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Objectives: To identify characteristics of jockey falls associated with high-risk landings using a modified Equestrian Fall Assessment Instrument.Design: Cross-sectional study.Methods: Video footage of 22 flat and 58 jump racing falls (N = 80) which occurred in Great Britain, Ireland, and New Zealand from 2013 to 2018 was systematically analysed using the modified Equestrian Fall Assessment Instrument. Race, horse, and jockey-level factors, including the nature of ground contact (landings), were characterised identifying factors associated with high-risk landings. High-risk landings refer to cases where the jockey's head impacted the ground or where there was potential horse impact on the jockey. A multivariable logistic regression model was applied identifying independent variables associated with high-risk landings.Results: In 79 % (63/80) of race falls examined, at least one high-risk landing factor was present. Three independent variables explained 40.3 % of variance in high-risk landings. Lower race class (odds ratio 1.5; 95 % confidence interval 0.96, 2.39; p = 0.054), hanging onto the reins upon ground impact (odds ratio 7.5; 95 % confidence interval 1.04, 53.63; p = 0.028), and no jockey tuck-and-roll behaviour following ground impact (odds ratio 4.9; 95 % confidence interval 1.65, 14.44; p = 0.001) were associated with high-risk landings.Conclusions: Jockeys who ride in lower race classes, who hung onto the reins before landing, and who didn't tuck-and-roll during a fall had increased risk of a high-risk landing. Further examination of relationships between race, jockey experience and fall behaviour characteristics upon injury outcomes, and evaluation of potential protective benefits of fall training are required. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the association between air jacket usage and rider injury severity in equestrian eventing competition falls world-wide.Design: Retrospective data analysis.Methods: An analysis was conducted on Fédération Equestre Internationale data for 1819 riders who fell wearing an air jacket and 1486 riders who fell while not wearing an air jacket from 2015 to 2017. Injury data were categorised as either 'no/slight injury' or 'serious/fatal injury'. A chi-square test determined whether an association was present between injury severity category and air jacket usage and binary logistic regression determined the effect size of this association.Results: As a result of falls, 3203 riders sustained no/slight injuries and 102 sustained serious/fatal injuries. While 55.0% of riders who fell were wearing an air jacket, they represented 67.6% of the serious/fatal injury outcomes. Air jacket usage was significantly associated with serious/fatal injuries in falls (X² = 6.76; p = 0.009). Riders wearing an air jacket had 1.7 times (95%CI 1.14-2.64) increased odds of sustaining a serious or fatal injury in a fall compared to riders not wearing an air jacket.Conclusions: Riders wearing an air jacket were over represented in the percentage of serious or fatal injuries in falls compared to riders who only wore a standard body protector. Further research is needed to understand the reason(s) for this finding. It is recommended that additional data on injury outcomes, rider characteristics and the biomechanics of falls be examined in future analyses, and that air jacket and body protector characteristics be further investigated. [ABSTRACT FROM AUTHOR]

Biomechanical strain is a major stimulus of subchondral bone (SCB) tissue adaptation in joints but may also lead to initiation and propagation of microcracks, highlighting the importance of quantifying the intratissue strain in subchondral bone. In the present study, we used micro computed tomography (μCT) imaging, mechanical testing, and digital image correlation (DIC) techniques to evaluate the biomechanical strains in equine SCB under impact compression applied through the articular surface. We aimed to investigate the effects of in vivo accumulated microdamage in equine SCB on the distribution of mechanical impact strain through the articular cartilage. Under the applied strain of 2.0 ± 0.1% (mean ± standard deviation, n=15) to the articular surface of cartilage-bone plugs, the overall thickness of the SCB developed e S C B O v e r a l l = 0.7 ± 0.2% in all specimens. Contours of high strains in specimens without microdamage (NDmg) aligned parallel to the cartilage-bone interface with peak tensile, ϵ t , and compressive, ϵ c , strains of 0.5 ± 0.3% and 1.2 ± 0.4%, respectively at the time of peak compression (n=7). In damaged specimens (Dmg), contours of high strains aligned with the cracks in the imaged plane with peak strains of ϵ t = 1.2 ± 0.8% and ϵ c = 3.5 ± 2.2%, respectively (n=7). Microdamage was the main predictor of the normalised compressive and tensile strains across the SCB thickness. Results of multivariable analyses revealed presence of microdamage, distance from the articular surface and TMD were the main predictors of normalised compressive and tensile strain. Strain was greater in the superficial bone, particularly for specimens with microdamage. In vivo fatigue-induced microdamage is an important predictor of local subchondral bone strains. [ABSTRACT FROM AUTHOR]

