Topic:Navicular Bone
The navicular bone is a small, boat-shaped bone located in the hoof of a horse, specifically situated behind the coffin bone and beneath the deep digital flexor tendon. It plays a role in the biomechanics of the equine foot by acting as a fulcrum for the deep digital flexor tendon, aiding in the horse's movement and weight distribution. The navicular bone is part of the navicular apparatus, which includes surrounding ligaments and the bursa, a fluid-filled sac that reduces friction. Issues with the navicular bone and associated structures can lead to a condition known as navicular syndrome, which is characterized by lameness and pain in the front feet. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, function, and pathophysiology of the navicular bone, as well as diagnostic and treatment options for navicular-related conditions in horses.
Comparison of inversion recovery gradient echo with inversion recovery fast spin echo techniques for magnetic resonance imaging detection of navicular bone marrow lesions in horses. To compare navicular bone marrow lesion (BML) conspicuity in the feet of horses as determined via 2 fat-suppressed MRI techniques, including standard short tau inversion recovery (STIR) and inversion recovery gradient echo (IRGE). Methods: Feet (n = 150) of horses with lameness referable to the distal portion of the digit. Methods: STIR and IRGE sequences were obtained prospectively in all feet with a standing low-field equine MRI system. Presence of a BML was ascertained by identification of a characteristic combination of marrow alterations in T1-weighted, T2*-weighted, T2-weighted, and STIR...
Hind foot lameness: results of magnetic resonance imaging in 38 horses (2001-2011). The distribution of lesions detected using magnetic resonance imaging (MRI) of hind feet has not been reported. Objective: To evaluate type and distribution of lesions detected using MRI in hind feet of lame horses and to compare the findings with those reported in front feet; to document follow-up information. Methods: Horses were selected if hindlimb lameness was abolished by plantar nerve blocks performed at the base of the proximal sesamoid bones. Magnetic resonance images were acquired using either a low-field or a high-field magnet, and all images were evaluated retrospectively by both a...
Response to injection of the navicular bursa with corticosteroid and hyaluronan following high-field magnetic resonance imaging in horses with signs of navicular syndrome: 101 cases (2000-2008). To determine treatment outcome on the basis of pathological changes identified on MRI and lameness duration in horses with navicular syndrome that underwent injection of corticosteroid and hyaluronan into the navicular bursa. Methods: Retrospective case series. Methods: 101 horses with navicular syndrome. Methods: Medical records of horses with signs of navicular syndrome evaluated between January 2000 and December 2008 were reviewed. Data on signalment, use of the horse, history, affected limbs, duration of lameness, findings on lameness examination, radiographic findings, MRI findings, treat...
Variation in foot conformation in lame horses with different foot lesions. Foot conformation in the horse is commonly thought to be associated with lameness but scientific evidence is scarce although it has been shown in biomechanical studies that foot conformation does influence the forces acting on the deep digital flexor tendon (DDFT) and the navicular bone (NB). The aim of this study was to determine the relationships between foot conformation and different types of lesion within the foot in lame horses. It was hypothesised that certain conformation parameters differ significantly between different types of foot lesions. Conformation parameters were measured on m...
Magnetic resonance imaging of navicular bursa adhesions. Adhesions occur in the navicular bursa between the deep digital flexor tendon (DDFT) and other structures. Our objectives were to describe the appearance of navicular bursa adhesions on high-field magnetic resonance (MR) images, to compare these findings to findings at navicular bursoscopy, and to determine the prevalence of lesions in the remainder of the podotrochlear apparatus. Sixteen forelimbs from 14 horses that underwent MR imaging and navicular bursoscopy were evaluated. Adhesions were considered type 1 when characterized by a discontinuity in the navicular bursa fluid signal between t...
Comparison between magnetic resonance imaging and histological findings in the navicular bone of horses with foot pain. There is limited knowledge about both histological features in early navicular disease and what histological features are represented by increased signal intensity in fat-suppressed magnetic resonance (MR) images of the navicular bone. Objective: To characterise increased signal intensity in the spongiosa of the navicular bone in fat-suppressed MR images and to compare this with histopathology; and to compare objective grading of all aspects of the navicular bone on MR images with histological findings. Methods: One or both front feet of 22 horses with foot pain and a median lameness duration ...
Standing low-field magnetic resonance imaging in horses with chronic foot pain. Conventional imaging modalities can diagnose the source of foot pain in most cases, but have limitations in some horses, which can be overcome by using magnetic resonance imaging (MRI). However, there are no reports of the MRI appearance and prevalence of foot lesions of a large series of horses with chronic foot lameness. Methods: In the present study, 79 horses with unilateral or bilateral forelimb lameness because of chronic foot pain underwent standing low-field MRI to make a definitive diagnosis. Results: Of the 79 horses, 74 (94%) had alterations in >1 structure in the lame or lamest foo...
