Effect of speed and water depth on limb and back kinematics in Thoroughbred horses walking on a water treadmill.

Water treadmill (WT) exercise may induce limb and back kinematics that meet specific training and rehabilitation goals. The study aimed to investigate the effects of walk speed, at different water depths (WDs), on limb and back kinematics of six Thoroughbreds exercising on a WT. Horses walked at 2.8/4.3/5.5/6.0 km/h (i.e. 0.8/1.2/1.5/1.7 m/s) at dry, metacarpophalangeal and carpal WD. Videography captured limb movement in the sagittal plane. Motion-capture measured thoracolumbosacral flexion-extension (FE), and lateral bend (LB) ranges of movement (ROM) using skin surface markers on the sixth, tenth, thirteenth, eighteenth thoracic, third and fifth lumbar, and third sacral spinous processes. Inertial-motion-sensors measured poll, withers and pelvic displacements. Following preliminary univariable analyses, multivariable mixed-effects linear-regression analyses were used to examine the relationship between speed, WD and each outcome variable (P < 0.05). Peak metacarpophalangeal, carpal and tarsal joint flexion increased with speed (P ≤ 0.002) and depth combined (P 0.001) while peak metatarsophalangeal flexion increased with WD only (P 0.001). Thoracolumbar FE-ROM between T10 and L3 and hindlimb retraction was increased by speed and WD combined (P 0.001). Hindlimb protraction was increased by speed (P 0.001) while hindlimb retraction was increased by speed and WD combined (P 0.001). Dorsoventral poll displacement was increased by speed (P 0.001) and carpal WD (P = 0.013), craniocaudal poll displacement was increased by speed and WD combined (P 0.001). Pelvic (tubera coxae and sacrum) dorsoventral displacements increased with speed and WD combined (P 0.001). Understanding the effects of speed and WD on limb, back and pelvic kinematics will improve decision making relating to dry and WT exercise within training.

Histological Features of the Distal Third Metacarpal Bone in Thoroughbred Racehorses, With and Without Lateral Condylar Fractures.

A detailed histopathological study of the distal third metacarpal bone of Thoroughbred racehorses was undertaken to characterize lesions observed previously on magnetic resonance imaging (MRI). The bones were selected and grouped on the basis of MRI features. Representative sections in different planes were processed for histopathology. All lesions observed in the articular cartilage (AC) and subchondral bone (SCB) were recorded and graded with a scoring system, based partially on the Osteoarthritis Research Society International grading system. The scoring system included the severity of the lesion. Descriptive statistics and linear mixed effects models were performed. A positive correlation was observed between the severity of histopathological changes in the superficial and deeper osteochondral tissues, and between the number of race starts and AC score. Age was not correlated with AC or SCB score. A moderate variation in AC and SCB scores was observed between the groups; however, there were differences within individual bones. Bones with focal palmar necrosis (FPN) showed significant differences in the histological scoring of the AC compared with bones without FPN. Bones with incomplete fractures or larger areas of bone remodelling showed significant differences in SCB pathology when compared with bones with FPN. Haematoidin was detected in areas with excessive SCB and cancellous bone sclerosis and/or irregular bone density. This finding is suggestive of poor blood perfusion in these areas.

Comparison of limb kinematics between collected and lengthened (medium/extended) trot in two groups of dressage horses on two different surfaces.

