Abnormal Q angle

Introduction Abnormal Q angle is one of the clinical symptoms of instability of the humerus. Unstable patella is a common cause of anterior knee pain. It is a common disease of the patellofemoral joint and is an important cause of patellofemoral softening or patellofemoral joint osteoarthritis. . Advances in biomechanics and imaging techniques, as well as the diversity of clinical testing methods, have led to the recognition that the degenerative changes in the patellofemoral joint are caused by the instability of the patellofemoral joint or the instability of the tibia caused by the sacral line. Metatarsal deviation, sacral tilt, high humerus, and humeral subluxation.

Cause

Cause:

The cause of patellofemoral joint instability, humeral deviation or subluxation actually includes abnormalities in each structure of the anterior knee region, which are broadly classified into four categories:

1. Abnormalities in the quadriceps and its dilatation: including atrophy or dysplasia of the medial femoral muscle, relaxation of the medial support ligament or tearing of the lateral support ligament and high tibia.

2. Knee joint line abnormalities: including Q angle increase, as well as knee valgus and knee flexion.

3. Abnormal shape of the humerus: such as patella bipartite, heteromorphic tibia (III, IV).

4. Congenital factors: mainly refers to the dysplasia secondary deformation of the femoral sputum cupping network or abnormal shape of the femoral condyle.

The common feature of all these changes is that the patellofemoral joint loses its normal structure, causing an abnormal tensile stress acting on the tibia, or an abnormal trajectory of the tibia, which makes the humerus unstable.

Pathogenesis:

Static factor

It mainly includes patellar ligaments, internal and external support ligaments, tendon bundles, internal femoral and external hemorrhoids and other health searches. The patellar ligament mainly restricts the upward movement of the humerus; the medial and lateral support ligaments limit the lateral displacement of the humerus; the tendon bundle also has the effect of reinforcing the outer tibia. Therefore, the restriction mechanism on the lateral side of the tibia is stronger than the medial side. When the knee joint is in the extension position, the healthy search tibia is slightly outwardly displaced when the quadriceps muscle is relaxed. The inner and outer sidewalls of the trochlear groove have the effect of restricting lateral slippage of the humerus. When the sulcus angle is increased, that is, the groove becomes shallow or the femoral condyle is developed, the tibia loses this restriction and is prone to dislocation. In addition, the length of the longitudinal axis of the normal human humerus is almost equal to the length of the iliac crest. When the iliac crest is longer than the humerus, it is a high tibia and is also a factor of instability of the tibia.

2. Dynamic factors

The main finger quadriceps function The medial muscle of the medial muscle search for the oblique head muscle fibers attached to the inner edge of the humerus. When the muscle contracts, it has the effect of pulling the tibia inward, which is important for antagonizing the patella extensor and stabilizing the tibia. Dynamic factor. The quadriceps-angle refers to the angle formed by the line connecting the anterior superior iliac spine to the central point of the tibia and the center of the tibia to the center of the tibial tuberosity. The normal Q angle is 5° to 10°. If the Q angle is greater than 15°, the quadriceps contraction produces a component that moves the tibia outward. As the Q angle increases, the component force of pulling the tibia to the outside gradually increases, and the stability of the tibia is also getting worse.

an examination

Related inspection

CT examination of bone and joint and soft tissue

Symptoms and signs:

1. Symptoms of unstable humerus

(1) Pain: The most common main symptoms are usually not consistent in their health search, but their location is in the anterior region of the knee. The pain in the anterior aspect of the knee is more likely to be aggravated by excessive activity, especially when climbing up and down the stairs. Time is more pronounced when flexing and stretching.

(2) Playing "soft legs": Playing "giving way" means that the knee joint appears weak and unstable when walking weight, and sometimes the patient can fall. This phenomenon is often caused by weakness of the quadriceps muscle, or due to the subluxation of the humerus sliding out of the intercondylar groove.

(3) False incarceration: Pseudolocking refers to the momentary involuntary restriction that occurs when knees are stretched. This phenomenon often occurs when the weight-bearing knee joint is flexed to the extension position, and the semi-dislocated humerus slides into the trochlear groove. It is often necessary to have a true incarceration caused by a twist or a loose body that is torn or displaced by the meniscus. Identification.

2. Symptoms of unstable humerus

(1) quadriceps atrophy: quadriceps atrophy is a common sign of knee joint disease, and the performance is more obvious when the knee extension device appears dysfunction, with the medial femoral muscle as the weight.

(2) Swelling: In severe cases of unstable humerus, quadriceps weakness, resulting in synovitis, joint swelling, and floating sputum test.

(3) "straight vision" of the humerus: squinting knee has skeletal valgus, high tibia, increased anteversion of the femur, excessive humeral external rotation and other knee deformities and line of force in order to maintain normal gait. The resulting tibia tilted to the medial side, which is a common factor in the instability of the tibia.

(4) Trajectory test: The patient sits on the side of the bed and sags the lower leg, and the knee flexes 90°, so that the knee joint is slowly extended, and whether the trajectory of the tibia is in a straight line. If there is an outward sliding health search, it is positive and is a specific sign of instability of the tibia.

(5) tenderness: more distributed in the inner edge of the humerus and the inner support zone. When the examiner presses the patient's tibia and performs the extension and flexion test, it can induce subgingival pain. The clinical tenderness is sometimes inconsistent with the painful part of the patient's complaint.

(6) Pressing sound: When the knee joint is straight, the health search, pressing the tibia and moving it up, down, left, and right, can feel or hear the reverse ligature (retropatellar crepitation) under the cheekbone, accompanied by soreness. . You can also feel or hear the press sound when the knee is actively flexing and flexing.

(7) Fear sign: The knee joint of the patient is in a mild flexion position. When the examiner pushes out the tibia to induce subluxation or dislocation, the patient develops fear and pain, and the knee joint is flexed and the pain is aggravated. The apprehension sign is also a specific sign of instability of the tibia.

(8) Increased patella extensibility or joint relaxation: The range of the passive movement of the humerus in the normal knee joint is not more than 1/2 of its width, and the range of the patella is smaller when the knee is 30°. If the joint is slack, the degree to which the tibia can move to the outside is divided into 3 degrees:

I degree: The center of the humerus is on the inside or axis of the axis of the lower limb.

II degree: The center of the humerus is located outside the axis.

III degree: The inner edge of the humerus crosses the axis of the lower limb.

(9) Q angle abnormality: Q angle is an important index to measure the tibial line of force. The internal rotation of the femur and the external rotation of the humerus can increase the Q angle and cause the sacrum to tilt.

According to the clinical manifestations of the medical history, X-ray examination and X-ray measurement, especially arthroscopy, CT and MRI examination can establish a clinical diagnosis.

Differential diagnosis

Pain in the knee: The pre-knee pain syndrome is a term that describes the pain that occurs in front of or around the cheekbone. Patellaofemoral Pain Syndrome, also known as anterior knee pain, is caused by abnormal movement of the femur during flexion.

Tibial pain: In the early stage of the tibia femoral pain syndrome, the knees may experience pain when walking, going up and down the stairs, and standing up under the armpits. In severe cases, there may be sudden knees unable to force or even stand unstable during walking.

Knee swelling: knee joint synovitis. Knee synovium is the most extensive and complex part of the human joint, and it also forms the largest synovial cavity. Because the knee joint is heavy, it has many movements and is most vulnerable to injury.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.