Degeneration and osteophyte formation in these structures are an additional indication of the excessive compressive force being transmitted through this structure, inhibiting remodeling and repair and leading to chronic degeneration. The soft tissue structures affected by navicular syndrome include the bursa, the DDFT and the various sesamoidean ligaments. ![]() Chronic degeneration and focal osteolysis give us an indication that the bone is unable to remodel or adapt to the forces being placed on it, possibly as a result of an increase in the force transmitted through this structure to such a degree that the bone is unable to effectively remodel. Lesions commonly seen in the navicular bone include degeneration, sclerosis and bone loss. These adaptations make the navicular apparatus adept at withstanding compressive force. The tendon attaches into a depression on P3, creating an additional ridge of bone or fulcrum around which the tendon turns before insertion.The presence of the digital cushion allows minimal changes in pressure within the navicular apparatus during movement, and effectively monitors the loading of this area through pain and pressure sensors.The DDFT transitions from dense connective tissue to fibrocartilage and then to bone as it flares to insert on P3.The presence of a navicular bursa between the bone and the DDFT minimises friction on the fibrocartilage.The presence of fibrocartilage on the palmar surface of the navicular bone where the DDFT crosses over it increases its ability to withstand compression and shear forces.The DDFT (deep digital flexor tendon) contacts and runs over the navicular bone before inserting on P3, allowing the angle of attachment to remain constant throughout various movements of the hoof, as well as creating a longer lever arm and giving the DDFT a mechanical advantage. ![]() The navicular complex is a great example of the above description of an enthesis organ, with some additional adaptations that make it phenomenal at transmitting mechanical force: A functional enthesis refers to the addition of a pivot point before the insertion of the tendon, creating a pulley system that allows the optimisation of force transfer, and a reduction of the force at the insertion point of the tendon. For this reason, equine navicular syndrome has been considered progressive and incurable.īy adjusting our approach to one where we aim to restore function to the entire navicular complex, and to restore and correct posture and biomechanics, we may have an improved prognosis.Īn enthesis refers to the site of attachment of a tendon to a bone that allows the transmission of force through different tissues. Horses will often become unresponsive to treatments over time, with the lameness recurring and worsening. Traditionally, we have treated navicular syndrome in a variety of ways, focusing on the alleviation of local symptoms through pharmacological interventions, corrective farriery and occasionally even surgery. The often bilateral forelimb lameness will usually be more severe in one limb than the other. Navicular disease or syndrome is commonly associated with chronic progressive lameness, caudal heel pain and degeneration of the navicular bone and the surrounding structures. If you have been faced with the frustration of assisting in the rehabilitation of navicular syndrome, and have met with chronic recurrent lameness in response, read on! The entire body impacts on this region, and a broader, more comprehensive approach may be warranted. However, taking a broader viewpoint and considering the origin of the mechanical load causing dysfunction in this region will allow us to identify the best approach to changing the prognosis of this disease in the long run. An improved understanding of navicular syndrome has highlighted the involvement of multiple anatomical structures, forcing us to look a little more closely at this anatomical region and its role in the movement of the entire horse.Ĭonsidering the equine navicular as an enthesis organ with multiple anatomical structures playing a role in it’s function, helps us to understand more deeply why and how the lesions are occurring that we commonly see. ![]() Equine Navicular Syndrome is known by many different names, but no matter what we have called it in the past, the prognosis has remained poor.
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