Risk rates for and predisposing factors to fractures occurring in Thoroughbred racing that have been published in peer reviewed journals are documented. The potential for currently available techniques to identify horses at increased risk for fracture is discussed on the bases of principles, practicalities, advantages, disadvantages and current data. All are reviewed in light of justifiable decision making and importance of fractures to horseracing's social license.

OBJECTIVE:To describe an arthroscopically guided technique for lag screw placement across subchondral bone cyst (SBC) in the medial femoral condyle (MFC) and to compare postoperative racing performance with corticosteroid injection and cyst debridement.STUDY DESIGN:Retrospective cohort study.ANIMALS:One hundred twenty-three horses with 134 MFC SBCs undergoing treatment at a single referral hospital in the UK between January, 2009, and December, 2020.METHODS:Sex, age, limb affected, radiographic cyst dimensions, preoperative and postoperative lameness, surgical technique (lag screw placement, cyst debridement, intralesional corticosteroid injection), and, where applicable, screw positioning were recorded retrospectively. A ratio was calculated using measurements from preoperative and postoperative radiographs. Outcome was assessed by resolution or improvement in lameness, reduction in cyst size, and starting one race after treatment. Outcome data was compared between treatment groups.RESULTS:Twenty-six of 45 (57.8%) horses that underwent transcondylar screw placement raced postoperatively, at a median of 403 days between surgery and first postoperative race. There was no difference between treatment groups with regard to racing or preoperative and postoperative lameness. Cysts treated with transcondylar screw placement had a greater reduction in cyst size and a reduced period of convalescence in comparison with those that underwent debridement; the results were similar to those treated by intralesional corticosteroid injection.CONCLUSION:Postoperative racing rates were similar for all techniques. Convalescence was reduced for lag screw placement and corticosteroid injection compared to debridement.CLINICAL SIGNIFICANCE:The arthroscopically guided technique results in radiographically consistent screw placement and cyst engagement and offers a viable alternative to other treatments.

Slab fractures of the third carpal bone (C3) are a common cause of lameness in Thoroughbred racehorses. Information on fracture morphology is commonly obtained from radiographs or CT. This retrospective, methods comparison aimed to explore the agreement between radiography and CT for imaging C3 slab fractures and discuss the contribution of the latter to clinical case management. Thoroughbred racehorses with a slab or incomplete slab fracture of C3 identified on radiographs that subsequently underwent CT examination were included. Fracture characteristics (location, plane, classification, displacement, comminution) and fracture length as a percentage of the proximodistal length of the bone, termed the proximodistal fracture percentage (PFP) were recorded independently from both modalities and then compared. Across all fractures (n = 82) radiographs and CT showed slight agreement on the presence of comminution (Cohen's Kappa (κ) 0.108, P 0.031) and moderate agreement on fracture displacement (K 0.683, P < 0.001). Computed tomography identified comminution in 49 (59.8%) and displacement in nine (11.0%) fractures that were not detected by radiographs. Half of the fractures were only seen on flexed dorsoproximal-dorsodistal oblique (DPr-DDiO) radiographs and therefore were of unknown length without additional CT imaging. Incomplete fractures that could be measured on radiographs (n = 12) had a median (IQR) PFP of 40% (30%-52%) on radiographs and 53% (38%-59%) on CT, a statistically significant difference (P = 0.026). Radiography and CT showed the poorest agreement when determining the presence of comminution. Additionally, radiography often underestimated the incidence of displacement, and fracture length, and resulted in more fractures being classified as incomplete when compared to CT.

OBJECTIVETo evaluate bone mineral content patterns between fracture configurations using novel CT image analysis.ANIMALSCT images from 97 Thoroughbred racehorses with third metacarpal/tarsal condyle fractures provide the case population for analysis.PROCEDURESFractures were grouped by radiographic appearance. Image analysis objectively measured area of highly attenuating pixels (aHAP), areal density of highly attenuating pixels (dHAP) utilizing novel convex hull analysis, and subjective assessment of apparent attenuation intensity ranking (AAIR) for each fracture. Differences between fracture configuration groups were evaluated.RESULTSAnalysis of dHAP identified lower-density regions of highly attenuating pixels in propagating fractures and higher-density regions of highly attenuating pixels in unicortical fractures (P = .028). Complete and incomplete configurations were almost indistinguishable in dHAP (P = 1.000). The ratio of dHAP between fractured and nonfractured condyles revealed higher density gradients between condyles in unicortical (P = .040) and incomplete (P = .031) fractures than propagating fractures.CLINICAL RELEVANCEDifferences in patterns of bone mineral content were identified between propagating, bicortical (incomplete and complete), and unicortical fractures of third metacarpal/tarsal bone condyles. Computer-assisted geometric measurement of dHAP identified on CT images could help to assess fracture risk in equine athletes. This application may have greater relevance as standing CT screening becomes more available.

