Knee Arthroscopy

The arthroscope is a fiber-optic telescope that can be inserted into a joint (commonly the knee, shoulder, and ankle) to evaluate and treat a number of conditions. A camera is attached to the arthroscope and the picture is visualized on a TV monitor. Most arthroscopic surgery is performed as same-day surgery and is usually done under general anesthesia. Knee arthroscopy is a very common procedure and millions of procedures are performed each year around the world.

Knee arthroscopy is useful in evaluating and treating the following conditions:

• Torn, floating cartilage (meniscus): The cartilage is trimmed to a stable rim or occasionally repaired.
• Torn surface (articular) cartilage
• Removal of loose bodies (cartilage or bone that has broken off) and cysts
• Reconstruction of the Anterior Cruciate ligament
• Patello-femoral (knee-cap) disorders
• Washout of infected knees
• General diagnostic purposes

Basic Knee Anatomy

The knee is the largest joint in the body. The knee joint is made up of the femur, tibia and patella (knee cap). All these bones are lined with articular (surface) cartilage. This articular cartilage acts like a shock absorber and allows a smooth low friction surface for the knee to move on. Between the tibia and femur lie two floating cartilages called menisci. The medial (inner) meniscus and the lateral (outer) meniscus rest on the tibial surface cartilage and are mobile. The menisci also act as shock absorbers and stabilizers. The knee is stabilized by ligaments that are both in and outside the joint. The medial and lateral collateral ligaments are located along the sides of the knee joint and support the knee from excessive side-to-side movement. The anterior and posterior cruciate ligaments are located inside the knee joint and support the knee from buckling and giving way. The knee joint is surrounded by a capsule (envelope) that produces a small amount of synovial (lubrication) fluid to help with smooth motion. Thigh muscles, such as the quadriceps and hamstring muscles, are important secondary knee stabilizers.

Investigations

Routine X-Rays of the knee, which include a standing weight-bearing view, are usually required. An MRI scan which looks at the cartilages and soft tissues may be needed if the diagnosis is unclear. There is little value in the use of ultrasound in investigating knee problems.

Meniscal Cartilage Tears

Following a twisting type of injury, the medial (or lateral) meniscus can tear. This results either from a sports injury or may occur from a simple twisting injury when getting out of a chair or standing from a squatting position. Our cartilage becomes softer and more brittle as we get older and, therefore, can tear a little easier. The symptoms of a torn cartilage include:

• Pain over the torn area, i.e. on the inside or outside of the knee
• Knee swelling
• Reduced motion
• Locking if the torn cartilage gets caught between the femur and tibia

Cartilage Tears

Once a meniscal cartilage has torn, it will not heal unless it is a very small tear that is near the capsule of the joint. Once the cartilage has torn it predisposes the knee to develop osteoarthritis (wear-and-tear arthritis) in 15 to 20 years. It is better to remove torn pieces from the knee joint if the knee is symptomatic.

Torn cartilage in general continues to cause symptoms of discomfort, pain, and swelling until the loose, ragged pieces are removed. Only the torn section is removed and the knee should recover and become symptom-free. If the entire meniscus is removed, the knee will develop osteoarthritis in 15 to 20 years. It is standard to remove only the torn section of cartilage in the hope that this will delay the onset of long-term, wear-and-tear arthritis (osteoarthritis).

Occasionally, provided the knee is stable and the tear is a certain type of tear in a young patient (peripheral bucket-handle tear), the meniscus may be suitable for repair. If repaired, one has to avoid sports for a minimum of three months.

Articular (Surface) Cartilage Injury

If the articular (surface) cartilage is torn, this is most significant, as a major shock-absorbing function is compromised. Large pieces of surface cartilage can float in the knee (sometimes with bone attached) which causes locking of the joint and can cause further deterioration due to the loose bodies floating around the knee causing further wear and tear. Most articular cartilage wear will ultimately lead to osteoarthritis. Mechanical symptoms of pain and swelling due to cartilage peeling off can be helped with arthroscopic surgery. The surgery smoothes the edges of the surface cartilage and removes loose bodies.

Anterior Cruciate Ligament Injuries

Rupture of the Anterior Cruciate Ligament (ACL) is a common sports injury. Once ruptured, the ACL does not heal and usually causes knee instability and the inability to return to normal sporting activities. An ACL reconstruction is required and a new ligament is fashioned to replace the ruptured ligament. This procedure is performed using the arthroscope.

Patella (Knee-Cap) Disorders

The arthroscope can be used to treat problems relating to kneecap disorders, particularly mal-tracking and significant surface cartilage tears. Patients may need to stay overnight in the hospital if a lateral release has been performed as knee swelling is quite common. The majority of common kneecap problems can be treated with physical therapy and rehabilitation.

Inflammatory Arthritis

Occasionally, arthroscopy is used in inflammatory conditions (e.g. Rheumatoid Arthritis) to help reduce the amount of inflamed synovium (joint lining) that is producing excess joint fluid. This procedure is called a synovectomy. After the surgery, a drain is inserted into the knee and patients generally require one or two nights in the hospital.

