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Ankle Sprain

The ankle is an extremely complex joint. Think of an ankle joint as being about the size of a walnut. It consists of three bones and a number of different ligaments that change and work in a wonderfully complex manner. Any small disruption of the normal function of the ankle joint, such as a sprain, results in a change of the fragile function of this joint.

As a surgeon, I've gained a deep respect for the complexity of joints, and particularly the ankle joint. The design and load capacity of this joint is incredible. And think of the longevity. There's really no man made machine that can compare to the uniqueness of the human ankle joint.

So let's take this special joint and twist it or turn it. And then, to add insult to injury, let's bear our full body weight on it during the injury. I think you can see how an ankle injury can quickly become trouble.

By far and away, the most common ankle sprain is the lateral ankle sprain (the outside of the ankle). At the lateral side of the ankle, the fibula, or smaller bone of the ankle, is attached to the talus (bone of the foot) by three small ligaments called the lateral collateral ligaments of the ankle. The anterior or front ligament is the one that is most often injured in ankle sprains. It's called the anterior talo-fibular ligament (ATF). It's a relatively small ligament that runs from the anterior aspect of the fibular forward to attach to the talus. The next most commonly injured ligament of the ankle is just behind the ATF and is called the calcaneal fibular ligament. It runs from the fibula to the heel bone (calcaneus). It's considered somewhat of a back-up ligament to the ATF in common lateral ankle sprains. And lastly there's the posterior talo-fibular ligament. It runs from the fibula back to the talus. It's hardly ever injured in a lateral ankle sprain.

There are specific contributing factor to ankle injuries. Many doctors look at them as an accident. I think you'll find that most podiatrists will look a little deeper into the reasons that a person would sprain an ankle. A lot has to do with the biomechanics of the foot. Let's take a closer look.

The first issue to consider is the center of gravity. Where does the center of gravity line up over the foot? Does a person have a tendency to roll to the outside of their shoe when the walk? Do they normally wear out shoes on the outside? If so, there's a strong likelihood that their body weight, or center of gravity, is not centered over their foot but more so over the outside of the foot. There's technical terms that are used to describe this combination of foot mechanics, such as forefoot valgus and rearfoot varus, but suffice it to say, these folks are predestined to sprain their ankles. (for more information on this topic see the biomechanics tab on this page)

When a person with these foot characteristics is put into a situation where they are prone to sprain the ankle, they will. Basketball is a great example. A player jumps up to grab a pass and leaves the ground. As he lands, he lands partially on the foot of another player. The normal ankle will be able to maintain it's integrity and not sprain, but the patient we've described with the bad ankle will be much more prone to an ankle injury in this sort of situation. Remember someone saying they had weak ankles? They really aren't weak, per say, they're just prone to sprains due to their center of gravity and biomechanical properties of the foot.

Ankle sprains are graded by doctors by the location of the injury and the degree of damage to the ligament. Typically we speak about a grade I, II or III ankle sprains. And usually they will affect the ATF ligament. These sprains hurt when they first happen and then calm down for an hour or so. As they start to swell they begin to hurt and become discolored, depending upon the extent of injury. In a grade I sprain, the swelling is typically localized to the site of the ATF ligament on the anterior ankle. The worse the sprain, the more diffuse the swelling and bruising.

Although the lateral ankle sprain is by far the most common, there are other sprains of the ankle that should be mentioned. The next most common sprain of the ankle is a sprain to a joint next to the ankle. The subtalar joint is the joint between the talus and the calcaneus (heel bone). It's the joint that controls the side to side motion of the ankle such as walking on uneven surfaces or on hillsides. For sake of conversation, most doctors will refer to the subtalar joint as part of the ankle. The subtalar joint is held together by the cervical ligament which is subject to sprain.

Treatment of ankle sprains

Let's assume we're treating a common lateral ankle sprain. Think about treatment in two phases. First is the management of the acute phase such as pain, swelling and the inability to walk. But the second phase may even be more important. The second phase is the prevention of recurrent sprains.

Phase I

In the first phase, think of the acronym RICE;

R- rest
I- ice
C- compression
E- elevation

Rest is imperative. Following a sprain, give the ankle several days before getting back to any activity. Bear weight to tolerance. Some weight bearing is good from the standpoint of breaking up scar tissue and gaining an early range of motion. Too much weight bearing leads to unnecessary swelling.

Another form of rest is casting. In severe sprains I'll have patients wear a removable walking cast. The cast limits motion and is removable for showers and at night.

Ice is a must to control swelling. Personally, I'm not a big fan of heat at any time during the healing of an ankle sprain. The more ice the better. Care should be taken not to injure the skin, particularly if a patient has a loss of sensation such as diabetic neuropathy.

Compression is also a must to control swelling. This can be accomplished with a lot of different aids such as ace wraps or ankle supports.