OBJECTIVE:To identify prognostic factors for return to racing after lag screw repair of condylar fractures and develop a predictive model for return to racing.STUDY DESIGN:Retrospective cohort study.ANIMALS:A total of 356 horses referred to a single referral hospital in the UK with a third metacarpal/metatarsal condylar fracture between January 1999 and December 2018.METHODS:Age, sex, fracture site, fracture characteristics, surgery related variables and complications were retrieved from case records. Data were divided into two sets for model training and model validation. Univariable analyses were performed, and predictors were selected in a stepwise fashion for inclusion in the multivariable logistic regression model. Sensitivity and specificity were evaluated using the second dataset.RESULTS:Older horses, fillies, fractures of forelimbs, complex, complete, displaced or propagating fractures and concurrent proximal sesamoid bone fracture were negatively associated with return to racing. Colts and geldings were 3 and 4 times more likely to race than fillies, respectively. Horses with hindlimb, incomplete or nonpropagating fractures were 4, 5 and 4 times more likely to race than those with a forelimb, complete or propagating fracture, respectively. Using a predicted probability cut-off threshold of 0.5, a predictive model was created within one dataset (sensitivity = 84%, specificity = 50.5%) and applied to another (sensitivity = 83.1%, specificity = 24.0%).CONCLUSION:Negative prognostic factors were identified and led to a predictive model with acceptable sensitivity and specificity in the tested population.CLINICAL SIGNIFICANCE:The results provide proof of concept for the model in the reported population and justify further validation in different populations of horses.

BACKGROUND:Fractures of the proximal phalanx are one of the most common long bone fractures of Thoroughbred racehorses. Although the degree of disruption and damage to the articular surface is generally considered a major prognostic determinant, associated arthroscopic findings have not previously been reported.OBJECTIVES:To describe the metacarpo/metatarsophalangeal (MCP/MTP) joint lesions associated with parasagittal fractures of the proximal phalanx arthroscopically identified at the time of fracture repair and compare radiographic and arthroscopic appearance of complete fractures.STUDY DESIGN:Retrospective case series.METHODS:Case records and arthroscopic images of horses with parasagittal fractures of the proximal phalanx admitted to Newmarket Equine Hospital from 2007 to 2017 were analysed.RESULTS:81 MCP/MTP joints in 78 horses underwent arthroscopic evaluation concurrent to parasagittal fracture repair. Tears of the joint capsule and dorsal synovial plica were noted in 43 cases. Arthroscopy identified articular incongruity in three horses where fracture displacement was not predicted at all on pre-operative radiographs, and incongruity in additional plane(s) to the radiographic displacement in 14 horses. Concurrent osteochondral fragmentation and disruption of cartilage were present in some cases.MAIN LIMITATIONS:As a retrospective study, the arthroscopic data available for review were variable. Arthroscopic assessment of fracture reduction and joint congruency was evaluated in all cases but there was variation in the completeness of evaluation of the entire dorsal joint space of the fetlock joint. This may have led to the underestimation of soft tissue lesions in these cases.CONCLUSIONS:Some horses suffering from parasagittal proximal phalanx fractures have concurrent tearing of the joint capsule and/or dorsal plica, which may have relevance in the acute course of events resulting in the development of fractures. Fracture displacement and incongruency at the articular surface cannot confidently be excluded pre-operatively by radiographs alone.

Background Slab fractures of the third carpal bone (C3) are a common injury of Thoroughbred racehorses. Results of arthroscopically guided repair have not been reported since the initial description of the technique in 1986. Additionally, fracture details and racing outcomes in a population of Thoroughbreds racing under UK jurisdiction have not previously been described. Objectives To report the frequency distribution of C3 slab fractures and to determine the impact on racing performance following arthroscopically guided repair in a population of Thoroughbred racehorses. Study design Retrospective case series. Methods Case records of Thoroughbred racehorses undergoing arthroscopically guided repair of C3 slab fractures at Newmarket Equine Hospital between 2006 and 2015 were retrieved. Radiographs and arthroscopic studies were reviewed. The effect of demography and fracture morphology on racing outcome was evaluated. Results C3 slab fractures occurred most commonly through the radial facet in a frontal plane (45/71 63.4%). Comminution was identified during arthroscopy in 42/71 (59.2%) fractures and occurred most frequently at the palmar margin of the fracture. Forty-one out of 65 horses (63.1%) raced at least once post-operatively. Females were less likely to return to racing compared to males (P<0.001). Horses that had raced before injury were more likely (OR 4.4, 95% CI 1.4-13.5, P = 0.01) to race after injury compared to horses that were unraced at the time of injury. After injury horses had a small but significant reduction in racing performance. Main limitations The series is a preselected population of Thoroughbred racehorses which referring veterinary surgeons considered potential candidates for surgical repair. Conclusion Fracture configurations can be identified radiographically but is not a reliable predictor of comminution or other intra-articular lesions. Arthroscopy not only directs repair but also identifies and facilitates management of concurrent lesions. The results reported should assist in formulating appropriate prognoses for Thoroughbred horses racing in the UK.

