Outline:   
In both sides of knee joint there is respectively a meniscus. Lateral meniscus is often of a congenital semilunar plate. The causes leading to meniscus rupture are classified into laceration force and trituration force. The former results in rotation of the knee joint in a hemiflexion position, in which the femur pulls collateral ligament, which further pulls the border of meniscus, hence the rupture. The latter often acts on the lateral meniscus that is mostly a congenital semilunar plate, which is triturated by the articular surface, thus, after a long time, an injury occurs. The commonly encountered injuries are marginal laceration, central longitudinal laceration (being likely to cause "interlock"), transverse laceration, horizontal laceration, anterior horn laceration and posterior horn laceration.


Major points for diagnosis  
1. There is mostly a history of sprain of the knee.
 
2. Immediately after sprain there are sharp pain, swelling and dysfunction of the knee joint. At the early stage, it is difficult to make a detailed examination due to the sharp pain, so an early diagnosis is almost impossible.
 
3. The disease duration is long and hard to cure for the chronic cases or the cases with no definite traumatic history. The main symptoms are knee pain on motion, claudication, flicking sound and "interlock sign" (When walking, there suddenly occurs sharp pain and the knee joint fails to extend and flex just like getting locked; after moving the knee a little bit or 2 or 3 minute massage, it will be relieved and can walk again). There is no swelling in the sick knee but atrophy of quadriceps femoris and tenderness in articular space of the knee. Both Mc. Murray's sign and Apley’s sign are positive.

4. Air or iodized oil arthrography, or arthroscopy of the knee can confirm the diagnosis.


Treatment  
Tendon-smoothing manipulation:      
For the case of acute injury, one time of passive extension and flexion of the knee joint should be done. The patient takes a supine position with his sick limb relaxed. The operator massages the tender point with his left thumb, holds the ankle with his right hand, slowly flexes the knee joint while making intorsion and extorsion of the leg, then straightens it out. This can relieve local pain.
 
For the chronic cases, local massage is done every day or every other day. First the operator presses the tender point on the margin of the joint with his thumb, then massages and kneads on around the tender point. This can promote local flow of qi and blood, making pain relieved.


Herbal therapy  
Internal treatment based on syndrome differentiation  
(1) Syndrome of qi and blood stagnation

Main symptoms and signs:
Serious pain and remarkable swelling in the knee, failure to walk; or ecchymoses on the tongue, stringy or thready-choppy pulse.

Therapeutic methods:
Promoting blood flow to remove the stasis, activating qi flow to stop pain.
 
Recipe and herbs:
Modified Taohong Siwu Decoction. The herbs see the treatment of syndrome of stagnant blood blockage in injury of collateral ligament of knee joint.

(2) Syndrome of collateral disharmony
 
Main symptoms and signs:
Aching and vague pain in the knee, rigidity and weakness of the knee joint, pale tongue and thready pulse.
   
Therapeutic methods:
Relaxing tendons and activating collaterals.

Therapeutic methods:
Relaxing tendons and activating collaterals.

Recipe and herbs:
Modified Huoxue Shujin Decoction. The herbs see the treatment of the same syndrome in injury of collateral ligament of knee joint.

External therapy:
In the early stage, Xiaoyu Zhitong Paste or Sanse Paste is externally applied. In the late stage, fumigation and bathing of the diseased part with Haitongpi Decoction is taken

Fixation:     
For the acute cases, splints or a plaster support is used to fix the sick limb in a position of the knee bent at the angle of 100 . The patient should not be allowed to walk and carry weight. The course is 3 or 4 weeks.

Functional exercise:    
When the pain and swelling are relieved 3 to 5 days after fixation. The patient should be encouraged to do exercises on contraction and relaxation of quadriceps muscle of thigh for preventing muscular atrophy. After removal of fixation, the patient also needs to practice exercise on flexion and extension of the knee joint and walking.

Operative therapy:   
The patients with marginal laceration of semilunar plate can generally be cured because of good blood supply locally. All other types of menisus injury should as early as possible be given an operation once diagnosed so as to prevent secondary traumatic arthritis.