Baker’s Cysts

Baker’s cysts or popliteal cysts are often found on clinical examination and ultrasound or an MRI scan. The cyst is a fluid-filled cavity behind the knee and, in adults, arises from a torn meniscus or worn articular cartilage in the knee. These cysts usually do not require removal as treating the cause (torn knee cartilage) will, in most cases, reduce the size of the cyst. Occasionally, the cysts rupture and can cause calf pain. The cysts are not dangerous and do not require treatment if the knee is asymptomatic.

Cartilage Grafting & Transplant

Isolated areas of articular cartilage loss can be repaired using cartilage transplant technology. This is a new and exciting field that is developing in the treatment of specific isolated cartilage defects in younger patients.

The process is called Autologous Chondrocyte Grafting. It involves harvesting cartilage cells from the affected knee, sending these cells to a laboratory, and then culturing the cells to multiply into many cells. The large amount of cells produced are then placed back in the affected knee and into the defect requiring resurfacing. Long-term results from the procedure are still to be determined but short-term results but are looking encouraging.

After a major cartilage or ligament injury has been treated, the knee can return to normal function. There is, however, a small increase in the risk of developing long-term wear-and-tear arthritis (osteoarthritis) and, depending on the degree of injury, activity modification may be required. Activities that help prevent knees deteriorating quickly include:

• Low-impact sports such as swimming, cycling, and walking
• Reducing weight and maintaining a healthy diet

Arthroscopy of the Knee: Patient Information

You must stop taking aspirin and anti-inflammatory medications 5 days prior to your surgery. You can continue taking all your other routine medications. If you smoke, you are advised to stop at least 3 days prior to your surgery.

You will be admitted to the surgical ward on the day of surgery and you cannot eat or drink anything at least 8 hours prior to the procedure.

You will meet with the nurses and your anesthetist who will ask you questions about your medical history.

The limb undergoing the procedure will be marked and identified prior to anesthesia being administered.

About 30 minutes prior to surgery, you will be transferred to the operating room.

Once you are under anesthesia, the knee is prepared in a sterile fashion. A tourniquet is placed around the thigh to allow a ‘blood – free’ procedure.

The arthroscope is introduced through a small (size of a pen) incision on the outer side of the knee. A second incision on the inner side of the knee is made to introduce the instruments that allow examination of the knee joint and treatment of the problem.

Once the procedure is over, the surgical incisions are closed with sutures and the knee is then dressed and bandaged.

Post-Operative Recovery

You will wake up in the recovery room and then be transferred back to the surgical ward.

A bandage will be around the operated knee.

Once you are recovered, your IV will be removed and you will be allowed to change back to your normal clothes.

Your surgeon will see your family prior to discharge and explain the findings of the operation and what was done during surgery.

Pain and nausea medication will be provided and should be taken as directed.

You may remove the bandage in 72 hours unless otherwise instructed and you may then shower. Do not scrub over your surgical incisions.

It is NORMAL for the knee to swell after the surgery. Elevating the leg when you are seated will help to reduce swelling. Placing ice packs on the knee for 15-20 minutes every hour, 3-4 times a day until the swelling is reduced will also help.

You are able to drive and return to work when comfortable unless otherwise instructed.

You will follow up with your surgeon 3-5 days after surgery to monitor your progress.

Risks of Arthroscopy

General anesthesia risks are extremely rare. Occasionally, patients have some discomfort in the throat as a result of the tube that supplies oxygen and other gases. Please discuss any concerns with your anesthetist prior to surgery.

Risks related to arthroscopic knee surgery include:

• Post-operative bleeding
• Deep Vein Thrombosis
• Infection
• Stiffness
• Numbness to part of the skin near the incisions
• Injury to blood vessels or nerves
• Chronic pain syndrome
• Progression of the disease process

The risks and complications of arthroscopic knee surgery are extremely small. One must, however, bear in mind that occasionally there is more damage in the knee than was initially thought and that this may affect the recovery time. In addition, if the cartilage in the knee is partly worn out then arthroscopic surgery has about a 65% chance of improving symptoms in the short-term but more definitive surgery may be required in the future. In general, arthroscopic surgery does not improve knees that have well-established osteoarthritis.

Post-Operative Exercises and Physical Therapy

Following your surgery, you will be referred to outpatient physical therapy to perform exercises that are helpful in speeding up your recovery. Strengthening your thigh muscles (quadriceps and hamstrings) is most important. Swimming and cycling are excellent ways to build these muscles up and improve movement.

Frequently-Asked Questions:

How long am I in the hospital?

A: You are usually in the hospital four hours from time of admission to time of discharge.

Do I need a knee brace or crutches?

A: A knee brace and crutches are usually not required unless you are having Anterior Cruciate Ligament reconstruction surgery.

When can I get the knee wet?

A: You may remove the surgical bandage and shower 72 hours after surgery unless otherwise instructed.

When can I drive?

A: You may drive 24 hours after surgery if the knee is comfortable.

When can I return to work?

A: You may return to work when the knee feels reasonably comfortable.

When can I swim?

A: You will be allowed to swim usually one week after surgery.

How long will my knee take to recover?

A: Depending on the findings and surgery, usually 4-6 weeks after surgery.

When can I return to sports?

A: Depending on the findings, you may return to sports usually 4-6 weeks after surgery.