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Rupture of the dorsal ligaments of the tarsus in the greyhound is a rare racing injury. This case report describes dorsal tarsal instability in three greyhounds. A stumble and somersault were observed in two cases and were thought to have caused the injury. Previous reports advocate partial intertarsal arthrodesis as the preferred treatment for dorsal instability of the proximal intertarsal joint, but not all dogs returned to successful racing. In these three cases, stability was restored by the insertion of a wire tension band anchored to two bone screws, allowing the development of periarticular fibrosis. The dogs raced again with no loss of form.

Anecdotal evidence suggested that many cases of third tarsal bone (T3) fracture encountered clinically were associated with an abnormal shape to this bone. The radiographs of 10 normal horses and 10 horses affected with slab fracture of T3 were therefore examined to ascertain if any pre-existent radiological abnormality was present in cases of fracture. Measurement of the maximum and minimum width between the proximal and distal articular surfaces of the dorsolateral aspect of this bone was carried out on a standardised dorso-50 degrees medial-palmarolateral radiographic projection of the tarsus of each horse. To avoid artefacts produced by possible image magnification, ratios of these values were used for comparison between horses. The results showed that wedge shaped conformation of T3, in which the articular surfaces of the bone converge and then diverge again on the dorsolateral aspect, was over-represented in the population of horses sustaining T3 fracture when compared to controls. This information may be important in making judgements on the suitability of horses during prepurchase examination for racing.

The densitometric and mechanical structural properties of the left and right fifth metacarpal bones of 10 racing greyhounds with a fracture of the central tarsal bone and 10 without a fracture were investigated by dual energy x-ray absorptiometry and a servo-hydraulic materials testing machine. In all the greyhounds the bone mineral density of the left fifth metacarpal bone was significantly greater than that of the right (P<0.001), but there was no significant difference between the degree of asymmetry in bone mineral density in the two groups. The ultimate torque and energy-to-failure of the left fifth metacarpal bone of the greyhounds with a fracture of the right central tarsal bone were significantly higher than in the right fifth metacarpal bone and higher than in both the left and right fifth metacarpal bones of the greyhounds with no fracture (P<0.05). The ultimate torque and energy-to-failure were significantly related to bone mineral density (P<0.005), and 22 per cent of the variation in these structural properties could be explained by variations in bone mineral density. Fifth metacarpal remodelling in response to asymmetric cyclic loading is bone-specific, and structural properties are enhanced in the left fifth metacarpal of greyhounds with a fracture of the right central tarsal bone.

The case records of eight greyhounds that had undergone a surgical repair of either a type III or type IV fractured central tarsal bone were reviewed. In some cases difficulties were encountered which resulted in less than ideal fixation methods being used, but the fractures healed satisfactorily by intertarsal ankylosis and were radiographically complete after four to six months. For a successful outcome it was not necessary to preserve functional intertarsal joints by interfragmentary reconstruction and compression. The absence of dorsal slab fixation, poor dorsal screw positioning, or loss of the dorsal fragment, had no influence on the results. It took from six months to one year for the dogs to return to racing.

A 2-week-old Miniature Horse foal was referred for evaluation and treatment of a luxated right tarsometatarsal joint. Treatment consisted of closed reduction and internal fixation using two partially threaded Steinmann pins placed in normograde fashion through the tuber calcis into the proximal third metatarsus. Traumatic luxation has been reported to occur in the tarsocrural, proximal intertarsal and tarsometatarsal joints within the equine tarsus. Treatment for luxation of the distal intertarsal joint has not been documented. The treatment method most commonly suggested for tarsal luxation is closed reduction and cast immobilisation. Internal fixation using lag screws and plating has also been described. A combination of internal fixation and external coaptation is thought to achieve maximal stability and allow faster convalescence in cases of tarsal luxation. This case report describes for the first time a technique using two Steinmann pins to achieve successful internal fixation of a traumatic tarsometatarsal joint luxation in a 2-week-old Miniature Horse foal.

Seventeen cats with injuries involving the distal tibia, talocrural joints, tarsus and metatarsus were treated with contoured connecting bar transhock external fixators as either primary or secondary fixation. The assemblies stabilised all the injuries successfully. Fracture union was achieved in 11 out of 12 cases. Excellent results were achieved in eight cats and the outcome was satisfactory in a further five. Those cats with injuries involving talocrural joint luxation with displacement and significant periarticular soft tissue disruption had poorer long-term results. Complications occurred in seven cases.

