$RACTURES of the cannon bone are the most common fracture of the racehorse, and by far the most widely-seen type of cannon bone fracture is the ‘condylar fracture’ by which the front legs are more frequently affected than the hind legs, while outside or ‘lateral’ condylar fractures are seen more often than inside or ‘medial’ condylar fractures. All types of condylar fractures are common, from minor stress fractures to more serious displaced fractures. According to David Nunamaker, a leading researcher in the field of equine orthopedics and professor at the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center, lateral condylar fractures are the most common type of fracture with which he is presented. There are numerous examples of great racehorses that have suffered condylar fractures and had them successfully repaired, such as 2005 Preakness and Belmont winner Afleet Alex. However, severe, displaced, lateral condylar fractures like those suffered by talented filly Eight Belles are also seen frequently and are in fact the most common cause of equine fatality on the racetrack in the United Kingdom (Parkin et al. Equine Veterinary Journal 2005). Clinical Examination Unsurprisingly, the severity of the fracture determines the level of lameness and the amount of swelling associated with the fetlock joint and lower cannon bone. Injuries can be caused by repeated stress or a single event but there is usually a specific time when the fracture becomes apparent. For example, a severe displaced condylar fracture is usually found either during or shortly after exercising or racing; whereas a non-displaced ‘stress’ condylar fracture may be found at evening stables or indeed the day after it actually occurred. As the fracture extends into the fetlock joint, there is usually an increased amount of joint fluid and the fetlock joint is sore to manipulate and flex. Generally, the more severe the fracture the easier it is to diagnose Condylar fractures are arguably the most common type of fracture suffered by the Thoroughbred racehorse. However, veterinarians have given them a slightly cryptic ‘pet-name’ so that many do not understand them quite as well as they would like. They are simply fractures of the lower cannon bone that extend into the fetlock joint and there are two types – outside or ‘lateral’ condylar fractures, and inside or ‘medial’ condylar fractures. By James Tate BVMS MRCVS An outside or lateral condylar fracture of the right fore fetlock. There is of ten swelling on the side of the fracture as well as increased joint fluid clinically, with displaced condylar fractures having obvious swelling on either the outside or inside of the fetlock joint depending on the location of the injury. Whether the fracture requires surgical repair using screws or whether it will be managed conservatively with rest, stopping any movement in the horse’s fetlock is vital to prevent further displacement of the injury. Any horse with a suspected condylar fracture found on the gallops or on the racecourse should have the limb immobilized, usually by means of a ‘Robert Jones’ bandage, and be carefully transported on a van to the nearest x-ray facility. A Robert Jones bandage is simply a thick, solid bandage made up of three layers of cotton wool and cotton bandage with a durable external layer on the outside. Splints can also be used in conjunction with the bandage as necessary and full limb casts are also occasionally used, particularly after surgery. Diagnosis Diagnosis of a condylar fracture is usually A horse with a condylar fracture arriving at a veterinary x-ray facility (above). Horses with suspected condylar fractures should have the injured limb immobilized using a Robert Jones bandage (left) straightforward as x-rays will clearly show even a minimally displaced fracture. However, there are occasions when a condylar fracture is suspected but not seen on x-ray. Sometimes taking extra views of the fetlock can highlight the fracture. On other occasions it is impossible to see the fracture on x-ray at the time of injury. This leaves the vet with two options. Firstly, he can continue to x-ray the fetlock because although the fracture may have been too small to see at the time of injury, as time goes by and the fracture remodels before healing, it may become visible on x-ray. Secondly, the vet can arrange for the horse to undergo nuclear scintigraphy (‘bone scanning’) or magnetic resonance imaging (MRI) where any fracture, however small, should be detectable. On the left is a specialized flexed view of a left fore fetlock highlighting a medial condylar fracture which was not visible on any other view. On the right is another specialized flexed x-ray of a right fore fetlock showing a ‘stress’ lateral condylar fracture On the left is an image of a condylar fracture showing up as a ‘hot spot’ on bone scan (nuclear scintigraphy). On the right is an MRI image of a lateral condylar fracture in a right fore fetlock, which was not detectable on x-ray CONDYLAR FRACTURES ISSUE 15 TRAINERMAGAZINE.com 53 Treatment The treatment