse injuries and the second, improved understanding of fracture courses and behavior. Data collected from UK flat racecourses between 2000 and 2013 demonstrated that 66% of fractures occurred in the lower limb (from knee and hock down) and of that over 50% of fractures involved the fetlock joints. Condylar fractures are most common, representing 27% of all reported fractures; and of these, approximately two thirds occurred in the forelimbs. Split pasterns were the second most common, accounting for 19% of all fractures with three quarters of these occurring in the forelimbs. These fractures have predictable planes and courses, which means that once recognized, they can effectively be immobilized in a standard manner that is optimal for each fracture type. For condylar fractures and split pasterns, this principally involves extension of the fetlock joint. By contrast, in order to preserve soft tissues and blood supply to the lower limb, fractures of the sesamoid bones require fetlock flexion. 

Figure 2

Figure 3

The compression boot is readily applied “trackside” and can be used to stabilize most distal forelimb fractures sufficiently for horses to be humanly moved off the course. It is the temporary immobilization of choice for forelimb condylar fractures and split pasterns (Figure 3). Radiographs can be taken with the boot in place (Figure 4), and this can be maintained for transport. The boot is a rigid construct of fiberglass made from a single mold. The divided front portion is contiguous with a foot plate on which the back of the boot is hinged.  Two sizes are available with internal foot widths of 135 and 160mm (5–6 inches). Removable foot inserts are also provided to make minor adjustments for hoof size. The boot is lined with foam rubber and has a rubber sole plate that protects the shell and provides a cushion grip for the foot. When the boot is opened, the injured limb is placed into the front of the boot while the back is closed and secured by sequential adjustment of ski boot clips. When the boot edges are apposed (it cannot be over tightened), immobilization is secure. It is made with a fixed fetlock angle of 150o which counteracts distracting forces and allows horses to weight-bear and load the limb to walk. 

Figure 4

Flexion splints (Figure 5) are critical for the survival of horses with breakdown injuries such as sesamoid fractures. They are also suitable for other lower limb injuries, which are supported by fetlock and pastern flexion such as tendon and suspensory ligament injuries and lacerations. The splints are made of aluminum alloy with a secure work-hardened foot plate and conjoined compressed foam-lined front splint, which is angled 30o at the level of the coffin joint and extends to the top of the cannon. Here, there is a shallow foam-covered concavity in which the upper cannon sits, allowing the horse to lean into the splint and load the leg while flexed. The splint is secured to the leg with nylon and Velcro straps. Splints are provided with internal foot widths of 135 and 160mm (5–6 inches) to accommodate variations in horse/hoof sizes.

The modular adjustable splints (Figure 6) are made from heat-treated aluminum alloy. They are lightweight and can be configured to fit the individual horse and regional needs. The splints are 38x19mm (1.5x0.75in) rectangular tubes with an enclosed locking screw I beam. They are light but rigid and secure and are tolerated well. In the hindlimb, the reciprocal apparatus which combines stifle, hock and fetlock joint positions precludes use of a compression boot. However, modular splints provide rigid support for condylar fractures and split pasterns in hindlimbs and are secured—over a bandage to create a parallel sided tube—on the inside and outside of the limb. The splints can also be adjusted and assembled to splint fractures that occur above the fetlock (Figure 7). 

Figure 7

Appropriate immobilization effectively stops fracture progression (i.e., getting worse) which not only improves the horse's prospects for recovery but also provides effective relief from pain and anxiety. As flight animals, loss of limb control or function is a major contributor to stress. The relief provided by effective immobilization is substantially greater than provided by any pain killer or sedative. It is also recognized that when fractures occur in the high-adrenaline environment of racing, horses exhibit latent pain syndrome. Application of appropriate rigid support at this time (i.e., on the track) limits pain generation and allows humane movement for considered evaluation, X-ray, etc., away from the racetrack. 

In the UK, techniques for application of the boots and splints are taught to racetrack veterinary surgeons at annual seminars run by the Association of Racecourse Veterinary Surgeons (ARVS). The Racecourse Association (RCA) has provided forms to record use and to collect data centrally which, in the fullness of time, will determine impact and help to guide future welfare strategies. 

Providing modern, scientifically rational equipment to racecourses has done two things in the UK. First, injured horses are optimally cared for immediately and secondly, it sends out a strong positive public relations message that people involved in racing care. The initiative has been widely welcomed by the British racing industry. “This new equipment will provide the best possible chance for an injury to be properly assessed while discomfort to the horse is significantly reduced and give the best chance of future rehabilitation” Caroline Davies, RCA (Racecourse Association) - Racecourse Services Director.

“The fracture support [system] kit is a major advance in the treatment of horses on the racetrack. It allows immediate effective support to be applied to an injured horse, resulting in pain control and stability, facilitating safe transport from the racecourse to a center of excellence without risk of exacerbating the injury. This will optimize the chance of horses to return to athletic function. This innovation must be seen as a major step forward in horse welfare for the participants in racing and all other equine disciplines.” Simon Knapp, Horse Welfare Board.