The greyhound is a fatigue fracture model of a short distance running athlete. Greyhounds have a high incidence of central (navicular) tarsal bone (CTB) fractures, which are not associated with overt trauma. We wished to determine whether these fractures occur because of accumulation of fatigue microdamage. We hypothesized that bone from racing dogs would show site-specific microdamage accumulation, causing predisposition to structural failure. We performed a fractographic examination of failure surfaces from fractured bones using scanning electron microscopy and assessed microcracking observed at the failure surface using a visual analog scale. Branching arrays of microcracks were seen in failure surfaces of CTB and adjacent tarsal bones, suggestive of compressive fatigue failure. Branching arrays of microcracks were particularly prevalent in remodeled trabecular bone that had become compact. CTB fractures showed increased microdamage when compared with other in vivo fractures (adjacent tarsal bone and long bone fractures), and ex vivo tarsal fractures induced by monotonic loading (P < 0.02). It was concluded that greyhound racing and training often results in CTB structural failure, because of accumulation and coalescence of branching arrays of fatigue microcracks, the formation of which appears to be predisposed to adapted bone.

Fatigue fracture of the cuboidal bones of the foot, especially the navicular tarsal bone, is common in athletes and dancers. The racing greyhound is a naturally occurring animal model of this injury because both microcracking and complete fracture occur in the right central (navicular) tarsal bone (CTB). The right limb is on the outside when racing in a counter-clockwise direction on circular tracks, and is subjected to asymmetric cyclic compressive loading. We wished to study in more detail adaptive modeling in the right CTB in racing greyhounds. We hypothesized that cyclic asymmetric loading of a cuboidal bone induced by racing on a circular track would induce site-specific bone adaptation. We also hypothesized that such an adaptive response would be attenuated in greyhounds that were retired from racing and no longer subjected to cyclic asymmetric loading. Central tarsal bones from racing greyhounds (racing group, n = 6) and retired greyhounds being used for breeding (nonracing group, n = 4) were examined using quantitative computed tomography (CT). Bone mineral density (BMD) was determined in a 3-mm diameter region-of-interest (ROI) in six contiguous 1-mm-thick sagittal CT slices of each CTB. Bones were subsequently examined histomorphometrically and percentage bone area (B.Ar./T.Ar., %) was determined in 10 ROI from dorsal to plantar in a transverse plane, mid-way between the proximal and distal articular surfaces. The BMD of the right CTB was greater than the left in all greyhounds (p < 0. 001). In comparing ipsilateral limbs between groups, BMD of the racing group was greater than the nonracing group for each side (p < 0.005). In sagittal plane histologic sections, bone in the dorsal region of the right CTB had undergone adaptive modeling, through thickening and compaction of trabeculae. B.Ar./T.Ar., % in the right CTB of the racing group was greater than in the contralateral CTB (p < 0.001), and the ipsilateral CTB of the nonracing group (p < 0.001). In the nonracing group, B.Ar./T.Ar., % in the right CTB was not significantly different from left CTB (p > 0.8; power = 80% at Delta = 48%). It was concluded that greyhounds racing on circular tracks develop site-specific bone adaptation with compaction of trabecular bone and increase in BMD in the right CTB in particular, the most common site for fatigue fracture. Our data also suggested that partial reversal of this adaptive process occurred in retired, nonracing greyhounds, after cessation of asymmetric cyclic loading at racing speed. Racing greyhounds provide a model in which to study fatigue fracture and adaptation of cuboidal foot bones subjected to cyclic loading.

The treatment of acute complete (grade III) tears of the lateral ligaments of the ankle has generated much controversy in the medical literature. Functional treatment has become the standard treatment as it has been shown that there is no significant difference in long term results whatever the treatment (operative repair and cast, cast alone, or early controlled mobilization). Functional treatment includes only a short period of protection by tape bandage or brace and allows early weight-bearing. Major trauma with avulsion of bone and severe ligamentous damage on both medial and lateral sides of the ankle is however an indication for surgical treatment in the acute phase. Secondary operative reconstruction can be performed in case of persistent instability and laxity of the ankle. Secondary anatomic repair as proposed by Brodström, Duquennoy et al. and Karlsson et al. has a high rate of success and avoids the potential morbidity of harvesting partially or totally the peroneus brevis or other tendon grafts. Evaluation of the injured ankle has improved and in selected patients ultrasonography, arthrography, magnetic resonance imaging or bone scintigraphy may be useful for further evaluation of the injury. The frequency of associated injuries has probably been underestimated. Although ankle sprain is often thought of as an injury involving only the lateral ankle ligaments, there are varied and multiple components to the common sprained ankle. This condition would perhaps more appropriately be designated as the sprained ankle syndrome.

