Jean-Marie Denoix

Functional anatomy of tendons and ligaments in the distal limbs (manus and pes).

Tendons and ligaments of the equine distal limbs have a prominent anatomic, functional, and clinical importance. This article reviews the descriptive and topographic anatomy of these structures in details. Special information is given about the mechanical properties and functional anatomy of the flexor tendons, accessory ligaments, and third interosseous muscle, as well as about their roles during the standing position and gaits.

Spinal Biomechanics and Functional Anatomy

Knowledge of the normal functional behavior and mechanical properties of the vertebral column is important to understand the pathogenesis of back lesions, to identify the clinical manifestations of back pain, and to ensure a rational approach to physical therapy. The purpose of this article is to present a synthesis of in vivo and in vitro data obtained from different but complementary investigations. Presently, in vivo studies are limited; few gait-specific kinematic and electromyographic investigations are in process. Higher stresses to reach the maximal range of intervertebral motion can be applied on the spine on anatomical specimens than in living horses, and anatomical functional data can be obtained at the level of intervertebral structures. For each movement of flexion, extension, lateroflexion, and rotation, regional and intervertebral mobility is presented with an emphasis on craniocaudal variations and their anatomical causes. Because of the location of their ICR, the dorsoventral movements of a thoracolumbar intervertebral joint can be defined as a rotation around the center of the more caudal vertebral body. This information supports the new concept of intervertebral mobility in the horse and provides additional elements to facilitate understanding of the pathogenesis of back problems in the horse.

Sub-clinical diseases affecting performance in Standardbred trotters: diagnostic methods and predictive parameters.

The objectives of this study were to determine the prevalence of sub-clinical diseases in poorly-performing Standardbred horses, compare their physiological response to exercise with control horses, and identify predictive parameters of poor-performance. Fifty horses underwent thorough clinical and ancillary examinations, including haematological and biochemical evaluation, Doppler echocardiography, standardised exercise tests (SETs) on both treadmill and racetrack, treadmill video-endoscopy and collection of respiratory fluids. Most of the poorly-performing horses exhibited many concomitant diseases. The most frequently diagnosed problems involved the lower and upper respiratory tract and the musculoskeletal system. Poor-performers had lower speeds at a blood lactate (LA) concentration of 4mmol/L (V(LA4)) and a heart rate (HR) of 200bpm (V(200)) on treadmill and racetrack, as well as lower values for haematological parameters, plasma angiotensin-converting enzyme and antioxidants, compared to control horses. Problems of the respiratory system were the most frequently diagnosed sub-clinical diseases affecting performance. SETs, together with some blood markers, may be useful as a non-specific diagnostic tool for early detection of diseases that may affect performance.

Design and validation of a dynamometric horseshoe for the measurement of three-dimensional ground reaction force on a moving horse

Properties of ground surfaces condition locomotion, and quality of track surfaces is believed to be involved in the pathogenesis of many musculoskeletal injuries in the horse. Measuring ground reaction forces (GRF) is an interesting approach to assess those interactions. Forceplates are the most commonly used but they are not well suited to compare different ground surfaces at fast gaits. Embarked equipment, fixed under the horses hoof, would allow force measurement on any track. The objective of this work was (1) to design a device which enables the measurement of 3-D GRF on any ground, at any gait, for a given subject, (2) to determine its accuracy, and (3) to evaluate its performance and usefulness under physiological conditions. The resulting dynamometric horseshoe was composed of 4 piezoelectric sensors sandwiched between 2 aluminium plates designed at the shape of an equine shoe. The measurements, evaluated after a quasi-static calibration, revealed that the root mean square error was 1.3% in the normal direction, and 3.1% in the transversal direction. In vivo tests at the walk and trot in straight line and at the trot on circles, were conducted on 3 different ground surfaces. The results demonstrate that this dynamometric horseshoe is well suited to study the effects of different ground surfaces on GRF in the moving horse.

Diagnostic Techniques for Identification and Documentation of Tendon and Ligament Injuries

Conventional clinical examination remains of medical and economic value for diagnosis of soft tissue injuries in the equine athlete. This procedure requires concentration and rigor to establish the diagnosis, and, if possible, some experience to better evaluate the prognosis. None of the new imaging techniques can replace the physical examination, but each may provide additional information. These sophisticated methods are bringing considerable progress in the knowledge of locomotor injuries in the horse and a tremendous improvement in our ability to diagnose precisely lamenesses and limitations of performance.

