Descriptive epidemiology of fractures occurring in British Thoroughbred racehorses in training

REASONS FOR PERFORMING STUDY: Musculoskeletal injury is the major cause of days lost from training and wastage in Thoroughbred racehorses. Little scientific information is available on the majority of injuries occurring in training. OBJECTIVES: To estimate the incidence of fractures in British racehorses in training and describe the occurrence of different fracture types and bones involved. METHODS: Thirteen UK racehorse trainers participated in a prospective study, providing data on horses in their care for 2 years. Details on horses, their daily exercise and fracture occurrence were recorded. RESULTS: A total of 1178 horses provided 12,893 months at risk. Nontraumatic fracture incidence was 1.15/100 horse months (95% CI = 0.98, 1.35) and 78% of fractures occurred during training. A wide variety of fracture types and bones were involved, although at least 57% were stress fractures. Pelvic and tibial stress injuries accounted for 28% of fractures diagnosed. CONCLUSIONS: It is important to study injuries in training as well as in racing. The number of stress fractures suggests that training regimes for young Thoroughbreds could often be improved to create a more robust skeleton, able to withstand injury. POTENTIAL RELEVANCE: Studying injuries in racehorses in training can provide a scientific basis for the design of safer training regimes.     

STRESS REMODELING AND STRESS FRACTURE OF THE HUMERUS IN FOUR STANDARDBRED RACEHORSES

Two 2-year-old pacers, a 3-year-old pacer and a 2-year-old-trotter with acute forelimb lameness were admitted for nuclear scintigraphic examination. Horses were grade 3-4/5 lame. There was increased radiopharmaceutical uptake (IRU) in the distal cranial medial aspect of the humerus in one horse and along the caudal humeral cortex in the other three horses. Two of the four horses were affected bilaterally. Radiographic abnormalities consisted of thickening of the caudal cortex of the mid-diaphysis of the humerus but radiographic changes were not present in all horses. All horses were managed with stall rest initially then stall rest with hand-walking followed by limited turn out for a total of four months. None of the horses had raced before injury. One horse has returned to race training and the other three horses have returned to racing. Average time to return to racing was 329 days. Humeral stress fractures in Standardbred horses are rare. Diffuse patterns of IRU have not been reported in the humerus and are likely indicative of severe stress remodeling. Standardbred racehorses with stress fractures or stress remodeling of the humerus appear to have a good prognosis for return to racing.     

Quantitative analysis of scintigraphic findings in tibial stress fractures in Thoroughbred racehorses

OBJECTIVE: To develop a quantitative method of interpreting tibial scintigrams of Thoroughbred racehorses with tibial stress fractures that may facilitate diagnosis of fractures and to provide prognostic information regarding future performance of affected horses. ANIMALS: 35 Thoroughbred racehorses. PROCEDURES: Static bone-phase scintigrams of tibial stress fractures were quantitatively analyzed by use of ratios of the mean radionuclide counts per pixel in a region of interest (ROI) drawn around the area of increased uptake of radiopharmaceutical to mean counts per pixel in a second ROI drawn around an apparently normal area of the tibial diaphysis. In horses with unilateral fractures, ratios for the contralateral tibia were determined by use of 2 ROIs drawn at the same positions as the ROIs in the fractured tibia. Ratios were compared between fractured versus apparently normal tibias, between horses that returned to racing versus those that did not, and among horses with various grades of lameness. The association between ratios for fractured tibias and intervals between diagnosis and return to racing was also assessed. RESULTS: Mean ratio of ROIs in apparently normal tibias was 1.35 (95% confidence interval [CI], 1.21 to 1.50); that in tibias with stress fractures was 3.55 (95% CI, 2.50 to 4.60). These ratios were significantly different. None of the associations between ratios for fractured tibias and grades of lameness or performance outcomes were significant. CONCLUSIONS AND CLINICAL RELEVANCE: Tibial stress fracture scintigrams can be quantitatively analyzed. A prospective study with a controlled rehabilitation period is necessary to evaluate the possible applications of this method.     

