The knee joint is complex and holds the greatest potential for injury than any other in the body. Knees are subjected to most daily activities, are key in practically every sport, and sustain the greatest impact when carrying excess weight. Care and maintenance of the knee is critical to quality of life.
Made up of four bones – the femur, tibia, fibula and patella – the knee relies heavily on the proper conditioning of surrounding muscles and ligaments as it bends and straightens with a slight rotation. Quadriceps muscle and tendon run across the front of the knee joint and powers knee extension. The patella (knee cap) exists within the quadriceps tendon and is directly above the patella tendon, which inserts on the tibial tubercle, sometimes known as the knob of the knee. The hamstrings run across the back of the knee and power knee flexion. The collateral ligaments, which travel from the outside of the tibia to the outside of the femur, hold it together. In addition, within the knee joint, is a semilunar (half-moon) shaped piece of tissue called meniscal cartilage, or the meniscus, which acts as a shock absorber between the femur and tibia. It also allows bones to slide over one another comfortably and serves as a stabilizer within the knee joint – allowing normal joint fluid and its nutrients into the articular cartilage, which is crucial in preventing arthritis. The Anterior Cruciate Ligament (ACL) and the Posterior Cruciate Ligament (PCL) are the two major stabilizing ligaments in the knee joint, crossing over one another in the shape of an “X.” The ACL prevents forward movement of the tibia (leg bone) on the femur (thigh bone), while the PCL prevents backward movement of the tibia on the femur.