Menisci is defined as a disk of cartilage located between the femur and the tibia preserving the health, integrity and functionality of the knee. The function of the menisci is to serve as a cushion between femur-tibia and protect the underlying articular cartilage from being damaged by absorbing a shock-wave from high-intensity vertical forces. The knee joint consists of two menisci, the lateral and the medial meniscus. Research has shown that lateral menisci tends to be more mobile than the medial menisci resulting in greater stresses in the area and lastly, more prone and vulnerable to injury. There are different types of meniscal tears such as longitudinal and acute tears which have a higher healing potential rate than radial, degenerative and chronic tears. There are various meniscus tears and a few examples are vertical tears, horizontal tears, radial tears, oblique and complex (degenerative tears).
Common signs and symptoms
The importance of history taking is considered crucial for the clinician in order to understand the underlying mechanism of injury, the location and character of pain (medial or lateral menisci), locking sensation or giving way, which is translated as joint instability and any related past medical history on the knee. Patients may also report a ‘popping’ sensation at the time of injury caused by altered biomechanics on the knee joint. Common mechanical symptoms in meniscus tears can be ‘clicking’ or ‘catching’ sensations, but these symptoms may indicate problems on other possible intra-articular structures of the knee such as patellofemoral dysfunctions or cartilage abnormalities. For instance, patella subluxation may be described as ‘pseudolocking’ because of its incorrect placement within the central groove of the femur, mimicking meniscal symptoms subjectively. Patients with meniscal tears may report localised pain where the menisci lie or vague pain all over the knee joint. Swelling of the knee joint may also occur depending on the severity of meniscal tear and the damage that has been done. Aggravating factors usually reported by patients are the rotational forces applied to the knee, sudden change of direction when walking, difficulties squatting and pain when ascending or descending stairs. Degenerative meniscal tears usually show up in people over the age of 40 caused by antecedent trauma and having a history of joint pain with or without the presence of mechanical symptoms.
Management of meniscal tears on the knee can be treated either surgically or conservatively depending on the severity of the tear. Regardless of whether surgical treatment is being considered or not, initially the RICE regime should be applied to reduce pain intensity. RICE treatment occurs always in the early stage of an injury and is consisted of rest, ice, compression bandages and elevation of the affected limb above the level of heart to reduce oedema and inflammation. Non-surgical treatments have been shown to be successful in specific types of tears depending on the degree and severity of injury. Patients with minimal loss of function, absence of swelling, manageable pain levels and reduction of activity participation, are prone to have beneficial outcomes with proper guidance on exercises, physical activities and daily modifications. Several studies have shown the benefits of early motion by demonstrating meniscal atrophy and decreased collagen after immobilisation. Range of motion of the knee up to 60 degrees has little effect on menisci displacement, but flexion angles greater than 60 degrees increase the menisci translation placing detrimental stresses on it. The combination of weight bearing and increasing the angle of knee flexion must be progressively controlled and balanced in the development of a rehabilitation protocol. Regarding surgical interventions, there are two types that are commonly used, the partial meniscectomy and meniscus repair. Partial meniscectomy is the process where the meniscus is trimmed away while meniscus repair requires suturing the torn pieces together. Recovery time for meniscectomy is usually less time-consuming than meniscus repair. The recovery time after a meniscus repair is about 3 months where regular exercise to restore strength and knee mobility are recommended. Rehabilitation after meniscal tear with decreased healing potential, limited weight bearing and flexion of more than 60 degrees for the first 4 weeks have been suggested in order to protect the repair. The exercise protocol consists of three phases, where each phase has different goals to achieve. For instance, phase 1, acute stage, inflammation and swelling should be diminished, restore range of motion and re-establish quadriceps muscle activity. In phase 2, muscular strength and endurance must be improved, establish full non-painful range of movement and gradually return to functional activities. Finally, after progression criteria have been met, the goals for phase 3 should be to enhance muscle strength and endurance, maintain full range of movement and return to sport.