STRESS FRACTURES OF THE HUMERUS, RADIUS, AND TIBIA IN HORSES

The medical records, radiographic and nuclear scintigraphic findings of 26 racing horses with 27 stress fracture episodes of the humerus, radius, or tibia were reviewed. The purposes of this study were to describe the radiographic and/or scintigraphic features of stress fractures of the humerus, radius, or tibia, and to evaluate the signalment and history of horses in which stress fracture occurred. Stress fractures of the three long bones examined were primarily seen in 2-and 3-year-old male Thoroughbred horses; commonly, the onset of lameness was immediately following training gallops or racing. There were 13 humeral stress fracture episodes in 12 horses. Ten were in the proximal caudolateral cortex, and three were in the distal craniomedial cortex. Radial stress fractures were seen in three horses, all in the midshaft radius. Tibial stress fractures were diagnosed in 11 horses. They were located in the proximal lateral tibia in six horses, the distal caudolateral tibia in three horses, and the midshaft tibia in three horses. Fifteen stress fractures were diagnosed with radiographs alone, one was diagnosed with scintigraphy alone, nine were diagnosed with radiographs and scintigraphy, and, in two horses, radiographs were negative, but the scintigraphic findings were consistent with stress fracture.     

Frequency distribution of carpal osteochondral fragmentation in a population of flat racing Thoroughbreds in the UK

Lameness associated with osteochondral fragmentation of the carpus is a common injury in racing horses. Frequency distributions of sites of fragmentation have previously been published in racehorses in the USA, Australia, New Zealand and Japan but not in racing Thoroughbreds in the UK. The objectives of the study were to document sites of osteochondral fragmentation in the carpus of a population of Thoroughbred flat racehorses in the UK and compare these with other Thoroughbred populations globally and other flat racing breeds. This study was a single centre retrospective observational study; case records of flat racing Thoroughbreds with sites of carpal bone fragmentation that underwent arthroscopic surgery at Newmarket Equine Hospital between 2008 and 2013 were reviewed. A total of 291 sites of fragmentation were identified arthroscopically within the carpal joints of 174 horses. This involved 135 (75%) middle carpal (MCj) and 44 (25%) antebrachiocarpal joints (ABCj), which differs from other populations reported. The most common sites of fragmentation were dorsodistal radial carpal bone (DDiCr) (49%), dorsoproximal third carpal bone (DPrC3) (22%), dorsodistal radius (DDiR) (15%), dorsoproximal radial carpal bone (DPrCr) (5%) and dorsoproximal intermediate carpal bone (DPrCi) (4%). The dorsodistal radial carpal bone is also the most common site in American (US) Quarter Horses (QHs) and Thoroughbreds (TBs) and Australian (AUS) TBs, while DPrC3 has a greater prevalence in US Standardbreds (SBs). Thereafter the frequency distribution differs between the reported study groups. Although all horses underwent bilateral radiographic examination, 45% of the total population had unilateral arthroscopic evaluation. This may therefore underestimate the total number of sites of fragmentation reported. In summary the frequency distribution of carpal fragmentation in flat racing Thoroughbreds in the UK appears to differ from other populations of racehorses.     

Lag screw fixation of dorsal cortical stress fractures of the third metacarpal bone in 116 racehorses

Reasons for performing study: The effectiveness and best method to manage dorsal cortical stress fractures is not clear. This study was performed to evaluate the success of lag screw fixation of such fractures in a population of Thoroughbred racehorses. Hypothesis: Lag screw fixation of dorsal cortical stress fractures is an effective surgical procedure allowing racehorses to return to their preoperative level of performance. Methods: The records of 116 racehorses (103 Thoroughbreds) admitted to Equine Medical Centre, California between 1986 and 2008 were assessed. Information obtained from medical records included subject details, limb(s) affected, fracture configuration, length of screw used in repair and presence of concurrent surgical procedures performed. Racing performance was evaluated relative to these factors using Fisher's exact test and nonparametric methods with a level of significance of P<0.05. Results: Of 92 Thoroughbred horses, 83% raced preoperatively and 83% raced post operatively, with 63% having ≥5 starts. There was no statistically significant association between age, gender, limb affected, fracture configuration or presence of concurrent surgery and likelihood of racing post operatively or of having 5 or more starts. The mean earnings per start and the performance index for the 3 races following surgery were lower compared to the 3 races prior to surgery; however, 29 and 45% of horses either improved or did not change their earnings per start and performance index, respectively. Conclusions and potential relevance: Data show that lag screw fixation is successful at restoring ability to race in horses suffering from dorsal cortical stress fractures.     

