There are medial and lateral meniscus bones on the articular surface of tibia, which are called meniscus. The meniscus is thick at the edge, closely connected with the joint capsule, and thin at the center, showing a free state (Figure 3- 13 1). The medial meniscus is C-shaped, with the anterior horn attached to the front of the attachment point of anterior cruciate ligament, the posterior horn attached to the attachment point of tibial intercondylar crest and posterior cruciate ligament, and the middle part of its outer edge is closely connected with the medial collateral ligament. The lateral meniscus is O-shaped, its anterior horn is attached to the attachment point of anterior cruciate ligament, its posterior horn is attached to the posterior horn of medial meniscus, and its outer edge is not connected with lateral collateral ligament, so its mobility is greater than that of medial meniscus. The meniscus can move with the movement of the knee joint, moving forward when stretching the knee and moving backward when bending the knee. Meniscus belongs to fibrocartilage and has no blood supply. Its nutrition mainly comes from synovial fluid, and only the edge part connected with the joint capsule gets part of the blood supply from synovium. Therefore, the meniscus can repair itself except the marginal part. After the meniscus is removed, a thin and narrow meniscus of fibrocartilage can be regenerated from synovium. Normal meniscus can increase the depression of tibial condyle and cushion the medial and lateral condyle of femur, thus increasing the stability of joint and buffering the impact.

Fig. 3- 13 1 knee ligament and meniscus structure

(1) damage mechanism and classification

Most of them are caused by torsional external forces. When one leg bears a load and the calf is fixed in a semi-flexion position, the body and thigh suddenly rotate inward, and the medial meniscus is between the femoral condyle and tibia, which is subjected to rotational pressure, resulting in meniscus tear. For example, the greater the flexion degree of knee joint and the more backward the tearing position, the mechanism of lateral meniscus injury is the same, but the force is in the opposite direction. If the ruptured meniscus slides between joints, the joint activity will be mechanically hindered, which will hinder the extension and flexion of the joints and form an "interlock".

In the case of severe trauma, meniscus, cruciate ligament and collateral ligament can be damaged at the same time.

The site of meniscus injury. It can occur in the anterior corner, posterior corner, middle part or marginal part of meniscus. The shape of the injury can be transverse crack, longitudinal crack, transverse crack or irregular shape (Figure 3- 132), or even broken into intra-articular free bodies.

Figure 3- 132 Various types of meniscus injury of knee joint

(2) Clinical manifestations and diagnosis

Most of them have obvious history of trauma. In the acute stage, the knee joint has obvious pain, swelling and hydrops, and the joint flexion and extension activities are blocked. After the acute phase, swelling and hydrops can subside by themselves, but there is still pain in joints during activities, especially when going up and down stairs, up and down slopes, squatting, standing up, running and jumping. In severe cases, you can limp or have flexion and extension dysfunction. Some patients have "locking" phenomenon, or there is a click when the knee joint flexes and stretches.

Examination methods and clinical significance:

1. Tenderness is generally the lesion site, which is of great significance for the diagnosis and judgment of meniscus injury. During the examination, the knee joint was placed in a semi-flexion position, and the upper edge of the tibial condyle (that is, the meniscus edge) was pressed point by point with the thumb from front to back, and there was fixed tenderness at the meniscus injury. If the knee joint flexes and stretches passively or the calf rotates inside and outside when pressed, the pain is more obvious, and sometimes the meniscus with abnormal activity can be touched (Figure 3- 133).

Figure 3- 133 Examination of tenderness point of meniscus of knee joint

Figure 3- 134 Maxwell test

2. In the mcmurry test (rotary extrusion test), the patient lies on his back. The examiner holds the ankle of the calf with one hand and the knee with the other hand, bending the hip and knee as much as possible, and then gradually straightening the calf after abduction, supination, adduction, pronation, adduction and supination (Figure 3- 134). If there is pain or noise, it is positive, and the damaged part is determined according to the pain and noise.

3. Strong hyperextension or hyperflexion test can make knee joint passively hyperextension or hyperflexion, such as anterior meniscus injury, which can cause pain; Such as posterior meniscus injury, flexion can cause pain.

4. The lateral pressure test shows that the knee joint is in a straight position, and the knee joint is passively adducted or abducted. If there is meniscus injury, it will squeeze the joint space of the affected side and cause pain.

5. One-leg squat test uses the weight of one leg to gradually squat from the standing position and then stand up from the squatting position. The healthy side is normal. When the affected side squats or stands to a certain position, the injured meniscus is squeezed, which may cause pain in the joint space and even make it impossible to squat or stand.

6. The gravity test patient takes the lateral position, lifts the lower limbs to actively flex and extend the knee joint, and when the joint space on the affected side is downward, it squeezes the injured meniscus, causing pain; On the contrary, there is no pain when the joint space on the affected side is upward.

