Arthroscopy is a procedure most often performed on the knee joint and requires the use of a device called an arthroscope. An arthroscope is a tubular instrument approximately 5 mm. (1/8 inch) in diameter, which contains fiberoptics and lenses to convey a cold light into a joint and return an image to a small television camera. The image is displayed on a monitor screen in the operating room. The arthroscope is used for both diagnosis and treatment.

Anatomy and Physiology

• The knee is a complex mechanism formed by the joining of bones, ligaments, muscles and protective cartilage (Figure 1)
• Bones
  1. Femur. The femur or thighbone extends from the hip to the knee and forms the upper aspect of the knee
  2. Tibia. The tibia is the major bone in the lower leg, sometimes called the shinbone. The tibial plateau is the portion of the tibia that forms the lower aspect of the knee
  3. Fibula. The fibula is a slightly shorter bone that runs parallel and along the outside of the tibia
  4. Patella. The small bone in front of the knee: the kneecap
• Major ligaments
  1. Medial collateral ligament---limits inward bending of the knee. This ligament extends from the lower end of the femur on the medial side (inside) of the knee to the tibia
  2. Lateral collateral ligament---limits outward bending of the knee. This ligament extends from the lower end of the femur on the lateral side (outside) of the knee to the fibula
  3. Anterior cruciate ligament--- This is a rope like ligament that runs from the center of the femur to the anterior aspect (front) of the tibia. It is a major stabilizer of the knee that prevents the femur from rotating and sliding back on the tibia (Figure 2)
  4. Posterior cruciate ligament--- This is a rope like ligament that runs from the center of the femur to the to the posterior aspect (back ) of the tibia. It works to stabilize the knee by preventing the femur from rotating and sliding forward on the tibia
• Muscles
  1. The quadriceps muscle ends in the patellar tendon that covers the patella
  2. The hamstring muscles strengthen the back of the knee
• Cartilage
  1. Smooth white cartilages cushion the knee, line the surface of the femur, tibia and patella within the joint
  • Menisci are C-shaped cartilages sandwiched between the femur and tibia, one on the inside (medial meniscus) and one on the outside side of the knee (lateral meniscus)
• Synovium is a special tissue that lines all motion joints and produces a lubricating fluid
• Knee function
  1. The knee is not just a simple hinged joint that bends backward (flexion)
  2. It also has a rotary motion that locks the femoral condyles into the tibial plateau on straightening (extension) the leg
  3. On extension of the knee, the ligaments become tight and convert the knee into a rigid locked structure
  4. The knee unlocks on flexion allowing the increased range of motion seen as the lower leg swings backward

Figure 1 - Anatomy of the knee

Figure 2 - Arthroscopic view of the anterior and posterior cruciate ligaments