BACKGROUND: Dressage horses are often asked to work in lengthened paces during training and competition, but to date there is limited information about the biomechanics of dressage-specific paces. Preliminary work has shown increased fetlock extension in extended compared with collected paces, but further investigation of the kinematic differences between collected, medium and extended trot in dressage horses is warranted. OBJECTIVES: Investigation of the effect of collected vs. medium/extended trot on limb kinematics of dressage horses. STUDY DESIGN: Prospective kinematic evaluation. METHODS: Twenty clinically sound horses in active dressage training were used. Group 1: Ten young horses (≤6 years) were assessed at collected and medium trot and Group 2: Ten mature horses (≥9 years) were assessed at collected and extended trot. All horses were evaluated on two different surfaces. High speed motion capture (240 Hz) was used to determine kinematic variables. Fore- and hindlimb angles were measured at mid-stance. Descriptive statistics and mixed effect multilevel regression analyses were performed. RESULTS: Speed and stride length were reduced and stride duration increased at collected compared with medium/extended trot. Lengthened trot (medium/extended trot) was associated with increased fetlock extension in both the fore- and hindlimbs in both groups of horses. Changes were greater in mature horses compared with young horses. Shoulder and carpus angles were associated with forelimb fetlock angle. Hock angle was not significantly influenced by pace. Surface had no effect on fetlock or hock angles. MAIN LIMITATIONS: Only 2D motion analysis was carried out. Results may have differed in horses with more extreme gait characteristics. CONCLUSIONS: Medium/extended trot increases extension of the fore- and hindlimb fetlock joints compared with collected trot in both young and mature dressage horses, respectively.

Can we use subchondral bone thickness on high-field magnetic resonance images to identify Thoroughbred racehorses at risk of catastrophic lateral condylar fracture?

REASONS FOR PERFORMING STUDY: Fractures of the lateral condyle of the third metacarpus (MC3) are a significant welfare concern in horseracing worldwide. OBJECTIVES: The primary aim of this work was to identify magnetic resonance (MR) image-detectable prefracture markers that have the potential for use as a screening tool to identify horses at significant risk of catastrophic fracture. STUDY DESIGN: Case-control study of bone-level risk factors for fracture in racehorses. METHODS: A total of 191 MC3s from horses, with and without lateral condylar fracture of MC3, were subjected to MR imaging. The depth of dense subchondral/trabecular bone was measured at several sites around the distal end of the bone and regression analyses were conducted to identify differences in this depth between horses with and without lateral condylar fracture. RESULTS: Greater depth of dense subchondral/trabecular bone in the palmar half of the lateral parasagittal groove of distal MC3 was associated with an increased likelihood of being from a horse that had sustained a fracture. Receiver operator characteristic analysis was used to identify the optimal cut-off in the depth of dense subchondral/trabecular bone at this site to best discriminate fracture status. Positive and negative predictive values were calculated using the prevalence of fracture within the current study and also a prevalence estimate for the wider racehorse population. CONCLUSIONS: There is a requirement to identify suitable prescreening test(s) to eliminate many true negative horses and increase the prevalence of prefracture pathology in the sub population that would be screened using MR imaging, in turn maximising the positive predictive value of this test.

Effect of superficial harrowing on surface properties of sand with rubber and waxed-sand with fibre riding arena surfaces: a preliminary study.

A recent epidemiological study identified various aspects of arena surfaces and arena surface maintenance that were related to risk of injury in horses and that arena maintenance is important in reducing injury risk. However, there has been little research into how properties of arena surfaces change with harrowing. This study aimed to compare the properties of different arena surface types pre- and post-harrowing. The Orono Biomechanical Surface Tester fitted with accelerometers and a single- and a three-axis load cell was used to test 11 arenas with two different surfaces types, sand with rubber (SR) and waxed-sand with fibre (WSF). Three drop tests were carried out at 10 standardised locations on each arena. Mixed models were created to assess the effect of surface type, pre- or post-harrowing, and drop number on the properties of the surface, including maximum horizontal deceleration, maximum vertical deceleration, maximum vertical load and maximum horizontal load. Post-harrowing, none of the parameters were altered significantly on SR. On WSF, maximum vertical deceleration and maximum vertical load significantly decreased post-harrowing. The differences in the effects of superficial harrowing on SR and WSF could be attributed to the different compositions and sizes of the surface material. The results suggest that different maintenance techniques may be more suitable for different surface types and that the effects of superficial harrowing are short-lived due to the rapid re-compaction of the surface with repeated drops on WSF. Further work is required to determine the effects of other maintenance techniques, and on other surface types.