of a condylar fracture depends on the severity of the injury. A tiny stress fracture can be treated with conservative management consisting of a period of stall rest, and a Robert Jones bandage may not even be necessary, whereas a significantly displaced fracture requires repair with screws in order to attempt to maintain the athletic status of the horse. Minimally displaced condylar fractures can be treated either conservatively or with surgery. Condylar fractures tend to heal well whether they are repaired with surgery or not; however, there are two main advantages of surgery. Firstly, fracture repair with screws usually ensures a speedier recovery and secondly, the actual repair is often improved. The main problem with condylar fractures is not the bone injury itself but the injury in the joint. As the fracture extends into the fetlock joint, any displacement here can result in an irregularity in the joint surface and so cause fetlock joint problems in the future. For this reason, condylar fractures are usually repaired under the guidance of arthroscopy (‘keyhole surgery’) to make sure that the fractured pieces of bone are screwed tightly together and the horse is left with a smooth joint surface. Recently, there has been a move by a few veterinarians to repair condylar fractures with screws while the horse is under standing sedation. However, while it is wise to avoid general anesthesia with horses as much as possible, there is a good reason why a general anesthetic might be preferable. Surgeons operating under general anesthesia are able to tighten the screws while viewing the fracture in the joint via arthroscopy and so know exactly how far to ighten the screws. In contrast, surgeons repairing condylar fractures under standing sedation are effectively tightening the screws ‘blind’ as they cannot be guided by arthroscopy. Complications At this point, the reader could start to assume that all condylar fractures heal well and recovered horses always return to racing successfully. However, this is not always the case and there are a variety of common problems that can occur. Firstly, horses can suffer from fetlock joint problems as a result of the injury. As the fracture involves the joint surface, osteoarthritic changes can develop at the injury site which means that the horse is never quite as sound as it was before the injury. This is why many vets recommend surgery on even a minimally displaced condylar fracture as these problems are less likely to occur in horses that have had their fracture repaired using screws guided by arthroscopy. Secondly, fractures do not always heal as well as anticipated and there are a minority of injuries that heal slowly or even refracture when full training is resumed. Although less likely, re-fractures can occur even if surgery has been performed and this is not the only potential problem postsurgery. While most horses do not have their screws removed following condylar fracture surgery, sometimes too much new bone forms around the screws and as a result the screws must be taken out. Finally, any enforced rest period such as that associated with a condylar fracture can cause problems. If a horse is out of work for a prolonged period of time, particularly if it is box rested for a while, then the horse’s skeleton becomes ‘soft’ and the recovery can be littered with niggling bony problems X-rays and arthroscopic images of a horse that has had a lef t hind lateral ‘condylar’ fracture in its fetlock joint repaired using screws inser ted under arthroscopic guidance. Note the smooth joint surface after fracture repair (bottom right) VETERINARY 54 TRAINERMAGAZINE.com ISSUE 15 X such as sore shins, splints or tibial stress fractures. Whilst all of these usually settle relatively quickly, they can greatly elongate the time in which the horse recovers from the injury and returns to the racetrack. Conclusion In summary, condylar fractures are very common and important in Thoroughbred racing. They should always be considered as a possibility for a horse that is lame following work or racing especially when there is filling and soreness associated with the fetlock joint. Each injury must be considered on its merits both with regard to the necessity for surgery and with regard to determining the correct recovery regime. While horses like Eight Belles warn of the possible catastrophic consequences of condylar fractures, it is possible to make a full and speedy recovery from less serious fractures. ■ An x-ray of a horse that suffered a condylar ‘re-fracture’ despite having had the original injury repaired using four screws Some horses can develop excessive amounts of new bone associated with the screws. Following the x-ray above, the horse in question had its screws removed$

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James Tate BVMS MRCVS (05 February 2010 - Issue 15)

Feb 5 Condylar Fractures - a common injury in racehorses, and how to treat them

Feb 5 Stem Cells: are they the future in treating injuries in racehorses?

Jan 20 JJ Crupi - from conditioner to consignor