Anatomy and Function
The meniscus is a crescent-shaped fibrocartilage that fills the knee between the femur and tibia. There are two menisci in each knee joint, the medial meniscus is “C” shaped and the lateral meniscus is “O” shaped. This allows for better stability of the knee joint. The meniscus in the knee joint carries gravity, absorbs shock and vibration, distributes synovial fluid to lubricate the joint, cooperates with the knee joint in flexion and rotation, and also prevents direct friction between the femoral and tibial surfaces and protects the articular cartilage surface.
Causes of injury
Soccer players and others who play competitive sports are susceptible to meniscal injuries during knee flexion, rotation, stopping and deceleration. Meniscal injuries in athletes can often be combined with other injuries, such as anterior cruciate ligament injuries. In older adults, meniscal injuries can occur without any trauma as the cartilage degenerates and wears away.
Signs and symptoms
1, only some cases of acute injury have a history of trauma. Chronic injuries have no obvious history of trauma.
2, more men than women, and more often seen in athletes and manual laborers.
3.After the injury, the knee joint has severe pain, cannot be straightened, and swells rapidly.
4. After the acute phase, the swelling disappears and the joint function is gradually restored. However, there is often discomfort or pain in the joint, and sometimes a popping sound can be heard, often in the activity room suddenly heard a “click”, then the joint can not move. It is necessary to move the lower leg several times before the knee joint can move again.
5, the meniscus injury may have a popping sound, most people can continue to walk, and athletes may continue to engage in sports. When the knee injury occurs after reactive inflammation, the knee joint will be painful, stiff feeling.
6, some patients sometimes appear in the knee when walking “flash” phenomenon
Without proper treatment, the broken meniscus fragments will loosen and free, resulting in a feeling of joint entrapment, popping or interlocking. Knee flexion at 45° often prevents knee extension and flexion, i.e., knee interlock, which can sometimes be relieved by manual manipulation. When a meniscal injury is felt to have occurred, it should be diagnosed and treated immediately.
[Diagnosis].
Inform the condition and time of the knee joint at the time of injury. Perform a physical examination to determine the extent of the meniscal injury. X-ray can be taken to exclude osteoarthritis or other diseases causing knee pain. When the knee is interlocked, knee arthroscopy technique can also be used to examine the knee joint to clarify the diagnosis.
There are several ways in which meniscal injuries can occur.
Longitudinal or “barrel stem” injuries often occur in young athletes during knee rotation
Younger athletes may have a radial or beak-like compound injury to the meniscus due to constant knee stress (less common)
In older adults, meniscal injuries often begin with a tear at the medial edge of the meniscus due to aging cartilage
Conservative treatment
Early meniscal injuries can be treated with rest, ice, compression bandages, elevation of the affected limb, and oral nonsteroidal medications to relieve pain. If the knee is stable and there are no symptoms of interlocking, then conservative treatment is sufficient. The meniscal periphery is rich in blood flow, and this part of the injury has the potential to heal itself, so small injuries to the meniscal periphery may heal spontaneously after rest.
Surgical treatment
When the meniscus does not heal on its own and the knee becomes painful, stiff or interlocked, surgery is required. Due to the importance of the meniscus within the knee joint, surgery should preserve as much of the meniscus as possible. The application of knee arthroscopic techniques greatly reduces the trauma of knee surgery and increases the accuracy and precision of the procedure. Currently, depending on the type of meniscal injury, the presence of cruciate ligament injury, and age and other factors, the surgeon will selectively perform meniscal repair, partial resection, and major resection depending on the situation. After surgery, the knee can gradually return to daily activities after completing functional exercises.
Meniscal repair suture techniques.
1.Inner-to-outside technique
2.External to internal technique
3.Total intra-articular technique
The above figure is the MIR showing the laminar fracture of the lateral disc meniscus as indicated by the red arrow
This is the lateral approach to the left knee: the lateral disc meniscus is divided into three lamellar fractures as seen in the red circle during surgery
Another patient with a meniscus injury
This is a 26-year-old male with an injury to the posterior horn of the medial meniscus of the left knee (red circle)
This patient’s left knee is seen on the lateral side of the left knee after the longitudinal tear of the posterior horn of the meniscus and the repair suture (in the red circle)
Clinical results after meniscus repair:]
1. The incidence of retear after meniscus repair for simple meniscus injury is 12%-43%.
2. The incidence of retear and symptoms 5 years after meniscus repair is 24%.
3. meniscus repair with ACL injury reconstruction can enhance the chance of meniscus healing. the Barett comparative study found a 4.5% clinical failure rate for meniscus repair with ACL reconstruction
4. The failure rate of meniscus repair alone was 27%.
[Complications after meniscus repair].
