Patellar Strain

Introduction Also known as "elbow softening" or "sacral osteochondrosis" is a common sports injury in the knee. Because the knee joint often over-extension and extension, the abnormal range of internal and external valgus, the cartilage surface under the tibia and the corresponding surface of the femur, long-term collision and crushing injury. Partial soreness at the beginning of the activity, reduced after the activity, and the end of the activity was aggravated after a rest, and there was no clear fixation of the pain. For a long time, there is a clear "knee soft" feeling on the stairs up and down, and the fluid in the joints is swollen in severe cases.

Cause

1. Trauma theory

Trauma, knee impact or acute dislocation of the tibia can directly or indirectly cause damage to the tibial cartilage, causing softening of the tibial cartilage. Someone has ever created an animal model that combats the softening of the tibial cartilage caused by the rabbit's tibia. In the rabbit tibial cartilage friction test, it was found that the cartilage was degenerated obviously after 45h, and chondroitin sulfate was seriously lost. 241 cases of tibia cartilage softening athletes were investigated, and the result was as high as 91%.

2, unstable humerus

The instability of the humerus mainly refers to the high tibia, the lower tibia, the sacral tilt, the subluxation or dislocation of the humerus. High tibia refers to the instability of the patella when the patellofemoral ligament is too long. During normal knee flexion, the quadriceps are in contact with the femoral condyle, and the pressure on the tibial articular surface is dispersed. When the patella is high, the quadriceps cannot contact the femoral condyle at the same flexion angle, so the pressure on the tibial articular surface increases. Large, high tibia can also cause patellofemoral joint movement disorders, resulting in instability of the patellofemoral joint. Low sputum means that the patellofemoral ligament is too short to cause the patella position to be too low. Because the lower position is not only due to the relatively short patellofemoral ligament, but also because of the increased length of the tibia, it may increase the tension of the knee extension device. The Q angle is the angle formed by the extension of the quadriceps tendon and the patellar ligament. The normal value should be less than 15°. If it is greater than 20°, it is considered abnormal. Due to the presence of the Q angle, during the extension of the knee joint, the tibia is pulled by the quadriceps muscle force and also produces an outward component. The larger the Q angle, the larger the lateral force of the tibia, the more unstable the tibia, and the abnormal distribution of patellofemoral joint pressure.

3, increased intraosseous pressure of the tibia

Bone pressure is an important indicator of blood circulation in the bone. The blood supply of the tibia is mainly in the middle, inner 1/3 and apex. Because the periorbital artery ring and the anterior iliac crest (sputum net) are easily damaged in the soft tissue injury or excessive knee joint activity, which affects the blood supply and venous return of the iliac crest, internal venous stasis occurs and intraosseous hypertension occurs. The Bjorkstrom test results were normal at 19 mmHg, and the average intraosseous pressure of the tibia in patients with patella softening was 44 mmHg, and the theory related to patella softening and tibia intraosseous hypertension was proposed. Hejgaard set the critical pressure of the tibia to 30mmHg.

4, cartilage dissolution theory

In 1959, Lack pointed out that after the synovial membrane injury, the osmotic pressure changes, the plasma enzyme in the plasma can enter the synovial fluid more, and its activity is also increased, thereby dissolving the cartilage, increasing the chondroitin content in the cartilage, and losing the elasticity of the cartilage degeneration. Qi Jianhong believes that collagenase plays an important role in the softening of the cartilage in the medial aspect of the tibia with reduced contact stress.

5, cartilage dystrophy

The tibial cartilage is a non-vascular nerve and lymphatic tissue. The synovial fluid is a small, light yellow, clear liquid in the joint cavity. There are about 1~2ml of synovial fluid in the normal knee joint. The basic component of synovial fluid. It is a plasma exudate with hyaluronic acid, collagen and proteoglycan. When the joint is active, the cartilage is compressed and deformed, and the extracellular fluid in the matrix is squeezed out. When the weight is released, the cartilage is elastic. To restore it, the cartilage is thus nutritious. On the contrary, if the infiltration effect disappears, the articular cartilage degenerates because it cannot obtain sufficient nutrition.