Racing Performance in 72 Racehorses Treated with Prosthetic Laryngoplasty for Laryngeal Hemiplegia

The purpose of this study was to compare racing performance before and after prosthetic laryngoplasty for treatment of laryngeal hemiplegia in inexperienced (horses without at least one start before surgery) and experienced (horses with at least one start before surgery) Thoroughbred and Quarter Horse racehorses. Medical records of 54 Thoroughbred and 18 Quarter Horse racehorses or horses intended for racing treated with prosthetic laryngoplasty and unilateral ventriculectomy for laryngeal hemiplegia were reviewed. Signalment, age at the time of surgery, resting endoscopic grade of laryngeal function, surgical procedure, and type of suture were recorded. Median performance index (PI), earnings, distance, and Beyer speed figure (BSF) per start for three races before and after surgery were compared, and factors associated with improved postsurgical performance were evaluated. Seventy-three percent of horses that had not raced before surgery and 84% of horses that competed in at least one race before surgery were able to return to racing after surgery. Fifty-nine percent and 27% of Thoroughbreds and Quarter Horses, respectively, were able to improve their PI after surgery. Sixty-two percent and 20% of Thoroughbreds and Quarter Horses, respectively, significantly increased their distance after surgery. Additionally, 61% and 66% of racehorses were able to increase their earnings and BSF after surgery, respectively. Horses treated with laryngoplasty and unilateral ventriculectomy have a good prognosis for return to racing. Inexperienced racehorses have a better prognosis for improvement after surgery than do experienced racehorses. Thoroughbred racehorses have a better success rate than Quarter Horse racehorses.     

Clinical evaluation of a titanium, headless variable-pitched tapered cannulated compression screw for repair of frontal plane slab fractures of the third carpal bone in thoroughbred racehorses

OBJECTIVE: To report clinical evaluation of third carpal bone (C3) frontal plane slab fracture repair with the Acutrak screw system. STUDY DESIGN: Prospective case series. SAMPLE POPULATION: Racing Thoroughbreds (n=17) with frontal C3 slab fractures. METHODS: C3 slab fractures in Thoroughbred racehorses (1999-2004) were repaired by use of the Acutrak screw system. Data collected were (1) preoperative variables--gender, age at injury, limb involved, injury occurrence, fracture thickness, complexity, and displacement, race starts and earnings and (2) postoperative variables were: surgical complications, days to first start, race starts, and earnings. A Wilcoxon signed-rank test was used to compare pre- and postoperative starts and earnings; significance was set at P<.05. RESULTS: Seventeen Thoroughbred racehorses (12 females, 3 males, 2 geldings) were enrolled. Mean (+/-SD) age at injury was 3.3+/-1.0 years. Right carpi (10) were affected more than left (7). Ten injuries occurred during training, 7 during racing. Twelve of 15 horses that raced before injury returned to racing. Average days to first start was 349.3+/-153.9 days. Horses that returned to racing had more starts after repair (median, 6.5 versus 3.5; P=.04) and did not have decreased earnings per start (median, $2452 versus $3061; P=.30). CONCLUSION: The Acutrak screw system is a useful repair technique for frontal C3 slab fractures in Thoroughbred racehorses. CLINICAL RELEVANCE: Adequate reduction and stability of C3 slab fractures can be achieved with the Acutrak screw system, decreasing the likelihood of fragment splitting and screw head impingement on carpal soft tissues.     

