When the knee bends and straightens, the quadriceps muscles and quadriceps tendon help to keep the kneecap within the trochlear groove. Muscular imbalances or weaknesses, especially in the quadriceps muscles at the front of the thigh.Problems in alignment may result in a kneecap that shifts too far toward the outside or inside of the leg, or one that rides too high in the trochlear groove-a condition called patella alta. Problems with the alignment of the legs between the hips and the ankles.This abnormality may cause increased pressure between the back of the patella and the trochlea, irritating soft tissues.įactors that contribute to poor tracking of the kneecap include: In this condition, the patella is pushed out to one side of the groove when the knee is bent. Patellofemoral pain syndrome can also be caused by abnormal tracking of the kneecap in the trochlear groove. Use of improper sports training techniques or equipment.Other factors that may contribute to patellofemoral pain include: It can also be in the duration or intensity of activity-such as running longer distances. This change can be in the frequency of activity-such as increasing the number of days you exercise each week. It can also be caused by a sudden change in physical activity. In many cases, PFPS is caused by vigorous physical activities that put repeated stress on the knee -such as jogging, squatting, and climbing stairs.
In addition, just below the kneecap is a small pad of fat that cushions the kneecap and acts as a shock absorber. The synovium produces a small amount of fluid that lubricates the cartilage. Articular cartilage helps your bones glide smoothly against each other as you move your leg.Īlso aiding in movement is the synovium-a thin lining of tissue that covers the surface of the joint. When you bend or straighten your knee, the patella moves back and forth inside this trochlear groove.Ī slippery substance called articular cartilage covers the ends of the femur, trochlear groove, and the underside of the patella. For example, the patella rests in a groove on the top of the femur called the trochlea. Several structures in the knee joint make movement easier. Stretching from your patella to your tibia is the patellar tendon. Segments of the quadriceps tendon-called the patellar retinacula-attach to the tibia and help to stabilize the patella. The quadriceps tendon connects the muscles in the front of the thigh to the patella. Muscles are connected to bones by tendons. Internal derangement should also be suspected if the notch is irregular.A healthy knee is made up of four main things: bones, cartilage, ligaments, and tendons. A notch depth of 1.5 mm is shown as a useful additional sign of a torn ACL 2. A study compared the depth of the lateral femoral notch in patients with proven ACL tear and healthy individuals. The depth of the abnormal depression/notch can then be measured. On a lateral projection, a line is drawn from the normal articular surface of the lateral femoral condyle. The depth of the lateral femoral notch sign has been shown to correlate with anterior cruciate ligament (ACL) tear 2.Ī normal sulcus is located within 10 mm of Blumensaat's line on lateral projection 3. Lateral femoral notch sign is usually first appreciated on the lateral radiograph and is suggestive of an osteochondral fracture 1,2. The likely mechanism is a hyperextension or impaction injury with a collision of the femoral condyle and the posterior tibial plateau during the rotational movement responsible for injuring the ACL, most commonly the pivot-shift. It is occasionally referred to as a deep sulcus sign, not to be confused with the deep sulcus sign in pneumothorax on supine chest radiograph. The (deep) lateral femoral notch sign describes a depression on the lateral femoral condyle at the terminal sulcus, a junction between the weight-bearing tibial articular surface and the patellar articular surface of the femoral condyle.
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