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I t p a y s t o b e A B M P C e r t i f i e d : w w w. a b m p . c o m / g o / c e r t i f i e d c e n t r a l 105 3 in a knock-kneed alignment. Lateral displacement of the knee results in genu varum, a bowlegged alignment. Excessive valgus or varus will change the Q angle, placing undue stress on joint structures. As little as 5 degrees of genu varum can increase compressive forces on the medial meniscus by 50 percent. 1 ROTATIONS IN THE KNEE Two types of tibiofemoral rotations occur in the knee: axial and terminal. Only possible when the knee is in a flexed position, axial rotation is important when quick direction changes are needed; for example, in sports such as tennis or basketball. When the knee is flexed at a 90-degree angle, the tibia can axially rotate an average of 30 degrees medially and 40 degrees laterally (Images 3A and 3B). If the foot is free, the tibia rotates under the femur; if the foot is fixed, the femur rotates over the tibia. During the last 30 degrees of knee extension, the tibia and femur counter-rotate into the close-packed position called terminal rotation. In this position, the femoral condyles screw into a locked position, medially rotating against the lateral rotation of the tibia. The screw-home mechanism stabilizes the knee in the extended position, twisting and locking the joint structures into a tight fit. When working with knee problems, you can access restrictions or hypermobilities by asking your clients to do these simple movements during a seated intake. Then assess their Q-angles in standing and/or supine position. To ensure safety, pay attention to rotations in this vulnerable joint during passive and resisted movement techniques. Note 1. D. Neumann, Kinesiology of the Musculoskeletal System: Foundation for Physical Rehabilitation (St. Louis, MO: Mosby, 2002). Mary Ann Foster is the author of Therapeutic Kinesiology: Musculoskeletal Systems, Palpation, and Body Mechanics (Pearson Publishing, 2013). She can be contacted at mafoster@somatic-patterning.com. Next Issue: Tracking Patella and Menisci Motion Exploring Technique Terminal Rotation of the Knee 1. Place one hand on your tibial tuberosity and the other hand on your quadriceps tendon (A). Notice how your hands line up vertically when your knee is bent. 2. Slowly straighten the knee and notice how the joint twists, causing the tibial tuberosity to shift toward the lateral side (B). 3. Slowly bend and straighten your knee several times to observe changes in alignment and feel the screw-home mechanism. 4. Stand facing a long mirror and assess your Q-angles. Then, watch your knees while doing a set of small knee bends to assess joint rotations. Axial rotation of the knee. A A B B