1.What is the meniscus?
The meniscus is a “C”-shaped “wedge” of fibrocartilage, or fibrocartilage pad, located between the tibia and femur. There are two pieces in each knee joint, the medial meniscus and the lateral meniscus.
2. What is the role of the meniscus in the knee joint?
The meniscus has the following functions.
(1) To disperse the stresses acting on the cartilage of the articular surface.
(2) Absorbing impact forces.
(3) To increase the stability of the joint.
(4) joint lubrication, so that the distribution of joint fluid is uniform, and better nutrition of joint cartilage.
3.What are the causes of meniscus injury?
Typical meniscal tears are associated with trauma, generally when the foot is fixed and the knee joint is twisted, or when the squatting position is suddenly standing, but not definitely with a history of trauma. While healthy young people usually suffer some degree of trauma to the knee before meniscal rupture occurs, a significant proportion of meniscal ruptures in older adults occur during daily activities or simple movements such as squatting. As we age, meniscal tears become almost the result of degenerative changes.
4.What are the clinical signs and symptoms of meniscus injury?
Patients with meniscal injuries often complain of pain, swelling, locking, “stuck feeling”, “squeezing pain”, and “weak leg” after knee movement, but they are not specific. Patients often have difficulty describing knee symptoms and can only express them simply as “my knee is stuck,” “something is wrong,” or “something keeps misaligning and resetting. In acute injuries, 55% of patients present with joint swelling and effusion, a positive “floating patella test”, and often quadriceps atrophy (thigh muscle) when the injury is prolonged (after several weeks). Knee gap crush pain is helpful in diagnosing injury localization of meniscal injuries, with a positive rate of 77%-86% after meniscal injury. The inter-articular crushing pain, McKay’s sign, and crush and grind test are the most commonly used physical examination methods for meniscal injuries, and magnetic resonance imaging (MRI) is helpful for meniscal injury diagnosis.
5.What are the abnormalities in the magnetic resonance imaging (MRI) signal of meniscal injury?
MRI is the imaging method of choice for evaluating meniscal disorders. However, MRI is more sensitive than specific, and the presence of signal abnormalities on MRI does not indicate a definite meniscal tear, so not all meniscal lesions require surgical treatment. Meniscal injury and degeneration can lead to meniscal MRI signal changes, which are classified as grade 0-III depending on the signal range. grade 0 is a normal meniscus with a uniform low signal and regular morphology; grade I is a focal elliptical or spherical high signal that is not in contact with the meniscal articular surface. Grade II is a horizontal, linear intra-articular high signal that extends to the capsule edge of the meniscus, but does not reach the articular surface edge of the meniscus. Grade III signal is a high signal within the meniscus up to one or two articular surfaces, representing a meniscal tear.
6.What types of meniscal injuries are there? Can it heal on its own?
Meniscus injuries are divided into four types: longitudinal tears, transverse tears, horizontal tears and compound tears. The treatment of each type of meniscus injury depends on the blood flow of the meniscus. The distribution of meniscus blood vessels determines whether suture surgery can be performed after meniscus injury. In adults, the meniscus is only vascularized in 10% to 30% of the peripheral rim. The meniscus can be divided into three zones based on its blood supply (as shown in the figure), namely the red zone, the red-white zone, and the white zone.
Red zone tears heal easily after suturing, red-white zone injuries have the possibility of healing after suturing by some special methods, and white zone injuries cannot heal after suturing.
The white zone is mainly supplied by the synovial fluid in the joint. Currently, the meniscus is treated by excision of the torn area or meniscal suturing whenever possible.
The inner 2/3 of the meniscus has no blood flow and usually needs to be excised at the time of injury. In adults, there is blood flow in the outer 1/3 of the meniscus and tears in this area often heal spontaneously if they are less than 15 mm. Larger tears require suturing. In recent years, the use of special meniscal sutures such as absorbable staples in meniscal repair has led to the widespread adoption of total intra-articular suturing techniques.
The healing rate after meniscal suturing is strongly related to standardized rehabilitation exercises. Sutureable meniscal injuries often coexist with ACL injuries. Reconstruction of the ACL to restore joint stability can protect the sutured meniscus, while standardized rehabilitation exercises are more readily accepted due to ACL reconstruction, so the success rate of this type of surgery is much higher than that of an unstable joint.
7.How to deal with the acute period after the injury?
If the joint has obvious fluid (or blood), the fluid should be extracted under strict aseptic operation; if the joint is “interlocked”, the “interlocking” should be released by manipulation, and then the knee should be fixed in the straight position for 4 weeks with a tubular cast from the upper 1/3 of the thigh down to the ankle. The cast should be properly shaped so that the patient can walk with the cast on the floor. During the fixation period and after the removal of the fixation, the quadriceps should be actively exercised to prevent muscle atrophy.
