Arthroscopic partial meniscectomy of the knee is the most commonly performed orthopedic surgery in the United States, with about 700,000 such procedures occurring annually. This is a minimally invasive surgery performed to address tears of the medial or lateral meniscus of the knee. The meniscus is a half-moon shaped piece of cartilage in the knee that distributes compressive forces through the knee, functioning as a shock absorber. Tears can occur in the medial meniscus, over the middle portion of the knee and the lateral meniscus, over the outer portion of the knee. Surgically, the torn portion of the meniscus is cut or removed to restore a stable rim or edge to the meniscus. Removing a portion of the meniscus compromises the ability of the meniscus to absorb the compressive forces of activities.
There are two mechanisms by which tears of the meniscus can occur. Acute tears occur when there is a forceful twist of a bent knee, most often during weight bearing activity. Degenerative tears are typically seen in older individuals and occur due to loss of elasticity of meniscus as a person ages. Degenerative tears also are often seen in the setting of osteoarthritic degeneration of the joint, as degeneration of the joint changes the compressive forces across the meniscus and thus contributing to meniscal injury. Meniscal tears are typically diagnosed through a history and physical examination in combination with magnetic resonance imaging(MRI). Individuals with a meniscus tear will present with pain in the knee, often exacerbated by activities such as walking. They may also report symptoms of swelling, locking/”catching”, or buckling/”giving way”. In research studies, pain and quality-of life measures are often used to quantify a person’s level of dysfunction, but are also used to document a person’s response to treatment.
Degenerative-type meniscal tears are exceedingly common in the aging population. Some population based studies have recorded a prevalence of tears or damage to the meniscus between 20-30% in 50 to 59 year-olds. The prevalence increases to as high as 60% of individuals older than 70, clearly demonstrating a higher incidence as one ages. Osteoarthritis is also more commonly seen as a person ages and we also see an increase in the incidence of meniscal tears and damage when there is underlying osteoarthritis. Ninety-five percent of individuals with severe joint degeneration had MRI evidence of damage to the meniscus. Interestingly, 60% of individuals in the same study were found to have damage or tearing of the meniscus on MRI and reported no symptoms in the previous month. Greater than 50% of arthroscopic surgery for tears of the meniscus are performed on individuals over the age of 45. Risks of an arthroscopic partial meniscectomy include bleeding and infection, but also includes an increased risk of osteoarthritis. With 20-30% of the population between 50 and 60 showing signs of meniscus tear in the absence of symptoms, it is important that the appropriate treatment be recommended. The severity of a person’s pain and their level of dysfunction should be considered in any treatment regimen. Pain is a prevalent complaint when someone has a degenerative tear of the meniscus. Because so many patients with degenerative tears of the meniscus have some level of underlying degenerative osteoarthritis, an arthroscopic surgery is not a guarantee of pain relief. If a person is having mechanical symptoms such as locking and buckling, an arthroscopic surgery may be helpful in alleviating these symptoms.
Multiple studies have shown conservative treatment measures to be just as beneficial, if not more beneficial than arthroscopy for degenerative meniscal tears. Patients who received conservative treatment often reported a reduction in pain, improved function, and increased quality of life regarding their knee. Conservative treatment includes pain relief measures such as non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen (Tylenol) and/ or corticosteroid injections. Improved overall function can often be achieved through a supervised exercise program in the form of physical therapy. Exercise programs lead to enhanced strength of musculature around the knee and of stabilizing musculature to help balance forces across the knee. A period of conservative treatment typically lasts six to eight weeks. This should also be followed by a maintenance home exercise program for the best overall outcome. In individuals with a degenerative meniscal tear, surgery should be reserved for those with painful clicking, locking, buckling, or recurrent swelling or for those who do not have improved pain or function following a course of conservative treatment. It is important to note, however, that an arthroscopic surgery for a degenerative meniscus tear is not a guarantee of symptom resolution and improved functioning.