Ankle Ligament Tear – Ankle Instability

1anklesprainThe ankle and the foot are held together by both ligaments and tendons. The ligaments on both sides of the ankle are tightly attached to the bones. On the outside (lateral) aspect of the ankle there are 3 major ligaments. On the inside (medial) aspect of the ankle there are a complex network of several ligaments, much stronger than the lateral ligaments. They help to restrict the motion of the ankle joint. The tendons that cross the joint are attached to the muscles in the leg and into the bones of the foot. When the muscle contracts it moves the tendon that then moves the foot at the ankle joint. The ankle joint moves primarily in one direction or plane; upwards (dorsiflexion) and downwards (plantarflexion). The normal joint does not move front to back nor does it tilt on either side. When there is an injury to the ligaments they can be stretched out or torn, leading to a sprain of the ligament, weakening them. In some cases, when the rotational forces are strong enough, the ankle fractures as well. There can also be damage done to the cartilage of the ankle joint leading to a defect of the cartilage (osteochondral defect) and ankle arthritis. The tendons that cross the ankle can be injured as well, leading to a tendonitis or tendon tears. In cases that are left untreated, or in cases after many sprains in a short period of time, there will weakening of the ligaments leading to instability of the ankle. This is called lateral ankle instability. This can lead to chronic pain and loss of function, which usually will need surgical correction.

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Picture showing all three lateral ankle ligaments torn.

Causes:

Sprains are caused by an injury to the ankle from normal walking events to sports injuries, to falls from a height. Most sprains are of the inversion type. When a patient “twists” the ankle this usually occurs with the bottom of the foot turning towards the other foot, leading the outside of the foot and ankle to roll to the ground. In some cases the foot can roll the other direction as well. During the roll there is a rotation of the foot as well. These excessive motions will pull on the ligaments with great force. Although the ligaments are strong, these forces are strong enough to do damage to the ligaments. The ligaments will either stretch out, partially tear, tear completely in the middle of the ligament, pull off its bone attachment from the ankle bone or the leg bone, or pull off a piece of bone as it tears. Depending of the severity of the injury and the rotation of the foot during the injury, 1 or 2 or all 3 of the ligaments can be injured. If the there are several sprains over a short period of time, this can lead to a weakening or laxity to the ligaments leaving an unstable ankle.

Symptoms:

Most patients can recall a specific injury that occurred that caused the sprain. There will be a large amount of swelling and pain on the outside of the ankle and foot. Some patients will not be able to place the foot on the ground without a great deal of pain. Bruising and discoloration of the area will then ensue. Pain is located over the bone on the outside of the ankle, over the ligaments and the tendons all on the lateral aspect of the ankle. There can be a feeling of imbalance as well. Patients will then have a feeling of caution and will describe an “unstable” ankle, as if they could roll the ankle at any time. This can also lead to chronic pain within the ankle. Some patients describe a feeling of the ankle locking or clicking when it is moved.

Diagnosis:

Clinical evaluation of the ankle is performed at the initial visit. The stability of the ankle is evaluated. The amount of abnormal rotation of the joint is determined by manipulating the ankle in certain directions. This will help to identify which of the ligaments are injured and to what extent they are injured. Muscle testing is also performed to identify tendon weakness or injury. X-rays will be taken in the office to determine if there are any fractures or bone chips from the ligament tear. In some cases, usually chronic cases, special stress x-rays will be taken to determine the amount of dislocation the ankle can undergo. The more the ankle dislocates under stress, the more damage there is to the specific ligament tested. In some cases, there will be the need for an MRI to get an image of the ligaments, tendons, and the cartilage of the joint to examine the extent of the injury.

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X-ray showing instability of the ankle with the ankle coming out of the joint laterally. X-ray showing instability of the ankle with the ankle coming out of the joint anterior.

Treatment:

In situations with a fresh injury (within the first few days and weeks) the ankle needs to be rested. Ice therapy will decrease the swelling. Anti-inflammatory medications will decrease the swelling and pain and increase the healing. Depending on the extent of the injury and the damage the foot and ankle may need to be immobilized in a boot with or without the use of crutches. If there is minimal damage, a simple lace up ankle brace will be used with weight-bearing. In moderate to severe cases, a removable boot will be used to lock down the ankle and foot. In cases with a fracture, a cast will most likely be used to immobilize the ankle and foot. Physical therapy is an essential part of the treatment protocol for ankle sprains. In all cases of sprains at some point in the treatment the patient will be sent to physical therapy. As the treatment progresses, the patient will be transferred to less and less immobility. Ankle sprains do not heal quickly. They can take several months to allow the patient to feel confident in the strength of the ankle. When patients begin activity too soon, this can lead to more sprains while the old sprain had not fully healed. This will lead to chronic ankle instability that often needs to be corrected surgically.

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Figure 8 strapping technique with ankle brace. Typical lateral stabilization ankle brace.

The type of surgical correction depends on the severity of the injury to the ligaments. In some cases the stretched out ligaments can be “tightened” through arthroscopy. Small incisions at the front of the ankle allow for the introduction of a camera and a special instrument that will “shrink” the ligaments, tightening them. In most cases the ankle joint will need to be opened over the area of the ligaments in order to visualize the ligaments themselves. The ligaments can then be repaired by placing them back onto the bone in their anatomic position. In some cases a small metal anchor will be used to anchor the ligaments into the bone. This repair will tighten and strengthen the ligaments again. In some cases when the ligaments are too weakened or destroyed to repair, cadaver tendon is used to create new ankle ligaments. This tendon is routed through the bones of the ankle to reinforce the ankle.

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Incision site for a lateral ligament repair. Picture showing one of the lateral ligaments identified by the forceps.
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Picture showing suture through the ligaments in order to repair and tighten them.
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Picture showing preparation of the cadaver tendon that will be used to reconstruct the ligaments.
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Picture showing introduction of graft into the ankle bone (talus). Picture showing introduction of graft into the ankle bone (talus).
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Picture showing routing of the graft through the leg bone (fibula). Picture showing final anchoring of the graft into the heel bone (calcaneus).

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