Staged bilateral total knee replacement: changes in expectations and outcomes between the first and second operations.

We explored the outcome of staged bilateral total knee replacement (TKR) for symmetrical degenerative joint disease and deformity in terms of patient expectations, functional outcome and satisfaction. From 2009 to 2011, 70 consecutive patients (41 female) with a mean age of 71.7 years (43 to 89) underwent 140 staged bilateral TKRs at our institution, with a mean time between operations of 7.8 months (2 to 25). Patients were assessed pre-operatively and at six and 12 months post-operatively using the Short Form-12, Oxford knee score (OKS), expectation questionnaire and satisfaction score. The pre-operative OKS was significantly worse before the first TKR (TKR1), but displayed significantly greater improvement than that observed after the second TKR (TKR2). Expectation level increased from TKR1 to TKR2 in 17% and decreased in 20%. Expectations of pain relief and stair-climbing were less before TKR2; in contrast, expectations of sporting and social activities were greater. Decreased expectations of TKR2 were significantly associated with younger age and high expectations before TKR1. Patient satisfaction was high for both TKR1 (93%) and TKR2 (87%) but did not correlate significantly within individuals. We concluded that satisfaction with one TKR does not necessarily translate to satisfaction following the second.

Variation in training regimens in professional showjumping yards.

REASONS FOR PERFORMING STUDY: Training regimens of showjumping horses under field conditions are largely undocumented. OBJECTIVES: The aims of this study were to quantify and compare training regimens used in professional-level showjumping yards, with respect to time exercised and type of activity. STUDY DESIGN: Prospective cohort study. METHODS: A prospective 6-month cohort study of showjumping horses in 4 European countries (The Netherlands, Sweden, Switzerland, Great Britain) was designed to analyse training and health data, in yards with several horses in training and riders competing at professional level. Riders documented the daily frequency and duration of all physical activities of the horses. Variation in training routines were compared between riders, location and time. Mixed-models analysis was used to examine factors associated with total time exercised and time spent in flatwork. RESULTS: In 4 countries, the 31 participating riders trained 263 European Warmbloods. The total days at risk (e.g. days in which the horses were considered fit for exercise) was 39,262. Mean time spent in daily exercise, including ridden work, lungeing and treadmill exercise, varied between riders from 19-52 min/day at risk. There was considerable variation in activities and level of heavy work and light exercise, i.e. turnout. Total time exercised and time spent in flatwork differed with month, country and proportion of days lost to training. Low variation of activities was associated with decreased total time trained and increased time spent in flatwork. CONCLUSIONS: Riders at this elite professional level of showjumping used training regimens that vary substantially in time spent training and other physical activities and showjumping horses are challenged differently during training despite competing at the same level. Whether all training regimens prepare the horses equally for the demands of competition remains to be determined.

Days-lost to training and competition in relation to workload in 263 elite show-jumping horses in four European countries.

Orthopaedic, or other, injuries in sports medicine can be quantified using the 'days-lost to training' concept. Both the training regimen and the surface used in training and racing can affect the health of racehorses. Our aim was to associate 'days-lost to training' in elite-level show-jumpers to horse characteristics, training and management strategies, and the time spent working on various training and competition surfaces. We designed a longitudinal study of professional riders in four European countries. Data were recorded using training diaries. Reasons for days-lost were classified into non-acute and acute orthopaedic, medical, hoof-related, and undefined. We produced descriptive statistics of training durations, relative to type of training, surfaces used, and days-lost. We created zero-inflated negative-binomial random-effects models using the overall days-lost as outcome. In the whole dataset, duration variables related to training surfaces were analysed as independent. The Swedish data only were also used to test whether duration variables were related to competition surfaces. Thirty-one riders with 263 horses provided data on 39,028 days at risk. Of these, 2357 (6.0%) were days-lost (55% and 22% of these were due to non-acute and acute orthopaedic injuries, respectively) in 126 horses. In the all-country model, controlling for season, a significant variable was country. Switzerland and the UK had lower incidence-rate ratios (IR) compared to Sweden (IRs 0.2 and 0.03, respectively). Horses with previous orthopaedic problems had almost a doubled IR (1.8) of days-lost due to orthopaedic injury, compared to baseline. If the horse had jumping training more than 1 min per day at risk the IRs were 6.9-7 (compared to less than this amount of time); this was, however, likely an effect of a small baseline. Variation in training was a protective factor with a dose-response relationship; the category with the highest variation had an IR of 0.1. In the Swedish model, controlling for season, there was an association of year (IR 2.8 year 2010). Further, if the horse rested >17-25% of the days at risk, or >33% of the DAR2, had IRs 3.5 and 3.0, compared to less time. Horses ≥ 6 years had IRs of 1.8-2.0, compared to younger horses. Limited training use of sand surface was a risk-factor (IR 2.2; >4 ≤ 12 min/day at risk), compared to not training on sand. Training/competing on sand-wood was a protective factor (IRs 0.4-0.5) compared to not using this surface.