And finally, elevation. Elevation is one more method of controlling swelling. Patients with ankle sprains usually recognize the advantages of elevation even weeks after the injury.

Phase II

There's a lot that can be done to prevent a second or recurrent series of sprains. The choice of treatment really depends upon the patient and their activities. Issues such as work, athletic activities and social activities are all considerations.

Let's look at some examples. Let's say a patient is involved in a unidirectional sport such as running. An ankle brace would be cumbersome and probably detract from the enjoyment of a run. For this patient we would use a prescription arch support referred to as an orthotic. The orthotic would be modified to control the lateral rotation of the foot and help to center the body weight back over the foot. An orthotic would be a great tool for the chronic ankle sprainer who is a runner or for use in street shoes.

But what about bi-directional sports like racquetball or tennis? An ankle brace is indicated for these sports. The side to side forces are just too great to be controlled by an orthotic. There's all kinds of splints and braces on the market. I'm not a big fan of stirrup braces for chronic sprains. They are helpful in the acute phase of sprains to control edema, but they really aren't all that helpful in controlling the biomechanics that cause lateral ankle sprains. I'm a fan of lace up braces, particularly those that will lace into the shoe. Lace up braces actually make the brace and shoe work together.

Some forms of physical therapy are helpful. Most of the exercises to strengthen and reorient the ankle can be performed at home. Physical therapists will use proprioception exercises to re-educate the ligaments of the ankle. Proprioception is the sense of knowing where you are in space. The lateral collateral ligaments benefit from this re-education process. The concept is to try to make the ligaments more responsive to the next possible injury.

Proprioception exercises:
When able, stand in a doorway placing all your body weight on the injured ankle. Balance by holding on to the door. As you start to gain more balance, close your eyes. This isolates the ankle and forces it to be 're-educated'. You'll be amazed at what spending just five minutes a day can do for gaining more ankle stability over 10 days or so.

Some patients are prone to chronic sprains even after their first sprain. If a patient tends to have severe, recurrent sprains, surgical stabilization of the ankle is indicated. Ankle stabilization is a surgical procedure that involves repair of the lateral collateral ligaments. Occasionally, in severe cases, a tendon transfer may be indicated to assist in stabilizing the lateral ankle. These procedures can be quite extensive and all require prolonged periods of imobilization.

A new arthroscopic method of ankle stabilization is being developed. This technique is referred to as arthroscopic monopolar radiofrequency thermal stabilization. AMRTS employs a radiofrequency probe to shrink the lateral wall, or capsule, of the ankle joint. The lateral collateral ligaments are also treated with AMRTS. This technique is currently under investigation but holds promise as a minimally invasive alternative to traditional methods of correction.

Nomenclature:


Anterior talo-fibular ligament (ATF)- ligament that runs anteriorly and distally from the fibula to the talus on the lateral side of the ankle. This is the ligament that is injured in almost every lateral ankle sprain. It is the anterior most of the three lateral collateral ankle ligaments.

Calcaneal fibular ligament (CF)- ligament that runs from the fibula to the calcaneus. It is the central ligament of the three lateral collateral ligaments. The CF is injured in grade II and grade III sprains.

Posterior talo-fibular ligament (PTF) - ligament that runs posteriorly from the fibula to the talus on the lateral side of the ankle. The PTF makes up the most posterior or the three lateral collateral ligaments. The PTF is rarely injured in lateral collateral ankle sprains.

Anatomy:


The lateral aspect of the ankle is supported by three ligament referred to as the lateral collateral ligaments. These three ligaments, from anterior to posterior are the anterior talo-fibular ligament (ATF), the calcaneal fibular ligament (CF) and the posterior talo-fibular ligament (PTF).

The ATF ligament is most prone to be damaged with lateral ankle sprains. The ATF functions much like the reins of a horse during the most common of lateral ankle sprains, pulling and trying to prevent a sprain. The ligament ranges in size from 3-7mm. There is a small pocket on the inner surface of the fibula referred to as the anterior colliculus which acts as the origin of the ATF. The CF and PTF may be injured as the degree of ankle sprain becomes more severe.

The medial collateral ligament is called the Deltoid ligament. This broad band is actually the combination of several ligaments. The Deltoid is a very strong ligament and rarely ruptures. In cases of injuries to the medial ankle, the Deltoid typically will not tear, but instead will pull away a small portion of bone from the tibia. This type of fracture is called an avulsion fracture.

Other ligaments of the ankle are found in the anterior and posterior aspects of the joint between the two bones of the leg. The anterior inferior tibio-fibular ligament may be ruptured in severe sprains.

Biomechanics:


Some ankle sprains are caused by bad luck, but the majority of ankle sprains are due, in part, to the biomechanics of the foot. The foot acts as a stable platform for the leg and the rest of the body. When the center of gravity is displaced laterally, there is a much greater tendency to sprain.