BACKGROUND:Suspensory ligament branch injuries are common in horses. Most of these injuries are grouped together and considered as a single pathologic entity.OBJECTIVES:To report a specific injury of the abaxial margin of the suspensory ligament branches and to report its surgical management and outcome.STUDY DESIGN:Retrospective case series.METHODS:All horses with suspensory ligament branch injuries over a 9-year period (2007-2015) were identified. Horses with injuries which, on ultrasonographic examination, appeared to have defects in the abaxial margin of the suspensory ligament branch, that were subsequently confirmed during surgery were selected.RESULTS:Twenty-nine cases fulfilled the inclusion criteria with a specific lesion location on the abaxial margin of the suspensory ligament branch. Nineteen horses raced successfully after surgery, nine returned to training but failed to race and one was lost to follow-up.MAIN LIMITATIONS:The absence of a comparable population of non-surgically managed horses in this study means that the contribution of removing torn tissue cannot confidently be assessed.CONCLUSIONS:The location and morphology of injuries described in this study is consistent, which suggests aetiopathogenic commonality. This case series suggests this type of injury has an identity of its own, differs from other types of suspensory ligament branch injuries and represents a previously undescribed subgroup.

BACKGROUND:Osteochondral fragmentation of the dorsoproximal margin of the proximal phalanx is commonly recognised in racing Thoroughbreds. Frequency distribution has been documented in racing Thoroughbreds and Quarter Horses in the USA and in European Warmbloods but no data have been published from the UK. Concurrent intra-articular soft tissue lesions and radiographic accuracy of fragment distribution in racing Thoroughbreds have not previously been reported.OBJECTIVES:To document frequency distribution of dorsoproximal fragmentation of the proximal phalanx in a UK population of racing Thoroughbreds and to compare this with published data. To document concurrent intra-articular lesions identified arthroscopically and radiographic accuracy of fragment distribution.STUDY DESIGN:A retrospective single centre-based, observational study.METHODS:Surgical reports and radiographs of all racing Thoroughbreds that underwent arthroscopic surgery for removal of fragmentation from the dorsoproximal margin of the proximal phalanx at Newmarket Equine Hospital between 2011 and 2015 were reviewed.RESULTS:Two hundred and forty-two (85.8%) horses were in or being prepared for flat racing. Osteochondral fragmentation of the dorsoproximal aspect of the proximal phalanx was present in 428 fetlock joints of 282 horses, consisting of 194 (45.3%) left and 188 (43.9%) right metacarpophalangeal joints, and 20 (4.7%) left and 26 (6.1%) right metatarsophalangeal joints. Fragmentation was located dorsomedially in 316 (73.8%), dorsolaterally in 32 (7.5%) and biaxially in 80 (18.7%) joints. Concurrent soft tissue lesions were identified in 168 (39.3%) joints. Radiographic evidence of fragmentation was visible in 320 joints (74.8%).MAIN LIMITATIONS:Limited numbers preclude conclusions with respect to yearlings and horses in jump race training.CONCLUSION:Dorsoproximal fragmentation of the proximal phalanx occurred most frequently medially and in the forelimbs. Sidedness was not demonstrated. Although similar to previously reported data, variance in limb distribution is evident. Further research is required to determine whether concurrent intra-articular soft tissue lesions are aetiopathogenic or an additional result of the pathological changes leading to fragmentation. Fragmentation site was not always accurately identified radiographically. The Summary is available in Spanish - see Supporting information.