• Race day CMI incidence for Thoroughbreds in Uruguay was 0.42 per 1,000 race starts • Incidence of CMI in training was 0.059 per 100 horse months • Catastrophic humeral fractures occurred more frequently during training than racing • The majority of race day CMIs involved the distal limb (71.8%) • CMI risk was greater for horses less intensively raced with more time between starts Catastrophic musculoskeletal injuries (CMI) pose a major welfare concern to horses and their riders, yet limited data are available describing their occurrence in South America. Using a retrospective cohort and case-control design, the objective of the study was to determine the incidence of CMI for Thoroughbreds in training and racing, and associated horse-level risk factors in Uruguay. Seventy-seven Thoroughbreds sustained a CMI, 37 of which were age- and sex-matched to 111 control horses in the same race. Training and racing data from 2011 to 2017 were collected. Incidence of race day CMI per 1,000 race starts and training CMI incidence per 100 horse months were calculated using Poisson regression. Univariable logistic regression was used to assess relationships between race history and occurrence of CMI by fracture location, and multivariable for all fracture locations. Overall race day incidence of CMI was 0.42 per 1,000 race starts (95% CI 0.29, 0.60). The incidence of CMI in training was 0.059 per 100 horse months. Twenty-nine percent (22/77) of horses that sustained a CMI had not raced prior. Most fractures were of the forelimbs (80.3%). There were 32 (41.6%) distal and 39 (50.6%) proximal limb fractures. The risk of CMI was greater for horses with fewer places (P =.001), and greater time between the previous race and the race in which CMI occurred (P =.020). The rate of race day CMI was low, despite Uruguay being a racing jurisdiction with policies and risk factors associated with greater CMI rates compared to other jurisdictions. Lightly raced horses with long periods since their previous race start should be monitored closely. [ABSTRACT FROM AUTHOR]

• Jockey injury surveillance and data collection guidelines have been published for professional horse-racing in Europe. • Substantial variation in jockey injury data collection and reporting practices exists worldwide, with little evidence of use of previously published guidelines. • Recommendations are presented for international horse-racing authorities in support of standardized jockey injury data collection and reporting practices. Jockey injuries are common in professional horse-racing and can result in life-threatening or career-ending outcomes. Robust injury data are essential to understand the circumstances of injury occurrence and ultimately identify prevention opportunities. This study aimed to identify jockey injury surveillance practices of international horse-racing authorities (HRAs) and the specific data items collected and reported by each HRA. A cross-sectional survey of representatives (e.g. Chief Medical Officer) from international HRAs was conducted. An online and paper questionnaire was designed comprised of 32 questions. Questions considered the barriers and facilitators to data collection within each HRA, and where available, what data were collected and reported by HRAs. Representatives from 15 international racing jurisdictions were included, of which 12 reported collection of race day injuries or falls, using varied definitions of medical attention and time loss. Six HRAs did not have a definition for a jockey injury, and eight HRAs had no parameters for describing injury severity. Race day exposure was collected by two HRAs. Results were commonly presented by HRAs as the number of injuries (n = 9/15) or proportion of injured jockeys (n = 6/15). The lack of a designated role for collection, collation and reporting of data was the main barrier for injury surveillance. Twelve HRAs agreed that mandatory collection would be a strong facilitator to improving practice. Enhancement and standardization of international jockey injury surveillance is required to move forward with evidence informed prevention. Concurrent investigation of how reporting practices can be best supported within existing HRA structures is recommended. [ABSTRACT FROM AUTHOR]