Five cats with fracture of the talar neck were treated using external skeletal fixation (ESF). In four of the cases, ESF was the only fixation technique used and this was applied in a closed manner coupled with traction. In the remaining cat, ESF was used in combination with a lag screw. All the fractures eventually healed, demonstrating that ESF provided a simple and effective method of treatment for these cases.

Medical records of 20 dogs with 23 shearing injuries of the tarsus leading to joint instability were reviewed. A transarticular external skeletal fixation device or prosthetic ligament was used to stabilize the joints. The most common complications were fixator failure and implant infection. The median times for wound healing and maximal joint function were 10 and 12 weeks, respectively. Clinical outcome was excellent in 22%, good in 56%, and poor in 22%. Comparison of the two stabilization methods showed no statistically significant differences in healing time, time to regain function, or clinical outcome.

In a retrospective study of tarsometatarsal joint subluxation in eight dogs, secondary fractures were identified in six dogs, particularly of the fourth tarsal bone and the proximal fifth metatarsal bone. Common causes of tarsometatarsal joint injury included jumping or falling and direct trauma to the foot. Partial tarsal arthrodesis, with the use of bone-plate stabilization and cancellous bone grafting of joint spaces after removal of articular cartilage, led to progressive bone healing in all dogs. Implant breakage did not occur in any dog.

From June 1994 to June 1996, 18 fledgling American crows (Corvus brachyrhynchos brachyrhynchos) from multiple locations on Long Island, New York, were presented with signs of metabolic bone disease characterized by folding fractures of the proximal tibiotarsus. Plasma alkaline phosphatase levels were elevated, and the calcium/phosphorus ratio and 25-hydroxycholecalciferol (25-(OH)D3) levels were decreased. The histopathologic diagnosis was parathyroid hyperplasia and generalized osteodystrophia fibrosa. A diet low in bioavailable calcium and/or vitamin D3 was the probable cause. Also, exposure to xenobiotics could have contributed to the depression of 25-(OH)D3 levels.

Twenty horses with central and third tarsal bone slab fractures, were treated internal fixation. Eighteen of the 20 cases were Standardbred trotters, one was a Thoroughbred racehorse and one a Swedish Warmblood. The central tarsal bone (CT) was involved in 12 cases and the third tarsal bone (T3) in 8 cases. The fractures were treated by lag screw fixation with one (18 cases) or two (2 cases) 3.5 or 4.5 mm cortical screws. Horses were confined to stall rest for one month and then put on a gradually increasing exercise programme. Convalescence time was 3-8 months until the fracture had healed and training could be resumed. Fifteen of the horses regained athletic soundness. Thirteen of the horses (72%) raced after surgery (12 Standardbreds and 1 Thoroughbred). Nine (69%) of these 13 horses won races after surgery.

Surgical repair of a fractured tibiotarsus in a scarlet macaw (Ara macao) is described. The forces imposed on the fracture site are discussed and the unique features of avian bone emphasised. Advantages of external skeletal fixation and specific details of the frame construction are highlighted.

Long digital extensor tendon avulsion is reported in a 5 month old Great Dane. Clinically the dog presented with a unilateral weight-bearing pelvic limb lameness. Joint effusion was present and there was pain and crepitance associated with flexion of the stifle. Orthopedic evaluation and radiographs were suggestive of a long digital extensor tendon injury which was confirmed by computed tomography and magnetic resonance imaging. The injury was surgically repaired with screw and spiked washer fixation.

Contrast radiography provides a clear survey of the size, shape, and location of extratendovaginal fluid-filled cavities, distended bursa, and tendon sheaths and demonstrates intersynovial communication. Ultrasonography effectively demonstrates Achilles tendon injury, slippage of the SDFT off the summit of the calcaneus, assorted ligamentous injuries, and cystic or solid extratendovaginal masses. It will also demonstrate distended bursae and tendon sheaths, but it is not as effective in demonstrating a synovial herniation, or a narrow synovial fistula. Contrast radiography may prove to be the imaging modality of choice for examination of fluctuating swellings, whereas ultrasonography is preferred for the assessment of firm swellings. Routine radiographic evaluation in the clinical assessment of soft tissue injuries in the hock region continues to play an invaluable diagnostic role.

