”Blown knee” or ”the unhappy triad,” also sometimes called ”terrible triad,” is a knee injury common in contact sports such as hockey, rugby, American football and combat sports. The term “the unhappy triad” itself was coined by D.R. O’Donoghue in 1950. The unhappy triad involves an A.C.L tear, an M.C.L tear, lateral meniscus and/or medial meniscus tear. This is a combined knee injury caused by an A.C.L tear. Usually, it occurs after receiving a blow on the lateral outside part of the knee joint, while the leg is fixed firmly on the ground. An A.C.L ligament tear causes the now unstable knee to shift. While the knee joint is shifting inward, it compresses the lateral meniscus between the femur and the tibia, causing the meniscus to tear. Now, due to the abnormal position of the knee joint, the M.C.L ligament also is torn. Sometimes you also can have a blown-knee injury by awkwardly landing on your knee, which means that contact is not always present, but usually so-called non-contact sports are more likely to trigger a ligament tear or meniscus tear.

So-called O’Donoghue’s triad at first involved A.C.L ligaments, M.C.L ligaments and medial meniscus, but statistics have shown that the lateral meniscus is more likely to be torn as a result of inward movement of the knee joint. However, in some cases, the medial meniscus also is torn while suffering the unhappy triad. The unhappy triad is not the most common knee injury, fortunately so, but it’s something you definitely want to avoid, the reason being that it takes long time to fully recover from this knee injury. It could take 10 to 18 months of rehabilitation before you will be able to participate in contact sports again.

Symptoms:

The knee is swollen, and severe knee pain usually is present. While trying to walk on the knee, you’ll feel like the knee is giving out.

Treatment:

You want to give rest to your knee, keep it in an elevated position and apply an ice and compression -R.I.C.E in order to reduce swelling and pain. Treatment, however, includes surgery in order to reconstruct the A.C.L ligament. During surgery, the lateral and/or medial meniscus tear also is treated. M.C.L ligament tears normally do not require surgery to fix, but most likely you will wear a knee brace in order to stabilize the knee joint during rehabilitation. Treatment also depends on the severity of the blown knee. Sometimes the A.C.L ligament is not torn but only strained. Thus, on rare occasions the conventional treatment also is possible, provided, of course, that the meniscus is able to heal by itself. The problem with the meniscus is that there is not much blood circulation, which usually is required for the healing process. The outermost edges of the meniscus have the most blood vessels, so it really depends on the severity and the type of the meniscus tear.

While it’s possible that the A.C.L ligament tear will not need surgery, it may not be as strong as a surgically reconstructed ligament. It’s an important question you will want to ask your doctor. Although conventional treatment might work, in case you want to participate in your favorite contact sport again, you may want the A.C.L ligament to be reconstructed surgically. A weak A.C.L ligament will possibly lead to chronic A.C.L tears. However, it might be tempting to choose conventional treatment, as the recovery time is much shorter. Remember that the A.C.L ligament is providing important stability to the knee joint, and every knee injury carries a risk to develop early osteoarthritis.

Prevention:

When participating in contact sports, there is not much you can do in order to prevent a combined knee injury. Keeping the leg muscles in good shape will certainly reduce the risk. However, wearing a knee brace that will support the knee joint usually is not a very good idea, as it gives you a false feeling of security. Wearing these kinds of knee braces is not a very efficient method to prevent knee injuries. Stabilizing knee braces are helpful only to immobilize the knee during the rehabilitation process. This is, of course, my personal opinion.

Rehabilitation:

Regardless of whether you have the unhappy triad treated surgically or conventionally, physical therapy is the most important part of rehabilitation process. Safely done, strengthening exercises are an important component of physical therapy, as are exercises to recover the range of motion of the knee joint. You gradually will return to full activity. Wearing a knee brace during rehabilitation will allow the M.C.L injury to heal. Best way to heal is use cold therapy using knee cryo cuff