The Anterior Cruciate Ligament (ACL) is a ligament in the knee which provides stability to the knee, particularly during pivoting, twisting or fast paced movements. Injury to this ligament is becoming increasingly common. Most commonly it results from a non-contact twisting injury, although it can also happen during a collision or contact injury.

The Anterior Cruciate Ligament is important in maintaining rotatory stability of the knee, particularly in pivoting sports. It is often torn in pivoting movements off a single leg or single leg landing after jumping.

Natural History (What happens if I do nothing?)

The ACL has minimal capability to heal itself, so once ruptured, the laxity within the knee remains. If patients are experiencing symptoms from the laxity within the knee, or wish to return to high level twisting and pivoting sports, then ACL reconstruction is often recommended. Repeated instability episodes with associated swelling over time may lead to damage of articular cartilage and menisci which can result in degeneration of the knee over time.

Treatment Options

The ACL does not heal on its own and it is generally not possible to repair it. Therefore, the ligament will need to be reconstructed. To achieve this, a ‘graft’ is obtained from another area of your body and then inserted in place of the old, torn ACL. Numerous graft options exist, including hamstrings, patella tendon and quadriceps tendon. Each case is unique, and your Orthopaedic Knee Specialist will discuss their preference of one graft over another for you.

This is followed by intensive rehabilitation and the patient should not return to pivoting sports for at least 6 months.

Arthroscopy is a common surgical procedure in which a joint (arthro) is viewed (scopy) using a small camera. Arthroscopy is usually done through two small incisions around the knee, through which a camera and small instruments can be inserted into the knee to feel, repair or remove damaged tissue. This approach minimizes trauma and generally results in faster recovery and lower complication rates.

Examples of operations commonly carried out with this method are partial meniscectomies, meniscal repair, removal of loose bodies, ACL and PCL reconstructions and surgery to the articular cartilage.

Knee replacements are usually performed for end stage osteoarthritis where the patient remains symptomatic despite appropriate non operative management. They are also performed for a variety of other conditions such as inflammatory arthritis (eg rheumatoid), avascular necrosis and occasionally, severe trauma.

During the operation, surgical instruments are used to resurface the ends of the femur and tibia. The knee cap (patella) may or may not be relined. This is done after making a vertical incision over the front of the knee to gain access to the joint surfaces. Various methods can be used to replace the knee, including robotics, computer navigation, patient specific instruments and traditional instrumentation to align the knee replacement. The knee replacement is made of metal, with a plastic liner articulating between the components. This removes the painful parts of the arthritic knee, with the aim of producing a knee which moves freely and is comfortable for the patient.

There are 2 menisci in the knee; one in the inside of the joint (medial) and one on the outside (lateral). They are important structures, as they bear load, shielding the joint surfaces for stress and making the joint more congruent.

During the knee’s movement, they glide backwards and forward with the femur (thigh bone) with respect to the tibia (shin bone) as the knee flexes and extends. During this movement, the edge of the meniscus may get caught between the two bones, tearing it. This both defunctions the torn portion of the meniscus and results in a loose flap which may get caught in the joint causing pain. If the flap is big enough, the joint will lock.

Meniscus was previously thought to be largely irreparable, although with current techniques and specific surgical training, the ability to repair meniscal tears has greatly increased.

If symptoms persist, patients are best treated with an arthroscopy and either a partial meniscectomy or repair, depending on the tear pattern and the age of the patient.