The main ones are
1. Neuropathy
2. Joint fibrosis
3. Joint infection
Arthroscopy in knee arthroscopy and the evolution of the disease after treatment
Although arthroscopic surgery is a minimally invasive and highly effective procedure, it is not always possible to achieve immediate results. Arthroscopic surgery is also not a one-and-done procedure. Different patients respond differently to arthroscopic surgery, with some patients experiencing immediate relief and others experiencing worsening symptoms. Many factors are involved, and only with a thorough understanding of these factors is it possible to predict the outcome of arthroscopic surgery and successfully guide patients through their recovery. The evolution of the disease after arthroscopic surgery is generally divided into three phases: the reactive synovitis phase, the periarticular aseptic inflammation phase, and the functional rehabilitation phase. Different stages have different rehabilitation methods.
Reactive Synovitis Phase
Although arthroscopic surgery is a minimally invasive procedure, the synovial membrane of the knee may still react to the procedure with great intensity. The normal knee cavity is always under negative pressure, and in order to expand the joint capsule during arthroscopic surgery it must be perfused with 100-150 mm of water column, or even higher. The large change in intra-articular pressure causes a disruption in the sympathetic response of the synovial membrane, which often results in reactive synovial congestion and edema when the positive pressure state is over, also known as reactive synovitis. Clinically, this is characterized by unrelieved or increased knee pain, fluid accumulation in the knee joint, and limited extension and flexion. It often takes up to three months for the synovial reaction to completely subside, and may take up to six months in individual patients; in patients suffering from menopausal syndrome, the synovial reaction may not even subside until the end of menopause.
Period of periarticular aseptic inflammation remission
Pain after a meniscal injury results from a sterile inflammatory response in the synovial membrane, joint capsule and peri-capsular tissues surrounding the damaged meniscus, which is caused by the inlay or abnormal movement of the damaged meniscus within the joint. When the damaged meniscus is removed or repaired by arthroscopic surgery, the factors causing the aseptic inflammatory response are removed, but because the aseptic response does not disappear, the patient’s pain does not disappear immediately and the patient will not experience the effects of arthroscopic surgery until most of this aseptic inflammation has subsided. The time required for this inflammation to subside is more related to the length of preoperative onset and less related to the degree of intra-articular damage. The longer the preoperative onset, the longer the postoperative time to resolution of symptoms. Similarly, there are no nociceptive nerve fibers in the articular cartilage, and the symptoms of articular cartilage degeneration are due to other secondary reactions, which also take time to resolve after joint debridement.
As with reactive synovitis, the resolution of periarticular aseptic inflammation is significantly related to gender and age. In men, the inflammation resolves most rapidly, typically in 2-4 weeks, while in menopausal women it resolves most slowly and the time required is often difficult to determine.
There are several reasons why arthroscopic surgery is ineffective or aseptic inflammation does not completely resolve in individual patients.
(1) Prolonged preoperative course of disease. Patients with an excessively long preoperative course should be psychologically prepared for the postoperative recovery time.
(ii) Incomplete arthroscopic surgery. In arthroscopic surgery, thorough examination and treatment can ensure the efficacy of the surgery.
(iii) Combined injuries and lesions cannot be treated. For example, if the medial meniscus injury is combined with knee inversion, after the meniscus injury is treated, the pain symptoms are often not relieved due to the lack of treatment of osteoarthritis in the medial space of the knee joint.
④ Sympathetic reactive bone atrophy (Sudeck’s bone atrophy). The onset of this disease is beyond the surgeon’s control. However, the likelihood of an attack can often be predicted by examining the patient before surgery. The chance of an attack is about 1-2%, making a mockery of the delicate and brilliant surgery performed by the arthroscopic surgeon.
Functional recovery period
After the first two phases, although knee mobility has largely returned and the painful symptoms of the knee have subsided, this does not mean that knee function has been restored. This is because knee related muscle strength, knee proprioceptive function, and knee responsiveness are as necessary for full knee function as knee mobility. At this stage, the focus should be on knee proprioceptive function and knee responsiveness.