BackgroundChip fractures of the dorsoproximal articular margin of the proximal phalanx are common injuries in racehorses. Large fractures can extend distal to the joint capsule insertion and have been described as dorsal frontal fractures. ObjectivesTo report the location and morphology of short frontal plane fractures involving the dorsoproximal articular surface of the proximal phalanx and describe a technique for repair under arthroscopic and radiographic guidance. Study designSingle centre retrospective case study. MethodsCase records of horses with frontal plane fractures restricted to the dorsoproximal epiphysis and metaphysis of the proximal phalanx referred to Newmarket Equine Hospital were retrieved, images reviewed and lesion morphology described. A technique for repair and the results obtained are reported. ResultsA total of 22 fractures in 21 horses commencing at the proximal articular surface exited the dorsal cortex of the proximal phalanx distal to the metacarpophalangeal/metatarsophalangeal joint capsule in 17 hind- and five forelimbs. All were in Thoroughbred racehorses. In 16 cases these were acute racing or training injuries; 20 fractures were medial, one lateral and one was midline. All were repaired with a single lag screw using arthroscopic and radiographically determined landmarks. A total of 16 horses raced after surgery with performance data similar to their preinjury levels. Main limitationsThe study demonstrates substantial morphological similarities between individual lesions supporting a common pathophysiology, but does not identify precise causation. There are no cases managed differently that might permit assessment of the comparative efficacy of the treatment described. ConclusionsShort frontal plane fractures involving the dorsoproximal margin of the proximal phalanx that exit the bone distal to the metacarpophalangeal/metatarsophalangeal joint capsule have substantial morphological similarities, are amenable to minimally invasive repair and carry a good prognosis for return to training and racing.

BACKGROUND:Thirty years have elapsed since the last published review of outcome following fracture of the proximal phalanx in Thoroughbred racehorses in the UK and contemporary results are needed to be able to advise of expected outcome.OBJECTIVES:Collect and analyse outcome data following repair of fractures of the proximal phalanx in Thoroughbred racehorses in the UK.STUDY DESIGN:Retrospective case series.METHODS:Case records of all Thoroughbred racehorses admitted to Newmarket Equine Hospital for evaluation of a parasagittal fracture of the proximal phalanx during a 5 years period were reviewed. Follow-up data regarding racing careers was collected for horses that underwent repair. Following exclusion of outliers, cases with incomplete data sets and comminuted fractures, mixed effect logistic regression was used to identify variables affecting returning to racing and odds ratios and confidence intervals calculated.RESULTS:Of 113 repaired cases, fracture configurations included short incomplete parasagittal (n = 12), long incomplete parasagittal (n = 86), complete parasagittal (n = 12) and comminuted (n = 3). A total of 54 (48%) cases raced after surgery. Horses that fractured at 2 years of age had increased odds of racing following surgery than those older than 2 years of age (OR 1.34; 95% CI 1.13-1.59, P = 0.002). Horses sustaining short incomplete parasagittal fractures had increased odds of racing following surgery compared with those with complete parasagittal fractures (OR 2.62; 95% CI 1.36-5.07, P = 0.006). No horses with comminuted fractures returned to racing.MAIN LIMITATIONS:Data are relevant only to Thoroughbred racehorses in the UK.CONCLUSIONS:Approximately half of the cases in this series raced following surgical repair. More 2-year-old horses raced following surgery, but this likely reflects horses, specifically older horses, passing out of training from unrelated factors. Fracture configuration affects odds of racing, which is relevant to owners when deciding on treatment.

SummaryEquine fractures occurring during racing are an emotive subject. Attending veterinary surgeons have an obligation to be well informed and decisive; actions taken and advice given are frequently subject to public scrutiny and there are in addition important welfare, financial and litigious considerations. This paper is the first of a trilogy of reviews aimed at providing veterinary surgeons with up to date information on racecourse fracture management. It details incidence and predisposing factors, contemporary reviews on pathogenesis and discusses insurance implications. It also gives guidelines for acute evaluation and first aid management including sedation and analgesia. The second paper will describe techniques for temporary immobilisation and transport and the third will report up to date recommendations and emergency care of specific fractures.

See correspondence by Hughes and article by Jago et al.

SummaryIn consideration of first aid of appendicular fractures in the horse, the literature is inconsistent and in some cases wrong or misleading. This in large part is due to misunderstanding of fracture mechanics and this paper aims to give a contemporary review of the subject. It is particularly relevant for fractures that occur on the racecourse or in horses in training which, due to their aetiopathogenesis, have substantial site and configuration commonality. However, the techniques discussed are frequently also applicable to non‐racing injuries. Clinical features are important in assessing horses on the racecourse when imaging techniques are limited. This paper highlights these in order to guide decision making.

