Learning About the Knee

            The knee is the largest joint in the body and one that everyone uses daily.  It is a hinge joint, which means it is only capable of flexing, or bending, and extending, yet dancers rely on it for almost every movement they execute and should, therefore, have a thorough understanding of it and how it works.
From Sci-eng.net
             The knee is made up of three bones – the tibia, which is the larger of the two shinbones; the femur, or thighbone; and the patella, or kneecap.  The joint is formed when the tibia and the femur meet to unite the upper leg with the lower leg.  The patella is a triangular shaped bone that covers and protects the surface of the joint so that we can kneel down without sacrificing the joint’s integrity.

            In between the tibia and the femur are two C-shaped pads of cartilage called the lateral meniscus and the medial meniscus.  Their job is to provide cushioning between the two bones and to absorb the shock that comes from the bones hitting against each other while walking, running, and jumping.

            The knee joint is surrounded by ligaments that provide stability and prevent unwanted movement that could harm the joint.  The collateral ligaments connect the tibia to the femur on the outside of the knee (the lateral collateral ligament) and on the inside of the knee (the medial collateral ligament).  These ligaments prevent sideways movement of the femur.  The anterior collateral ligament, or ACL, crosses the center of the joint, connects the tibia to the femur, and prevents the tibia from sliding forward during movement.  The posterior collateral ligament, or PCL, runs directly behind the ACL and prevents the tibia from sliding backward.
            The patella slides along a groove on the front of the femur and is held in place above by the quadriceps tendon which connects the thigh muscles to the joint and below by the patellar tendon which connects the patella to the tibia.

            The knee contains many fluid-filled sacs called bursae that help cushion the joint and keep the bones moving smoothly against each other.

            The four quadriceps muscles found on the front of the thigh – the rectus femoris, the vastus intermedius, the vastus lateralis, and the vastus medialis are responsible for extending the knee.

            The hamstring muscles which are found on the back of the thigh as well as the gastrocnemius, which is the major calf muscle, and the popliteus, which runs across the back of the knee, are responsible for bending, or flexing the knee.

            Next week’s post will focus on common knee injuries and concerns that dancers may have and how to prevent and care for them.

Ankle Sprains

          “There are three steps you have to complete to become a professional dancer: learn to dance, learn to perform, and learn how to cope with injuries.” - D. Gere

         Last week’s post on the anatomy of the ankle explained how the two joints that comprise the ankle and the ligaments surrounding the ankle work.  When everything goes as planned, the ankle moves as it should and is prevented from moving in directions that could damage and/or compromise its stability.  Sometimes, however, there are factors that cause the ankle to move in dangerous ways and an injury occurs.
            Ankle sprains account for 15% of all athletic injuries, and an ankle sprain is the most common injury among all forms of dance.  A 2006 article published in Physical Medicine and Rehabilitation Clinics of North America reported that ankle injuries account for up to 62% of all dance injuries, up to 24% of all modern dance injuries, up to 95% of all ballet injuries and up to 45% of musical theatre dance injuries in professional dancers.  The same article reports that females are at a higher risk of injuring the ankle because of the amount of stress placed on the joint during pointe work.

            A sprain occurs when one or more of the ligaments surrounding the ankle joint are overstretched or possibly torn.  Since ligaments are designed to prevent movements from occurring, an overstretched or torn ligament allows for movement in a direction that the joint is not meant to go.

Lateral sprain
            The most common sprain among dancers is on the lateral, or outside, of the ankle.  This sprain occurs in the lateral collateral ligaments when the foot turns inward, or inverts, while the ankle rolls outward.  A less common sprain can occur on the medial, or inner side, of the ankle if the foot twists outward, or everts, while the ankle rolls inward.   Consequently, one or more of the deltoid ligaments and/or the calcaneonavicular ligament can be overstretched.  The least common type of sprain among dancers occurs at the top of the ankle and is called a high sprain.  It would involve the syndesmosis ligaments that connect the tibia to the fibula.

            Sprains can caused by either rolling over when on demi-pointe or pointe, landing a jump incorrectly, or dancing on poor surfaces like slippery floors.  Rolling over or a poor landing could be the result of poor alignment at the ankle joint.  If a dancer’s foot tends to pronate, or roll in, the ankle may become chronically misaligned.  Ankle misalignment can also occur if there are muscular imbalances in the leg, if turnout is forced, or if there are misalignments in other parts of the body.  Fatigue and/or a sudden increase in training or rehearsal time can also stress the body and cause it to respond to movement differently than expected.  Slippery floors limit the amount of control a dancer has when dancing and can cause unexpected movements or falls.

            When a sprain occurs, the dancer will experience immediate pain followed by swelling.  A mildly sprained ankle will be swollen, be tender and stiff, and cause a small amount of pain when walking.  When the swelling and tenderness are accompanied by bruising and extreme pain while walking, the sprain is classified as serious or moderate.  A severe sprain often results in an audible pop or snap and a feeling of tearing when it occurs.  The ankle will seem “wobbly”, and the dancer will be unable to walk on it.

            As with all injuries, the dancer should immediately stop dancing, ice the injured area, and elevate it.  The reasons for following these steps are reviewed in my post on caring for injuries.  Dancers should always be evaluated by a dance medicine specialist.  Depending upon the severity of the sprain, the injury can take anywhere from 6 weeks to 3 months to heal.  After the injury heals, it is important that the dancer work with a physical therapist to re-establish the strength of the ankle joint and to determine what may have caused the injury.  If the cause was misalignment and/or a muscular imbalance, a physical therapist can help the dancer retrain his/her body to keep another injury from occurring.

Kadel, N. (2006). Foot and Ankle Injuries in Dance. Physical Medicine and
            Rehabilitation Clinics of North America, 17, 813-26.
O’Loughlin, P., Hodgkins, C., & Kennedy, J. (2008).  Ankle Sprains and Instability in
Dance.  Clinics in Sports Medicine, 27, 247-62.
Russell, J. (2010).  Acute Ankle Sprain in Dancers.  Journal of Dance Medicine and
            Science, 14(3), 89-96.