The knee is one of the most complex and largest joint in the body, and is more susceptible to injury. Meniscal tears are one among the common injuries to the knee joint. It can occur at any age, but are more common in athletes playing contact sports. Meniscus tear is the commonest knee injury in athletes, especially those involved in contact sports. A suddenly bend or twist in your knee cause the meniscus to tear. This is a traumatic meniscus tear. Elderly people are more prone to degenerative meniscal tears as the cartilage wears out and weakens with age. The two wedge-shape cartilage pieces’ present between the thighbone and the shinbone are called meniscus. They stabilize the knee joint and act as “shock absorbers”.
What is the meniscus?
The meniscus is a small, "c" shaped piece of cartilage in the knee. Each knee consists of two menisci, medial meniscus on the inner aspect of the knee and the lateral meniscus on the outer aspect of the knee. The medial and lateral meniscus act as cushion between the thigh bone (femur) and shin bone (tibia). The meniscus has limited blood supply and for that reason, when there is an injury to the meniscus, healing often cannot take place. The meniscus acts like a “shock absorber” in the knee joint.
How do you injure the meniscus?
Meniscal tears often occur during sports. These tears are usually caused by twisting motion or over flexing of the knee joint. Athletes who play sports such as football, tennis and basketball are at a higher risk of developing meniscal tears. They often occur along with injuries to the anterior cruciate ligament
What types of tears are there?
Various types of meniscal tears that can occur are longitudinal, bucket handle, flap, parrot-beak and mixed or complex. These often occur in younger patients after a moderate degree of trauma.
There are also degenerative or atraumatic meniscal tears. Atraumatic meniscal tears typically develop slowly in middle aged and older patients, typically as part of developing osteoarthritis. These tears are often seen on MRIs, and occur more frequently as patients age.
What are the symptoms of a meniscal tear?
- Locking: The inability to extend the affected knee to the same extent as the contra-lateral side. Crucially this is due to a mechanical block and whilst pain may be a feature it is not the sole reason the knee is unable to extend. This presentation is caused by a bucket handle tear (an unstable vertical longitudinal tear) prolapsing out of position creating the mechanical block to movement.
- Pain: This is characteristically intermittent in nature and associated with activities such as stair climbing or running. Patients will often complain of an inability to fully squat. Patients will also exhibit tenderness along the joint line of the affected knee.
- Swelling: In large peripheral tears the injury may be associated with a post-traumatic effusion. More commonly, the irritation caused by the damaged meniscus causes recurrent effusions associated with exacerbations of the symptoms. A 3rd form of swelling is the localized meniscal cyst caused by a complex meniscal tear acting as a flap valve to synovial fluid leading to the gradual formation of a para-meniscal cyst that may be apparent clinically.
- Clicking: Patients will often complain of, and sometimes be able to reproduce clicking. This is a palpable demonstration of the ongoing damage that is being caused by the displaced meniscal fragment. The description patients find most easy to understand is of a broken tooth within a gear box jamming the machinery.
The symptoms of a meniscal tear include:
- Knee pain when walking
- A “popping “or “clicking” may be felt at the time of injury
- Tenderness when pressing on the meniscus
- Swelling of the knee
- Limited motion of the knee joint
- Joint locking can occur if the torn cartilage gets caught between the femur and tibia and may prevent you from straightening of the knee
How can you diagnose a meniscal tear?
A careful medical history and physical examination can help diagnose meniscal injury. The McMurray test is one of the important tests for diagnosing meniscal tears. During this test, your doctor will bend the knee is, then straighten and rotate it in and out. This creates pressure on the torn meniscus. Pain or a click during this test may suggest a meniscal tear. Your doctor may order imaging tests such as knee joint X-ray and MRI to help confirm the diagnosis.
X-ray
This is particularly useful in the assessment of additional knee pathology, such as osteoarthritis that may impact on the prognostic information given to the patient. Weight-bearing X-rays should be the 1st-line investigation (AP standing, Lateral, Skyline and Rosenberg views) in the older patient with a possible degenerative meniscus.
