Ligaments are soft tissue structures that connect bone to bone in the skeleton. Injury of these supporting structures is a common cause of lameness in the horse. The severity of lameness and prognosis varies greatly according to the location and degree of ligament injury. Ligaments generally take a long time to heal and gradual return to exercise plays an essential part in the management of these injuries.
Ligaments are elastic soft tissue structures which connect the ends of bones at joints. Their role is to maintain bones in alignment and provide support to the joint. They are usually located on either side of the joint (termed collateral positioning). Some joints simply have one ligament on either side and others have multiple ligaments in a more complex arrangement, such as those found in the stifle.
Ligamentous injury can occur in a number of ways. Direct trauma, e.g. a skin laceration, or abnormal or excessive forces placed on a joint, e.g. turning at speed, are common causes of such injuries. According to the severity of injury lameness can vary from mild to very severe. In cases of complete rupture there may be gross instability of the joint such that it may appear to be sub-luxated (dislocated), and the horse will show marked lameness. As with any soft tissue injury heat, pain and swelling are common presentations.
Common ligament injuries in the horse include the following:
- Collateral ligaments of the coffin/fetlock and hock joints.
- Palmar annular ligament of the fetlock.
- Accessory (check) ligament of the deep digital flexor tendon in the lower limb.
- Meniscal and cruciate ligaments of the stifle.
In cases of severe ligament injury the presence of heat, pain and swelling may enable your vet to identify the source of the problem and ultrasound examination can be used to confirm the diagnosis. In other, more subtle cases a full lameness investigation will be necessary. Your vet will begin with diagnostic anaesthesia (nerve blocking), followed by radiography and/or ultrasonography. Magnetic resonance imaging can frequently be a useful diagnostic tool in the identification and evaluation of ligament injuries in the lower limb.
As with all soft tissue injuries first aid should be implemented to reduce inflammation and associated pain. Your vet may recommend non-steroidal anti-inflammatory drugs such as bute (phenylbutazone) in the acute phase post injury. Rest, ice and supportive bandaging can be helpful in reducing inflammation – remember never to put ice directly onto a horses skin as this can cause skin burns. In severe cases, surgical arthrodesis (surgical fusion) of a joint may be necessary and/or cast application of the limb to enforce immobilisation of the affected area.
Your vet will be able to suggest a suitable period of box rest and gradual return to work depending on the severity of the injury. Repeat ultrasonographic examination may be used to monitor healing and it enables suitable adjustments in the proposed exercise regime to be made.
This depends completely on the degree of ligament damage and the location of injury. In cases of ligament rupture and joint instability the prognosis is extremely guarded for return to athleticism. Osteoarthritis of the affected joint is a possible sequelae due to abnormal forces of weightbearing on the joint in the absence of the previously normal supportive ligamentous structures. Generally, with any ligament injury the healing process is prolonged and gradual return to work is essential in regaining strength of the damaged ligament(s).