Effect of a Pessoa training aid on temporal, linear and angular variables of the working trot.

Development of core muscle strength is important for training and during rehabilitation following injury. A Pessoa training aid (PTA) is a system of ropes and pulleys which is commonly used during equine training and rehabilitation, but there is limited information on its effectiveness. The objective of the study was to determine the effect of the PTA on the temporal, linear and angular kinematics of the working trot. Influence of testing order on effect of a PTA was assessed in four horses. Twelve riding horses were lunged at working trot on a 16 m diameter circle without (WO) and with a PTA (WP) that was set level with the shoulder. Objective measurements were carried out using high-speed motion capture (125 Hz) and inertial measurement units. Subjective video assessment was also undertaken. When a PTA was applied there was a significant reduction in speed, stride length, head angle (P<0.0001 for all) and lumbosacral angle at maximal hindlimb retraction (P=0.0028), but no effect on limb joint angles. The highest point of the horse was significantly different between conditions (WO, poll; WP, crest) (P=0.0010). Dorsoventral displacement of the middle of the back (P≤0.0001) and overall impression grade (P=0.0002) were significantly greater WP compared with WO. These findings indicated that a PTA may be beneficial for general training and rehabilitation as a method of improving posture, stimulating core muscle activation and improving overall way of going, without increasing the loading of forelimb and hindlimb structures. Further work is warranted to understand the mechanism which induces these changes.

The effect of collection and extension on tarsal flexion and fetlock extension at trot.

A recent epidemiological study indicated that various factors may be related to injury in dressage horses, but the mechanism by which these injuries occur has yet to be determined. The suspensory ligament (SL) is a frequent site of injury, and it is assumed that greatest strain is placed on this structure in collected trot; this has yet to be proved conclusively. The study aimed to investigate the effect of collected and extended trot on the hindlimb movement pattern. Four dressage horses were fitted with markers and inertial motion sensors (IMS). High-speed video was obtained for 2 strides on each rein in collected and extended trot on 3 different surfaces: waxed outdoor; sand/plastic granules; and waxed indoor. Maximal tarsal flexion during stance and distal metatarsal coronary band ratio (MTCR), representing fetlock extension, were determined. Inertial motion sensor data determined stride duration, speed and stride length. Data were compared between collection and extension within horses on each surface, and compared between surfaces. Collected trot had significantly lower speed and stride length but longer stride duration than extended trot on all surfaces. All horses had less tarsal flexion and fetlock extension in collected compared with extended trot (P<0.05), which is likely to increase SL loading. The study findings indicate that extended trot may increase SL strain, providing a possible explanation for the high incidence of SL injury in horses trained for extravagant movement. It is possible that substantial use of extended trot could be a risk factor for development of suspensory desmitis, which might be one contributory factor in the prevalence of suspensory desmitis in young horses repeatedly undertaking extravagant movement.

Reliability of high- and low-field magnetic resonance imaging systems for detection of cartilage and bone lesions in the equine cadaver fetlock.

