Knee arthroscopy is a surgical procedure to allow evaluation and repair of the various structures and areas of the knee joint.
The knee is a complex, hinged joint, made up from three bones, the femur (thighbone), tibia (shinbone), and the patella (kneecap). Strong ligaments attach the bones to each other, keeping the joint in correct alignment, and tendons run from muscles to bones. Surrounding the joint is a fibrous articular capsule with an inner membrane called the synovium. This membrane secretes a lubricating and nourishing fluid that flows around the joint. Within the joint, the articulating ends of the femur and tibia are covered with smooth cartilage that allows the bones to slide over each other without friction. Also within the joint, between the bones and attached to the synovium, are crescent-shaped pads of meniscal cartilage that act as shock absorbers for the knee.
Injuries that have resulted in an unstable knee joint, or chronic conditions causing ongoing pain, are reasons to consider knee arthroscopy. The procedure might be suitable for:
- Repairing or removing a torn meniscus
- Reconstructing a torn anterior cruciate ligament or, rarely, a torn posterior cruciate ligament
- Clipping broken or torn articular cartilage
- Removing pieces of floating bone or cartilage
- Removing damaged or swollen synovial tissue
- Realigning a dislocated patella
- Removing a Baker’s cyst
- Repairing some fractures
- Smoothing rough bone surfaces
Knee arthroscopy can repair or relieve many, but not all, conditions, so careful consultation with an orthopedic surgeon is essential. Some knee problems caused by arthritis may not be successfully resolved by arthroscopy and pain might continue. Your health care providers will make as accurate a diagnosis as possible, based on your medical history, a physical examination, and imaging tests such as x-ray, MRI and CT scans. Occasionally the diagnosis might be uncertain, and your surgeon will only be able to fully assess the situation while performing the knee arthroscropy. In this case you would be advised beforehand of the probable course of treatment.
You will be given detailed instructions on which, if any, medications you are allowed to take and which you should stop taking before the procedure. Medications that prevent blood clotting have to be discontinued for a brief period before surgery. For the same reason, alcohol intake should be stopped two or three days prior to the arthroscopy. Smoking delays healing of bone and tissue, so if you smoke it would be wise to attempt to stop. You may be asked to fast for 6-12 hours before surgery, depending on the anesthetic that will be administered.
Knee arthroscopy is normally performed on an outpatient basis, meaning that you will not stay overnight in the hospital.
You will meet with an anesthetist who will inform you about the particular form of anesthetic you will receive. Sometimes a local anesthetic is administered, where only the knee is numbed. In other situations a spinal epidural anesthetic is more appropriate, in which case you will be numb below the waist. Occasionally a general anesthetic is used to send you completely to sleep. With a local or regional (spinal) anesthetic it is sometimes possible to look at a screen and watch the surgery as it takes place.
After proper anesthesia, a small incision is made into the knee joint to allow for the insertion of the arthroscope. The arthroscope is a very narrow, soft, tube with a fiber-optic light, a magnifying lens, a fluid-exchange system, and a tiny camera. It is attached to a cable leading to a large video monitor, enabling the surgeon to easily view the knee during evaluation and surgical treatment.
The knee joint is filled with a sterile saline fluid. This serves three purposes: it replaces the fluid in the knee with a clear liquid, giving the surgeon a better view of the structures, the pressure of the fluid helps to control bleeding, and the joint space is expanded, giving the surgeon more room in which to operate.
When the surgeon has properly evaluated the joint and decided on the course of treatment, between 2 and 4 further incisions are made around the knee. These are again small, less than half an inch in length. Various instruments can be inserted through these incisions and used by the surgeon to repair or remove damaged tissue.
A knee arthroscopy usually takes under 2 hours to complete. When the surgeon has finished, the incisions are closed with sutures and a compression bandage put on the knee. Normally you will be allowed home after an hour or two. You will not be able to drive, so you will need to have arranged transport.
Recovery times depend upon your original state of health, the particular injury or condition that has necessitated surgery, the level of activity you wish to return to, and how willing you are to spend the necessary time recovering. Simpler conditions such as a torn meniscus, or the removal of a Baker’s cyst, usually heal quickly and a return to normal activity is possible within 6-8 weeks. Ligament reconstruction, on the other hand, can take up to a year to fully heal.
Using a crutch temporarily will prevent weight being put on the recovering knee and, depending on the surgery you have undergone, you may also wear a knee brace for a time. Your surgeon will advise you on this matter.
Ice packs placed on the knee will help to relieve swelling, as will elevating the knee above the level of the heart, whenever possible. Pain medications can be taken, according to instruction.
Physiotherapy after knee arthroscopy is sometimes needed, in which case you will be taught certain exercises to restore strength and range of motion in the joint. To begin with, any exercises will be to stretch the muscles, and should only be performed if no pain is felt and you have your doctor’s approval.
Lie on your back on the floor with a rolled up towel under the ankle of the affected leg. Gently press the ankle down onto the towel and straighten your knee as much as you can. Hold for 5 seconds then relax. Repeat 10 times.
Lie on your back on the floor with your knees slightly bent. Without moving the leg, pull the heel down into the floor. You should feel the stretch in the back of the thigh. Hold for 5 seconds then relax. Repeat 10 times.
Lie on your back on the floor with your knees slightly bent. Squeeze the buttock muscles and hold the squeeze for 5 seconds. Relax then repeat 10 times.
Straight leg raise:
Lie on your back on the floor. Bend the unaffected leg to a 90-degree angle, keeping the foot flat on the floor. Keep the affected leg straight and, using the thigh muscles, slowly lift the leg 6 inches off the floor. Hold for 5 seconds then slowly lower to the floor. Repeat 10 times.