Macroscopic changes in the distal ends of the third metacarpal and metatarsal bones of Thoroughbred racehorses with condylar fractures

OBJECTIVE: To determine changes in the distal ends of the third metacarpal and metatarsal bones (MCIII and MTIII) of Thoroughbred racehorses that had sustained a catastrophic condylar fracture during high-speed exercise. SAMPLE POPULATION: Fractured and contralateral MCIIIs and MTIIIs from 11 Thoroughbred racehorses that sustained a displaced condylar fracture during racing, both MCIIIs from 5 Thoroughbred racehorses euthanatized because of a catastrophic injury other than a condylar fracture, and both MCIIIs from 5 horses of other breeds that had not been professionally trained or raced. PROCEDURE: Macroscopic observations were made of the distal ends of the bones before and after digestion of the articular cartilage with NaOH. RESULTS: In all 11 racehorses with a displaced condylar fracture, the fracture was associated with a branching array of cracks in the condylar groove. In this region, fracture margins were smooth, and there was loss of subchondral bone. Comminution of the dorsal cortex was also seen. Parasagittal linear wear lines in the articular cartilage, erosions in the articular cartilage of the condyles, loss of the underlying subchondral bone, and cracking of condylar grooves were all more severe in the Thoroughbred racehorses than in the horses that had not been professionally trained or raced. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that condylar fractures in horses are pathologic fatigue or stress fractures that arise from a preexisting, branching array of cracks in the condylar groove of the distal end of MCIII or MTIII.     

Humeral stress remodelling locations differ in Thoroughbred racehorses training and racing on dirt compared to synthetic racetrack surfaces

Reasons for performing study: Veterinarians have observed a putative change in the location of humeral stress remodelling in Thoroughbred racehorses with change from dirt to synthetic racetrack surfaces. Objectives: To determine whether the location and severity of humeral stress remodelling differs between Thoroughbred racehorses exercising on dirt and synthetic racetrack surfaces, the potential significance of different locations of stress remodelling, and the potential usefulness of scintigraphy for prevention of complete humeral fracture. Methods: Scintigraphic images of humeri from 841 Thoroughbred racehorses at 3 racetracks during 2 years before and after conversion from dirt to synthetic surfaces were evaluated for location and severity of lesions. The effects of surface on lesion distributions were examined using Chi‐square or Fisher's exact tests. Archived fractured humeri were examined to determine the location and severity of stress remodelling associated with complete fracture. Databases were queried to determine whether racehorses with scintigraphic lesions suffered humeral fracture and whether racehorses with a complete humeral fracture had had a scintigraphic examination. Results: Horses at synthetic racetracks had a greater proportion of distal humeral lesions, whereas horses at dirt racetracks had a greater proportion of caudoproximal lesions (P<0.001). Proximal lesions were more likely to be severe than distal lesions (P<0.001). Most complete fractures were associated with caudoproximal lesions, which were more often severe than distal lesions (P = 0.002). None of the horses with a scintigraphic lesion had a complete humeral fracture. None of the horses with a complete humeral fracture underwent scintigraphic examination. Conclusions: Race surface affected humeral scintigraphic lesion location and hence the location of stress remodelling. Lesion severity was associated with lesion location. Complete humeral fracture was associated with caudoproximal stress remodelling and lack of scintigraphic examination. Potential relevance: Risk for complete humeral fracture may be lower on synthetic surfaces than on dirt surfaces, and, by inference, for horses examined using scintigraphy.     

Racing performance after arthroscopic removal of apical sesamoid fracture fragments in Thoroughbred horses age > or = 2 years: 84 cases (1989-2002)

