The knee meniscus has several important functions in the knee including shock absorption, load transmission and joint stability. Small tears in the meniscus are often asymptomatic (no symptoms). Larger tears often become painful and produce mechanical symptoms of catching or locking in the knee joint and the knee may swell. Unfortunately as we age, the meniscus undergoes degeneration that increases the risk for tears.
Meniscus tears in children and young adults are usually the result of a major traumatic injury the result of a major traumatic injury to the knee. After the age of 40 (“over the hill”) meniscus tears are often degenerative-type tears and patients may not recall any specific injury. Many patients first report symptoms after getting in and out of a bed or car. They often report a catching type pain with twisting or bending the knee.
In addition to the history and physical examination, the orthopedic surgeon will often obtain an MRI to evaluate the knee for torn meniscus cartilage. The orthopedic surgeon will use the patients’ symptoms, exam, age, health status and MRI findings to determine if arthroscopic surgery is warranted. Arthroscopic surgery on the knee is an out-patient procedure when a scope and arthroscopic instruments are used to perform the surgery through small puncture wounds in the skin.
The ability of meniscus tears to heal is primarily dependent on the vascular supply of the meniscus. Degenerative tears with poor vascularity do not heal and often require arthroscopic shaving of the torn meniscal fragments (partial meniscectomy). The surgeon attempts to preserve all remaining meniscal tissue. In younger patients with traumatic meniscus tears; however the location of the tear ultimately dictates the rate of healing. Because the vascular supply of the meniscus is from the periphery inward, peripheral tears in the vascular zone heal the best. Tears on the inner rim of the meniscus with no blood supply will not heal and require shaving of the torn fragments. Surgical techniques have continued to improve this the results have improved. Efforts to replace or regenerate the meniscus through methods such as tissue engineering show promise but the results are limited thus far. The orthopedic surgeon will always consider the best long-term options to benefit the patient. The post-op rehabilitation needs to factor in the type, location and stability of the repair. Rehabilitation after a meniscus repair is purposely slower to allow biologic healing of the slow healing tissue. An experienced orthopedic surgeon along with a cooperative patient is the key to success.