Role: suspensory ligaments
Our equine anatomy series takes a closer look at these tough, fibrous structures, which play a vital
supporting role in the mechanics of the limbs. explains
BOTH front and hind limbs have a suspensory ligament, which runs down the back of the leg parallel to the cannon bone (see diagram). In the forelimb, the top of the ligament is attached to the back of the cannon bone, just below the knee, with a small accessory branch attaching to the back of the lower bones of the knee. In the hindlimb, the ligament starts at the back of the hock, with one part attaching to the back of the fourth tarsal bone (within the hock joint) and a second, larger part attaching to the back of the cannon bone below the hock.
From the mid-cannon region, the ligament splits into two branches, which continue down to the level of the fetlock joint where they attach to the proximal sesamoid bones.
The suspensory ligament acts to support the fetlock when the limb is loaded. Considerable strain is placed upon it as the fetlock is extended (drops), particularly when the hock is flexed (or the knee is extended) at the same time. It is not surprising that horses with injury to the hind suspensory ligament can also have associated hock pain.
Made up of strong ligament/ tendon tissue, surrounding a mixture of muscle and fat, the ligament is packed with tiny nerves and blood vessels. A sudden-onset single injury — or, more frequently, repetitive overload — can result in tearing of ligament fibres or disruption of the muscle, fat, nerve or vascular tissue.
Suspensory desmitis (inflammation and damage to the ligament) or suspensory desmopathy (a more degenerative type of damage) can occur at all levels of the ligament, or in the cannon bone or proximal sesamoid bones in the attachment areas.
Damage at the bone/ligament interface sometimes results in a bone reaction or attempted repair, where the ligament pulls repeatedly on its bony attachment, or in an “avulsion fracture” where a small piece of bone may be pulled off at the ligament attachment.
The origin (top) of the suspensory ligament is prone to injury, known as “proximal suspensory desmitis”, often as a result of repetitive Origin of the suspensory ligament on the back of the cannon bone and the bones of the knee (with attachments to the splint bones) Body of the suspensory ligament Branches of the suspensory ligament Proximal sesamoid bones overloading. Dressage horses are particularly at risk from damage to the hindlimb origin. In a survey of affiliated dressage horses, 25% had experienced pain associated with the hock or suspensory ligament.
Damage to the body of the ligament usually occurs as an extension of injury from its origin or branches. A single branch can