REASONS FOR PERFORMING STUDY: Studies have shown that surgical removal of apical fracture fragments in Standardbred racehorses carries the best prognosis for return to racing performance, but there are no reports involving mature Thoroughbred (TB) racehorses. OBJECTIVES: To describe the incidence of apical proximal sesamoid fractures in TB racehorses and determine probability and quality of racing performance after arthroscopic removal of such fractures in TB racehorses age > or = 2 years. METHODS: Medical records and pre- and post operative race records of TB racehorses age > or = 2 years that underwent arthroscopic surgery for removal of apical proximal sesamoid fracture fragments were reviewed. RESULTS: Sixty-four percent of fractures occurred in the hindlimbs and 36% in the forelimbs. Horses with forelimb fractures had a reduced probability of return to racing (67%) compared to those with hindlimb fractures (83%), but the majority (77%) of treated horses recovered to return to race post operatively. Horses with medial forelimb fractures raced at only a 47% rate; those with suspensory desmitis at 63%. Unlike Standardbreds, there was no difference in probability of racing post operatively between horses that had, and had not, raced preoperatively. CONCLUSIONS: Data show that arthroscopic removal of apical proximal sesamoid fracture fragments is successful at restoring ability to race in skeletally mature TB horses without evidence of severe suspensory ligament damage. Prognosis for return to racing is excellent (83%) in horses with hindlimb fractures and good (67%) in those with forelimb fractures. Medial fractures of the forelimb have the worst prognosis. POTENTIAL RELEVANCE: The determination of prognosis for differing sites in TB racehorses should increase knowledge of apical proximal sesamoid bone fractures and improve communication from veterinarian to owner, and trainer, on the potential for arthroscopic restoration of the ability to race.     

Resting concentrations of cardiac troponin I in fit horses and effect of racing

ObjectivesTo determine normal resting values for cardiac troponin I (cTnI) in healthy Standardbred, Thoroughbred and Warmblood horses and investigate if racing has an influence on cTnI concentrations.BackgroundMeasuring cTnI concentrations in plasma is the gold standard for detecting myocardial injury in humans. Cardiac troponin I is highly conserved between species and has gained interest as a marker for cardiac injury in horses. Increased levels of cTnI have been reported in association with endurance and short-term strenuous exercise on a treadmill in horses. However, the effect of true racing conditions has not yet been reported.Animals, materials and methodsBlood samples for analysis of cTnI concentrations in plasma were collected from 67 Standardbred racehorses, 34 Thoroughbred racehorses and 35 Warmblood dressage horses at rest. Blood samples were also collected prior to and after racing in 22 Standardbred racehorses and 6 Thoroughbred racehorses.ResultsAll horses except one had resting plasma cTnI concentrations <0.022 μg/L. Mild increases in cTnI concentrations were seen in some horses 1–2 h after the race (1/17 Standardbreds and 2/6 Thoroughbreds) as well as 10–14 h after the race (4/21 Standardbreds and 1/6 Thoroughbreds).ConclusionsResting cTnI concentrations in horses are low but mildly elevated cTnI concentrations may be detected in some horses 1–14 h after racing. These findings could be of importance when evaluating horses with suspected cardiac disease that recently have performed hard exercise.     

Arthroscopic removal of fractures of the lateral malleolus of the tibia in the tarsocrural joint: A retrospective study of 13 cases

There is limited information on the treatment of lateral malleolus (LM) fractures in the horse, with no previously published case series for the outcome following arthroscopic removal of such fractures. This report reviews and evaluates findings of a retrospective study of 13 horses admitted to a private equine referral hospital over a 10 year period (1999–2009) that underwent arthroscopic removal of fractures of the LM. Hospital records were reviewed and details including patient history, aetiology of the fracture and limb affected, results of all diagnostic tests and surgical reports were documented. Performance information concerning Thoroughbred horses that went onto race post operatively was collected using an online database. Owners and trainers were contacted regarding the return to performance for non‐Thoroughbred cases or those that did not go onto race post operatively. Of the 13 horses presented, 12 were Thoroughbreds, 9 of which were National Hunt racehorses and 3 were Flat racehorses. The other horse in the study was used for general purpose riding. All cases presented with an acute unilateral fracture. Eleven of the 13 had >6 months post operative follow‐up and all were nonlame. Of the 12 Thoroughbreds, 10 have raced again, a total of 104 times (median 5 times). The median time from surgery to return to racing was 241 days (180–366 days). It is concluded that horses with fractures of the LM have an excellent prognosis for return to full athletic performance following arthroscopic debridement; and that arthroscopic fragment removal is an appropriate treatment method for fractures of the LM.     

