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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 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...
Fine mapping a quantitative trait locus on horse chromosome 2 associated with radiological signs of navicular disease in Hanoverian warmblood horses. Navicular disease or podotrochlosis is one of the main causes of progressive forelimb lameness in warmblood horses. The objective of this study was to refine a quantitative trait locus on horse chromosome 2 for radiological alterations in the contour of the navicular bone (RAC) in Hanoverian warmblood horses. Genotyping was performed in 192 Hanoverian warmblood horses from 17 paternal half-sib groups. The marker set was extended to 58 informative microsatellites including nine newly developed microsatellites. QTL for RAC could be delineated at 32.50-43.13 Mb and a further new QTL for RAC could...
Intra- and interobserver agreement in the interpretation of navicular bones on radiographs and computed tomography scans. Criteria for the radiographic evaluation of navicular bones in horses have been published to standardise classification of radiographic signs. However, intra- and interobserver agreement have not been established. Objective: To determine intra- and interobserver agreement in the evaluation of radiographic and computed tomographic (CT) navicular changes. It was hypothesised that: 1) intraobserver agreement would be better than interobserver agreement; 2) agreement would be better for CT than for radiography; and 3) pathological changes would be recognised with greater certainty with CT. Methods...
Outcomes of podotrochlear (navicular) bursa injections for signs of foot pain in horses evaluated via magnetic resonance imaging: 23 cases (2005-2007). To determine clinical outcome following intrathecal injection of the podotrochlear (navicular) bursa for signs of foot pain in horses evaluated via magnetic resonance imaging (MRI) and evaluate efficacy of corticosteroids administered with or without hyaluronate. Methods: Retrospective case series. Methods: 23 horses. Methods: Data collected included signalment, history, intended use, duration and severity of lameness, results of diagnostic anesthesia, radiographic abnormalities, MRI abnormalities, and outcomes for return to use. Results: MRI was conducted on 23 horses with lameness localized ...
Characterization of the magic angle effect in the equine deep digital flexor tendon using a low-field magnetic resonance system. Three isolated equine limbs were imaged with a low-field magnetic resonance system with a vertical magnetic field. Each limb was scanned in multiple positions with mild variation of the angle between the magnetic field and the long axis of the limb. When the long axis of the limb was not perpendicular to the magnetic field, a linear hyperintense signal was present at the palmar aspect of one of the deep digital flexor tendon lobes, at the level of the navicular bone and collateral sesamoidean ligaments, in proton density and T1-weighted pulse sequences. With increased angulation of the limb, t...
Deep erosions of the palmar aspect of the navicular bone diagnosed by standing magnetic resonance imaging. Erosion of the palmar (flexor) aspect of the navicular bone is difficult to diagnose with conventional imaging techniques. Objective: To review the clinical, magnetic resonance (MR) and pathological features of deep erosions of the palmar aspect of the navicular bone. Methods: Cases of deep erosions of the palmar aspect of the navicular bone, diagnosed by standing low field MR imaging, were selected. Clinical details, results of diagnostic procedures, MR features and pathological findings were reviewed. Results: Deep erosions of the palmar aspect of the navicular bone were diagnosed in 16 matu...
Evaluation of clinical examination for differential diagnosis of lameness by navicular apparatus or heel pain in horses. To evaluation of clinical examination for differential diagnosis of navicular region pain from other forms of palmar heel pain in the forelimb in horses the present study was undertaken. Thirty four horses with lameness referable to the palmar aspect of the hoof based on their response to the palmar digital nerves analgesia were divided into 2 groups based on their response to both distal interphalangeal joint and navicular bursa analgesia. Horses that were profoundly improved by both analgesic blocks (distal interphalangeal joint and navicular bursa) were considered to have navicular region p...
Evaluation of the diffusion of corticosteroids between the distal interphalangeal joint and navicular bursa in horses. To determine whether clinically effective concentrations of methylprednisolone or triamcinolone can be achieved in the navicular bursa after injection of methylprednisolone acetate (MPA) or triamcinolone acetonide (TA) into the distal interphalangeal joint (DIPJ) and whether clinically effective concentrations of these drugs can be achieved in the DIPJ after injecting the navicular bursa with the same doses of MPA or TA. Methods: 32 healthy horses. Methods: Horses in groups 1 through 4 received 40 mg of MPA in the DIPJ, 10 mg of TA in the DIPJ, 40 mg of MPA in the navicular bursa, and 10 mg of...
