Meddleton Equine Hospital

Hindlimb lameness in the horse can be a very frustrating experience. It can be difficult to pinpoint the exact anatomical location of the lameness because the joints of the rear leg of the horse move together in unison and are not easily isolated from one another. The hock, stifle, hip, and lower limb joints and associated tendons and ligaments are all structures that can contribute to a hindlimb lameness. One common cause of lameness in the rear leg is Proximal Suspensory Desmitis.

Proximal Suspensory Desmitis Defined

integral part of the support of the fetlock joint when the horse is bearing weight. When a ligament is inflamed or torn, the condition is known as a "desmitis". Therefore, a Proximal Suspensory Desmitis is an inflammation or disruption of the Suspensory Ligament.

Predisposing factors

• Most commonly seen affecting horses age 8-10 years of age.
• Commonly affects horses used for dressage, jumping, or eventing.
• Seen in horses with straight hocks or with upright conformation.

Diagnostics

• Lameness Examination:

  Hind limb lameness seen with this condition is usually characterized by a decrease in the arc of foot flight with a shortened stride length. Lameness is most obvious when the horse is ridden and usually exacerbated in 85% of the horses by flexion of the affected limb.

• Nerve Blocks

  Confirmation of the diagnosis is achieved by elimination of the lameness with local anesthesia (nerve block) of the deep branch of the lateral plantar nerve, the nerve that innervates the origin of the suspensory ligament.

• Imaging

  Ultrasound examination of the origin of the suspensory ligament typically reveals inflammation, fiber disruption, and enlargement (hypertrophy) of the proximal suspensory ligament.

  Radiographs of the origin of the suspensory ligament also support the diagnosis. Horses with proximal suspensory desmitis will exhibit sclerosis at the origin of the suspensory ligament and in severe cases can even have avulsion fractures which, if evident, will decrease the prognosis for recovery.

  MRI: With the introduction of MRI (Magnetic Resonance Imaging) to equine practice, it can be used as the gold standard for a conclusive diagnosis of proximal suspensory desmitis.

TREATMENT OPTIONS

• Extended stall rest for a period of 9-12 months has shown a success rate of approximately 15%, in a retrospective study of having these horses return to their intended use and remain sound for a 1 year period.
• Shockwave therapy can also be employed, and the success rate has been shown to be approximately 40% for return to athletic soundness.
• There is also a surgical treatment which was developed in the last few years in the United Kingdom which involves removal of a segment of the deep branch of the lateral plantar nerve.
• This author has performed over 50 of these procedures, and the success rate in his hands of return to athletic soundness is approximately 80%. This is supported by a retrospective study which looked at 271 horses where this procedure was performed; 214, or 79%, of these horses returned to athletic soundness. The post surgery rest period varies from 4-8 weeks depending on the severity of the desmitis.

This condition, which was once thought to be a career ending problem, can now be diagnosed easily and treated effectively. Diagnosis and treatment options are offered here at Meddleton Equine Hospital.

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