Background and Etiology
The knee is the largest joint in the body. It is built for weight bearing, stability and mobility. The knee complex is composed of four bones: the femur, tibia, fibula and the patella. There are also three osseous bone-to-bone joints. These are the patellafemoral joint, tibiofemoral joint and the tibiofibular joint. Attached to the joint surface of the tibia are two fibrocartilagenous structures called menisci. The menisci lie between the tibia and femur. There is a medial meniscus on the medial (inner) aspect of the knee and a lateral meniscus on the lateral aspect of the knee.
Function of Menisci
- The menisci are “C” shaped fibrocartilage wedges. The wedge shape keeps the rounded joint surface of the femur from sliding off the flat tibia. This adds stability to the knee joint.
- The menisci also function to cushion the knee joint during weight bearing activities
- Both medial and lateral menisci help distribute the body’s weight evenly over the knee joint and prevent wear and tear of the chondral (joint) cartilage of the femur and tibia.
Causes of Meniscal Tear
- Traumatic injury to the knee like getting hit on the outside or inside of the knee. Sometimes this trauma can be associated with medial collateral or cruciate ligament injuries. The “unhappy triad” is a traumatic injury of the anterior cruciate ligament, medial collateral ligament and medial meniscus.
- Degeneration or age related wear and tear of the knee and meniscus. Older people may not be able to identify a particular incident that caused their pain. In older individuals it could even be as simple as getting up from a chair or squatting.
- The most common mechanism of injury is a combination of a bending and a twisting motion while the foot is planted firmly on the ground.
- Knee pain, especially over the joint line that varies based on which meniscus is injured, the medial or lateral
- Loss of motion specifically flexion (bending) and extension (straightening).
- Swelling of the knee joint.
- Pain with walking and weight bearing especially with bending and twisting movements.
- A popping or clicking sound within the knee.
- Weakness, locking and buckling of the knee can be reported with meniscal injuries.
- A clinical examination that includes a good medical history and a clinical exam that uses several special tests can often be used to diagnose a meniscal or cartilage injury or tear.
- X-rays cannot visualize a meniscus, but can determine if there is any degeneration or arthritis affecting the joint.
- An MRI can be useful for diagnosis because it can visualize the ligaments and menisci in the knee.
Degree of Tear
There are three degrees of meniscal or cartilage tears:
- Small tears often cause mild pain while walking, squatting and during activities like rising from a chair. Symptoms typically improve in two to three weeks. There may be discomfort with twisting and bending motions.
- Moderate tears result in joint line pain, swelling, pain with walking and squatting. These symptoms may improve in two to four weeks with medication and physical therapy. If significant enough these tears can get worse with time.
- Large tears result in pieces of the meniscus interfering with the joint mechanics. This can cause locking, buckling and an unstable feeling in the joint. The knee can also feel stiff. There can be moderate swelling, loss of motion, and difficulty walking, squatting and kneeling.
Treatment of a meniscal tear can depend on a number of factors including size of tear, the patient’s age, activity level, motion restrictions, pain level and the doctor’s preference. When surgery is necessary it can be done arthroscopically, which is minimally invasive. Treatment options include:
- Conservative nonsurgical treatment including rest, ice, anti-inflammatory medication and physical therapy.
- Surgical repairs can usually be performed in younger patients and for longitudinal tears in areas of good circulation. The outer or lateral meniscus generally responds better to a surgical repair than the medial meniscus.
- Partial Meniscectomy can be performed to remove the torn sections of the meniscus. The remaining meniscus will become critical to prevent wear and tear that can result in early onset osteoarthritis of the knee.
- Complete Meniscectomy is usually avoided if at all possible to prevent early joint degeneration and early onset of osteoarthritis.
A meniscal implant is a new treatment option. Patients must meet certain criteria for this procedure:
- Individuals should be under 40 years of age.
- There is no evidence of arthritis in the knee
- There is good alignment of the knee.
- Pain and swelling is present with no response to other treatments.
Physical Therapy Interventions
Physical Therapists are professionals, educated and trained to administer interventions. As defined by The Guide to Physical Therapist Practice, interventions are the skilled and purposeful use of physical therapy methods and techniques to produce changes consistent with the diagnosis, prognosis and the patient or client’s goals.
Physical therapy for a meniscal tear will vary depending on whether the condition requires or does not require a surgical intervention. Goals will include reducing pain and swelling, restoring full range of motion in the knee, increasing muscle strength to assist in stabilization and absorption of forces at the knee while returning to full function.
Physical Therapy Interventions
Common Physical Therapy interventions in the treatment of a meniscus or cartilage injury to the knee include:
- Manual Therapeutic Technique (MTT): hands on care including soft tissue massage, stretching and joint mobilization by a physical therapist to regain mobility and range of motion of the knee. Use of mobilization techniques also helps to modulate pain.
- Therapeutic Exercises (TE) including stretching and strengthening exercises to regain range of motion and strengthen the muscles of the knee to support, stabilize, and decrease the stresses placed on the knee joint.
- Neuromuscular Reeducation (NMR) to restore stability, retrain the lower extremity, and improve movement techniques and mechanics (for example, running, kneeling, squatting and jumping) of the involved lower extremity in daily activities.
- Modalities including the use of ultrasound, electrical stimulation, ice, cold laser and others to decrease pain and inflammation of the involved knee.
- Home programs including strengthening, stretching and stabilization exercises and instructions to help the person perform daily tasks and advance to the next functional level.
Following a physical examination your physician may recommend the following:
- Rest to reduce the stress placed on the knee and meniscus.
- Crutches may be used to reduce stress on the meniscus and knee joint.
- Ice to reduce swelling and inflammation
- NSAIDS (non steroidal anti-inflammatory drugs) to reduce inflammation.
- Physical therapy to reduce pain and swelling, and restore motion and strength to the knee.
- Surgical intervention depending on the severity of the tear and response to conservative non-operative treatment. (For more information on surgical interventions, see above).
Recovery from a meniscus or cartilage injury will depend on several factors:
- Age of patient
- Severity of injury
- Surgical vs. Nonsurgical intervention
- Condition of joint (for example: arthritic vs. non-arthritic)
- Activity level of the patient
- Any other procedures performed on the knee
- The general health and condition of the patient
As a general rule it takes 4-8 weeks to recover from a meniscus tear (whether intervention is surgical or nonsurgical). If there are degenerative changes or arthritis of the knee it can take longer to recover. In general, the older the patient the longer the recovery,
Meniscal or Cartilage Repairs
Individuals who have meniscal repairs or other procedures performed on the knee will take longer to recover full function. With surgical meniscal repairs there will be a period of non-weight bearing to protect the surgical sight. This period will delay restoration of full function to approximately three months. Other surgical procedures that are often performed in conjunction with meniscal repairs (like anterior cruciate ligament repairs) will delay restoration of full function. This may take up to six months.