Commonly referred to as knock knees, valgus knee refers to a condition in which the knees angle inward. It is often accompanied by inward hip rotation and a flattened foot arch. More common in women than men, valgus knee often causes no symptoms. However, people with valgus knee are at increased risk for anterior cruciate ligament injury, which involves stretching or tearing of one of the ligaments that holds the knee in normal alignment. Valgus knee also causes increased pressure on the outside compartment of the joint, which may eventually lead to knee arthritis. Strengthening the knee and hip muscles can improve a valgus knee.
Side Plank Exercise
Side plank exercises strengthen the hip abductor muscles on the outside of the thigh. These muscles help pull the knee and hip outward and away from the valgus position. Side planks can be performed lying on the affected side with the legs stacked on each other. The forearm is placed on the ground with the elbow directly under the shoulder. The hip is lifted off the ground and then slowly lowered back down without rocking forward or backward.
Side step-ups also strengthen the hip abductor muscles. In addition, it works the quadriceps, which help maintain proper knee alignment and add stability to the joint. It is performed by standing sideways next to a step with the involved foot on it. An upright posture is maintained and the other foot slowly steps up and then is lowered back down to the ground. It is important to avoid letting the involved knee go beyond the end of the toe or into a valgus position when performing this exercise. A mirror can be used to ensure good knee position.
Stationary Lunge Exercise
The stationary lunge exercise also works the quadriceps and helps prevent an inward knee angle. It is performed by taking a large step forward while in the standing position. Once this is done, both knees are bent as if trying to bring the back knee down to the ground. Finally, the knees are straightened back out into the standing position. At no point should the front knee move beyond the end of the toes or into the valgus position while performing this exercise.
Single-Leg Bridge Exercise
The single-leg bridge exercise helps strengthen the gluteal and external rotator muscles in the buttocks. These muscles counteract the inward rotation of the hip that occurs with knee valgus. The exercise is performed by lying on the back with the knees bent and the feet on the ground. With the abdominal muscles engaged, the buttocks are lifted into the air. One leg is then lifted off the ground and the knee is straightened while keeping the buttocks elevated. Then the buttocks are slowly lowered back to the ground.
A study published in December 2007 in the "Journal of Orthopedic and Sports Physical Therapy" found that each of the exercises previously described can effectively activate the hip and knee muscles that prevent valgus. The American College of Sports Medicine recommends that 1 to 3 sets of 8 to 12 repetitions of each exercise be performed to improve strength in novice individuals. More dynamic activities, such as jumping and running, can be attempted as strength progresses -- making sure to maintain proper knee alignment.
Warnings and Precautions
Knee valgus is a relatively common condition. However, it's important to seek medical attention if it is accompanied by progressive weakening of the leg muscles, a sudden onset of swelling or pain, or buckling of the knee joint. These may be signs of more serious health concerns and should reported to a doctor immediately.
Is This an Emergency?
- American Journal of Sports Medicine: Biomechanical Measures of Neuromuscular Control and Valgus Loading of the Knee Predict Anterior Cruciate Ligament Injury Risk in Female Athletes
- Journal of Orthopaedic and Sports Physical Therapy: Electromyographic Analysis of Core Trunk, Hip and Thigh Muscles During 9 Rehabilitation Exercises
- Medicine and Science in Sports and Medicine: Progression Models in Resistance Training for Healthy Adults