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December 30, 2011

Collateral Damage

Rounding Up the Usual Suspects: Ankle Sprains

by Corey Dawkins and Ben Lindbergh

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The ankle is among the most commonly injured body part across all sports. Thousands of people sprain their ankles every day during relatively routine activities. In baseball, ankle sprains don’t usually end up requiring an extended stay on the disabled list, but when they do, they’re gruesome to watch. In 2011 alone, severe ankle injuries took out Stephen Drew and Buster Posey, but they don’t have to be that severe in order to affect performance. Velocity and control can be affected in pitchers, while bat speed and control can be affected in hitters. With that in mind, let’s examine the different types of ankle sprains.

Anatomy
What we consider the ankle joint is actually two different joints called the subtalar joint and the talocrural joint, which are composed of the tibia, fibula, talus, and calcaneus. For our purposes, the subtalar joint is the interaction between the talus and the calcaneus, while the talocrural joint is made up of the tibia, fibula, and talus. Together, these three bones of the talocrural joint are also called the mortise. The talocrural joint allows dorsiflexion and plantarflexion, while the subtalar joint allows for inversion, eversion, pronation, and supination.

Source 1 Concordortho Source 2: ActiveMotionPhysiotherapy

The fibula, which serves as the origin of several muscles acting on the ankle and foot, plays a vital role in the ankle’s stability. While the fibula is weight-bearing, it’s potentially more important for the stability of the ankle that the fibula moves inferiorly toward the ground and deepens the mortise about two millimeters, further increasing the bony stability of the talocrural joint.

Many different ligaments throughout the ankle can suffer injuries, i.e. sprains. These include the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), posterior talofibular ligament (PTFL), anterior-inferior tibiofibular ligament (AITFL), interosseous ligament, posterior-inferior fibular ligament (PITFL), inferior transverse ligament, and deltoid ligament. We could spend about four to five paragraphs describing the origins and insertion points of each of these ligaments, but it’s much easier to show a picture.

Source: Orthopedics.ygoy.com Source: Gray’s Anatomy

The ligaments play multiple roles. The main functions of the ATFL are anterior subluxation and medial shifting of the talus. It also resists posterior displacement and lateral rotation of the tibia and fibula while in plantar flexion. As if it didn’t have enough on its plate already, it also helps prevent lateral talar tilt. Ultimately, the strain on the ATFL progresses as it moves further into plantar flexion.

The PTFL is the strongest of the outside (lateral) ligaments and prevents rotation and posterior subluxation of the talus. It resists excessive external rotation of the talus of the foot but plays only a bit part in ankle stability when all the ligaments are intact. The PTFL is generally only ruptured in the most severe of ankle sprains.

When someone is standing, the CFL is normally relaxed. That doesn’t mean it’s not important, though. Its primary role is to limit inversion and subsequent talar tilt within the mortise. Unlike the ATFL, which is stressed most in inversion and plantarflexion, the CFL is most strained with dorsiflexion and inversion. It is commonly injured in conjunction with the ATFL.

The broad, fan-shaped deltoid ligament is on the inside aspect of the ankle. Like many larger and important ligaments, it is made up of multiple components. The superficial deltoid layer crosses both the subtalar and the talocrural joints and resists eversion of the hindfoot, while the deep deltoid ligament layer crosses only the subtalar joint and prevents external rotation and lateral displacement of the talus. The deep deltoid layer also essentially extends the function of the medial malleolus.

The ligaments of the syndesmosis are the AITFL, interosseous ligament, PITFL, and inferior transverse ligament, and in combination, they work to keep the fibula stable above all else. When weight transfers onto the leg, the natural inclinations of the tibia and fibula are to try to separate. These ligaments must be strong in order to eliminate that tendency. Without these ligaments working properly, performance at a high level is essentially impossible.

Injury
Almost everyone has experienced it at some point: the foot twists inward, commonly while having a component of plantarflexion, and next thing you know, you’re limping and there’s a softball-shaped lump growing on the side of your ankle. Sometimes all it takes is a little uneven ground. Many have thought that ligaments only stretch with mild ligament injuries, but there is always some degree of tearing. It’s just a question of what percentage.

The ATFL is the ligament injured most often, in large part because it is the weakest of the lateral ankle ligaments. In its defense, the ankle is more prone to injury in plantarflexion when there is less bony support. The CFL is often injured along with the ATFL, but the PTFL is rarely injured.

Because of the function of the deltoid ligament, especially the deep deltoid layer, severe injuries to the ligament often result in fractures of the lower leg and ankle. To see this occur, all we have to do is watch Buster Posey’s injury (scroll to around 2:40 for the best view).

Syndesmotic sprains are what most call the “high ankle” sprains. They are not as common as the lateral ankle sprains and make up about 10 percent of all ankle sprains. Posey disrupted these ligaments as well, not to mention the fibular fracture. Syndesmotic injuries take longer to heal because of the unique anatomy and functions of the ligaments. While many improve within six to eight weeks, a large percentage are still symptomatic up to six months later.

Source: NIH.gov

Isolated injuries to the syndesmotic ligaments can happen but are rare. Cadaver studies have shown that isolated cutting of the AITFL changed the overall stability of the mortise only slightly. External rotation of the ankle significantly increases when the AITFL is disrupted in combination with disruption of the anterior portion of the deltoid ligament or the PTFL. Forced excessive external rotation with dorsiflexion is the primary source of an injury to the syndesmosis, but almost any motion of the ankle can cause a syndesmotic injury if the force is extreme.