6, autoimmune theory

The articular cartilage surface tissue has the function of preventing the anti-collagen antibody from entering the deep tissue of the cartilage, and has a protective effect on the deep cartilage tissue. Anti-type II collagen antibody was found in the joint fluid of patients with articular cartilage injury. It is believed that the pathological mechanism of synovitis after articular cartilage injury may be related to the autoimmune reaction of type II collagen. It is suggested that there may be II in the pathological process of cartilage injury. The autoimmune response of collagen is involved. Immunocholasic histology was used to examine the lesion cartilage specimens of 12 patients with patella softening disease. It was found that all the cartilage lesions in the cartilage specimens and the remaining chondrocytes had immunoglobulin IgG, IgA, IgM and complement C3 attached. And concluded that the mechanical factors caused by articular cartilage injury, the pathological process of lesion cartilage injury has the pathological mechanism of autoimmune participation.

7, the impact of stock pressure

For many years, most scholars have emphasized the effect of exposure to high pressure on patella softening. It is believed that the degeneration caused by high stress first leads to the destruction of the cartilage matrix, the collagen fiber network is broken, the proteoglycan is lost, and the matrix damage causes the normal microenvironment. Changes occur, leading to degeneration of chondrocytes, and high stress causes early cartilage matrix damage can cause partial chondrocyte proliferation, and has an active synthetic secretion function, but then most of the cells degenerate. However, it is difficult to explain the phenomenon that the medial temporal surface of the humerus is a high incidence area of patella softening. Because the medial aspect is the "non-habitual contact area" of the tibia, only when the knee is over 120°, the contact is generated, and it is rarely subjected to stress.

Qi Jianhong reduced the medial stress of the tibia by tightening the lateral support band of the rabbit tibia, which caused the deep degeneration of the deep chondrocytes followed by the degeneration of the surrounding matrix. It is believed that the mechanism of cartilage degeneration under the low stress environment and high stress environment is different. Gu Yan found that the proper stress environment plays a very important role in maintaining the integrity of articular cartilage. Without sufficient stress, even if the joint activity is preserved, the cartilage can not effectively obtain nutrients, thus leading to cartilage degeneration. In recent years, the uneven distribution of patellofemoral joint pressure has attracted attention, and it is considered that stress imbalance is the cause of cartilage degeneration.

an examination

Related inspection

CT examination of the limbs and joints of the extremities

Physical examination:

1. There is a subgingival friction sound when the knee joint is active, and the position is not fixed.

2, there is diffuse pain after the sputum, there is a soft leg phenomenon when walking, the discomfort is obvious when going up and down the stairs.

3, knee joint pain and weakness in the semi-squat, the cheekbone has a tender feeling.

4, tibia compression quadriceps contraction test was positive.

5, humeral pressure test: the examination of the tibia and its opposite femoral condyle joint surface squeezed or rubbed up and down, left and right, there is a rough friction, friction and pain and discomfort; or the examiner pushes the tibia to one hand On the side, the thumb of the other hand presses behind the edge of the humerus to cause pain.

6, single leg squat test: the patient's single leg weight, gradually squatting to 90 ° -135 ° pain, soft, after a single leg can not stand up.

Film degree exam:

1, X-ray film: X-ray film of patella softening has no positive findings. Because it is a cartilage lesion, when it is seen that there are obvious bone spurs to form the upper and lower ends of the tibia, cystic changes under the cartilage of the humerus, and subchondral insufficiency, this is actually degenerative osteoarthrosis, not patella softening.

2, arthroscopy: for the diagnosis of patella softening has a higher value.

3, internal iliac vein angiography: for the detection of internal iliac hypertension.

4, CT: Diagnostic value of the diagnosis of sputum alignment disorder and femoral condyle dysplasia, can be used as a supplementary means of X-ray film diagnosis.

5, MRI: a greater diagnostic value for patella softening.

6. In addition, in recent years, B-ultrasound has also been used to diagnose patella softening.

Differential diagnosis

A fracture of the tibia can cause a fracture of the tibia due to direct or indirect violence, accompanied by tearing of the aponeurosis on both sides of the humerus. Such as kicking, falling, etc., most of the fractures are transverse or upper and lower avulsion. Due to intra-articular fractures, there is blood in the joints.

Patellar softening is a common disease of the knee joint, which occurs in young adults. It is especially common among athletes and sports enthusiasts. The incidence of women is higher than that of men. The main pathological change is the degenerative changes of cartilage, including cartilage swelling and fragmentation. The same lesion occurred in the corresponding part of the last femoral condyle and developed into patellofemoral osteoarthritis.

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