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Home > The Unhappy Triad – A Complex Injury of the Knee

The Unhappy Triad – A Complex Injury of the Knee





Boyd W. Haynes III, MD

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Knee injuries are one of the most common reasons for people to seek care from an Orthopaedic physician.  Because the knee joint is complex and consists of bones, cartilage, ligaments, tendons and other soft tissues, a lot can go wrong.  Sometimes, the ACL (anterior cruciate ligament), the meniscus and the MCL (medial collateral ligament) can all be damaged at the same time in a single traumatic injury. This is known as the Unhappy Triad, Blown Knee or the Terrible Triad.  Why?  Because an injury like this is extremely painful, debilitating and always requires surgery to repair the damage, making for an unhappy athlete indeed!

The Unhappy Triad is most commonly seen in rugby, skiing, martial arts, and ball sports, such as football. It can happen whenever a lateral force is applied to the knee while the athlete is standing in a fixed position or in a sport that requires a great deal of pivoting from a fixed point.  To illustrate how this injury can occur, I’ll provide two examples:  1) envision a down-hill skier whose ski remains in a fixed position while their leg twists or 2) envision a football player who gets tackled from the outside at the knee while his foot is planted on the ground.  If thinking about that makes you wince inside, imagine how it feels to the injured athlete.

In the old days, any athlete who had a blown knee typically would have to kiss their athletic career goodbye.  With the advent of Sports Medicine, modern arthroscopic techniques and other surgical advancements, the Unhappy Triad can be successfully treated with surgery, intensive post-surgical Physical Therapy and training modifications. Most athletes can expect to fully recover from having a blown knee if they adhere to the strict rehabilitation guidelines and recovery protocols, although some will never regain the strength and range of motion they once had.

As anyone who has had a blown knee will tell you, this isn’t the type of injury you tough out, rub some dirt on or just ignore, hoping it gets better. Symptoms of a blown knee are extreme pain, rapid swelling, stiffness, limited range of motion and a feeling of instability in the knee.  Bruising typically occurs 1-3 days after the injury.  As this injury often occurs to athletes, acute treatment immediately after injury typically includes the PRICE protocol: Protection, Rest, Ice, Compression and Elevation.  It is imperative that the patient be seen by a qualified Orthopaedist as soon as possible so that the injury can be accurately evaluated and treatment begun, which always includes surgery. 

When I see an athlete whom I suspect has the Unhappy Triad, I do a thorough physical exam, order x-rays and ask lots of questions about the specific circumstances surrounding the injury.  I will also order a stat MRI scan that will allow me to visualize all of the soft tissue components of the knee and to determine the severity of the injuries and develop the necessary surgical plan. Each injured knee component must be treated separately.  The ACL and meniscus will require surgery to repair, however, all but the most severe MCL injuries can be treated non-surgically with supportive measures, such as bracing.

While we wait for a surgery date, I will have the patient continue rest, icing, compression and elevation of the knee. Pain management will be necessary and I will prescribe crutches, so that the patient is non-weight bearing.  I may also splint or brace the knee to provide added support.

Most of the ACL and meniscal repairs that I perform now are done arthroscopically, through tiny incisions using specialized surgical tools and a camera.  Addressing the ACL will depend on the severity of the tear and if the patient’s ligament can be salvaged.  If not, I will have to use an Allograft or cadaver ACL or a tissue I take from the patient, called an autograft.  Autografts can be taken from the hamstring, quadriceps or patellar tendon. I make the decision whether to use donated tissue or the patient’s own tissue based on their age and the type of injury.  Sometimes, I will use a combination of graft types.  I typically try to salvage as much of the meniscus as possible during surgery and tack down and smooth out any rough edges. 

Recovery from surgery will take anywhere from six months to a year. Immediately after surgery, the patient will be non-weight bearing for four weeks.  I will put them in a knee brace to hold it straight for two weeks, except when doing gentle ROM exercises. Icing throughout the day during this early phase is recommended. After the initial post-surgical phase of two weeks, the knee brace will be unlocked to allow for movement of the knee.  The brace may be worn until eight weeks post-op.  After four weeks, gradual weight bearing will be allowed and increased incrementally.

Physical Therapy will be an essential part of the athlete’s rehabilitation.  The athlete should expect to spend several hours a week, if not more, with their Therapist, and will be expected to spend even more time exercising on their own at home. The goal of PT is to increase muscle strength and range of motion while not overtaxing the newly implanted graft(s).  In partnership with the Orthopaedic physician, the Physical Therapist will employ a variety of modalities to decrease swelling and pain and to encourage healing, while prescribing an exercise regimen to help the athlete achieve his or her rehabilitation goals.  Slow and steady wins the race, and with time, patience and persistence, the athlete can expect to return to and participate in the sport that they love.

Make an appointment with Dr. Haynes or another OSC provider by clicking the “Request Appointment” button below or by calling (757) 596-1900.  

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