Last updated: 11/24/2009

Arthroscopic surgery for acute injuries

The knee bone sits between the femur and the tibia, attached by four ligaments that keep the knee stable as the leg moves. These ligaments can be damaged or torn through injuries and accidents. Once damaged, they do not offer stability to the knee and can cause buckling, or allow the knee to "give way." Ligaments can also "catch" and freeze the knee or make the knee track in a different direction than its leg movement, causing the knee to dislocate. Traumatic injuries such as automobile accidents may cause more than one ligament injury, necessitating multiple repairs to ligaments.

Four arthroscopic procedures relate to damage to each of the four ligaments that stabilize the knee joint movement. The four procedures are:

• Anterior cruciate ligament (ACL). A front-crossing ligament attaching the femur to the tibia through the knee; this ligament keeps the knee from hyperextension or being displaced back from the femur. The ACL is a rather large ligament that can withstand 500 lb (227 kg) of pressure. If it is torn or becomes detached, it remains that way and surgery is indicated. In the most severe cases, a graft to the ligament is necessary to reattach it to the bone. The surgery can use tissue from the patient, called an autograft, or from a cadaver, called an allograft. The patella tendon, which connects the patella to the tibia, is the most commonly used autograft. ACL reconstructive surgery involves drilling a tunnel into the tibia and the femur. The graft is then pushed through the tunnels and secured by stapling or sutures.
• Posterior cruciate ligament (PCL). A back-crossing ligament that attaches the front of the femur to back of the tibia behind the knee that keeps the knee from hyperextension or being displaced backward. PCL injuries are not as frequent as ACL injuries. These injuries are largely due to falls directly on the knee or hitting the knee on the dashboard of a car in an accident. Both displace the tibia too far back and tear the ligament. Surgery to the PCL is rare, because the tear can usually be treated with rest and with rehabilitation. If surgery is required, it is usually to reattach the PCL to the tibia bone.
• Medial collateral ligament (MCL). This is an inside lateral ligament connecting the femur and tibia and stabilizing the knee against lateral dislocation to the left or to the right. The injury is usually due to external pressure against the inside of the knee. In the case of a grade I or II collateral ligament tear, doctors are likely to brace the knee for four to six weeks. A grade III tear may require surgery to repair ligament tear and is followed by three months of bracing. Physical therapy may be necessary before resuming full activity.
• Lateral collateral ligament (LCL). An outside lateral ligament connecting the femur and tibia and stabilizing the knee against lateral dislocation. In the case of a grade I or II collateral ligament tear, doctors are likely to brace the knee for four to six weeks. A Grade III tear may require surgery to reattach the ligament to bone. Surgery will be followed by three months of bracing. Physical therapy may be necessary before resuming full activity.

Patello-femoral syndrome (PFS)

The patella rests in a groove on the femur. Anything but a good fit can cause the patella to be unstable in its movement and very painful. Some individuals have chronic problems with the proper tracking of the patella with the femur. This may be associated with conditions related to physical features like foot pronation, or to types of body development in exercising or overuse of muscles. In the case of damage, an examination of the cartilage surrounding the patella can identify cartilage that increases friction as the patella moves. Smoothing the damaged cartilage can increase the ease of movement and eliminate pain. Finally, a tendon can occasionally make the patella track off center of the femur. By moving where the tendon is attached through lateral release surgery, the patella can be forced back into its groove.

Pain management with lavage and debridement

In addition to the ligament and patella surgeries that are largely required for traumatic injuries, arthroscopic surgery treats the wear and tear injuries related to a torn meniscus, which is the crescent-shaped cartilage that cushions the knee, as well as injuries to the surface of bone that makes joint movement painful. These are related to osteoarthritis and rheumatoid arthritis.

In lavage and debridement, the surgeon identifies floating or displaced tissue pieces and either flushes them out with a solution applied with arthroscopy or smoothes the surface of bone to decrease pain. These two surgical treatments are controversial because research has not indicated that alternatives to surgery are not as successful.

All of the above procedures are conducted through the visualization offered by the lighted arthroscope that allows the surgeon to follow the surgery on a television monitor. Instruments only about 0.15 in (4 mm) thick are inserted in a triangular fashion around the knee. The arthroscope goes in one incision, and instruments to cut and/or smooth and to engage in other maneuvers are put through the other incisions. In this fashion, the surgeon has magnification, perspective, and the ability to make tiny adjustments to the tissue without open surgery. The triangular approach is highly effective and safe.