7. In the grinding test, the patient takes a prone position and the knee joint flexes. The examiner holds the ankle with both hands, presses down the calf and does internal and external rotation at the same time. The injured meniscus is painful because it is squeezed and ground; On the contrary, if the calf is lifted up and then rotated inside and outside, there is no pain.

X-ray examination: taking positive and lateral X-rays can not show meniscus injury, but can exclude other bone and joint diseases. Knee arthrography is of little significance for diagnosis, which can increase the pain of patients and is not suitable for use.

Knee arthroscopy: The position and type of meniscus injury and other structures in the joint can be directly observed through arthroscopy, which is helpful for the diagnosis of difficult cases.

In short, the diagnosis of meniscus injury is mainly based on medical history and clinical examination. Most patients have a history of trauma, and the affected joint space has fixed pain and pressure energy. Combined with comprehensive analysis of various tests, most of them can make a correct diagnosis. For patients with severe trauma, we should pay attention to check whether there are side collateral ligament and cruciate ligament injuries. For advanced cases, we should pay attention to check whether there is secondary traumatic arthritis.

Discoid meniscus is a kind of thick discoid meniscus, which is easy to be damaged, often bilateral. The main symptom is that joint activity often makes a crisp sound. When the joint moves, a lump can be felt at the lateral meniscus with tenderness. Mucous degeneration after meniscus injury can produce meniscus cyst, and the symptoms are similar to those of meniscus injury, and there are obvious masses in some areas, especially when stretching the knee.

(3) treatment

1. In the acute stage, if there is obvious effusion (or hematocele) in the joint, the effusion should be extracted under strict aseptic operation; If the joint is "locked", release the "locked" manually, and then fix the knee joint in a straight position for 4 weeks from thigh 1/3 to ankle with plaster (Figure 3- 135). Plaster should be properly shaped, and patients can walk with plaster. During and after fixation, the quadriceps femoris should be actively exercised to prevent muscle atrophy.

Fig. 3- 135 Long leg plaster fixation after meniscus injury release.

2. In the chronic stage, if the non-surgical treatment is ineffective, the symptoms and signs are obvious and the diagnosis is clear, the injured meniscus should be surgically removed as soon as possible to prevent traumatic arthritis. On the second day after operation, quadriceps femoris began to do static contraction exercise, and after 2 ~ 3 days, it began to do straight leg lifting exercise to prevent quadriceps femoris muscle atrophy. After two weeks, he began to walk on the ground and generally returned to normal function 2 ~ 3 months after operation.

3. Application of arthroscopy Arthroscopy can be used for the treatment of meniscus injury, and meniscus edge tear can be repaired by suture. Usually, the meniscus is partially removed and the undamaged part is retained. For those who are suspected of meniscus injury at an early stage, emergency arthroscopy is feasible, and meniscus injury can be treated at an early stage to shorten the course of treatment, improve the therapeutic effect and reduce the occurrence of traumatic arthritis. Arthroscopic surgery has the advantages of less trauma and quick recovery.

Second, the lateral collateral ligament injury

There are medial and lateral collateral ligaments on both sides of the knee joint. The medial collateral ligament starts from the adductor tubercle of femur and ends at the medial condyle of tibia, while the lateral collateral ligament starts from the lateral condyle of femur and ends at the fibular head. When the knee joint is completely straight, the medial and lateral collateral ligaments are tense, maintaining joint stability and controlling abnormal lateral displacement; When the knee joint flexes, the medial and lateral collateral ligaments are slack, and the joint is unstable and easy to be injured.

(1) Causes and types of damage

When the knee joint is straight, the knee joint or the outside of the calf is hit by strong violence or heavy pressure, resulting in excessive abduction of the knee joint and partial or complete rupture of the medial collateral ligament (Figure 3- 136, 3- 137). On the contrary, when the knee joint or the medial calf is hit by violence or heavy pressure, the knee joint is adducted excessively, and the lateral collateral ligament may be partially or completely broken. In severe trauma, the lateral collateral ligament, cruciate ligament and meniscus may be damaged at the same time (Figure 3- 138).

Figure 3- 136 Partial rupture of medial collateral ligament

Fig. 3- 137 schematic diagram of complete rupture of medial collateral ligament and surgical repair

Fig. 3- 138 (1) medial collateral ligament and anterior cruciate ligament rupture with medial meniscus rupture.

(2) Resection of medial meniscus and repair of medial collateral ligament and anterior cruciate ligament.

(2) Clinical manifestations and diagnosis

Generally, there is an obvious history of trauma. The injured side of the knee has local pain, swelling, and sometimes ecchymosis, and the knee joint cannot be completely straightened. Tenderness of ligament injury is obvious. When medial collateral ligament is injured, the tender point is often at the lower edge of medial epicondyle of femur or medial condyle of tibia. When the lateral ligament is injured, the tender point is in the lateral epicondyle of femur or fibula capitulum.

