Meniscus Tears
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Anatomy
There are two menisci in the knee, one medial (inside) and one lateral (outside).
The menisci act as cushioning and stabilizers of the knee. The cushioning is generally the effect most associated with meniscus and plays an important role in decreasing the load on the cartilage in the knee. It is when the cartilage loading forces are too large you can get injuries and eventually osteoarthritis of the knee.
The loading from your bodyweight goes through the knee when standing. The menisci distribute the forces over a larger area of the knee and thereby lower the impact on the cartilage.
Injury
First of all, there are two different types of injuries to the meniscus, degenerative and traumatic. Degenerative tears happen due to overload of the knee for long time, generally for years. This can be due to prolonged activities, lower muscle strength to support the joint or during ageing when some wear and tear can be seen. The typical patient is above 40 years old with some minor knee issues in the past, now presented with increased pain to one side of the knee without a major trauma.
The second type of injury is traumatic, meaning the meniscus is healthy before an injury and due to high impact sudden load, for example sports, the meniscus is torn. The typical patient for this type of injury is a young individual that had no previous issues with the knee, but during activity got a twist to the knee or even just standing up from a sitting position got sudden onset of significant pain to one side of the knee.
Not too rarely, it can be a combination of both, where a mildly degenerative meniscus has a significant trauma and ends up with a symptomatic tear.
Classic symptoms are one-sided pain to the knee with some swelling and if it is a bigger tear, it can cause mechanical symptoms like hinging, clicking or locking of the knee.
Different kind of meniscal tear patterns
Evaluation
As there are different types of meniscal injuries, the history is crucial to evaluate the menisci. The more precise information given regarding onset of pain, trauma/no trauma, previous symptoms and more, the easier it is to evaluate what type of tear it is and how it should be treated.
A complete evaluation of the knee, including other injuries and instabilities and the patient’s activity level and desired future function is needed.
X-rays can be important, especially if other injuries are present or if there is a suspicion of malalignment or osteoarthritis.
MRI is gold standard to evaluate a meniscal tear. With modern MRI techniques you can see the tears and help to decide what kind of treatment is indicated.
There are multiple different ways a meniscus can tear.
Horizontal – usually degenerative, common in the posterior horn of the medial meniscus
Radial – from top to bottom split of the meniscus, usually traumatic, can completely compromise the function of the meniscus
Root – detachment of the meniscus from the bone, leaving the meniscus non-functioning
Ramp – detachment of the medial meniscus from the joint capsule, increasing mobility of the meniscus and instability to the joint, commonly seen with ACL tears
Bucket handle – when part of the meniscus is dislocated into the center of the knee, usually causing locking, not being able to fully extend the knee
Complex – sometimes combination of tears can leave the meniscus with poor function
Arthroscopic image of medial meniscus bucket handle tear
Arthroscopic image of the same meniscus repaired
Treatment
Treatment of meniscal tears can be anything from advice on activity modifications to urgent surgery depending on the knee, the patient and the tear.
Isolated meniscal tears are usually (but not always) treated as follows:
Horizontal tears – first line of treatment is physiotherapy and anti-inflammatory medicine. If the pain persists through the physiotherapy, further evaluation with an MRI and possibly surgery with repair or partial resection can be needed.
Radial tears – surgical repair
Root tears – surgical repair
Ramp lesions – surgical repair
Bucket handle tears – urgent surgical repair if possible
All the repairs are primarily done arthroscopically, sometimes aided with a small incision to properly suture the meniscus back in position and close the tears.
Schematic video of meniscus root repair
Arthroscopic video of a meniscus root repair
Rehabilitation
An arthroscopy with partial resection of the meniscus is a short procedure and you can fully weight bear afterwards, generally needs crutches for a few days and physiotherapy for a few weeks afterwards.
An arthroscopic repair of a meniscus tear needs time to heal before putting pressure on it, and therefore the patient is non-weightbearing for 6 weeks. This can vary depending on the tear and repair needed, but expectation is to be on crutches for at least 6 weeks. During this time, physiotherapy is ongoing to regain range of motion and to make sure the muscles stay active even without walking. After 6 weeks the physiotherapy program increases to first improve strength and thereafter function.
Everyday life with walking, climbing stairs and biking is usually achieved withing 3 months, and going back to running and sports take 4-6 months. Deep flexion, like squatting or kneeling, can sometimes be recommended to avoid up to 12 months after surgery.