Differences in the morphology of distal border synovial invaginations of the distal sesamoid bone in the horse as evaluated by computed tomography compared with radiography. Distal border synovial invaginations of the distal sesamoid bone are radiographically assessed during the selection process of horses admitted as breeding stallions or in purchase examinations. Nowadays, many moderately or some deeply penetrating proximally enlarged synovial invaginations are considered as moderate or severe radiographic findings. Objective: To measure the difference between and agreement of the morphology of distal border synovial invaginations on radiography vs. computed tomography (CT). It was hypothesised that the morphology of distal border synovial invaginations would be...
Treating navicular syndrome in equine patients. Navicular syndrome is a chronic, progressive condition affecting the navicular bone and bursa, deep digital flexor tendon (DDFT), and associated soft tissue structures composing the navicular apparatus. The treatment options for navicular syndrome are as varied as the proposed causes of the condition. The severity of clinical signs, intended use and workload of the horse, and owner compliance with therapy are important considerations in developing a treatment plan. Nonsurgical treatment of navicular syndrome consists of rest, hoof balance and corrective trimming/shoeing, and medical therapy, i...
Endoscopic evaluation of the navicular bursa: observations, treatment and outcome in 92 cases with identified pathology. Diagnostic navicular bursoscopy has been described in limited cases. Review of greater numbers is needed to define its contribution to case management and prognostic values. Objective: To report: 1) clinical, diagnostic and endoscopic findings in a series of cases, 2) surgical techniques and case outcomes and 3) prognostic values. The authors hypothesise: 1) lameness localising to the navicular bursa is commonly associated with dorsal border deep digital flexor tendon (DDFT) lesions, 2) endoscopy allows extent of injuries to be assessed and treated, 3) case outcome relates to severity of DDFT ...
Distal border fragments and shape of the navicular bone: radiological evaluation in lame horses and horses free from lameness. The significance of distal border fragments of the navicular bone is not well understood. There are also no objective data about changes in thickness and proximal/distal extension of the palmar cortex of the navicular bone. Objective: To describe the distribution of distal border fragments and their association with other radiological abnormalities of the navicular bone and describe the shape of the navicular bone in sound horses and horses with foot-related lameness, including navicular pathology. Methods: Sound horses had radiographs acquired as part of a prepurchase examination. Lame horses...
Comparisons of computed tomography, contrast enhanced computed tomography and standing low-field magnetic resonance imaging in horses with lameness localised to the foot. Part 1: anatomic visualisation scores. To date, few reports exist comparing magnetic resonance imaging (MRI) and computed tomography (CT) for imaging of the equine distal limb, yet clinicians are required to decide which modality to use regularly. Objective: To report and compare anatomic visualisation scores obtained for CT, contrast enhanced CT (CECT) and standing low-field MRI (LFMRI) in the equine foot. Objective: Anatomic visualisation score discrepancies would exist between CT, CECT and LFMRI. Methods: Images of 22 lame horses (31 limbs) undergoing both CT and LFMRI of the foot were reviewed. When available, CECT images were ...
Positive contrast magnetic resonance bursography for assessment of the navicular bursa and surrounding soft tissues. Magnetic resonance (MR) imaging is often performed to determine the cause of palmar heel pain. We evaluated how distension of the navicular bursa affected the MR appearance of the navicular bursa and associated structures. An MR evaluation was performed on normal cadaver limbs and cadaver limbs from horses with lameness localized to the foot. The normal navicular bursae were injected with 2, 4, or 6 ml of solution. The bursae of the feet from lame horses were injected with 4 or 6 ml, and the MR study was repeated. All bursae were examined grossly to verify the presence or absence of adhesions....
High-field magnetic resonance imaging investigation of distal border fragments of the navicular bone in horses with foot pain. Distal border fragments of the navicular bone can be seen in lame and nonlame horses and their clinical significance remains open to debate. Objective: To describe the magnetic resonance imaging (MRI) appearance of distal border fragments and the adjacent navicular bone. To investigate the relationship between fragments and other abnormalities of the navicular bone and the distal sesamoidean impar ligament (DSIL). Methods: Horses were included if pain causing forelimb lameness was localised to the foot and high-field MR images were acquired. The size and location of distal border fragments wer...
Ultrasonographic findings in horses with foot pain but without radiographically detectable osseous abnormalities. Foot pain is an important cause of lameness in horses. When horses with foot pain have no detectable radiographic abnormalities, soft-tissue assessment remains a diagnostic challenge without magnetic resonance (MR) imaging. Ultrasonography can provide an alternative to MR imaging when that modality is not available but the extent of changes that might be seen has not been characterized. We reviewed the ultrasonographic findings in 39 horses with lameness responding positively to anesthesia of the palmar digital nerves and without radiographically detectable osseous abnormalities. Thirty of the...