REASONS FOR PERFORMING STUDY: To determine the reliability of 2 magnetic resonance imaging (MRI) systems for detection of cartilage and bone lesions of the equine fetlock. OBJECTIVES: To test the hypotheses that lesions in cartilage, subchondral and trabecular bone of the equine fetlock verified using histopathology can be detected on high- and low-field MR images with a low incidence of false positive or negative results; that low-field images are less reliable than high-field images for detection of cartilage lesions; and that combining results of interpretation from different pulse sequences increases detection of cartilage lesions. METHODS: High- and low-field MRI was performed on 19 limbs from horses identified with fetlock lameness prior to euthanasia. Grading systems were used to score cartilage, subchondral and trabecular bone on MR images and histopathology. Sensitivity and specificity were calculated for images. RESULTS: High-field T2*-weighted gradient echo (T2*W-GRE) and low-field T2-weighted fast spin echo (T2W-FSE) images had high sensitivity but low specificity for detection of cartilage lesions. All pulse sequences had high sensitivity and low-moderate specificity for detection of subchondral bone lesions and moderate sensitivity and moderate-high specificity for detection of trabecular bone lesions (histopathology as gold standard). For detection of lesions of trabecular bone low-field T2*W-GRE images had higher sensitivity and specificity than T2W-FSE images. CONCLUSIONS: There is high likelihood of false positive results using high- or low-field MRI for detection of cartilage lesions and moderate-high likelihood of false positive results for detection of subchondral bone lesions compared with histopathology. Combining results of interpretation from different pulse sequences did not increase detection of cartilage lesions. MRI interpretation of trabecular bone was more reliable than cartilage or subchondral bone in both MR systems. POTENTIAL RELEVANCE: Independent interpretation of a variety of pulse sequences may maximise detection of cartilage and bone lesions in the fetlock. Clinicians should be aware of potential false positive and negative results.

Chronic streptococcal and non-streptococcal pharyngitis.

Pharyngitis is a common medical problem in the outpatient medical setting, resulting in more than seven million pediatric visits each year. Most types of pharyngitis are caused by infectious etiologies. The most common cause of pharyngitis is viral infection; however, some of the more serious types of pharyngitis are attributed to bacterial etiologies, such as group A ß-hemolytic Streptococcus pyogenes (GAS). Complications from GAS pharyngitis include rheumatic fever, deep space abscesses, and toxic shock. Although most episodes of pharyngitis are acute in nature, a small percentage becomes recurrent or chronic. With regards to chronic pharyngitis, non-infectious etiologies, such as laryngopharyngeal reflux and periodic fever, aphthous ulcers, pharyngitis, and adenitis syndrome also need to be considered. Both medical and surgical therapies are effective in managing pharyngitis. First-line medical therapy includes antibiotic therapy. For certain indications, surgical management via adenotonsillectomy is recommended. Adenotonsillectomy has been shown to be effective in reducing disease burden and improving disease-specific and global quality of life. Several techniques for adenotonsillectomy exist, including traditional and intracapsular tonsillectomies.

Magnetic resonance imaging-detected adaptation and pathology in the distal condyles of the third metacarpus, associated with lateral condylar fracture in Thoroughbred racehorses.