Lateral pressure test (separation test): when the knee joint is straight, the examiner holds the ankle of the affected limb with one hand, and the thenar of the other hand abuts against the inside or outside of the knee joint, so that the calf is strongly adducted or abducted, such as partial injury of the medial collateral ligament, which causes pain when abduction; If the fracture is complete, there is abnormal abduction activity (Figure 3- 139). On the other hand, if the lateral collateral ligament is partially damaged, adduction will cause pain when it involves the damaged ligament; If it is completely broken, there is abnormal adduction activity (Figure 3- 140).

Fig. 3- 139 lateral pressure test: the medial collateral ligament is completely broken and the abduction activity is abnormal.

Figure 3- 140 lateral pressure test: the lateral collateral ligament is completely broken and adduction activity is abnormal.

X-ray examination: under local anesthesia, straighten the knee joint, adducte or abduct the knee joint forcibly according to the above examination method, and take a positive X-ray film. If the collateral ligament is completely broken, the joint space on the injured side will be widened.

(3) treatment

1. fresh collateral ligament injury

(1) partial fracture, put the knee joint in flexion position of 150 ~ 160, fix it with long leg plaster (excluding ankle joint), walk with plaster after one week, remove the fixation after 4 ~ 6 weeks, practice knee flexion and extension activities, and pay attention to exercise quadriceps femoris.

(2) Surgical repair of the broken ligament (Figure 3- 137) is an emergency of complete rupture, and it was fixed with long leg plaster for 6 weeks after operation. If combined with cruciate ligament injury, the cruciate ligament should be repaired first, and then the side collateral ligament should be repaired; When the meniscus is injured, the injured meniscus should be removed first, and then the injured ligament should be repaired (Figure 3- 138).

2. Old lateral collateral ligament rupture

We should strengthen the exercise of quadriceps femoris to enhance the stability of knee joint. If the knee joint is unstable, the tendon in the adjacent area can be used for ligament reconstruction. Recently, it has been reported that carbon fiber is used as the material for reconstructing lateral collateral ligament, and satisfactory results have been achieved.

Third, cruciate ligament injury.

There are anterior and posterior cruciate ligaments (also called cruciate ligaments) in the knee joint (Figure 3- 13 1). The anterior cruciate ligament begins in front of the intercondylar eminence of the tibia and ends at the inner surface of the lateral condyle of the femur. The posterior cruciate ligament begins at the posterior part of the tibial intercondylar eminence and ends at the lateral side of the medial malleolus of femur. Whether the knee joint is straight or flexed, the anterior cruciate ligament can prevent the tibia from moving forward, and the posterior cruciate ligament can prevent the tibia from moving backward.

(1) Causes and types of damage

Excessive extension or violent abduction of knee joint can cause anterior cruciate ligament injury of knee joint. For example, when the knee joint is bent, the anterior cruciate ligament can be broken by applying external force to the femur from front to back, or by impacting the upper end of the tibia from back to front. Anterior dislocation of knee joint is often caused by hyperextension, which will inevitably hurt anterior cruciate ligament. If it is caused by excessive abduction, medial collateral ligament rupture can occur at the same time, and anterior cruciate ligament injury combined with medial meniscus injury is also very common. When you bend your knees, the external force hits the upper end of the tibia from front to back, causing excessive posterior displacement of the tibia, which can cause posterior cruciate ligament damage and even posterior dislocation of the knee joint.

(2) Clinical manifestations and diagnosis

The knee joint has severe pain, obvious swelling, bloodshot joints and flexion and extension disorders.

Drawer test: bend your knees 90 degrees and fix the femur. The examiner holds the upper leg with both hands and pulls or pushes the tibia forward. If the anterior cruciate ligament is broken, the tibia has abnormal forward movement ability; If the posterior cruciate ligament is broken, the tibia has abnormal backward mobility (Figure 3- 14 1).

Figure 3- 14 1 drawer test

(3) treatment

1. fresh cruciate ligament fracture

If the cruciate ligament is broken, or the avulsion fracture of tibial spine has obvious displacement, the broken ligament should be repaired by surgery at an early stage, or the avulsion fracture should be reduced and fixed internally (Figure 3- 142, 3- 143), and fixed with long leg plaster for 4-6 weeks after operation to strengthen quadriceps exercise.

Fig. 3- 142 fresh anterior cruciate ligament rupture method

Fig. 3- 143 fresh posterior cruciate ligament rupture method

If there is no displacement of tibial spine fracture, it can be fixed with long leg plaster for 4 ~ 6 weeks in the knee extension position after joint extraction and bleeding, and then strengthen quadriceps femoris exercise.

2. Old cruciate ligament rupture

Old cruciate ligament rupture, the surgical effect is not ideal. It is advisable to strengthen quadriceps exercise to strengthen the stability of joints. If it is unstable, ligament reconstruction can be considered with fascia lata, tendon inside or near patellar ligament. Recently, it has been reported that carbon fiber is used as cruciate ligament reconstruction material, and its curative effect needs further observation.