REASONS FOR PERFORMING THE STUDY A technique for minimally invasive repair of slab fractures of the third tarsal bone has not previously been reported. Results of third tarsal bone slab fracture repair in Thoroughbred racehorses are lacking. OBJECTIVES To report the outcomes of repair of uniplanar frontal slab factures of the third tarsal bone using a single 3.5 mm cortex screw in lag fashion. STUDY DESIGN Retrospective case series. METHODS Case records of horses that had undergone this procedure were reviewed. RESULTS Seventeen horses underwent surgery. Eighteen percent of cases had wedge shaped third tarsal bones. A point midway between the long and lateral digital extensor tendons and centrodistal and tarsometatarsal joints created a suitable entry site for implants. The fracture location, configuration and curvature of the third tarsal bone and associated joints requires a dorsolateral proximal-plantaromedial distal trajectory for the screw, which was determined by preplaced needles. There were no complications and fractures healed in all cases at 4-6 months post surgery. Seventy-nine percent of horses returned to racing and, at the time of reporting, 3 are in post operative rehabilitation programmes. CONCLUSION The technique reported provides a safe, appropriate and repeatable means of repairing slab fractures of the third tarsal bone. Surgical repair is a viable alternative to conservative management.

REASONS FOR PERFORMING STUDY Peri-anaesthetic complications are relatively common in equine patients and further investigations are warranted to identify manageable risk factors. OBJECTIVES To report morbidity and mortality rates and identify associated risk factors for horses undergoing general anaesthesia, within a predominantly racing Thoroughbred (TB) population. STUDY DESIGN Single centre retrospective observational study. METHODS Anaesthetic and case records of all horses ≥12 months old undergoing general anaesthesia at Newmarket Equine Hospital between August 2010 and April 2012 were analysed, excluding emergency abdominal/dystocia procedures or traumatology cases with cardiovascular compromise. Mortality and morbidity rates were calculated and described. Uni- and multivariable analyses were used to investigate the relationship between the principal complication, post anaesthetic colic (PAC) and risk factors. RESULTS A total of 1067 anaesthetic records of 1021 horses were included in the study; of these, 702 horses (65.8%) were TB, 169 (15.8%) developed a complication within 7 days of general anaesthesia and 10 (0.94%) died as a result. The most prevalent morbidity was PAC, 111 horses (10.5%) developed colic within 7 days of general anaesthesia. Thoroughbred horses (odds ratio [OR] 2.93, 95% confidence interval [CI] 1.73-4.96) and horses receiving sodium benzylpenicillin (NaBP) (OR 2.77, 95% CI 1.69-4.50) were at increased risk of PAC. CONCLUSIONS Thoroughbred racehorses were identified as at increased risk of PAC in this study and might benefit from more critical evaluation of post anaesthetic gastrointestinal function. An alternative to the administration of NaBP for prophylactic antimicrobial therapy needs to be further investigated if its role in PAC is confirmed by other studies.

Veterinary Clinical PathologyVolume 44, Issue 4 p. 609-610 What Is Your Diagnosis? What is your diagnosis? Swelling of the left antebrachium and carpus in a horse Francesco Cian, Corresponding Author Francesco Cian Animal Health Trust, Newmarket, UK Correspondence F. Cian, Animal Health Trust, Newmarket, Suffolk, UK, CB8 7UU E-mail: francesco.cian@aht.org.ukSearch for more papers by this authorJennifer Stewart, Jennifer Stewart Animal Health Trust, Newmarket, UKSearch for more papers by this authorGaynor J. Minshall, Gaynor J. Minshall Newmarket Equine Hospital, Newmarket, UKSearch for more papers by this authorIan M. Wright, Ian M. Wright Newmarket Equine Hospital, Newmarket, UKSearch for more papers by this author Francesco Cian, Corresponding Author Francesco Cian Animal Health Trust, Newmarket, UK Correspondence F. Cian, Animal Health Trust, Newmarket, Suffolk, UK, CB8 7UU E-mail: francesco.cian@aht.org.ukSearch for more papers by this authorJennifer Stewart, Jennifer Stewart Animal Health Trust, Newmarket, UKSearch for more papers by this authorGaynor J. Minshall, Gaynor J. Minshall Newmarket Equine Hospital, Newmarket, UKSearch for more papers by this authorIan M. Wright, Ian M. Wright Newmarket Equine Hospital, Newmarket, UKSearch for more papers by this author First published: 27 July 2015 https://doi.org/10.1111/vcp.12277Citations: 3Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume44, Issue4December 2015Pages 609-610 RelatedInformation