What can displace the center of gravity? Podiatrists speak in a language called biomechanics. Essentially, biomechanics discusses the relationship of the bones of the forefoot to the rearfoot. In cases of ankle sprains, and particularly in cases of recurrent sprains, the biomechanical relationship seen in the foot is rearfoot varus and forefoot valgus.

Rearfoot varus refers to an inverted position of the heel upon heel strike. Rearfoot varus can be a fixed position (uncompensated), partially flexible (partially compensated) or flexible (fully compensated). An uncompensated rearfoot varus deformity is a significant contributing factor to acute and chronic ankle sprains.

Forefoot valgus is a term that refers to the position of the bones in the forefoot in relationship to the heel. Once again, the terms uncompensated, partially compensated and fully compensated are used to describe this bone position. Forefoot valgus is a position where the medial side of the forefoot is lower than the lateral side of the forefoot. During the midstance phase of gait, as the body passes over the foot, forefoot valgus rolls the foot to the lateral side, throwing the center of gravity to a position that invites an ankle sprain.

The picture at the right hand side of this page shows the relationship of severe forefoot valgus FF valgus RF varus.jpg (59997 bytes) and rearfoot varus. The position of the finger represents level ground. With each step, the foot has to roll to the outside to become level with the ground. Each time it does so, it throws the center of gravity out over the lateral aspect of the ankle making one much more prone to sprain.


The combination of forefoot valgus and rearfoot varus is a dead ringer for an ankle sprain. All it takes to happen is a little bit of imbalance such as stepping off a curb wrong or walking on the edge of a sidewalk. The ankle is bound to roll.

Symptoms:


Since the onset of an ankle sprain is acute, the reason for pain is quite obvious. There is significant pain with the injury followed by an hour of dull ache. An hour after the injury, the ankle has begun to swell and will increase in pain and stiffness.

The majority of pain with an ankle sprain, regardless of grade, is pain in the anterior lateral aspect of the ankle at the anterior talo-fibular ligament. Localized edema is common along with varying degrees of ecchymosis (bruising) as seen in this picture. Pain may persist for several weeks depending upon the degree of sprain.

The ability to bear weight varies in ankle injuries. Some sprains are tough to walk on and others aren't so bad. Inevitably they all take a matter of weeks to resolve. Typically, the worse the injury, the longer it'll take to get back to normal weight bearing and activities.

Differential Diagnosis:


A simple ankle sprain can represent a number of different injuries that will; become more clear as the acute nature of the injury begins to calm down a bit. It's not unusual to re-x-ray a patient 4-6 weeks after an injury to the ankle and find a fracture. What's important to recognize is the fact that we have an advantage over the ER doctor. What we're looking at isn't really the fracture, but more so where a fracture is healing. As bone heals it forms additional bone referred to as bone callus. Bone callus is very apparent on non-displaced fractures and can easily be seen 4-6 weeks after an injury. We'll pick up chips and flakes of bone, tendon injuries, avulsion fractures; just a whole bundle of unique injures found only around the ankle. The differential diagnosis for this condition should include;

Ankle fracture

Fracture of the 5th metatarsal base

Peroneal tendon rupture

Sheppard's fracture (posterior tubercle of the talus)

Sprain of the biforcate ligament or cervical ligament

References:


This article was written by Jeffrey A. Oster, DPM, C.Ped and last updated 3/24/05.

Additional references include;

Andrews, J.R., Previte, W.J., Carson, W.G., Arthroscopy of the Ankle: Technique and normal anatomy, Foot Ankle 6:29, 1985

Oloff, L.M., Bocko, A. P., Fanton, G. Arthroscopic Monopolar Radiofrequency Thermal Stabilization for Chronic Lateral Ankle Instability: A Preliminary Report on 10 Cases. J. Foot and Ankle Surg. 39:3 144-153 2000

Balduini, F.C., et al. Management and rehabilitation of ligamentous injuries to the ankle. Sports Med. 4:364, 1987

Mack, R.P. Ankle Injuries in athletics. Clin. Sports Med. 1:71, 1982

Lundeen, R.O., Hawkins, R.B. Arthroscopic lateral ankle stabilization. J. Am. Podiatr. Assoc. 75:372, 1985

Ray, R.G., Christensen, J.C., Gusman, D.N. Critical Evaluation of anterior drawer measurement methods in the ankle. Clin Orthop. 334:215-24, 1997

Peters, J.W., Trevino, S.G., Renstrom, P.A. Chronic lateral ankle instability. Foot Ankle 12:182-191, 1991

Johannsen, A. Radiologic diagnosis of lateral ligament lesion of the ankle. A comparison between talar tilt and anterior drawer sign. Acta Orthop. Scand 49:295-301, 1978

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Neoprene Ankle Support


Ankle Cryo/Cuff by AirCast®


AirHeel® By AirCast®


Biofreeze® - 4 oz.


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