At times there is no substitute for simply looking inside of a knee joint to find and correct a problem. Knee arthroscopy is a minimally invasive technique for doing just that; it refers to a broad category of surgical procedures (typically outpatient) that involve looking within the knee joint using a fiberoptic video camera and small instruments. Knee arthroscopy is useful for the diagnosis and treatment for a number of common problems within the knee.
Many patients may have internal derangement of the knee, which refers to the knee having a problem from within that keeps it from moving and functioning in the normal manner that it should. Common symptoms include locking, catching, clicking, popping, and buckling or giving way. These types of problems are often caused by a problem within the joint, such as a loose body or a meniscal tear (commonly referred to as a "torn cartilage"). Arthroscopy is useful not only for diagnosing these problems by looking inside the knee, but also for correcting them by removing a loose piece of bone, trimming or repairing a torn area of cartilage, or removing excessive synovial lining or scar tissue.
There is a limited role for arthroscopy with arthritis. In the past, some surgeons have advocated "cleaning out" an arthritic knee (e.g., arthroscopic lavage), and in fact arthroscopy is very good at relieving mechanical symptoms such as locking even in an arthritic knee. Flushing the knee does remove inflammation, at least temporarily. However, it cannot "cure" arthritis, and for that reason many surgeons will not recommend its use for simple arthritic changes unless there are also mechanical symptoms.
Arthroscopy also can be used to wash out an infection within the knee joint, without requiring a large incision and opening the entire joint.
Chondroplasty refers to smoothing out roughened joint surfaces or cartilage, and sometimes isolated "craters" in the joint surface can be drilled during arthroscopy to try to get them to fill in with scar tissue. These procedures are fairly quick outpatient procedures, but they may require limited weightbearing for a few weeks using crutches while the cartilage heals. Arthroscopy also may be used to visually inspect a knee to help determine the extent of arthritis and damage, particularly for helping a surgeon to determine if a patient may be best helped by a partial versus total knee replacement.
Occasionally there may be a discrete area of severe damage in the form of an osteochondral defect (see previous chapters). An isolated lesion can sometimes be treated with microfracture or arthroscopic drilling, techniques that are designed to stimulate formation of scar tissue to fill in the defect. This typically requires a period of limited weightbearing while it heals.
Meniscal tears and loose bodies are frequently seen on imaging studies such as an MRI. However, not all meniscal tears or loose bodies can be detected with an MRI, and the "gold standard" for diagnosis is to then perform a diagnostic arthroscopy. The idea of looking inside an area of the body with a camera is not limited to just orthopaedics; similar procedures include endoscopy (looking down the esophagus with a fiberoptic camera) or colonoscopy (from the other end!), and like those procedures arthroscopy is typically a short, outpatient procedure that often does not require full anesthesia and can even be performed under local anesthesia only in many cases.
Some meniscal tears are amenable to repair, but many have a "shredded" appearance or may not be good candidates for repair because of their location (some regions do not have good healing potential because of the way the blood supply is arranged). In these cases, the rough edge is resected back to a smooth, stable edge, which usually makes a significant improvement in symptoms. In past decades before fiberoptic arthroscopic instruments were available, surgeons would often remove the entire meniscus through an open procedure, but this often led to severe arthritis over the following years. Arthroscopy allows surgeons to remove just the torn portion of the meniscus, leaving as much as possible to cushion the joint.
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