Summary Reasons for performing study: The differential diagnosis of foot pain has long proved difficult and the use of magnetic resonance imaging (MRI) offers the opportunity to further the clinical understanding of the subject. Objectives: To determine the incidence of deep digital flexor tendon (DDFT) injuries in a series of 75 horses with lameness associated with pain localised to the digit, with no significant detectable radiographic or ultrasonographic abnormalities, using MRI; and to describe a variety of lesion types and relate DDF tendonitis with anamnesis, clinical features, response to local analgesic techniques and nuclear scintigraphic and ultrasonographic findings. Methods: All horses undergoing MRI of the front feet between January 2001 and October 2002 were reviewed and those with DDFT injuries categorised according to lesion type; horses with primary tendonitis (Group I) and those with concurrent abnormalities of the navicularbone considered to be an important component of the lameness (Group II). The response to perineural analgesia of the palmar digital nerves and palmar (abaxial sesamoid) nerves, intra‐articular analgesia of the distal interphalangeal (DIP) joint and analgesia of the navicularbursa were reviewed. The result of ultrasonography of the pastern and foot was recorded. Lateral, dorsal and solar pool and bone phase nuclear scintigraphic images were assessed subjectively and objectively using region of interest (ROI) analysis. Results: Forty‐six (61%) of 75 horses examined using MRI had lesions of the DDFT considered to be a major contributor to lameness. Thirty‐two horses (43%) had primary DDFT injuries and 14 (19%) a combination of DDF tendonitis and navicular bone pathology. Lesions involved the insertional region of the tendon alone (n = 3), were proximal to the navicular bone (n = 23) or were at a combination of sites (n = 20). Lesion types included core lesions, focal and diffuse dorsal border lesions, sagittal plane splits, insertional injuries and lesions combined with other soft tissue injuries. Many horses had a combination of lesion types. Lameness was abolished by palmar digital analgesia in only 11 of 46 horses (24%). Twenty‐one of 31 horses (68%) in Group I showed >50% improvement in lameness afterintra‐articular analgesia of the DIP joint, whereas 11 of 12 horses (92%) in Group II had a positive response. Twelve of 18 horses (67%) in Group I had a positive response to analgesia of the navicular bursa. Nineteen horses had lesions of the DDFT extending proximal to the proximal interphalangeal joint seen using MRI, but these were identified ultrasonographically in only 2 horses. Scintigraphic abnormalities suggestive of DDFT injury were seen in 16 of 41 horses (41%), 8 in pool phase images and 8 in bone phase images. Conclusions and potential relevance: DDFT injuries are an important cause of lameness associated with pain arising from the digit in horses without detectable radiographic abnormalities. Lameness is not reliably improved by palmar digital analgesia, but may...
Further investigation is needed to establish the clinical significance of MRI abnormalities in the palmar processes of the distal phalanx and their relationship with lesions in adjacent structures.
The purpose of this study was to investigate the presence, position and relative sizes of the meniscofemoral ligaments (MFL) in three quadrupeds and humans and relate these to the caudal slope of the lateral tibial plateau. Canine, ovine and equine stifles and human knees were dissected to identify the presence of MFLs, their obliquity in relation to the caudal cruciate ligaments (CCL), the relative size and shape of the MFLs compared with the CCL, the points of femoral attachment of the MFLs and CCL, and the distance between the MFLs and CCL at their midpoints. The lateral tibial condyle was divided sagittally with a handsaw and the caudal slope was measured. An MFL was present in all quadrupeds. It was caudal to the CCL, being analogous to the human posterior MFL. There was no structure analogous to the human anterior MFL, a structure that has a different femoral attachment from the human posterior MFL and MFLs in other species examined. The meniscotibial attachments were of varying sizes. The size ratio between the MFL and CCL was greater in all three quadrupeds than it was in the human knee. The MFL lies more obliquely than the CCL in all species examined. The caudal tibial slope was steeper in the quadrupeds. In the stifle joints of quadrupeds, the MFL is a substantial structure and appears to be related to the caudal tibial slope. It is known to resist caudal translation of the tibia in conjunction with the lateral meniscus. This must be borne in mind when considering its function in the human knee.
Objective The case histories described each presented with a visual deficit, varying from permanent total blindness with ophthalmoscopic evidence of optic atrophy to variable and transient visual disturbances, including occasional blindness, but with absence of ophthalmoscopic or any other ocular abnormality. Animals studied Three horses of widely different age and type, but all with an original history of upper respiratory tract infection. Procedure All three cases were examined by a specialist veterinary ophthalmologist. In addition, magnetic resonance imaging (MRI) and, where possible, postmortem and histopathological examinations were performed. Results The common factor to all three cases proved to be infection of the sphenopalatine sinuses with subsequent distension and compression of adjacent optic nerve(s) and optic chiasm. Conclusions Specialist veterinary ophthalmological examination proved of extremely limited value. The importance of MRI (and CT) scans for accurate diagnosis, and therefore possible successful treatment, is emphasized. Our cases were compared with similar cases in man, where visual disturbances due to spheno-palatine sinus involvement are recognized, but rare, in similar situation.
Nuclear scintigraphy is a potentially useful tool in the evaluation of a horse with thoracolumbar region pain.
MAGNETIC resonance imaging (MRI) involves the interaction between an external magnetic field, radiowaves and hydrogen nuclei in the body. Although MRI has been used in human medicine for over 20 years, its value as an imaging modality in equine orthopaedic disease has only recently been recognised. The high tissue contrast afforded by MRI makes it ideal for the assessment of articular cartilage, ligaments, tendons, joint capsules, synovium and bone marrow. In humans, MRI has become the imaging technique of choice for the investigation of many musculoskeletal structures, and the procedure is also increasingly being used for the diagnosis of orthopaedic conditions in small animals. In the horse, experience so far suggests that MRI has great potential for improving the diagnosis and understanding of lameness, and its clinical use is currently being undertaken at several centres around the world. This article explains the principles of MRI and describes how the technique may be used clinically to aid the diagnosis of equine lameness.
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