Full-thickness, cutaneous autografting was successfully performed on an adult female ostrich to heal a granulomatous wound on the right tarsus. With surgical techniques used in domestic species such as dogs and horses, skin grafting is an alternative in avian species when conventional wound closure is not appropriate.

A 14-year-old Quarter Horse x Thoroughbred gelding was admitted to the teaching hospital because of inability to bear weight on its right hind limb, associated with a severe deviation of the tarsus. The provisional diagnosis was tarsal joint luxation or fracture. Radiography revealed complete luxation of the tarsocrural joint. The luxation was reduced, using minimal force. The horse was confined to a box stall and was maintained in a full-length hind-limb cast for 33 days. Box stall confinement was continued for 3 months after removal of the cast. On reexamination 18 months after the injury, the horse had only mild lameness (grade 1 of 5), but had marked reduction in the range of motion of the tarsus. Radiography revealed extensive changes indicative of severe degenerative joint disease. The horse was still used occasionally as a light pleasure riding horse and maintained itself on pasture well.

A flexed dorsoplantar radiographic view of the talocrural joint was a useful additional view to diagnose abnormalities of the lateral trochlear ridge of the talus of 2 dogs. This view outlined the subchondral bone of both trochlear ridges of the talus and the apposing cochlea tibiae of the distal portion of the tibia. The tarsus was flexed at the level of the talocrural joint, and an x-ray beam was centered on the joint. With this additional view, fractures of the lateral trochlear ridge were readily diagnosed. This view would help to demonstrate osteochondral lesions of the lateral trochlear ridge.

Injury of the lateral collateral ligaments of the tarsocrural joints was diagnosed in nine Standardbred pacers. The average age was 4.9 years. The severity of the lameness varied from severe to subtle and joint effusion was seen in eight of 10 tarsocrural joints. A positive hindlimb flexion test was seen in four of six cases in which results were recorded. The identification of the site of involvement was based on a focal intense 'hot spot' seen on scintigraphy, and new bone formation seen radiographically at the anatomical sites of insertion of the long lateral collateral ligament of the tarsocrural joint in nine limbs and the short lateral collateral ligament of one limb. The authors believe this injury to be enthesitis caused by the cyclic trauma of training and racing speed. The primary therapy was rest. Of six cases which returned to training, three raced as well or better than before injury.

A case of tibio-tarsal dislocation in a dog with fracture of both malleoli is described. An unusual feature was the absence of lateral instability in the hock despite fracture of the lateral malleolus.

Three horses and three ponies were treated for traumatic luxation of the proximal intertarsal or tarsometatarsal joint. In each case, there were fractures of one or more tarsal bones. Three of the animals had disruption of one of the collateral ligaments. Five animals were treated by closed reduction and external coaptation. One pony was treated by open curettage, a cancellous bone graft, and cast immobilization. No internal fixation was used in any of these animals. From this series of cases, it would appear that closed reduction and external coaption alone is adequate treatment for most cases of tarsal luxation.

An 8-year-old Thoroughbred gelding was determined to have a sagittal fracture of the central tarsal bone. Lag screw fixation of the fracture enabled the horse to return to jumping, although degenerative arthritis of the distal intertarsal joint was apparent radiographically 17 months after the injury.

Although most type IV fractures in dogs can be treated with screw fixation, type V fractures usually lead to an unsuccessful clinical result. A central tarsal replacement composed of a titanium alloy was developed by our investigation team to treat type V fractures. The implant was used to successfully treat a greyhound and to allow it to return to racing. Continual development of this new surgical procedure hopefully will give the veterinarian predictable and reliable clinical results and return injured greyhounds to active racing.

Methods of repair of central tarsal bone (Tc) fractures in the racing greyhound can involve coaptation, single-screw fixation, or 2-screw fixation. Successful management, defined as a return to competitive racing, was obtained in 71% of 114 affected dogs treated by these methods. Both 1- and 2-screw fixation, with interfragmentary compression, was used to repair Tc fractures in 81 dogs. It was concluded that satisfactory results can be expected by use of open reduction and screw fixation in all types of Tc fractures except those that are severely comminuted.