Scapula stress fractures in Thoroughbred racehorses: Eight cases (1997–2006)

No case series exists in the literature describing scapula stress fractures. The purpose of this study was to review the clinical findings, diagnostic images and outcome of 8 horses diagnosed with scapula stress fractures. Scapula stress fractures were seen in Thoroughbred racehorses displaying acute moderate forelimb lameness. Nuclear scintigraphy identified the mid‐distal scapula spine and/or scapula supraspinous fossa as predilection sites. Conservative management resulted in a good prognosis for return to racing, but stress fracture recurrence may be seen.     

Correlation of performance with endoscopic and radiographic assessment of epiglottic hypoplasia in racehorses with epiglottic entrapment corrected by use of contact neodymium:yttrium aluminum garnet laser

Epiglottic entrapment in 35 Thoroughbred and 44 Standardbred horses was corrected transendoscopically by use of a neodymium:yttrium aluminum garnet laser. Before surgery, the entrapped epiglottis was classified as hypoplastic or normal in each horse on the basis of endoscopic appearance alone. Using a digitizer, thyroepiglottic length was determined from lateral-view laryngeal radiographs. For 78 racehorses, earnings (less than $5,000 or greater than $5,000) were compared before and after surgery. Earnings category and racing performance after surgery were tested for association with endoscopically determined epiglottic hypoplasia and radiographically determined thyroepiglottic length. Endoscopy and radiography were useful methods of evaluating the epiglottis in horses with epiglottic entrapment. Mean (+/- SD) thyroepiglottic length for both breeds of horses with epiglottic entrapment was significantly (P = 0.0001) smaller (Thoroughbreds, 7.28 +/- 0.67 cm; Standardbreds, 7.21 +/- 0.62 cm), compared with thyroepiglottic length measured from control groups composed of clinically normal Thoroughbred (8.56 +/- 0.29 cm) and Standardbred (8.74 +/- 0.38 cm) racehorses. Both breeds of horses with epiglottic entrapment that had endoscopically apparent hypoplastic epiglottis had significantly (P less than 0.0001) smaller thyroepiglottic length (Thoroughbreds, 6.64 +/- 0.60 cm; Standardbred, 6.93 +/- 0.72 cm) than did horses with epiglottic entrapment that had endoscopically normal epiglottis (Throughbreds, 7.57 +/- 0.47 cm, Standardbreds, 7.36 +/- 0.50 cm). Significant difference was not detected in endoscopic appearance of the epiglottis among age, gender, or breed distributions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Scintigraphic appearance of stress-induced trauma of the dorsal cortex of the third metacarpal bone in racing Thoroughbred horses: 121 cases (1978-1986)

Review of 121 bone scintigrams obtained on racing Thoroughbred horses with clinical histories indicative of forelimb lameness revealed 3 scintigraphic patterns of stress-induced trauma to the dorsal cortex of the third metacarpal bone: (1) focal, intense uptake associated with recent stress fracture; (2) regional uptake of varying intensity or a mixed pattern of uptake associated with chronic stress fracture; and (3) diffuse, mild to moderate uptake associated with periostitis (bucked shins). The latter scintigraphic pattern appeared to be an exaggerated manifestation of the normal remodeling process evident in immature horses (2 to 3 years old). Scintigraphy was most helpful in identifying radiographically occult stress fractures, determining the extent of cortical involvement before surgical intervention in cases of chronic stress fractures, and monitoring the fracture healing process.     

