The meniscus is a half moon shaped piece of cartilage that lies between the weight bearing joint surfaces of the thigh and the shin, and is attached to the lining of the knee joint. There are two menisci in a normal knee; the outside – the lateral meniscus and the inner side – the medial meniscus.
Traumatic tears result from a sudden load being applied to the meniscal tissue that is severe enough to cause the meniscal cartilage to fail and let go. These usually occur from a twisting injury or a blow to the side of the knee that causes the meniscus to be pushed against and compressed. These tears typically occur in the young patients and are associated with a “memorable knee injury or twist”. Swelling of the joint may occur although meniscal tears by themselves usually don’t cause a large, tensely swollen knee. Typically, slight swelling sets in the next day after the injury and is associated with stiffness and limping. If the torn portion of the meniscus is large enough, locking may occur.
Degenerative tears are best thought of as a failure of the meniscus over time. With age the meniscus changes its structure and becomes less elastic and more friable. As a result the meniscus may fail with only minimal trauma (such as just getting down into a squat). Sometimes there are no memorable injuries or violent events that can be blamed as the cause of the tear. With such tear the signs and symptoms come more gradually. Stiffness of the knee often occurs. This is usually because of fluid accumulating inside the knee joint.
The most common problem caused by a torn meniscus is pain. The pain may be felt along the joint line where the meniscus is located or may be more vague and involve the whole knee. Any twisting, squatting or impacting activities will pinch the meniscus tear or flap and cause pain. Often the pain may improve with rest after the initial injury, but as soon as aggressive activity is attempted the pain recurs.
Swelling of the joint may occur although meniscal tears by themselves usually don’t cause a large, tensely swollen knee. Typically, slight swelling sets in the next day after the injury and is associated with stiffness and limping.
If the torn portion of the meniscus is large enough, locking may occur. Locking simply refers to the inability to completely straighten out the knee. Locking occurs when the fragment of torn meniscus gets caught in the hinge mechanism of the knee, and will not allow the leg to straighten completely. The torn fragment actually acts like a wedge to prevent the joint surfaces from moving. Stiffness of the knee often occurs. This is usually because of fluid accumulating inside the knee joint.
There are long-term effects of a torn meniscus as well. The constant rubbing of the torn meniscus on the cartilage may cause wear and tear on the surface, leading to degeneration of the joint. Generally the age of the patient along with the type of onset of symptoms is good indicator of the type “traumatic” or “degenerative” tears.
If the patient is young and had a twisting injury more likely that will be a “traumatic” meniscal tear. If the patient is pass middle-age and didn’t have a knee injury more likely that will be a “degenerative” type.
The difficulty lies with the middle-aged patient who had a minor knee twist and had a traumatic tear on the background of a degenerative meniscus.
More commonly the patient will present to the GP with a MRI report where the tear is diagnosed by the reporting Radiologist.
In such instance the GP should make the patient aware of the two different type of tears. A referral to an Orthopaedic Surgeon, Specialist Knee Surgeon is indicated at that stage.
The patient should be advised that not all meniscal tears need surgery.
No not all meniscal tears need surgery.
The treatment of a meniscal tear largely depends on the patient’s age, the type of tear (acute or degenerative), the extend and location of the tear, the general status of the joint and also on the presence of associated knee injuries. If the knee is locked and cannot be straightened out, surgery may be recommended as soon as reasonably possible to remove the torn portion that is caught in the joint. Once the meniscus is torn it will most likely not heal on its own.
If there is a traumatic meniscal tear and with a flap that could potentially irritate the joint and damage the articular cartilage surgery is indicated to smoothen out the meniscus and the damaged articular cartilage. In young patients with a meniscal tear my preference is to try my best to repair the meniscus and preserve its protective role for the knee joint. This is done with an arthroscopic technique and involves ‘stitching’ the tear back to its native shape.
I do not recommend arthroscopic knee surgery as part of the management of knee osteoarthritis.
Since 2002, six high quality, randomized clinical trials (RCTs) of arthroscopic management of knee osteoarthritis (OA) have been published, two focusing on the efficacy of arthroscopic debridement and lavage on pain and function and four on the efficacy of arthroscopic partial meniscectomy in patients with symptomatic meniscal tear and underlying mild to moderate knee OA.
These studies showed that arthroscopic debridement for OA was no better than a sham procedure in relieving knee pain or improving functional status, and that patients who underwent arthroscopic partial meniscectomy (AMP) for a degenerative meniscal tear generally did not show more improvement than those who underwent sham surgery or an intensive course of physiotherapy.
The latest American Academy of Orthopaedic Surgeons (AAOS) Guidelines (2013) for treatment of knee osteoarthritis does NOT recommend performing arthroscopy with lavage and/or debridement in patients with primary diagnosis of symptomatic osteoarthritis of the knee. The strength of the recommendation, based on the quality of the reviewed evidence is strong.
Aggressive non-operative modalities including physiotherapy, home exercises, non-impact loading exercise, weight reduction, anti-inflammatories and simple analgesics remain the main stay of treatment and avoid the potential complications of operative treatment.
Four RCT’s have been published in the last several years that begin to address the question about the role of surgery in patients with meniscal tear and concomitant OA. Patients across all these studies were randomized to receive either physiotherapy alone focused on strengthening or APM followed by physiotherapy.
The results documented that subjects in both groups improved considerably in the first 6 months with no statistically significant or clinically important differences between randomized groups at 6 and 12 months of follow-up.
Those findings support initial treatment with non-operative therapy in middle-aged individuals with symptomatic meniscal tear and concomitant OA, with subsequent surgery in those who failed to improve.
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