Review of genetic aspects of radiological alterations in the navicular bone of the horse. Navicular disease or podotrochlosis has long been known to cause forelimb lameness in horses. It had been proposed that the development of podotrochlosis has similarities to the human osteoarthritis (OA) complex. Alterations of the navicular bone can be made visible early in life only on the basis of radiographs. Reports on the prevalences of navicular disease indicate that radiological alterations in the navicular bone are present in different warmblood populations at frequencies of between 14.9% and 87.6%. Genetic factors play an important role in the development of the radiological signs. E...
Effects of analgesia of the digital flexor tendon sheath on pain originating in the sole, distal interphalangeal joint or navicular bursa of horses. Specific analgesic techniques are required in diagnosis of lameness to isolate the exact origin of pain to the many structures of the foot that may be involved. Objective: To determine if analgesia of the digital flexor tendon sheath (DFTS) results in anaesthesia of other portions of the foot, such as the sole, distal interphalangeal joint (DIPJ), or navicular bursa (NB). Methods: Lameness caused by pain in the dorsal margin or heel region of the sole of the foot was induced in 18 horses by: using set-screws to create solar pressure (Trial 1: n = 5); or administering endotoxin intrasynovially ...
Evaluation of foot pain in the standing horse by magnetic resonance imaging. The records of 41 horses with previously undiagnosed foot pain that had been examined by standing magnetic resonance imaging were reviewed and follow-up information was obtained from their owners two years after the examination. A range of soft tissue and osseous abnormalities were identified, with multiple lesions frequently occurring. Deep digital flexor tendonitis was recorded in 12 of the horses, and distension of the distal interphalangeal joint was identified in 15, but it was not always associated with lameness; in contrast, distension of the navicular bursa was always associated with l...
Morphologic changes associated with functional adaptation of the navicular bone of horses. Failure of functional adaptation to protect the skeleton from damage is common and is often associated with targeted remodeling of bone microdamage. Horses provide a suitable model for studying loading-related skeletal disease because horses are physically active, their exercise is usually regulated, and adaptive failure of various skeletal sites is common. We performed a histologic study of the navicular bone of three groups of horses: (1) young racing Thoroughbreds (n = 10); (2) young unshod ponies (n = 10); and (3) older horses with navicular syndrome (n = 6). Navicular syndrome is a painfu...
Verification of scintigraphic imaging for injury diagnosis in 264 horses with foot pain. Nuclear scintigraphy is commonly used as a diagnostic aid for foot pain, but there is limited information about different patterns of radiopharmaceutical uptake (RU) and their correlation with the results of other imaging modalities. Objective: To describe patterns of RU in horses with foot pain. Methods: Scintigraphic images of the feet of 264 horses with front foot pain were analysed subjectively and using region of interest analysis. Magnetic resonance images of all feet were analysed prospectively; the navicular bones were reassessed retrospectively and assigned a grade. A Spearman rank co...
Magnetic resonance imaging evaluation of 264 horses with foot pain: the podotrochlear apparatus, deep digital flexor tendon and collateral ligaments of the distal interphalangeal joint. To improve understanding of the interrelationships between injuries of the podotrochlear apparatus and deep digital flexor tendon (DDFT). Objective: There is a difference in frequency of different types of lesions at different anatomical sites of the DDFT. Lesions of the collateral sesamoidean ligament (CSL), distal sesamoidean impar ligament (DSIL), distal interphalangeal (DIP) joint and navicular bursa are seen in association with lesions of the navicular bone. Methods: The magnetic resonance (MR) images of 264 horses with unilateral or bilateral foot pain were analysed and graded. Descripti...
Use of concurrent scintigraphic and magnetic resonance imaging evaluation to improve understanding of the pathogenesis of injury of the podotrochlear apparatus. Use of physiological methods of diagnostic imaging could provide insight into the pathogenesis of foot pain in live horses. Objective: To describe patterns and intensity of increased radiopharmaceutical uptake (IRU) in the navicular bone, and relate this to distribution and types of signal intensity change in the navicular bone and to the presence or absence of lesions of the related soft tissue structures detected using MRI. Methods: Scintigraphic and MR images of 264 horses with unilateral or bilateral foot pain were analysed and graded. A Spearman rank correlation was used to test for relat...
