The importance of meniscus in biomechanics of knee joint is already well known, and the knowledge grew over time. Today it is known that it has a conjoint function with other structures of knee joint in normal movement mechanic. That is of special importance in sportsmen treatment.
Meniscus is actually crescent-shaped fibrocartilaginous structure (C-shaped). There are two menisci in each knee, lateral and medial. Menisci are attached to tibia and are connected to ligaments and all the joint structures, making movements both safe and possible together with joint capsule. With meniscus injuries blood supply is especially important, as it is often limited to periphery and is a key factor in meniscus repair.
Biomechanics and mechanism of injury – menisci follow the movements of the femur while the knee bends and straightens, keeping the congruently of the joint and the maximum surface of connection between the femur and tibia.
Injures of meniscus, especially sport injuries, usually include the damage due to rotation movement. The usual injury mechanism is a force aimed outward or inward of bent knee (rotation inward causes the injury of medial meniscus and outward rotation causes the lesion of lateral meniscus).
Due to the fact that medial meniscus is placed more firmly than the relatively mobile lateral meniscus, there is a higher rate of injury of medial meniscus. Chronic or constant stress might cause the degenerative tears of meniscus.
Symptoms and Examinations
Meniscus injuries of the knee are usually associated with sports activities of adults, and are rare in children younger than 10.
They occur more frequently in men, but it is assumed that it is due to men being more involved in aggressive sports.
Symptoms are sudden sharp pain in knee, and in a couple of hours the swelling of the knee develops.
An usual symptom is the joint locking, the knee cannot be fully straightened, or a clicking sound can be heard, or a snap after the joint is somehow extended.
It is imperative to describe to the doctor the situation during which the injury was sustained, with a detailed description of the movement.
The examination includes symmetric checking of both knees, then palpation, examination of the movement rage in joints, walking, measurement of knee girth and evaluation the state of meniscus and other structures of knee joint by different tests (such as McMurray test, Apley’s test, Bragard sign, Merkel sign, O’Donoghue test and others).
Examinations after the clinical examination include: arthrocentesis (synovial fluid is drawn from the joint by a syringe and then sent to analysis, the fluid can be clear or clouded, or can be blood), image examinations – x-ray scan of knee in multiple directions, MR (magnetic resonance) that replaced arthrography and is today a method for the scanning of mensicus.
It helps to confirm the diagnosis and gives additional info on the status of ligaments and fibrocartilage of joint, but it isn’t necessary in all cases before arthroscopy.
Among the procedures performed there is also arthrocentesis which is both a diagnosis and therapy. Not all leakages of bodily fluids into joint require arthrocentesis even though the aspiration of fluids or blood from the joint reduces pain and helps evaluate the extent of the injury.
Arthroscopy of the knee is a standard examination of diagnosing the tear of meniscus.
Treatment
Physical therapy for meniscus injury is individual and is adjusted to each patient, his general condition, advancement and the goals of rehabilitation. There is no foreseeable duration of rehabilitation that included multiple phases of different duration which may overlap.
Rehabilitation after meniscectomy (removal of meniscus): initial phase begins after 4-7 days after the surgery and consists of methods that are intended to reduce pain and swelling (changing of hot and cold, cooling down only, transcutaneous electrical nerve simulation or TENS and so on) and flexibility exercises as need arises. The emphasis of that phase is the increase of scope of passive movements in knee. Additional exercises improve the strength of lower extremity muscles.
Intermediary phase should begin when the complete movement range in knee joint is reached, and is continued by certain methods according to symptoms present. Flexibility and strength exercises are continued in tolerable limits. Running exercises under surveillance can also commence in this phase.
Advance phase is when the patient continues to advance in strength exercises while gradually returning to sports activities.
Rehabilitation after meniscus repair – rehabilitation programme is similar to the one described, but there are greater limits on placing weight on the knee, and the time of every phase of rehabilitation is extended so the healing process can take place. Placing weight on the knee is postponed for about 4-6 weeks after the surgery in order to reduce the strain on operated area.
Rehabilitation without surgery is also similar to the protocol following meniscectomy already described. Pain relief by non- steroidal anti-inflammatory medications (such as ibuprofen, diclofenac, naproxen and so on) and ice therapy play an important part. They reduce the swelling and relieve pain. Sometimes arthrocentesis is required for pain relief, and in some cases of sports injuries local application of corticosteroids in knee joint is performed. It is important to maintain the flexibility of the joint as well as muscle strength and endurance.
Multiple factors are involved in making the decision of surgical treatment of a known or suspected meniscus injury with sport players. In some cases it is apparent, as with a strained knee with distinct pain and scan proving the tear of meniscus. During the surgical procedure itself decision is made on repair or excision of tear or leaving it as it is. The main goal is to preserve as much as healthy tissue as it is possible.
Prognosis depends on associated injuries and the extent of the meniscus injury itself. During a longer time period, meniscus injuries make up the predisposing factor for the development of osteoarthritis due to the greater strain of joint surfaces in the knee, but the extent of such connection isn’t well grounded for the time being.
Prevention
Prevention isn’t always possible because the majority of meniscus injuries happen at accidents, but there are ways to help that:
- strong thigh and hamstring muscles.
- light stretch-out exercises before and after physical activity
- wearing appropriate clothes during the physical activities that are appropriate to the activity type
- with skiing, always check the buckles so the ski might be let loose at fall