Meniscus TearSummary & Treatment
One of the common cause of sudden knee pain is a meniscus tear inside the knee joint.
The meniscus is a crescent shaped piece of fibro-cartilage between the ends of the thigh bone and shin bone inside the knee joint. Each knee has 2 menisci – a medial meniscus and a lateral meniscus. The meniscus serves as a cushion or shock absorber between the ends of the bones that meet in the knee joint.
The role of the meniscus is crucial to the functional health of the knee joint. Being a shock absorber, the meniscus protects the articular cartilage of the knee joint from prematurely wearing out. In other words, the meniscus has a “chondro-protective” effect on the knee cartilage. A knee with worn out cartilage will have arthritis symptoms of knee pain, stiffness and difficulties with walking.
Causes of Meniscus Tear
A meniscus tear can occur when:
- Knee is twisted or over-flexed
- Quickly stop moving and changing direction while running, landing from a jump, or turning (often in sports)
- Kneeling down
- Squatting down low and lifting something heavy
- Hit on the knee, such as during a football tackle
In some patients, the meniscus tear is related to major knee ligament tear such as a rupture of the anterior cruciate ligament (ACL).
In older patients, the meniscus substance can undergo degeneration and tear with minor injuries e.g. performing a deep squat. These tears are termed degenerative tears.
Occasionally, patients have congenital malformations in their meniscus which predispose to tears. These meniscus are discoid shaped and not crescent shaped. These are termed “Discoid Meniscus” and they tend to be on the lateral meniscus and can tear easily causing symptoms of pain and/or knee jamming.
Signs & Symptoms of a Meniscus Tear
A sudden sharp pain initially, sometimes with a ‘pop’ or ‘crack’ felt/heard inside the knee. Unlike a ligament rupture, where initial symptoms are normally very severe and most patients are unable to continue doing whatever it was they were doing, often with a meniscus tear patients can actually continue to function reasonably well initially. However, the joint often then swells up, often only moderately and often not until a number of hours after the actual injury.
The classic symptoms of a meniscus tear are:
- Intermittent sharp pains on either the inner (medial) or outer (lateral) side of the knee, depending on which meniscus is actually torn. If the back part of the meniscus (the posterior horn) is torn, then patients often feel pain around the back of the knee, particularly with deep knee flexion (bending) eg squatting. These sharp pains are often aggravated by any twisting on the knee.
- Patients often also complain of a more constant dull aching pain on the affected side of the joint.
- Swelling – this is due to increased joint fluid in the knee (an effusion).
- Clicking – painless clicking is not of any real significance. However, painful clicking and/or clicking associated with feelings of catching, giving way or locking often indicates the presence of a meniscus tear.
- Giving way – Intermittent sudden giving way, particularly when associated with sudden sharp pains and particularly when occurring with twisting on the knee, can be due to unstable flaps of meniscal cartilage catching in the knee.
- Locking is where the knee joint gets stuck in a bent position and unable to straighten (extend the knee). The joint may click or clunk back into place by wiggling the joint. Locking of this nature often indicates an unstable meniscal tear.
The physical examination is a relatively reliable tool for the diagnosis of a meniscus tear. With a symptomatic meniscus tear, there will likely be swelling of the knee (effusion) and tenderness along the joint line when the meniscus is pressed (palpation). In addition, loading the knee with specific maneuvers or a squat will cause pain in the compartment with the meniscus tear.
X-rays are important in the diagnosis of knee injuries. They are screening tools to rule out fracture in cases of acute knee injuries and to rule out arthritis in chronic knee pain. In cases of a chronic knee condition the X-rays show the amount of joint space (cartilage) left in the knee.
MRI (magnetic resonance imaging) has become an essential tool for knee surgeons. While X-rays are excellent at showing bony anatomy, arthritis, and fractures, MRI is very sensitive for detecting injuries to the soft tissues of the knee including cartilage, meniscus, and ligament.
Treatment of Meniscus Tears
Because of the poor healing capacity of the meniscus, most symptomatic meniscus tears caused by trauma require arthroscopy (key-hole surgery to the knee joint) to repair the meniscus or remove the torn piece of meniscus.
A degenerative tear is often given a chance to improve with time. Initial treatment is with R.I.C.E. (rest, ice, compression, and elevation), anti-inflammatories, and physical therapy for a period of 4-6 weeks prior to making a decision for surgery.
At the time of surgery, the surgeon will make a determination of whether or not the meniscus tear is repairable. Complex tears and degenerative tears are usually not amenable to repair and are treated with arthroscopic partial meniscectomy (removal). If at all possible, the torn meniscus should be repaired.
A common question is: “If the meniscus is so important, why remove it?”
The problem is the torn part of the meniscus no longer functions properly as a shock absorber. Instead it is a source of knee pain and inflammation. The torn portion also acts as a pebble in a shoe, causing damage to the articular cartilage. Hence in such situations, the reasonable option is to remove the torn portion and preserve as much functional meniscus tissue as possible.
The surgery is an outpatient surgery – come in and go home the same day. Post-surgery, the knee will be in an Ace bandage and the patient will use crutches for 3-7 days. Bearing weight on the leg is safe.
For Partial Meniscectomy: In 5-7 days, the patient will likely be walking comfortably, followed by a physical therapy program.
For Meniscus Repair: Meniscus repair rehabilitation is longer than a partial meniscectomy as the meniscus requires time to heal. The patient will be in a brace for six weeks after surgery and motion will be limited to 90 degrees of flexion for this period. Weight bearing will be allowed with the brace locked only.