The menisci are structures formed by fibrocartilage found in the knee joint. They function as cushions, promote joint congruence and distribute the load forces exerted on the knee, cushioning the impact between the tibia and femur and preventing contact and friction between the two bones.
In the knee there is a meniscus in the internal part and another one in the external part, both adhered just to the edge of the tibial plateau increasing this way the articular surface between the femur and the tibia, favoring the mobility of the knee. The external meniscus is almost circular unlike the internal one that has semilunar form and it is the one that is broken more frequently, since it is united to the articular capsule and has smaller freedom of movements than the external one.
Since they are not closed rings, the ends or horns of each meniscus are one in front (anterior horn) and the other behind (posterior horn) in the direction of the knee.
Causes and types of rupture
The meniscus tear is one of the most frequent injuries in the knee joint and can be produced by diverse causes:
- Traumatic: caused by an impact, either direct or indirect.
- Degenerative: due to progressive deterioration over the years.
- Mechanical: due to poor posture, and consequently a malfunction.
Most meniscal tears occur in young people who play sports (soccer, skiing…). The movement that produces the damage in the meniscus is usually a sudden movement of rotation with the leg resting on the ground or a movement of excessive flexion. There are also degenerative tears that occur in older adults who after simple gestures such as kneeling, squatting or lifting something heavy, the tear occurs.
Not all meniscal tears are the same. They are classified into different types, depending on whether they are complete or incomplete and depending on the area of the meniscus that has ruptured.
The meniscal cyst is generally associated with a horizontal tear in which the center of the meniscus degenerates and ends up expelling the contents to the side forming the cyst.
Symptoms
Depending on the cause and type of tear, we will find a variability of symptoms, being the most frequent:
- Clicking and pain in the meniscal area, at the time the injury occurs.
- Inflammation of the knee to a greater or lesser extent.
- Joint effusions.
- Blockage of the joint.
- Pain when performing flexion and extension movements, especially in the final range of motion.
- Difficulty to move after remaining seated during a prolonged time.
The pain in many occasions is difficult to define in a zone in concrete, although it can happen that it is located with greater intensity in the internal or external face of the knee, depending on the injured meniscus. Also, it is possible to perceive pinching and failures in the stability of the knee.
Diagnosis of meniscus pathology
The basis of the diagnosis is the examination of the knee. It is evaluated if there is deformity of the knees, if there is effusion and if the mobility of the knee is complete and equal to that of the other leg.
Imaging tests such as radiography, ultrasound and magnetic resonance imaging are also used. Knee radiology does not allow direct visualization of the meniscus but it does allow observation of the joint space and bone involvement, depending on the patient’s age and type of injury.
If meniscal injury is suspected, an MRI should be performed to visualize the meniscus and determine the type of tear, if there is dislocation of the meniscus, and if there is associated effusion.
- Physical examination
- Conventional Rx
- Magnetic Resonance Imaging
In case of doubt, diagnostic arthroscopy of the knee is used. Arthroscopy uses a camera that is introduced into the joint through a small incision, which makes it possible to observe the structures of the knee from the inside and identify any meniscal lesion.
What treatment options are available?
Chronic or degenerative lesions and some of the acute ones do not require surgical treatment. It is sufficient to carry out a rehabilitation program.
The objective of this program will be:
- Facilitate the resorption of the inflammatory state.
- To stabilize the knee avoiding the muscular atrophy and promoting the tone of these muscles.
- Ensure meniscus healing conditions if they exist.
Surgery is not always the best option and it will be your doctor who will determine it. In cases of degenerative meniscal tears the patient can lead a normal life and even practice sports without it being a nuisance, there are patients that with a proper recovery and relying on physiotherapy and even infiltrations such as hyaluronic acid or plasma rich in growth factors come to have an asymptomatic knee for long periods.
The vast majority of meniscal lesions after the age of 50 years are degenerative, with appropriate measures improvements in 2-4 months and we must explain to the patient that arthroscopy to remove the meniscus most of the time is not the solution and also involves an approach to osteoarthritis and prosthesis worrying.
There are also meniscal lesions that require surgical treatment. Your specialist will explain the therapeutic indications and the prospects of your case. Depending on the type of tear that occurs in the meniscus, the location and future expectations, two types of arthroscopic surgical treatment are basically indicated: meniscal suture and partial regularization of the meniscus (removal of the injured fragment).
The meniscus is divided into 3 zones depending on the blood supply: red-red zone, red-white zone and white-white zone. The most common is that in red-red and red-white areas, we try to repair the meniscus with meniscal suture, we restore the meniscus without removing anything, so if the surgery is successful we will have a complete meniscus. This is not without complications as not all sutures “stick” and recovery is much longer, about 3-4 months on average. If the meniscus cannot be repaired (white-white area), the most usual is to remove only and exclusively the torn area of the meniscus.
And the easy question to ask is whether there is a suitable meniscal substitute. For years, two methods have been used as meniscal substitutes: meniscal transplantation and collagen inserts. The review of the literature shows good results in meniscal transplantation, with a decrease in pain, although there is still a long way to go in this area to achieve better results.
It is interesting to note the absence of reaction or rejection in this type of transplantation due to the acellularity of the meniscus and the few cells that live isolated by an extracellular matrix, which confers an immune privilege. It can be said that menisci are like personal footprints, their shape is related to the shape of the bony structures, the loads it supports and the way of carrying and walking, all this makes it very difficult to find a suitable replacement and research is still ongoing.
In the case of both surgical and conservative options, physiotherapy is crucial. After an acute meniscus tear should:
- Rest for 24-48 hours.
- Apply cold to deflate the joint and reduce pain.
- To make a compressive bandage.
- Keep the leg elevated to facilitate drainage of synovial fluid.
If surgical treatment is performed, later physiotherapy will be necessary to regain lost mobility, re-establish muscle tone and regain stability and proprioception of the joint.
In the case of opting for conservative treatment, we must be aware that the meniscus does not repair itself, it does not regenerate by itself. However, there are many people who live a normal life without any discomfort or even unaware that they have a torn meniscus.
Physiotherapy treatment should be tailored to each patient and taking into account if you have undergone surgery, will consist mainly of:
- Manual therapy to reduce pain.
- Drainage to evacuate the inflammatory liquid.
- Articular techniques to gain movement.
- Exercises to increase muscle strength.
After arthroscopy, what are the deadlines to be met?
Most patients with satisfactory evolution and without complications remain admitted to the hospital less than 24 hours after surgery. Crutches will be used for progressive partial support for a few days and normally after 4 weeks normal life is done in terms of walking short distances and mobility (without effort or overload, without referring to sport). In the case of meniscal suture your doctor may recommend not to support for 3-6 weeks depending on the location of the injury and techniques performed.
Postoperative and rehabilitation
The recovery time after meniscus surgery varies depending on the type of injury, the type of treatment and the patient himself. Although in the case of meniscus surgery by knee arthroscopy, the recovery time is significantly less because it is a minimally invasive surgery.
Correctly performing the rehabilitation indicated by the physician, either at home or with a physiotherapist, is crucial to reduce recovery time and ensure the success of the intervention. It is also important to start rehabilitation as soon as possible to avoid the loss of muscle mass in the leg, promote blood flow to the joint and strengthen the knee.
If rehabilitation is performed correctly and with the appropriate periodicity and intensity, the patient will usually recover full functional use of the joint between 3 weeks (partial resection) and 3-4 months (meniscal suture) after surgery. Approximate recovery time for return to sport varies between 2 and 5 months.