REASONS FOR PERFORMING THE STUDY: Lateral condylar (LC) fractures of the third metacarpus (McIII) are a common reason for euthanasia in racehorses, and may be the result of repetitive overloading or cumulative pathological change. Magnetic resonance imaging (MRI) allows monitoring of bone and cartilage to detect pathological and adaptive changes that may be precursors of fracture. OBJECTIVES: To describe bone and cartilage MRI features in the distal condyles of McIII of Thoroughbred racehorses, with and without condylar fracture. HYPOTHESES: 1) A greater degree of bone and cartilage adaptation or pathology will be seen in fractured McIIIs compared with their respective contralateral McIIIs. 2) Contralateral McIIIs will have a greater degree of bone and cartilage adaptation or pathology than McIIIs from control horses that did not sustain a LC fracture. METHODS: The McIIIs from 96 horses subjected to euthanasia at racecourses were divided into 3 groups: Group 1: nonfractured bones from horses without LC fracture; Group 2: nonfractured bones from horses with unilateral LC fracture; and Group 3: fractured bones from horses with unilateral LC fracture. The MR images were examined and graded for bone and cartilage changes. RESULTS: Nine percent of Group 1 (n = 9) and 11% of Group 2 bones (n = 5) had incomplete LC fractures. Focal palmar necrosis was most frequently detected in bones from Group 1 (12%) compared with Groups 2 (9%) and 3 (4%). The prevalence of bone and/or cartilage abnormalities tended to increase from Group 1 to Group 2 to Group 3. CONCLUSIONS: Magnetic resonance imaging is able to detect cartilage and bone changes that may be associated with LC fracture. There was no significant difference in bone/cartilage changes between bones from Groups 1 and 2, despite increased pathology in Group 2 bones. POTENTIAL RELEVANCE: Periodic monitoring of bone and/or cartilage changes in distal McIII of Thoroughbred racehorses may help to prevent catastrophic LC fractures.

Radiological anatomy of the donkey's foot: objective characterisation of the normal and laminitic donkey foot.

REASONS FOR PERFORMING STUDY: Anatomical change within a laminitic foot is of diagnostic and prognostic importance. A lateromedial radiograph represents the current 'gold standard' by which these changes are identified. Detection of anatomical change is dependent upon a priori knowledge of normality and subjective assessment alone may not identify modest change. Normal baseline data is, therefore, needed against which objective comparisons can be made. There is little information regarding the radiological anatomy of the donkey foot, hence an equine model has been widely adopted. However, descriptive accounts suggest fundamental anatomical differences between these 2 species. OBJECTIVES: To characterise objectively the radiological anatomy of normal donkey feet and define the nature and extent of anatomical change associated with laminitis. METHODS: The anatomy of the forefoot was quantified from lateromedial radiographs of 83 normal and 74 laminitic donkeys, using a computer based imaging system. Data were analysed using univariate and bivariate statistical methods. RESULTS: Baseline data were established that define the radiological characteristics of the anatomy of normal donkey feet. The key hoof, bone and weightbearing stance parameters of lateromedial radiographs have been evaluated. Laminitis was associated with significant rotation and distal displacement of the distal phalanx, increases in integument depth and morphometric change to the distal phalanx (P<0.05). CONCLUSIONS: This study challenges the validity of applying an equine model to the radiological anatomy of donkey feet. Hence, the diagnosis of anatomical change cannot be based on baseline data previously given for the horse and guidelines should be revised accordingly for the donkey. POTENTIAL RELEVANCE: This study provides an objective basis for the identification of anatomical change associated with laminitis in donkey feet.

An investigation of the relationships between angles and shapes of the hoof capsule and the distal phalanx.

REASONS FOR PERFORMING STUDY: There is little scientific evidence to support the premise that poor foot conformation predisposes to foot pain and lameness. OBJECTIVES: To determine relationships between external characteristics of the hoof capsule and angles of the distal phalanx; to determine variability in shape of the distal phalanx; and to investigate association between distal phalanx angles and the injury causing lameness. MATERIALS AND METHODS: Feet were documented photographically and radiographically. Linear and angle measurements were obtained for the hoof capsule and distal phalanx and compared statistically. Horses were categorised according to injury group, and angles and linear ratios were compared between groups. RESULTS: There was modest correlation between hoof wall and heel angles and angles of the distal phalanx. There was variation in shape of the distal phalanx. There was no significant association between injury type and angles of the distal phalanx, although there was a trend for the angle of the dorsal aspect of the distal phalanx with the horizontal to be smaller in horses with injuries of the podotrochlear apparatus or deep digital flexor tendon compared with other groups. CONCLUSIONS: There are variations in shape of the distal phalanx largely due to differences in orientation of the concave solar border and the solar border to the horizontal. Variations in shape of the distal phalanx were not accurately correlated with external characteristics of the hoof capsule. There were weak associations between injury groups and angles of the distal phalanx. CLINICAL RELEVANCE: Further work is required to elucidate risk factors for foot-related lameness.