A total of 114 central tarsal bone (Tc) fractures, including associated secondary fractures, were identified in 114 racing Greyhounds. The fractures were classified according to a previously described scheme. The type IV Tc fracture, dorsal and medial slab fractures, was most common. A Tc fracture alone, or a Tc fracture with associated fractures of the 4th tarsal bone (T4), calcaneus, or T4 and lateral base of the 5th metatarsal bone were the most commonly observed. The prevalence of secondary fractures increased with the severity of the Tc fracture. Management of Tc fractures involved 3 methods: coaptation, single-screw fixation, and 2-screw fixation. Additional repair was performed as indicated by the presence of concurrent secondary fractures. A total of 71% of the dogs returned to competitive racing.

The methods described are those currently employed by the authors for the injuries described. As surgical results accumulate, we hope to modify and improve our methods. Many injuries to the carpus and tarsus have been omitted. Many questions remain unanswered. How long must external coaptation be applied? When is the optimum time for removal of internal fixation devices? Are sclerosing agents more successful for the management of interphalangeal luxations than primary suturing? Should autogenous cancellous bone be used in all arthrodeses? What is the best method of handling sesamoid fractures, and what is the best postoperative care for these fractures? When should passive joint movement be initiated? What is the owner's optimum role in providing rehabilitative physical therapy? Only be evaluating large numbers of clinical cases or controlling experimental cases can these questions be answered.

Fifty-one calcaneus fractures associated with (41) or without (10) central tarsal bone (Tc) fractures in racing greyhounds were evaluated and categorized. All calcaneal fractures with no Tc fractures had a plantar proximal intertarsal subluxation. No subluxations were found in dogs with both calcaneal and central tarsal fractures. The calcaneal fractures were treated either with coaptation splints or surgical repair. Surgical techniques included a Steinmann pin with a figure eight tension band device or screw or plate fixation as primary techniques supplemented by Kirschner wires and cerclage wires. In all calcaneal fractures associated with plantar proximal intertarsal subluxation, an arthrodesis of the calcaneoquartal joint was performed. All 22 surgically repaired fractures in dogs available for physical and radiographic reexamination had healed within 1 to 6 months. Eight dogs with fractures of the calcaneus associated with fractures of Tc returned to a racing career. None of the dogs with plantar proximal intertarsal subluxation raced again. Based on the orientation of the fracture lines and on dissection of two tarsi with calcaneal fractures, a hypothesis on the pathogenesis of calcaneal fractures in racing greyhounds was formulated.

Tarsal fractures were diagnosed in a heifer and a bull. In both cases, radiography confirmed intra-articular fractures, with subluxation of the fracture fragment. Sudden, nonreducible hock flexion was a clinical sign in both cases. This sign may be highly suggestive of intra-articular fracture when diagnosis must be made without radiography.

History, physical examination, and bone scintigraphy were used to diagnose central and/or third tarsal bone trauma in 3 acutely lame horses. In all 3 cases, the results of initial radiographic examination were negative. Bone scintigraphy revealed focal, intense radioisotope uptake at the level of the distal tarsal bones in the 3 horses. Radiographs obtained 4 weeks after injury in one horse demonstrated a slab fracture of the central tarsal bone. Conservative management of the tarsal bone disease resulted in acceptable return to function in all 3 horses.

A sagittal fracture of the navicular bone in five horses was treated by means of lag screw. Intra-operative radiographic monitoring and a specially developed guide apparatus was necessary to implant the screw precisely along the transverse axis of the navicular bone. Internal fixation resulted in progressive radiographic narrowing of the fracture zone. In all five patients the fracture healed (bony union) without superfluous callus formation.

The case histories and follow-up data for 11 horses with slab fractures of the central or 3rd tarsal bones were examined for information pertaining to the diagnosis, which was difficult to identify, treatment, which was proven ineffective, and the prognosis, which was shown to be poor for return to racing. The purpose of the study was to define the results that could be obtained by nonoperative methods, in an attempt to determine whether surgical treatment was advisable. Nine of the horses were Standardbreds and 2 were Thoroughbreds; all horses were 2 to 4 years old and were being exercised at race speed when the injury occurred. The diagnosis usually was made at the referral examination, some time after injury. Distention of the tibiotarsal joint usually developed following fracture of the central tarsal bone. In some fractures, local anesthetic injection or multiple radiographic views were required for diagnosis. Not all fracture planes were demonstrable radiographically. Prolonged rest was ineffective in restoring athletic soundness. Lag screw fixation was used in 1 horse, the only horse in the series that raced successfully after injury.