Non-Operative Treatment
Most ankle sprains do not require surgery. In fact, in many cases, the player is back to normal within three weeks, and almost all lateral ankle sprains heal within six weeks. Depending on the severity of the injury, crutches may or may not be used initially. A walking boot is used to take pressure off the area, which allows the body to lay down the framework for healing uninterrupted. Physical therapy is a mainstay in a course of treatment focused on limiting pain, decreasing swelling, restoring normal motion, improving strength, and eventually returning the athlete to baseball activities.

Syndesmotic injuries generally take longer to heal than simple lateral ankle sprains—sometimes up to twice as long. Weight bearing has to be limited until the athlete is pain-free; otherwise, healing is delayed even further. Syndesmotic injuries can often take months, rather than weeks, to heal because of the amount of external ankle rotation associated with playing baseball. Throwing, hitting, and running all involve some degree of external rotation.

Surgical Treatment
Generally surgeries on the ankle ligaments fall into one of two categories: lateral instability or syndesmotic injury. Surgery for ankle instability resulting from lateral ligament insufficiency can be corrected by either the Brostrom procedure or the Chrisman-Snook procedure. The indications for these surgeries are the clinical presentation and overall function of the ankle, although a tibiotalar tilt angle above 20 degrees is often considered in the overall picture as well.

Source: FootandAnkleInstitute.com (now offline)—Tibiotalar joint angle indicating instability

There are many different variations of both the Brostrom and Chrisman-Snook techniques, depending on the surgeon’s preference and the age of the patient. In the Brostrom procedure, an incision is made over the area with caution to avoid the peroneal tendons, sural nerve, and branches of the superficial peroneal nerve. The ankle is then placed into a dorsiflexed and inverted position to assess the functional integrity of the lateral ligaments. Stitches are then placed through the ATFL and CFL before passing through drill holes in the distal fibula and being tied. In one variation, the edge of the extensor retinaculum is used to reinforce the repair and limit inversion.

Source: Orthosportssg.com—Brostrom Procedure

In the Chrisman-Snook procedure, a portion of the peroneus brevis tendon is used to stabilize the lateral ankle. A tunnel is drilled through the distal fibula so that the harvested tendon can be passed through. This repair is not as anatomic as the Brostrom and therefore not used as often. If you’re wondering what the procedure looks like, you know what they say: a picture is worth a thousand words.

Source: Radiographics.rsna.org—Chrisman-Snook Procedure

A greater percentage of syndesmosis injuries require surgery than the typical lateral ankle sprain, in part because of concurrent injuries, such as fractures to the fibula or medial malleolus. If there are associated fractures of the medial or lateral malleoli, tibia or fibula shaft, those injuries need to be corrected before addressing the syndesmosis, in order to ensure a proper reduction. One or two screws are placed in the fibula and tibia to keep them in close approximation to one another and allow the ligament to heal. Even though it may seem extremely simple, there is some technique to it.

Source: Shortreports.rsmjournals.com—Two syndesmotic screws

The fibula is situated somewhat posteriorly to the tibia, meaning this isn’t as simple as drilling a hole in the wall to hang a heavy picture. When the drill holes and screws are placed, the surgeon must angle them from the posterolateral to anteromedial direction, or else the screws can kick out the back end of the tibia. The screw should not be over-tightened, because it could limit dorsiflexion in the future. The screw is generally removed between three and four months after the operation, unless a bio-absorbable screw is used. Usually, full weight bearing is not allowed until after the screw is removed, for fear of the screw breaking.

Return to Play
In non-surgical cases, the player can return to play once he has full motion and full strength and has passed a battery of functional tests. This almost always occurs within four weeks, even in cases of severe sprains of the ATFL or CFL. If the syndesmosis is involved, the time required to return to the field is typically bumped up to anywhere from four to eight weeks.

In surgical cases, each surgeon has his or her own protocol that lays out the plan from the day of surgery onward. With Brostrom or Chrisman-Snook repairs, full baseball activities are often not introduced until approximately the four-to-six-month mark, although again, each surgeon is different. A return to play after syndesmotic screw fixation is, as you can imagine, delayed. Once the screw is removed at the three-to-four-month mark, new bone needs to form in the tunnel, or else there is a much higher risk of complications, such as fractures. Therefore, impact training usually is delayed another four to six weeks after removal of the screw. In a study involving hyper-aggressive therapy, some collegiate athletes returned in as little as six weeks. We’re not sure we’d want to be guinea pigs in that study.

Summary
Ankle sprains come in all shapes in sizes. One day a pitcher may tweak his ankle on the mound; the next day, Buster Posey might suffer severe sprains and associated fractures. If it’s a simple lateral or low ankle sprain, the player will usually be back within two to three weeks and won’t need surgery except in cases of chronic instability. A syndesmotic or high ankle sprain could force your favorite player to ride the pine for a month or two; if he has to have surgery, his season is almost certainly over.

Corey Dawkins is an author of Baseball Prospectus. 
Click here to see Corey's other articles. You can contact Corey by clicking here
Ben Lindbergh is an author of Baseball Prospectus. 
Click here to see Ben's other articles. You can contact Ben by clicking here

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