The meniscus of the knee has been the topic of numerous research studies in recent years, attempting to aid in improved clinical practice guidelines for treating patients with suspected meniscal tears. The medial and lateral meniscus aid in knee joint lubrication, load transmission, shock absorption, and knee joint stability. They are attached to the tibia (shin bone) by coronary ligaments, and have the ability to shift slightly with flexion (bending) and extension (straightening) of the knee. The outer 1/3, and a portion of the middle 1/3, of the meniscus have a blood supply, and the outer 2/3 of the meniscus is neural (has a nerve supply). These anatomical characteristics are important, and aid practitioners in making decisions regarding treatment for meniscal lesions.
Meniscal tears are common injuries in the knee, and can occur traumatically or insidiously. Activities which require a lot of twisting and cutting of the lower leg increases risk for meniscal lesions, and are common in sports such as basketball, soccer, and football, as well as others. The meniscus also wears with time, known as a degenerative meniscal tear. Research has shown that 91% of the older population with knee pain have abnormal meniscii on imaging, as well as 76% of the older individuals without knee pain, indicating an increased likelihood of having a meniscal tear in the knee as you age. Pain typically occurs with twisting maneuvers of the knee or large impact activities, such as getting in/out of the car or bed, coming up from a squatted position, cutting/diagonal movements of the legs, walking on uneven surfaces, and running/jumping activities.
Historically, meniscal lesions were treated with total meniscectomies, where the surgeon would remove the entire structure, thinking the meniscus did not serve much purpose. Studies have shown complete removal of the meniscus drastically increases the amount of force going through the knee joint (increase of 235% with total meniscectomy), and increases joint contact area by 75%. Because of these findings, surgical treatment has turned to partial meniscectomies, or meniscal repairs. A partial meniscectomy looks to retain as much of the meniscus as possible, while removing the frayed or torn regions through arthroscopy. A meniscal repair can be accomplished if the area of tear is within the vascular zone of the meniscus, but typically requires longer rehabilitation times secondary to the early need for protection of the meniscal healing region.
Conservative treatment options for meniscal tears have become more the first option to practitioners treating patients with suspected meniscal tears, secondary to recent research showing similar outcomes with physical therapy versus surgery for meniscal lesions. Since the meniscus moves slightly with varying degrees of knee flexion/extension, the belief is that some tears may not be painful because they have the ability to ‘get out of the way’ during various activities. Because of the joint stability role the meniscus has within the knee, however, the patient will require increased neuromuscular control through joint strength and joint proprioception, in order to avoid future knee catching episodes and increased likelihood of pain.
Research has also identified that a physical therapy assessment can identify a probable meniscal lesion in the knee at the same rate as an MRI, at significantly less cost to the patient and the insurance company. Surgeons have also identified that the better a patient is going into surgery (no knee joint swelling, full range of motion of the knee, normal gait (walking), and maximized leg strength), the better the patient does post-operatively with rehabilitation. Therefore, most surgeons will have the patient maximize their outcomes with physical therapy prior to knee surgery, in hopes of avoiding surgery altogether or preparing the patient for a successful outcome post-operatively if surgery becomes the best option for the patient.