Comparison of high-field and low-field magnetic resonance images of cadaver limbs of horses.

Eleven limbs taken postmortem from 10 lame horses were examined by MRI in a low-field 0.27T system designed for standing horses and a high-field 1.5T system used to examine anaesthetised horses. Nine limbs were examined in the foot/pastern region and two in the fetlock region, and the results were compared with gross pathological examinations and histological examinations of selected tissues. The appearance of normal tissues was similar between the two systems, but the anatomical arrangement of the structures was different due to differences in positioning, and a magic angle artefact was observed at different sites in some imaging sequences. Articular cartilage could be differentiated into two articular surfaces in most joints in the high-field images but could generally be separated only at the joint margins in the low-field images. Abnormalities of tendon, ligament and bone detected by gross examination were detected by both forms of MRI, but some details were clearer on the high-field images. Articular cartilage found to be normal on pathological examination was also classified as normal on MRI, but lesions in articular cartilage detected on pathological examination were identified only by high-field MRI. An abnormality was detected on MRI of all the limbs that had abnormal navicular flexor fibrocartilage on pathological examination.

Thirty-two component finite element models of a horse and donkey digit.

REASONS FOR PERFORMING STUDY: The finite element (FE) method is the most powerful modelling technique available to explicate the biomechanics of the digit. It has already proved to be of high value in human podiatry. However, accurate models of the complex anatomy of the horse and donkey digit are currently lacking. OBJECTIVES: To develop FE models of the horse and donkey digit from computed tomography data, including all functionally relevant anatomy, and to perform simulations to replicate prestrain in the flexor tendons and quasistatic weightbearing. METHODS: Computed tomography data of the front right digits were obtained under general anaesthesia. The anatomy was rationalised into 32 functional components. The FE models were generated using a forward engineering technique. Linear or nonlinear material properties were applied according to published data. Prestraining of the flexor tendons was achieved by z-direction displacement, and loading by the application of 1 x body mass. RESULTS: The resultant FE models comprised over 10(6) elements. Z-direction displacement of the digital flexor tendons to compensate for general anaesthesia relaxation gave von Mises stress levels up to 134 MPa for the deep and 0.56 MPa for the superficial in the horse and 0.78 MPa and 0.27 MPa in the donkey, respectively. Weightbearing resulted in capsular deformation patterns consistent with in vivo observations, and maximum stress levels of 1.46 MPa for the horse and 0.89 MPa for the donkey. CONCLUSION: These high resolution FE models could give new insight into the biomechanics of the equid digit and provide new data regarding stress and strain levels within the tissues of the digit that are unobtainable by other means. POTENTIAL RELEVANCE: Application of the FE modelling technique could enable investigation of the biomechanics of orthopaedic problems and may provide a mechanistic basis for enhanced preventative and remedial management and treatment.

Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint: part 1.

