Orthopaedic Research
Staff | Sport horse Injury and Performance | Validation of Imaging Techniques | Foot Pain | Joint Problems | Tendon Problems | Ligament Problems | Bone Structure | Recent Publications
Staff
Dr Sue Dyson MA VetMB DEO PhD FRCVS
Dr Rachel Murray MA VetMB MS PhD MRCVS Dip ACVS Dip ECVS
Raymond Wright
Carolyne Tranquille
Dr Simon Collins PhD BSc (Hons)
Jodi Miller BSc Honours
Miss Meredith A Smith MA VetMB CertES (Soft Tissue) DipECVS MRCVS
Sport horse Injury and Performance
Research at the AHT has a direct impact on clinical work and on the advancement of our knowledge both at the Centre for Equine Studies and throughout the veterinary profession.
Validation of Imaging Techniques
Magnetic Resonance Imaging (MRI)
Research and clinical work at the AHT over the past 8 years using a 1.5 Tesla high field magnet have conclusively demonstrated that MRI is an excellent tool for diagnosis of abnormalities within the tissues in the foot, pastern, fetlock and carpus (knee) of the horse. MRI is now considered the gold standard diagnostic tool for the evaluation of many causes of lameness in horses. Since August 2006, a 0.27 Tesla low field standing MRI system has also been part of our diagnostic armoury at the Centre for Equine Studies. Standing MRI has been under development during the past 6 years within referral clinics, and in routine clinical use for the past 3 years. In conjunction with clinical use of the system, active research helping to validate this system is ongoing at the AHT.
Recent research projects include comparison of scintigraphic (bone scan) and MRI findings in lame horses, evaluation of adaptive change within the small bones of the hock in response to exercise, evaluation of the appearance of the distal sesamoidean ligaments, and evaluation of the occurrence of a magic angle effect within tendons and ligaments of the lower limb during standing MRI. Ongoing comparative research using both the high field and low field MRI systems includes investigation of geometrical changes in the third metacarpus (canon bone) of racehorses and comparison of tissue abnormalities of the foot, pastern and fetlock identified using both MRI systems, with examination of tissues at pathology and under the microscope as a gold standard means of validation of image analysis.
Research at the AHT has a direct impact on clinical work and on the advancement of our knowledge both at the Centre for Equine Studies and throughout the equine veterinary profession.
Foot Pain
The team at the Animal Health Trust has pioneered the understanding of equine foot pain using a variety of imaging, pathological and biomechanical approaches. This has led to vital changes in the understanding of diagnosis and pathogenesis of foot pain in horses.
Our research related to the foot has followed several parallel paths, involving clinical investigation, nuclear scintigraphy, magnetic resonance imaging and post mortem investigations. To further our understanding of scintigraphic or bone scan images we first investigated factors that might influence blood flow to the foot, because we realised that a proportion of horses on the day of examination had poor blood flow to the foot, which resulted in poor delivery of radiopharmaceutical to the foot and thus a poor quality, sometimes non-diagnostic bone scan. We investigated the influence of bandaging the limbs for at least 15 hours prior to injection compared with exercising the horse prior to injection of the radiopharmaceutical, and also a combination of exercise and bandaging compared with no bandages and no exercise. We clearly demonstrated that exercise was by far the most important feature, and we therefore adopted this as part of the routine bone scan protocol unless it was clinically contraindicated to do so.
Subsequently we have completed studies looking at different patterns of radiopharmaceutical uptake, quantitative assessment of radiopharmaceutical uptake and how these are influenced by different disease processes in the foot. After we had amassed a lot of data comparing the results of scintigraphy and magnetic resonance imaging we are beginning to understand better that there are probably a variety of different pathological processes that influence the navicular bone, with or without closely related soft tissue structures, such as the distal sesamoidean impar ligament, the collateral sesamoidean ligament and the deep digital flexor tendon. The insertions of the collateral ligaments of the distal interphalangeal joint and the insertion of the deep digital flexor tendon appear to be sites of major stress, and presence of increased radiopharmaceutical uptake may reflect severity of injury and influence prognosis.
Magnetic resonance imaging is still a relatively novel technique in the diagnosis of equine musculoskeletal injury and we have been world pioneers in leading research to validate this technique, demonstrating that in clinically normal horses, although low grade changes can be seen within the foot, in lame horses lesions are consistently more severe. We have verified that the lesions that can be seen fit very well with post mortem findings. We are gaining further information about the different disease processes that influence the navicular bone.
We have ongoing projects trying to understand better why some of the injuries occur. It is clear that in the deep digital flexor tendon, blood vessels may become occluded with thrombi, thus compromising blood flow. Lack of essential nutrients and correct physiological environment can lead to cell death and areas of necrosis, which are ultimately replaced by fibrosis. In the lower parts of the collateral ligaments of the distal interphalangeal joint were are finding a unique type of fissuring degeneration. Thus it seems likely that there are inherent degenerative changes in these structures, superimposed on which may be work related trauma.
We have recognised in many clinical patients that lesions of multiple structures can be identified using magnetic resonance imaging. Many of these are likely to have predated the onset of lameness. We are now trying to elucidate better what actually induces pain that causes lameness. We have done some pilot studies mapping out the distribution of sensory nerve endings in a variety of structures within the foot in lame and sound horses. We need to develop this further and are currently seeking further funding for this important project. Meanwhile we have further ongoing work looking at injuries of the distal sesamoidean impar ligament. We are also trying to understand better the different pathological processes that can result in increased signal intensity in bones in fat suppressed magnetic resonance images. This is important if we want to know how to target treatment.
This research work is driven by the clinical cases and the questions that arise from their investigation, as we strive to understand better the causes of foot pain, the mechanisms of injury and any possible influences on treatment.
Recently we have expanded the team to include Dr Simon Collins, with the aim of improving understanding of the biomechanics of injury in foot pain and development of preventative and managament strategies using computer modelling. The finite element method of computer modelling uniquely enables the functional interpretation and assessment of information derived from modern imaging techniques including MRI. Computer based simulations reveal the distribution and levels of stress and strain within the different tissues of the foot. This non-invasive technique is therefore ideally suited to provide new insight into the adverse functional effects of such foot disorders as palmar foot pain and laminitis, and to assist in the development of enhanced foot management and improved remedial and therapeutic trimming and shoeing treatments.
Joint Problems
Tendon Problems
Ligament Problems
Bone Structure
Recent Publications
Please click here to view the list of publications.