Fatigue-induced subchondral bone (SCB) injuries are prevalent among athletes due to the repetitive application of high magnitude loads on joints during intense physical training. Existing fatigue studies on bone utilize a standard fatigue test approach by applying loads of a constant magnitude and frequency even though physiological/realistic loading is a combination of various load magnitudes and frequencies. Metal materials in implant and aerospace applications have been studied for fatigue behavior under physiological or realistic loading, however, no such study has been conducted on biological materials like bones. In this study, we investigated fatigue behavior of SCB under the range of loads likely to occur during a fast-workout of an equine athlete in training. A loading protocol was developed by simulating physiological loads occurring during a fast-workout of a racehorse in training, which consisted of a sequence of compression-compression load cycles, including a warm-up (32, 54, 61 MPa) and cool-down (61, 54, 32 MPa) before and after the slow/fast/slow gallop phase of training, also referred to as a training loop. This loading protocol/training loop was applied at room temperature in load-control mode to cylindrical SCB specimens (n = 12) harvested from third metacarpal medial condyles (MCIII) of twelve thoroughbred racehorses and repeated until fatigue failure. The mean ± standard deviation for total time-to-failure (TTF) was 76,393 ± 64,243 s (equivalent to 18.3 ± 15.7 training workouts) for n = 12 specimens. We observed the highest relative energy loss (REL, hysteresis loss normalized to energy absorbed in a load cycle) under loads equivalent to gallop speeds and all specimens failed under these gallop loads. This demonstrates the importance of the gallop speeds in the development of SCB injury, consistent with observations made in live racehorses. Moreover, specimens with higher mean REL and lower mean stiffness during the first loop had a shorter fatigue life which further confirms the detrimental effect of high energy loss in SCB. Further studies are required to reconcile our results with fatigue injuries among equine athletes and understand the influence of different training programs on the fatigue behavior of subchondral bone. • Fatigue tests on equine subchondral bone were conducted undersimulated physiological loads which occurr in a fast-workout. • The subchondral bone recorded the highest energy loss under loads equivalent to the gallop gait in a racehorse. • Relative energy loss appears to be a useful indicator of fatigue life that can be measured within a single training loop. [ABSTRACT FROM AUTHOR]

Subchondral bone injuries often precede articular cartilage damage in osteoarthritis and are common in thoroughbred racehorses due to the accumulation of fatigue damage from high speed racing and training. Thus, racehorses provide a model to investigate the role of subchondral bone in joint disease. We assessed the association of horse and racing related factors and micro-CT based micromorphology of three separate subchondral bone layers with the initial stiffness and compressive fatigue life of bone plugs. Furthermore, we investigated three different definitions of fatigue failure of subchondral bone during compressive fatigue testing. Initial stiffness was 2,362 ± 443 MPa (mean ± standard deviation). Median compressive fatigue life during cyclic loading to -78 MPa was 16,879 (range 210 to 57,064). Subchondral bone stiffness increased over a median of 24% (range 3%–42%) of fatigue life to a maximum of 3,614 ± 635 MPa. Compressive fatigue life was positively associated with bone volume fraction in the deeper layers of subchondral bone, maximal stiffness, and the number of cycles to maximal stiffness. Initial stiffness was positively associated with tissue mineral density in the deeper layers and bone volume fraction in the superficial layer. Most specimens with a fatigue life of less than 5,500 cycles fractured grossly before reaching 30% reduction of maximal stiffness. Cycles to 10% reduction of maximal stiffness correlated strongly with cycles to lowest recorded stiffness at gross fracture and thus is a valid alternative failure definition for compressive fatigue testing of subchondral bone. Our results show that subchondral bone sclerosis as a result of high speed exercise and measured as bone volume fraction is positively associated with compressive fatigue life and thus has a protective effect on subchondral bone. Further research is required to reconcile this finding with the common collocation of fatigue damage in sclerotic subchondral bone of racehorses. • Subchondral bone fatigue life increases with increasing bone volume fraction. • Subchondral bone stiffness is positively associated with tissue mineral density. • Superficial subchondral bone differs from deeper subchondral bone layers. [ABSTRACT FROM AUTHOR]