Anterior cruciate ligament (ACL) injury

• a "pop" noted at the time of injury
• knee swelling within 6 hours
• knee joint instability
• knee joint pain on inner ( medial ) side of knee

Signs and Tests:
Physical examination may show signs of ACL injury. Manipulations of the joint may show:

• Lachman's test - the health care practitioner will have you lay on your back with your knee bent at a 30 degree angle. He/she then holds the end of your thigh ( distal femur) in one hand, and the top of the shin ( proximal tibia) in the other, and applies slow pressure to the back of the proximal tibia just below the knee. Increased looseness in the knee joint is indicative of ACL injury. You must be sure to relax your hamstring muscles or it could result in a false positive Lachman's test.
• anterior drawer test - This test is less accurate at diagnosing ACL injury. The health care practitioner will have you lay on your back with your knee bent to 90 degrees and foot resting on the table. The practitioner then grasps the top of the shin (proximal tibia) with both hands and places both thumbs on the end of the thigh bone ( tibial condyles). Your foot is stabilized by another person, or by the practitioner sitting on it, then slow pressure is placed on the proximal tibia. Any looseness in the joint could indicate ACL injury.
• pivot shift test of MacIntosh - this test requires relaxation and usually cannot be performed in acute injury. The health care practitioner will have you lay on your back. The foot on the symptomatic side is lifted with the leg straight and the foot turned inward. Pressure is applied to the outside of the knee while the knee joint is slowly bent. ACL injury is noted if the tibia moves out of joint at 30-40 degrees of knee flexion. Note: this test can be painful.
• ballotment test for hemarthrosis (joint bleeding ) - a physical examination test that allows the practitioner to detect the presence of fluid in a body space.

Procedures that show ACL injury include:

• a knee MRI
• a knee X-ray

Treatment:
Initial treatment of an ACL injury includes splinting, ice to the area, elevation of the joint (above the level of the heart), nonsteroidal anti-inflammatory drugs (NSAIDs), and limited physical activity until the swelling is down, motion is normal, and the pain is gone. Physical therapy may be recommended to help regain joint and leg strength. If the injury is acute or you have a high activity level, surgery may be necessary; this may be either knee arthroscopy or "open" surgical reconstruction. Age has an effect on treatment; younger patients are more likely to have problems without surgery.

Prognosis:
When tissue is damaged, the body begins a healing process almost immediately by moving various cells and elements to the area necessary to rebuild, or replace the injured tissue. Certain types of body tissues including ligaments and cartilage have little blood supply (vascularization) and they take longer to heal than comparable injuries to other tissues that are more highly vascularized (such as skin). This means that the ACL injury could take from weeks, months, or years to completely heal.

Complications:

• weakness of the joint, making it more susceptible to reinjury
• chronic pain

Call Your Healthcare Provider:
Call your health care provider if symptoms of ACL injury occur.

Call your health care provider if you are being treated for ACL injury and you notice increased instability in your knee, if pain or swelling return after they initially subsided, or if your injury does not appear to be resolving with time.

Also call if you reinjure your knee.


Arthroscopy allows for the visualization of the interior of a joint through the use of optic instruments. Surgery can now be performed on larger joints using direct visualization and miniaturized techniques. After this procedure, the person can often go home the same day.