Characteristics of Thoroughbred and Quarter Horse racehorses that sustained a complete scapular fracture

Reasons for performing study: To determine if scapular fractures occur in racehorses with distinctive characteristics. Objectives: To test the hypothesis that Thoroughbred (TB) and Quarter Horse (QH) racehorses with a scapular fracture have similar characteristics that are different from those of their respective racetrack populations. Methods: Necropsy findings, case details, last race information and career earnings for TB and QH racehorses that had a scapular fracture in California between 1990 and 2008 were retrospectively compared between breeds. Horse signalment, career earnings, career starts and race characteristics were obtained for all California racehorses. Comparisons were made between affected horses, other racehorses that died, and all horses that raced, in California during the 19 year period. Results: Seventy‐three TB and 28 QH racehorses had a similar, complete comminuted scapular fracture with an articular component, and right forelimb predilection. The QHs had a higher incidence of scapular fracture incurred during racing than TBs (0.98 vs. 0.39/1000 starters). The TB and QH incident rates for musculoskeletal deaths incurred racing were 20.5 and 17.5/1000 starters, respectively; however, a greater proportion of TB musculoskeletal deaths occurred training (40% vs. 8%). Horses with a scapular fracture were more likely to be male and aged 2 or ≥5 years than the racetrack population. Most affected QHs (64%) were 2‐year‐olds; most TBs (74%) were aged ≥3 years. Scapular fractures occurred more commonly during racing in QHs (70%) than TBs (44%). Race‐related scapular fracture was more likely to occur in a Maiden race than in a non‐Maiden race. Horses with a scapular fracture had fewer career starts than the racetrack population. Conclusions and potential relevance: Despite breed differences for signalment and exercise distances, both breeds incur a complete scapular fracture that is more likely to occur in the right scapula of young and older, male racehorses, early in their race career or after few races. Quarter Horses sustain a catastrophic scapular fracture more frequently than TBs.     

A clinical evaluation of a headless, titanium, variable-pitched, tapered, compression screw for repair of nondisplaced lateral condylar fractures in thoroughbred racehorses

OBJECTIVE: To report clinical evaluation of headless compression screws for repair of metacarpal/metatarsal (MC/MT3) condylar fractures in horses. STUDY DESIGN: Retrospective case study. SAMPLE POPULATION: Racing Thoroughbreds (n=16) with nondisplaced lateral condylar fractures of MC/MT 3. METHODS: Medical records (1999-2004) of horses with nondisplaced longitudinal fractures of the lateral condyle of MC/MT3 were reviewed. Pre-operative variables retrieved were: patient age, gender, limb involvement, injury occurrence, fracture length, and width, evidence of palmar comminution and degenerative joint disease, number of pre-injury starts, and pre-injury earnings. Post-operative variables retrieved were: surgical complications, surgical time, number of race starts, and post-operative earnings. RESULTS: MC3 (n=11) and MT3 (5) nondisplaced longitudinal fractures of the lateral condyle were repaired with Acutrak Equine (AE) screws. Left front limb fractures were most common (8) followed by left hind (5) and right front (3). Nine fractures occurred during training and 7 during racing; 4 fractures had palmar comminution. No surgical complications occurred. Of 15 horses that returned to training, 11 (73%) raced 306+/-67 days after injury and had greater mean (+/-SD) post-injury earnings/start ($5290.00+/-$8124.00) than pre-injury ($4971.00+/-$2842.00). Screw removal was not required in any horse. CONCLUSION: The AE screw is a viable option for repair of nondisplaced lateral condylar MC/MT3 fractures in Thoroughbred racehorses. CLINICAL RELEVANCE: Adequate stability of nondisplaced lateral condylar fractures can be achieved with a headless tapered compression screw while avoiding impingement on the collateral ligaments and joint capsule of the fetlock joint.     

An association between complete and incomplete stress fractures of the humerus in racehorses.

Twenty-one horses had a complete unilateral humeral fracture during race training or racing at a California racetrack during the period 24 February 1990 to 10 July 1991. Fractures occurred approximately equally in left and right limbs, and in males and females. Most fractures occurred during training, and in 2- and 3-year-old horses. Only 5 of 16 Thoroughbred horses with known racing records had previously raced more than once, and their mean time between races was less than the time between their last race and fracture (P = 0.07). Ten of 13 humeri studied further had gross evidence of periosteal callus bridging one portion of the fracture line, indicative of a pre-existing stress fracture.