Equine Podotrochlear Apparatus - Histologic Characterization





Background: The navicular syndrome may be associated with alterations in other podotrochlear apparatus components, such as the deep digital flexor tendon, collareral sesamoid and distal sesamoid ligaments, podotrochlear bursa and distal sesamoid bone. However, the clinical significance and nature of these changes are not well understood, many of descriptive reports about distal sesamoid bone lesions are rarely accompanied by a complete and comprehensive comparison with animals of the control group. The aim of this study was to described histologically findings of the podrotrochlear apparatus components, allowing the understanding of the inserts and their microscopic appearance, thus providing the future recognize of their alterations.

Materials, Methods & Results: Fourteen samples of the podotrochlear apparatus were taken out of 44 equine thoracic limbs specimens, separated at the radiocarpal joint of Crioulo and Thoroughbred horses, with an average age of 6.0-year-old, coming from a private clinic in southern Brazil. The thoracic limbs specimens were refrigerated at 4ºC at the clinic and then they were sent to the University Federal of Santa Maria (UFSM). Once at the University laboratory, the specimens were dissected to isolate the podotrochlear apparatus from each one.  Subsequently, transversal and longitudinal samples from the distal sesamoid bone, deep digital flexor tendo,             distal sesamoid ligament, colateral sesamoid ligament, were collected and podotrochlear            bursa which were processed at the Veterinary Pathology Laboratory of the UFSM and University Federal of Santa Catarina (UFSC). The tissues samples were fixed in a 10% formaldehyde solution for 14 days and routinely processed for histology. The samples were sectioned at 3 µm and stained using the hematoxylin-eosin (H-E) routine method. The bone samples, after fixation, underwent a decalcified process in a formic acid-sodium citrate aqueous solution and routinely processed for histopathology. Histologic tendons evaluation showed that it is arranged in honeycombs fascicles in a transverse section observation. The tendinous fibers have a more compact and aligned collagen fibers arrangement due to the dense connective tissue. The synovial membrane of the podotrochlear bursa is composed of a cubic pseudo conjunctival epithelium arranged with a layer of synoviocytes forming villi towards the lumen. This characterization is very similar to that of the synovial joint membrane. The collateral sesamoid ligament fibers are not perfectly aligned, occurring at their confluence in some areas accompanied by the dissection of adipose tissue. The distal sesamoide ligament fibers, composed by of loose connective tissue associated with synoviocytes and vascular stroma. The articular surface of the distal sesamoid bone is arranged in 3 layers of chondrocytes embedded in a hyaline matrix. There was a clear differentiation between the subchondral bone area and the fibrocartilage tissue in the palmar aspect of the distal sesamoid bone.

Discussion: The morphophysiological characterization of the podotrochlear structures inside the hoof capsule it is important for the future recognition of abnormalities and the possible hypothesis that originates the podotrochlear syndrome. These changes have great clinical relevance and very often associated of distal limb lameness in horses. The normal macroscopic, ultrasonographic and radiographic images along with the histomorphometric study of the podotrochlear structures have contributed for the morphophysiological comprehension and consequently future interpretation of the podotrochlear structures diseases.

Keywords: podotrochlear apparatus, distal sesamoide bone, deep digital flexor tendon, navicular syndrome, histological findings.


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Barone R. 1989. Articulations metacarpo-phalangienne. In: Anatomie Comparée des Mammifères Domestiques - Tome 2: Arthrologie et Myologie. Paris: Vigot, pp.187-204.

Bowker R.M., Atkinson P.J., Atkinson T.S. & Haut R.C. 2001. Effect of contact stress in bones of the distal interphalangeal joint on microscopic changes in articular cartilage and ligaments. American Journal of Veterinary Research. 62: 414-424.

Blunden A., Dyson S., Murray R. & Schramme M. 2006. Histopathology in horses with chronic palmar foot pain and age-matched controls. Part 1: Navicular bone and related structures. Equine Veterinary Journal. 38: 15-22.

Blunden A., Murray R. & Dyson S. 2009. Lesions of the deep digital flexor tendon in the digit: a correlative MRI and post-mortem study in control and lame horses. Equine Veterinary Journal. 41: 25-33.

Busoni V., Snaps F., Trenteseaux J. & Dondelinger R.F. 2004. Magnetic resonance imaging of the palmar aspect of the equine podotrochlear apparatus: normal appearance. Veterinary Radiology & Ultrasound. 45(3): 198-204.