Effect of toe and heel elevation on calculated tendon strains in the horse and the influence of the proximal interphalangeal joint

The sagittal alteration of hoof balance is a common intervention in horses, with corrective shoeing being one of the most frequently applied methods of managing tendonitis. However, the effect of toe or heel elevation on tendon strains is poorly understood. This study aimed to examine the effect of toe and heel wedges on the superficial digital flexor tendon, deep digital flexor tendon, and the third interosseous muscle or suspensory ligament strains using in vivo data and an accurate subject‐specific model. Kinematic data were recorded using invasive markers at the walk and trot. Computerized tomography was then used to create a subject‐specific model of an equine distal forelimb and strains were calculated for the superficial digital flexor tendon, the deep digital flexor tendon accessory ligament and the suspensory ligament for seven trials each of normal shoes, and toe and heel elevation. As the proximal interphalangeal joint is often ignored in strain calculations, its influence on the strain calculations was also tested. The deep ligament showed the same results for walk and trot with the heel wedge decreasing peak strain and the toe wedge increasing it. The opposite results were seen in the suspensory ligament and the superficial digital flexor tendon with the heel wedge increasing peak strain and the toe wedge decreasing it. The proximal interphalangeal joint was shown to be influential on the strains calculated with normal shoes and the calculated effect of the wedges. Our results imply that corrective shoeing appears to decrease strain in the tendon being targeted; the possibility of increases in strain in other structures should also be considered.

Ultrasonographic Evaluation of Back Lesions

With progressive advances in ultrasonographic equipment, evaluation of a number of axial skeletal structures is now possible. Ultrasonography is presently the best technique for evaluation of the SSpL and lumbosacral intervertebral discs. It is a useful adjunct to radiography for assessment of spinous processes and AP injuries.

Association of growth, feeding practices and exercise conditions with the severity of the osteoarticular status of limbs in French foals.

The aim of this study was to identify the risk factors for the severity of Juvenile OsteoChondral Conditions (JOCC) in limbs of French foals. Twenty-one farms in Normandy, France, were sampled and enrolled in a cohort study including 378 foals from three breeds, followed from the 8th month of pregnancy of the mares until the foals were approximately 6months old. Data on growth, feeding practices and exercise conditions were regularly collected. The carpus, the front and hind digits, the hock and the stifle of the foals were radiographed at the end of follow-up. JOCC severity in each foal was described using a global appraisal of its osteoarticular status (OAS) depending on the number and the severity of radiographic findings. Of the 378 foals, 53% had a good OAS, 34% had an intermediate OAS and 13% had a poor OAS. The breed (Selle Français and French Trotter Standardbred vs. Thoroughbred), a high girth perimeter at early age and an irregular exercise were significantly associated with a poor OAS. This study contributes to the understanding of the development of JOCC. An increased growth and reduced or irregular physical activity during the first weeks of life would be responsible for more severe lesions. Growth and exercise conditions should be carefully monitored to reduce the prevalence of severe JOCC in foals.

Study design for the investigation of likely aetiological factors of juvenile osteochondral conditions (JOCC) in foals and yearlings

The possible aetiology of osteochondrosis and, to a lesser extent, other developmental orthopaedic diseases or juvenile osteochondral conditions (JOCC), has been intensively investigated. However, most studies have focused on single factors of this multi-factorial disorder, or have been conducted under experimental conditions. This paper aims to present and discuss the scientific background of the BOSAC (Breeding, Osteochondral Status and Athletic Career) research program, a multi-factorial investigation on JOCC risk factors in field conditions. The epidemiology of JOCC in horses born in Normandy between 2002 and 2004 was studied. Horses were subjected to repeated body measurements, blood sampling and locomotion evaluation from birth until yearling sales. A radiographic examination, including 10 views of the limbs, was performed on each subject at approximately 6 and 17months of age. Information on nutrition and management programmes was collected by specialists from visits to the farms and the use of questionnaires. A total of 393 foals of three French breeds were monitored from birth to weaning, and 321 of these remained available for further follow-up, making the study unique as regards both the number of subjects and the variety of information collected. The study was designed to describe the evolution of JOCC, and determine possible early markers, risk factors and prognostic factors with respect to performance. Relevant data, suitable for epidemiological analyses, were collected under various field conditions that reflect current management practices in Normandy, Frances main horse breeding region.

A reliable severity scoring system for radiographic findings in the limbs of young horses.

The validity of methods used to score the severity of radiographic findings (RFs) in horses is uncertain since only one or two joints are usually studied, classification criteria are heterogeneous and the internal validity is not assessed. The aim of this study was to assess the internal validity of a severity scoring system (SSS) of RFs by repeated scoring of a sample of radiographs. This SSS of RFs is based on four criteria that can be applied to every type of RF observed in limb joints. It consists of five weighted severity indexes (0, 1, 2, 4, 8) and was used to assess RFs found on the limbs of 392 young horses. The internal validity of the SSS was assessed using Kappa coefficients calculated on a subsample of 137 horses whose radiographs were interpreted twice. The final RF severity indices from these radiographs were obtained after three experienced veterinarians had reached a consensus, similar to the procedure used at foal and yearling sales. The majority of RFs from the 392 horses were scored either 1 or 2, while scores of 8 were only observed in the stifle and tarsus. Among the subsample, the overall agreement on the presence or absence of RFs was good (κ=0.63; 95% Confidence Interval [CI], 0.56-0.69), and was excellent for the severity of RFs (weighted κ=0.82; 95% CI, 0.75-0.87). Most disagreements involved RFs that scored 1. The fore fetlock and the carpus experienced the lowest agreement. The SSS was a stable and reliable procedure applicable to any RF on any limb joint of the horse. It will be of potential interest in clinical practice and in the pre-purchase evaluation of young horses and could also be used in additional studies on the evolution or risk factors of RFs.