8.What kind of damage is often caused to the joint after meniscus injury?
Since the meniscus itself has no blood flow and only blood circulation at the periphery, only marginal tears may heal. A torn meniscus not only loses its role in helping to stabilize the joint, but also interferes with the normal movement of the knee joint, even causing interlocking. Long-term wear and tear can also lead to increased injury, wear and tear of the articular cartilage, osteophytes, synovitis and other pathological changes, i.e. traumatic arthritis. Therefore, early diagnosis of meniscus injury and timely treatment are important.
9.Why should meniscus repair treatment be performed?
Since meniscus has important physiological functions, which can conduct load, absorb shock, reduce stress, improve joint stability, and coordinate and lubricate joints, most people now believe that the functionally intact meniscal tissue should be preserved as much as possible.
Therefore, meniscal injuries should be diagnosed and treated early to minimize the chance of total meniscectomy, and the earlier the treatment, the better the results.
Unstable meniscus injury should be operated as early as possible, if operated late there will be the following problems.
(1) The tear will increase, resulting in more meniscus being removed in future surgery, and the more meniscus removed, the greater the postoperative impact on the knee.
(2) With an acute meniscal injury, there is an opportunity for suture repair, and the suture will heal similarly to an uninjured meniscus. Postponing the surgery will make the suture opportunity lost.
(3) Even if the meniscus is completely removed, it will cause less wear and tear on the joint than a torn meniscus in the joint. In order to prevent accelerated degeneration of the knee joint, early surgery should be performed.
(4) Early surgery can resume all activities such as life, work, physical exercise or normal training of athletes as soon as possible.
10.What are the indications for meniscus injury surgery?
According to the patient’s medical history, there are painful symptoms, symptoms of strangulation and joint swelling; examination reveals that the meniscus has joint space pressure, fluid and secondary signs; MRI shows grade III signal. However, not all meniscal tears have clinical symptoms. Meniscal tears have significant symptoms near the joint capsule and less significant symptoms near the central free edge. Arthroscopy has both examination and treatment functions.
11.What surgical procedures are available for meniscal injuries?
(1) Meniscal repair: Since the outer l/3 of the meniscus is a vascular area, it can heal and has a good prognosis, so meniscal repair can be performed. It is suitable for young patients with acute injury, with longitudinal tears of l to 2 cm in length and located at the peripheral edge, and with an intact ACL. If there is damage to the ACL, the ACL with damage is repaired at the same time.
Specific repair procedures include.
① Incisional repair: only for tears at the peripheral edge of the posterior horn of the meniscus. It has the advantage of operating under direct vision and accurate suture alignment.
Arthroscopically assisted external and internal repair: suitable for injuries to the anterior horn of the meniscus. It has the advantages of precise needle insertion, avoiding damage to vascular nerves and intra-articular structures.
③Arthroscopic assisted internal and external repair method: slightly wider application, care should be taken not to damage the vascular nerve.
④Total intra-articular repair: It is suitable for the posterior part of the posterior horn of the meniscus and the central part of the posterior horn. It has a small incision and can be closed with vertical mattress suture, which is favorable for the firmness of the suture. However, specially designed surgical instruments must be used.
(2) Meniscectomy.
(1) Arthroscopic meniscectomy: According to the amount of meniscus tissue removed, there are partial, subtotal and total meniscectomy.
(2) Open meniscectomy: open meniscectomy has been used for many years as a method of meniscectomy.
In recent years, due to the development of arthroscopic technology, arthroscopic treatment of meniscal injury has replaced open meniscectomy, and open meniscectomy has been used less frequently, except when combined with ligament injury or osteochondral injury that must be treated by incision. Since arthroscopic surgery has the advantages of less trauma and faster postoperative recovery, open meniscectomy is only used as an alternative method for meniscectomy without arthroscopic equipment or without mastering arthroscopic meniscectomy.
(3) Meniscus transplantation: Since meniscectomy has different degrees of adverse effects on the knee joint, and meniscal repair has shown that the closer to the edge of the joint capsule the higher the healing rate. Therefore, allogeneic meniscus transplantation has been carried out and has achieved good clinical results.
12.What are the advantages of arthroscopic treatment of meniscus injury?
Arthroscopy is a set of precise optical imaging system that uses microscopic integumentary tractors to enjoin the need for the more urgent ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎÌ_ÌÎå It has the advantages of less trauma, less pain, faster recovery and fewer complications than traditional incisional surgery. It is a minimally invasive surgery.