Dyson S., Murray R., Blunden T. & Schramme M. 2006. Current thoughts on the pathogenesis of navicular disease. Equine Veterinary Education. 18: 45-56.

Dyson S. & Murray R. 2007. 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. Equine Veterinary Journal. 39(4): 340-343.

De Zani D., Polidori C., Di Giancamillo M. & Zani D.D. 2016. Correlation of radiographic measurements of structures of the equine foot with lesions detected on magnetic resonance imaging. Equine Veterinary Journal. 48: 165-171.

De Bastiani G., De La Corte F.D., Kommers G.D., Brass K.E., Pereira R., Cantarelli C. & Silva M.T. 2017. Aspectos ultrassonográficos, anatômicos e histológicos normais da articulação metacarpofalangeana equina. Pesquisa Veterinária Brasileira. 37(10):1165-1171.

De Bastiani G., De La Corte F.D., Brass K.E., Cantarelli C., Dau S., Kommers G.D., Silva M.T. & Silva A.M. 2018. Histochemistry of equine damage tendons, ligaments and articular cartilage. Acta Scientiae Veterinariae. 46: 1612. 8p.

Holowinski M.E., Solano M., Maranda L. & Garcia Lopez J.M. 2012. Magnetic resonance imaging of navicular bursa adhesions. Veterinary Radiology & Ultrasound. 53(5): 566-572.

Jacquet S. & Denoix J. 2012. Ultrasonographic examination of the distal podotrochlear apparatus of the horse: A trans cuneal approach. Equine Veterinary Education. 24: 90-96.

Kristoffersen M. & Thoefner M.B. 2003. Ultrasonography of the navicular region in horses. Equine Veterinary Education. 15: 150-157.

Murray R., Blunden T., Schramme M. & Dyson S. 2006. How does magnetic resonance imaging represent histological findings in the equine digit? Veterinary Radiology & Ultrasound. 47: 17-31.

Maher M.C., Werpy N.M., Goodrich L.R. & McIlwraith C.W. 2011. Positive contrast magnetic resonance bursography for assessment of the navicular bursa and surrounding soft tissues. Veterinary Radiology & Ultrasound. 52: 385-393.

MacDonald J.L., Richter R.A. & Wimer C.L. 2018. Ultrasonographic variations are present in the distal sesamoidean impar ligament f clinically sound horses. Veterinary Radiology & Ultrasound. 59: 607-612.

Marsh C. 2016. MRI in the diagnosis of foot lameness and therapeutic approaches following an accurate MRI diagnosis. In: Proceedings of the 62nd Annual Convention of the American Association of Equine Practitioners - AAEP (Orlando, USA). pp.138-148.

Pool R.R., Meagher D.M. & Stover S.M. 1989. Pathophysiology of Navicular Syndrome. Veterinary Clinics of North America: Equine Practice. 5(1): 109-129.

Rijkenhuizen A.B.M., NBmeth F., Dik K.J. & Goedegebuure S.A. 1989. The arterial supply of the navicular bone in adult horses with navicular disease. Equine Veterinary Journal. 21: 418-424.

Sherlock C., Mair T. & Blunden T. 2008. Deep erosions of the palmar aspect of the navicular bone diagnosed by standing magnetic resonance imaging. Equine Veterinary Journal. 40: 684-692.

Waguespack R. & Hanson R. 2010. Navicular syndrome in equine patients: anatomy, causes, and diagnosis. Compendium: Continuing Education for Veterinarians. 32(12): E7. pp.1-14.

Wright I.M., Kidd L. & Thorp B.H. 1998. Gross, histological, and histomorphometric features of the navicular bone and related structures in the horse. Equine Veterinary Journal. 30: 220-234.

Van Wulfen K.K. & Bowker R.M. 2002. Microanatomic characteristics of the insertion of the distal sesamoidean impar ligament and deep digital flexor tendon on the distal phalanx in healthy feet obtained from horses. American Journal of Veterinary Research. 63: 215-221.



How to Cite

De Bastiani, G., De La Côrte, F. D., Ramos, A. T., Jacobsen, T. K., Kommers, G. D., & Martinez-Pereira, M. A. (2022). Equine Podotrochlear Apparatus - Histologic Characterization. Acta Scientiae Veterinariae, 50. https://doi.org/10.22456/1679-9216.119100




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