Genome-wide search for microsatellite markers associated with radiologic alterations in the navicular bone of Hanoverian warmblood horses. The aim of this study was to identify quantitative trait loci (QTLs) for pathologic changes in the navicular bone in Hanoverian warmblood horses. Seventeen paternal half-sib groups comprising 192 individuals were analyzed in a whole-genome scan. These families included 144 progeny and grandchildren, which were randomly chosen from the Hanoverian warmblood. Three different traits were considered: deformed canales sesamoidales and radiographic changes in the contour and in the structure of the navicular bone. The genome scan included in total 214 highly polymorphic microsatellite markers. The pu...
Endoscopic assessment and treatment of lesions of the deep digital flexor tendon in the navicular bursae of 20 lame horses. Clinical lesions of the deep digital flexor tendon and navicular bone are being reported with increasing frequency. However, the role of direct visualisation by navicular bursoscopy in the diagnosis and management of such injuries has not been explored. Objective: Navicular bursoscopy: 1) corroborates information obtained from other, noninvasive imaging modalities; 2) allows direct visualisation of lesions unidentified by other diagnostic modalities; 3) provides further information on morphology of lesions; and 4) permits minimally invasive surgical access to lesions. Methods: The case records...
MRI and CT diagnosis of acute desmopathy of the lateral collateral sesmoidean (navicular) ligament and long-term outcome in a horse. Clinical, magnetic resonance imaging (MRI) and computed tomography (CT) findings of acute desmopathy of the lateral collateral sesmoidean (navicular) ligament (CSL) in a 13-year-old Hanoverian mare are presented. On admission to the clinic the horse showed a grade 5/6 left front-limb lameness at the walk, pain on coffin joint manipulation, and coffin joint effusion. Despite a positive palmar digital nerve block, radiographs and ultrasonography did not indicate reasons for the severe clinical signs. However, MRI revealed damage to the CSL and bone marrow oedema of the navicular bone (NB), where...
Use of magnetic resonance imaging to diagnose distal sesamoid bone injury in a horse. A 5-year-old Appaloosa mare was examined for severe left forelimb lameness of 4 months' duration. Results: Lameness was evident at the walk and trot and was exacerbated when the horse circled to the left. Signs of pain were elicited in response to hoof testers placed over the frog of the left front hoof, and a palmar digital nerve block eliminated the lameness. Radiographs revealed no abnormalities, but magnetic resonance imaging (MRI) revealed increased bone density in the medullary cavity of the distal sesamoid (navicular) bone in the proton density and T2-weighted images and a defect in the...
Genetic analyses of the radiographic appearance of the distal sesamoid bones in Hanoverian Warmblood horses. To evaluate whether additive genetic correlations existed between certain aspects of the radiographic appearance of the distal sesamoid (navicular) bones (RNB) or between RNB and other types of radiographic changes in the limbs of Hanoverian Warmblood horses. Methods: 5,157 horses. Methods: Quasi-linear and binary traits were defined by the appearance of canales sesamoidales (CSs) and the structure and contour of the forelimb navicular bones (NBs). Prevalences of osseous fragments in the metacarphophalangeal and metatarsophalangeal (fetlock) and tarsocrural joints and deforming arthropathy in ...
Use of force plate analysis to assess the analgesic effects of etodolac in horses with navicular syndrome. To evaluate the musculoskeletal analgesic effect of etodolac administered PO every 12 or 24 hours in chronically lame horses by use of force plate analysis. Methods: 22 horses with navicular syndrome. Methods: Horses received etodolac (23 mg/kg, PO, q 12 h; n = 7), etodolac (23 mg/kg, PO, q 24 h; 8), or corn syrup (20 mL, PO, q 24 h; control treatment; 7) for 3 days. Combined forelimb peak vertical ground reaction force (PVF) was measured via force plate analysis before the first treatment (baseline) and at 6, 12, 24, and 36 hours after the last treatment. Differences in mean PVF (mPVF) betwee...
