By Steven A. Marciniak, M.D.
The adult skeleton is made up of two hundred six bones, each of which is rigid and relatively unyielding. Motion occurs not within the bones but at the joints, which are the places where two or more bones come together. There are various kinds of joints in the body including hinge, balland- socket and mortise joints, but they all have a common characteristic – they are held together by ligaments. Ligaments are specialized bands of tissue (much like leather) which join the bones together and serve as checkreins to prevent a joint from moving too far in a given direction. Take the knee for example. It only straightens so far and then a ligament pulls tight and prevents it from straightening any further. Similarly, knees don’t move much at all from side to side and it is ligaments that provide that stability and prevent the knee from wobbling uncontrollably. When a ligament is injured the injury is called a sprain. And the joint in the body that is most commonly sprained is the ankle joint.
The ankle allows for motion to take place between the lower leg and the foot and it is formed by the tibia and fibula (bones above the ankle in the lower leg) and the talus (one of the bones of the foot). The large bony prominence on the inside of the ankle is part of the tibia known as the medial malleolus, while the bony prominence on the outside of the ankle is a part of the fibula known as the lateral malleolus. The ankle joint is a mortise joint, allowing only for motion upwar (dorsiflexion) and downward (plantarflexion). It doesn’t allow much side to side motion at all and what keeps it from doing so is, of course, the ligaments. On the medial (inside) of the ankle, the deltoid ligament connects the tibia (medial malleolus) to the talus. On the lateral (outside) of the ankle is a complex of three ligaments which serve to connect the fibula (lateral malleolus) to both the talus and to the calcaneus (the heel bone), which are bones of the foot. Going from front to back around the lateral malleolus the three ligaments are the anterior talo-fibular ligament (ATFL), calcaneo-fibular ligament (CFL), and the posterior talo-fibular ligament (PTFL). The ATFL is the most commonly sprained ligament in the body. There are also ligaments that hold the tibia and the fibula together above the ankle joint, and they are known as the syndesmotic ligaments.
There are three broad categories of ankle sprain. The most common type of ankle sprain is an inversion injury and it occurs when the ankle is “rolled over” with the foot twisting inward below the ankle. About 90% of ankle sprains are inversion injuries. With this type of ankle sprain one or more of the three ligaments on the outside of the ankle (ATFL, CFL or PTFL) are stretched too far. Pain is localized to the outside of the ankle, and there is usually no pain on the inside of the ankle joint. Another type of sprained ankle is called an eversion injury, where the foot is twisted outwards. When this occurs, the inner (deltoid) ligament is stretched too far resulting in pain on the inner side of the ankle. Finally a “high” ankle sprain occurs when the syndesmotic ligaments holding the tibia and fibula together just above the ankle are injured. These injuries are typically the result of more serious twists and may even be associated with a fracture of the fibula higher in the leg.
Sprains are graded by severity of the injury to the ligament. A Grade I sprain occurs when one or more ligaments is over-stretched and damaged microscopically but not actually torn. Since there is no tear, the stability of the joint is maintained and not compromised at all. These are the most common ankle sprains. They heal most rapidly and require the least treatment and recovery. A Grade II injury is more severe and indicates that the ligament has been partially torn, but there is no significant instability since at least some of the injured ligament remains intact. But such a ligament is definitely weakened and, therefore, more likely to be reinjured, especially if not appropriately treated. A Grade III sprain is the most severe. This indicates that one or more ligaments have been completely torn and that instability has resulted. These injuries obviously require the most aggressive treatment and the longest recovery time. Some risk factors for ankle sprains include uneven ground, previous untreated (or inadequately treated) ankle injuries, obesity and the use of poorly fitting or worn out shoes.
Pain and swelling are the most common symptoms of an ankle sprain. Patients often notice bruising over the area of injury. This bruising typically moves down the foot towards the toes in the days after the ankle sprain, the result of simple gravity. Differentiating between a sprained ankle and an ankle fracture can be difficult, and sometimes an x-ray is needed. While moderate pain and swelling are common symptoms following a simple sprained ankle, symptoms such as inability to place weight on the leg, numbness of the toes, or pain that is difficult to adequately control should be a red flag that an orthopaedic evaluation is warranted.
The early treatment of an ankle sprain is the “RICE” method of treatment. Rest: The first 24-48 hours after the injury is considered a critical treatment period and activities need to be curtailed. Stay off the injured ankle except for necessary activity but try to keep it moving so it doesn’t stiffen up. Ice: For at least the first 48 hours post-injury apply ice 20 minutes out of each waking hour. Compression: Using an Ace bandage, wrap the ankle from the toes all the way up to the top of the calf muscle, overlapping the elastic wrap by one-half of the width of the wrap with each turn but being careful not to make any turn of the bandage any tighter than the one below it . The wrap should be snug but not tight -- not cutting off circulation to the foot and ankle. So, if your foot becomes cold, blue, or falls asleep, loosen the bandage. Elevate: Keep your ankle higher than your heart as often as possible. Your doctor may choose to immobilize your ankle to aid in comfort and allow early weight bearing. This can include a cast, a cast boot also called a cam-walker, or a brace.
Once the sprain begins to heal adequately, rehabilitation is focused on regaining motion, flexibility, strength and proprioception. Proprioception is neuromuscular feedback from the ligament to the brain that allows us to reflexively react to an impending sprain and its recovery is very important in preventing recurrent injury. Most ankle sprains will heal without surgery, but if instability persists the ligaments may need to be repaired or reconstructed. Lingering pain, persistent swelling or repeated episodes of the ankle “giving way” are all signs suggesting that an injured ankle may not have healed properly and are reasons to seek an expert evaluation by an orthopaedic or sports medicine specialist.
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