REASONS FOR PERFORMING STUDY: Osseous abnormalities associated with collateral ligament (CL) injury of the distal interphalangeal (DIP) joint have been documented using magnetic resonance imaging (MRI) but there is currently limited information about the frequency of osseous pathology associated with CL injury. OBJECTIVES: To determine the frequency of occurrence of osseous abnormality coexistent with CL injury of the DIP joint and describe the distribution and character of osseous lesions; and to establish if there was an association between osseous abnormality and increased radiopharmaceutical uptake (IRU). HYPOTHESES: There would be a higher incidence of osseous abnormality at the insertion of an injured CL than at the origin; and a relationship between the presence of osseous abnormality and duration of lameness. MATERIALS AND METHODS: Magnetic resonance images of 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence and type of osseous abnormality in the middle and distal phalanges. Scintigraphic images were examined and the presence of IRU in the middle or distal phalanges recorded. RESULTS: Osseous abnormalities were detected in 143 (45.7%) feet, 27 (18.8%) of which had osseous and CL injury alone, while the remaining 116 had CL related osseous injury and multiple injuries within the hoof capsule. Entheseous new bone and endosteal irregularity of the middle and distal phalanges were the most frequent types of osseous abnormality. There was a higher incidence of osseous abnormalities medially than laterally and at the ligament insertion than at the origin. There was a significant association between presence of IRU and osseous injury. CONCLUSIONS: A variety of osseous lesions of differing severity are associated with CL injury. Normal radiopharmaceutical uptake does not preclude significant osseous pathology associated with CL injury. CLINICAL RELEVANCE: Further studies are necessary in order to determine if osseous abnormalities associated with CL injury influence prognosis for return to performance.

Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint. Part 2: treatment and outcome.

REASONS FOR PERFORMING STUDY: There are currently few long-term follow-up data relating to recovery from injury of a collateral ligament (CL) of the distal interphalangeal (DIP) joint and limited information about the effect of associated osseous injury on prognosis. OBJECTIVES: To describe long-term follow-up results for horses with CL injury, with and without associated osseous injury; and to determine the effect of extracorporeal shock wave therapy (ECSWT) or radial pressure wave therapy (RPWT) on outcome. HYPOTHESES: Prognosis for return to performance for horses with CL-related osseous injury would be worse than for horses with CL injury alone. METHODS: Magnetic resonance images from 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence of osseous abnormality associated with the ligament origin or insertion and the middle and distal phalanges. Horses were assigned to groups according to the combination of their injuries. Type of treatment was recorded and follow-up information obtained. Thirty-two horses with additional sources of lameness were excluded from analysis of outcome. RESULTS: Follow-up data were available for 182 horses, 55 of which had follow-up information for up to 2 years after presentation. Twenty-seven percent of horses with CL injury alone and 34% of horses with CL related osseous injury returned to their previous performance level. Prognosis for a combination of injuries to multiple soft tissue and osseous structures within the hoof capsule was substantially worse. There was no effect of ECSWT or RPWT on outcome. CONCLUSIONS: The presence of mild to moderate CL related osseous injury does not appear to influence prognosis compared with CL injury alone. CLINICAL RELEVANCE: Further studies of a larger number of horses are necessary in order to ascertain if specific types of osseous pathology influence return to performance levels.

How does exercise intensity and type affect equine distal tarsal subchondral bone thickness?

Adaptation of osteochondral tissues is based on the strains experienced during exercise at each location within the joint. Different exercise intensities and types may induce particular site-specific strains, influencing osteochondral adaptation and potentially predisposing to injury. Our hypotheses were that patterns of equine distal tarsal subchondral bone (SCB) thickness relate to the type and intensity of exercise, and that high-intensity exercise leads to site-specific increases in thickness. SCB thickness was measured at defined dorsal and plantar locations on magnetic resonance images of cadaver tarsi collected from horses with a history of low [general purpose (n=20) and horse walker (n=6)] or high [elite competition (n=12), race training (n=15), and treadmill training (n=4)] exercise intensity. SCB thickness was compared between sites within each exercise group and between exercise groups. SCB thickness in elite competition and race training, but not treadmill training, was greater than low-intensity exercise. For general purpose horses, lateral SCB thickness was greater than medial throughout. Horse walker exercise led to relatively thicker lateral and medial SCB compared with the midline. Elite competition was associated with increased SCB thickness of the proximal small tarsal bones medially and the distal bones laterally. For race training and treadmill training, there were minimal differences between sites overall, although the lateral aspect was greater than medial, and medial greater than midline at a few sites for race training. In conclusion, different types of high-intensity exercise were associated with different patterns of SCB thickness across the joints from medial to lateral and proximal to distal, indicating that both exercise intensity and type of exercise affect the SCB response at any particular site within the equine distal tarsal joints.