Association between navicular bone fragmentation and shape in Belgian Warmblood horses. To investigate whether in navicular bones (NB) from warmbloods, distal border fragmentation is associated with the shape of the proximal articular border or other radiological findings. Methods: Radiographs of the front feet of 325 normal, subadult horses presented for admission as breeding stallions were reviewed. Results: The proximal articular border of the total of 650 NB was classified as straight (n = 278), convex (n = 184), undulating (n = 147) or concave (n = 41). Distal border fragments were present in 57 NB (8.8%). They were significantly more prevalent in NB with a concave (9/41; 22...
Core decompression of the equine navicular bone: an in vivo study in healthy horses. To determine the physiologic response of the equine navicular bone to core decompression surgery in healthy horses. Methods: Experimental in vivo study. Methods: Healthy adult horses (n=6). Methods: Core decompression was completed by creating three 2.5-mm-diameter drill channels into the navicular bone under arthroscopic control. The venous (P(V)), arterial (P(A)), articular (P(DIPJ)), and intraosseous pressures (IOP) were recorded before and after decompression drilling. Each IOP measurement consisted of a baseline (IOP(B)) and a stress test (intramedullary injection of saline solution, IOP(...
Core decompression of the equine navicular bone: an in vitro biomechanical study. To determine the effect of core decompression surgery and bone mineral density (BMD) on the mechanical properties of equine navicular bones. Methods: Experimental, in vitro study. Methods: Fore limb navicular bones (n=36 pairs) from sound 2-5-year-old horses with no radiographic abnormalities of the distal aspect of the forelimbs. Methods: Navicular BMD was measured using dual energy X-ray absorptiometry. One randomly assigned navicular bone from each pair served as control. The contralateral test specimen was allocated to 1 of 6 treatment groups defined by drill bit size (3.2 versus 2.5 mm di...
Navicular syndrome in equine patients anatomy, causes, and diagnosis. Navicular syndrome is a chronic and often progressive disease affecting the navicular bone and bursa, deep digital flexor tendon (DDFT), and associated soft tissue structures composing the navicular apparatus. This syndrome has long been considered one of the most common causes of forelimb lameness in horses. Diagnosis of navicular syndrome is based on history, physical examination, lameness examination, and peripheral and/or intraarticular diagnostic anesthesia. Several imaging techniques (e.g., radiography, ultrasonography, nuclear scintigraphy, thermography, computed tomography [CT], magnet...
Refinement of quantitative trait loci on equine chromosome 10 for radiological signs of navicular disease in Hanoverian warmblood horses. Navicular disease is characterized by a progressive degenerative alteration of the equine podotrochlea. In this study, we refined a previously identified quantitative trait locus (QTL) on horse chromosome 10 for the abnormal development of canales sesamoidales (DCS) of the navicular bone in Hanoverian warmblood horses. Genotyping was done in 192 Hanoverian warmblood horses from 17 paternal half-sib groups. The whole marker set comprised 45 markers including seven newly developed microsatellites and 13 single nucleotide polymorphisms (SNPs) within positional candidate genes. Chromosome-wide sig...
Comparison between radiological and magnetic resonance imaging lesions in the distal border of the navicular bone with particular reference to distal border fragments and osseous cyst-like lesions. There are no data concerning the accuracy of conventional and computed or digital radiography for evaluation of the equine foot. Objective: To compare conventional film-screen and computed radiography with magnetic resonance imaging (MRI) for detection of distal border fragments of the navicular bone; and to establish which type of fragment was more likely to be detected radiologically. Methods: Horses were included if forelimb lameness was localised to the foot and both radiography and high-field MR images had been acquired. Horses were divided into 2 groups based on acquisition of convention...
Comparison of conventional and alternative arthroscopic approaches to the palmar/plantar pouch of the equine distal interphalangeal joint. The conventional arthroscopic approach to the palmar/plantar aspect of the distal interphalangeal joint (DIPJ) may result in the inadvertent penetration of the digital flexor tendon sheath (DFTS) and the navicular bursa (NB). This iatrogenic communication would be undesirable subsequent to arthroscopic lavage of a septic DIPJ. Objective: A lateral/medial approach to the palmar/plantar aspect of the DIPJ will result in a significantly lower rate of inadvertent penetration of the DFTS and NB, whilst still providing adequate intra-articular evaluation. Methods: The conventional palmar/plantar app...
