Injury to the Suspensory Ligament

Injury to the Suspensory Ligament:
A Suspenseful Affair
Injury, Diagnosis, and Treatment
By Dr. Kara Spillman
Drawings by Dr. Kara Spillman
Your horse has become lame. You have the vet out and they have diagnosed a
“suspensory”. What does this mean, and what can be done about it?
The suspensory ligament refers to a structure located on the back of all four limbs that
functions to support the lower limb as part of the “stay apparatus”. Although it is mostly
comprised of collagen (ligamentous) tissue, it is interspersed with muscle fibers in the upper
portion, particularly in the hindlimb. This mixture of muscle and ligamentous tissue can be
especially tricky in ultrasounding the proximal suspensory area of the hindlimb.
The suspensory ligament is shorter in length in the forelimb than the hindlimb,
originating from the lower part of the back of the knee (carpus) and from the back of the
cannon (metacarpal) bone. In the hindlimb it originates from the back of the lower hock bones
and also the back of the upper part of the cannon bone, as shown in red in the above drawings.
The uppermost portion of the ligament is referred to as the “origin of the suspensory” and will
often cause lameness if injured. Generally the onset of lameness is gradual compared to other
injuries lower down on the ligament, but can become quite significant over time. Moving
further down the leg, the suspensory portion is referred to as the “body of the suspensory”,
and it is generally much less common to incur an injury within this area of the suspensory
compared to the origin or branches. About two thirds of the way down the cannon bone area,
the suspensory body splits into two branches that ultimately attach onto their respective
sesamoid bones at the fetlock. These branches can readily be seen in a normal horse’s limb.
Injury to the branches can be quite painful, particularly if the attachment to the sesamoid
bones is compromised. Generally radiographs are included in the work-up of a suspensory
branch lesion to rule out boney changes in the fetlock region.
A small extension of the suspensory can usually be seen externally on the horse crossing
obliquely over the lower leg bones to join an extensor tendon in the front (the extensor tendon
is shown in blue in the pictures). These extensions may become more apparent when they are
stressed from workload, poor conformation, or injury that has compromised the stay apparatus
of the limb. Generally injury to the extensor portions of the suspensory ligament do not cause
significant lameness and are less concerning than an injury to the body or branches of the
suspensory ligament.
The first step after assessing the gait of a horse during a lameness exam is palpation and
visual assessment of the structures of the leg. There may be heat, swelling, and pain noted that
may point to a particular area of the suspensory that seems to be affected. It is very important
to note that palpation of the suspensory ligament can be very subjective and diagnosis of a
suspensory lesion should almost always be verified with appropriate diagnostics, such as
regional nerve blocks and ultrasound examination.
Once a suspensory lesion has been identified, treatment is focused on decreasing
inflammation and promoting good fiber repair within the ligament. The majority of positive
effect on ligament and tendon healing is rest, anti-inflammatory medication, supportive
bandaging, and cold therapy. It is crucial to develop a proper rehabilitation program to bringing
the horse back into work slowly, with constant monitoring of the ligament via visual and tactile
aids. Repeated ultrasound examinations are strongly advised to make sure that any increase in
workload is not causing further damage to the ligament.
In addition to the good old-fashioned therapies, there are an increasing number of
modalities to support proper healing within the ligament structure. Ligaments and tendons are
generally fairly avascular, meaning that they do not have a good blood supply. Blood is
necessary for oxygenation and repair of tissues. Shockwave treatment can be used to promote
angiogenesis, the growth of blood vessels, to the area.
Another key aspect to recovery is the promotion of anti-inflammatory effects.
Modalities such as PRP, IRAP, and stem cell therapies have shown promise for treatment of
many injuries, including the suspensory apparatus. These modalities use the body’s own
cellular components to create an anti-inflammatory effect and promote proper healing and
fiber alignment. Fiber alignment is important because the closer the fibers align in their original
orientation and strength, the closer the ligament returns to its original function.
An up-and-coming modality that is making its way to the equine world is elastic taping.
This modality has become popular with human athletes and physicians worldwide, and was
seen being used extensively during the summer Olympic Games. Working with Dr. Beverly
Gordon and The Horse In Motion, Athletic Equine is now able to offer this supportive technique
with Equi-tape™, elastic tape designed specifically for horses. Below demonstrates a taping
performed by Dr. Gordon that supports an injured suspensory ligament.
Athletic Equine is proud to offer this non-invasive, drug-free technique in conjunction
with shockwave, PRP, IRAP, and in Florida locations, stem cell therapy (coming soon to Long
Island!) to help improve healing for an injured athlete. For more questions concerning the
suspensory ligament, injuries, and treatments, please contact Dr. Kara Spillman on her website, or call her at 561-316-8381.