M.R.I.
This is the most useful investigation for cases where diagnostic doubt exists. It is highly sensitive and specific but it is important to remember that both false negatives and positives still do occur.
How do you treat a meniscal tear?
The treatment depends on the pattern and location of the tear. If the meniscal tear is not severe, your doctor may begin with non-surgical treatments that may include:
- Rest: Avoid activities that may cause injury. Your child may need to use crutches temporarily to limit weight bearing.
- Ice: Ice application to reduce swelling
- Pain medications: Paracetamol and nonsteroidal anti-inflammatory drugs (NSAIDs) to help reduce swelling and pain
- Physical Therapy: Physical therapy may be recommended for muscle and joint strengthening.
If the symptoms are persisting and non-operative treatment fails, you may need a knee arthroscopic surgery.
What about degenerative and atraumatic meniscal tears?
Atraumatic meniscal tears are common on MRI. For example, 25 per cent of 50-year-olds will have a meniscal lesion on MRI, while 45 per cent of 70-year-olds will have a meniscal lesion on MRI. Up to 95 per cent of patients with osteoarthritis will have a meniscal tear. Secondly. atraumatic knee pain is often not due to a meniscal tear. Usually the pain is due to co-existing osteoarthritis and bone bruising. Thirdly, atraumatic meniscal tears are typically part of the osteoarthritis process. Pain, swelling and stiffness are common in osteoarthritis and are usually not due to a meniscal lesion seen on MRI.
How do you treat degenerative meniscal tears?
Treatment of degenerative meniscal tears is essentially the same treatment for acute arthritic knee pain.
- Pain relief such as NSAIDs. The benefits of paracetamol in isolation remain marginal. Opiates are best avoided, especially for chronic pain.
- Activity modification to low-impact activity such as bike riding.
- Quadriceps strengthening exercises and muscle strengthening (often with physiotherapy).
- Weight (BMI) reduction in overweight patients.
- Consider braces in those who undertake moderate-impact activity.
- Injectable therapy such as PRP and hyaluronic acid could be considered; however, the cost-benefits remain unclear. Corticosteroids can damage the joint and theirbenefit is mild, hence theyshould be used sparingly andonly in acute painful settings. Stemcells do not benefit patients.
Occasionally, a patient with a repairable tear or obstructive (locked) symptoms may warrant arthroscopic surgery; however, most patients do not benefit from it.
The treatment of a meniscal tear depends on the type, size and location of tear as well your age and activity level. If the tear is small with damage in only the outer edge of the meniscus, nonsurgical treatment may be sufficient. However, if the symptoms do not resolve with nonsurgical treatment, surgical treatment may be recommended.
Knee arthroscopy is the commonly recommended surgical procedure for meniscal tears. The common surgical treatment options include meniscus removal (meniscectomy) or meniscus repair. Surgery can be performed using arthroscopy where a tiny camera will be inserted through a tiny incision which enables the surgeon to view inside of your knee on a monitor and through other tiny incisions, surgery will be performed. During meniscectomy, small instruments called shavers or scissors may be used to remove the torn meniscus. In arthroscopic meniscus repair the torn meniscus will be pinned or sutured depending on the extent of tear.
Arthroscopic excision
This is the most commonly performed treatment option and provides excellent, long term symptom relief for most patients. Although most patients will experience improvement within a few weeks of surgery some may require longer periods due to extensive quadriceps atrophy or other intra-articular pathology.
Arthroscopic repair
In certain, specific cases the meniscus may be able to be repaired. This is usually restricted to those cases where a fresh, peripheral tear is identified at arthroscopy in a young patient. The limited application for meniscal repair is due to the poor blood supply found within most the meniscus meaning only the outer 25% has a viable healing potential. It is an important consideration for many patients that a meniscal repair will necessitate a much-prolonged period of rehabilitation when compared to a simple excision.