Outcome of medical treatment for horses with foot pain: 56 cases. Currently, there are limited data regarding the long-term outcome of horses with foot pain treated with corrective shoeing, rest and rehabilitation, and intrasynovial anti-inflammatory medication to target lesions detected with MRI. Objective: To report the long-term (≥12 months) outcome of horses with foot lesions following medical therapy. Objective: 1) There is no association between clinical parameters considered and a poor response to therapy. 2) Horses with a deep digital flexor tendinopathy are less likely to respond to medical therapy than horses without a deep digital flexor tendino...
The distal sesamoidean impar ligament: comparison between its appearance on magnetic resonance imaging and histology of the axial third of the ligament. There is limited knowledge about the interpretation of alterations in the distal sesamoidean impar ligament (DSIL) detected using magnetic resonance imaging (MRI) and their correlation with histopathology. Objective: There would be: 1) a correlation between histopathology and MRI findings; and 2) a relationship between MR abnormalities at the origin and the insertion of the DSIL, between insertion and body; and origin and body. Methods: Fifty limbs from 28 horses were examined using high-field MRI and histopathology. MR abnormalities of the DSIL, its origin on the navicular bone and its insert...
Tenoscopy of the navicular bursa: a new therapeutic approach for horses affected by “palmar pain syndrome.” Endoscopic technique review and personal experiences. Tenoscopy of the navicular bursa has been recently introduced as a diagnostic and therapeutic treatment in cases of palmar foot pain syndrome. A deep digital flexor tendon transthecal approach was suggested in 1999, and the endoscopic technique has been reviewed. Smith and coworkers have recently reported good and promising results. An anatomic cadaver limb study was performed, and the endoscopic technique was evaluated. Subsequently, a 14-year-old Argentine mare, affected by palmar foot pain syndrome, was treated. Clinical data, MRI and endoscopic findings, and a 6-month follow-up evaluation ...
Navicular bursoscopy in the horse: a comparative study. To compare the proportion of the proximal recess of the navicular bursa that could be examined through a single endoscopic portal and the severity of iatrogenic lesions between conventional and modified approaches. Methods: Descriptive study. Methods: Equine cadaver forelimbs (n=16). Methods: Arthroscopic access to the navicular bursa in 1 limb of each pair was by a conventional approach and in the other limb, by a modified approach using sharp dissection through the distal digital flexor sheath, immediately palmar to the T ligament. The time required to access the bursa and the estimated prop...
Evaluation of diffusion of triamcinolone acetonide from the distal interphalangeal joint into the navicular bursa in horses. To determine whether triamcinolone acetonide diffuses from the distal interphalangeal joint (DIPJ) to the navicular bursa, diffusion is direct or systemic, and addition of sodium hyaluronan has an effect on diffusion in horses. Methods: 11 adult horses without forelimb lameness. Methods: 1 randomly chosen forelimb DIPJ of each horse received an injection of 10 mg of triamcinolone acetonide plus 20 mg of sodium hyaluronan (group 1), and the contralateral forelimb DIPJ received an injection of 10 mg of triamcinolone acetonide plus 2 mL of lactated Ringer's solution (group 2). Synovial fluid samp...
Improved identification of the palmar fibrocartilage of the navicular bone with saline magnetic resonance bursography. Fibrocartilage degeneration is the earliest pathologic finding in navicular disease but remains difficult to detect, even with magnetic resonance (MR) imaging. We hypothesized that injection of the navicular bursa with saline would improve accuracy of MR imaging evaluation of palmar fibrocartilage. Thoracic limbs were collected from 11 horses within 6 h of death. Imaging was performed with a 1.5 T magnet using sagittal 2D proton density and transverse 3D FLASH sequences with fat saturation. For the purpose of determining sensitivity and specificity of the MR images, fibrocartilage was classifi...
Magnetic resonance imaging findings in horses with recent onset navicular syndrome but without radiographic abnormalities. Seventy-two horses with recent onset of navicular syndrome and normal radiographs were assessed. Horses underwent magnetic resonance (MR) imaging of both front feet. All abnormalities were characterized and the most severe abnormality identified, if possible. Abnormal signal intensity in the navicular bone was the most severe abnormality in 24 (33%) horses. Pathologic change in the deep digital flexor tendon was the most severe abnormality in 13 (18%) horses. Pathologic change in the collateral sesamoidean ligament was the most severe abnormality in 11 (15%) horses. Pathologic change in the di...
Pressure distribution between the deep digital flexor tendon and the navicular bone, and the effect of raising the heels in vitro. The objectives of this study were to topographically map pressure distribution across the palmar surface of the navicular bone in response to forces applied by the deep digital flexor tendon (DDFT), and evaluate the effect of raising the heels in vitro . A rig was constructed to hold an equine cadaver limb and apply controlled pressure to the navicular bone from the DDFT. Pressure-sensitive paper was used to quantify and map the resultant pressure. Changes in response to heel wedges (5 degrees and 10 degrees ) were recorded. The areas subject to maximum pressure from the DDFT were: the central...