Ask a Vail Sports Doc column: I think I tore my ACL, now what?
October 17, 2016
The town is buzzing with excitement over the recent snowfall at high altitude here in the Vail Valley. While we wish everyone a safe winter season, with just 50 days until the opening of Vail Mountain, we want our winter enthusiasts to be informed about anterior cruciate ligament injury and what to expect if you experience a forceful twisting injury to the knee.
The anterior cruciate ligament, or ACL, is one of four major ligaments that provide stability to the knee joint. ACL injuries are very common among athletes of all ages and competition levels, with approximately 200,000 reported cases in the United States each year. Skiing, soccer, football and basketball are activities in which we see a higher incidence of ACL injuries due to the cutting and pivoting nature of these sports.
The ACL stabilizes the knee, preventing giving way episodes and instability of the knee joint. When the ACL tears, the knee joint subluxates, or partially disloates, and this commonly results in a tear of the either the medial or lateral meniscus, which are the shock absorber cartilages in the knee.
Causes of injury
When skiing, ACL injuries most often occur as the result of a slip-catch mechanism. In this scenario, the skier is typically in the back seat; the downhill leg is fairly straight when the downhill ski catches the snow, forcing the knee into a valgus, or inward collapsing, position with internal rotation of the tibia and the ACL tears.
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Other common causes of ACL injury when skiing include landing in the back seat with the knee bent or a forceful snowplow mechanism. Many skiers report feeling a sudden pop or tear at the time of injury.
After the injury
So you've caught your edge and felt a pop to the knee — now what? Following an ACL injury, patients often report feelings of immediate pain and instability upon standing or that the knee will "give out" when trying to place their boot back in the binding. While some skiers may be able to make it down the mountain under their own power, others may require the assistance of ski patrol with a toboggan.
Skiers who find themselves in the mountain base clinic or emergency department will likely undergo a series of X-rays, as well as a physical exam so that the emergency physician can make a diagnosis and refer you to an orthopedic specialist. If X-rays are negative for a fracture, the patient may bear weight as tolerated but may require crutches.
You will most likely be placed in a knee brace, provided with pain medications for comfort, told to ice and elevate and referred to the appropriate specialist for follow-up evaluation and recommendations for treatment.
Specialized orthopedic evaluation includes a series of ligamentous knee tests to assess the four major ligaments of the knee. The Lachman's test and pivot shift test are used to assess the status of the ACL. If a Lachman test is positive, there is increased anterior translation of the tibia in relationship to the femur. If a pivot shift test is positive, there is increased rotational instability of the tibia in relationship to the femur.
There is typically point tenderness on the lateral joint line. If there is point tenderness to the medial joint line with positive McMurray or Thessaly's testing, there may be a medial meniscus tear. Following this series of clinical tests, MRI imaging is obtained for a definitive diagnosis. This will also help determine if there is additional injury to the knee, such as meniscus tears, another injured ligament or articular cartilage injury. The MRI is very helpful for pre-surgical planning.
After confirming a torn ACL, it is not uncommon that your orthopedic sports medicine specialist will recommend reconstructing the ligament so that you can return to cutting and pivoting sports such as skiing without continued feelings of instability. An ACL reconstruction is recommended for young or active patients and in almost all patients who report instability to the knee with cutting or pivoting activities.
This surgery is done arthroscopically, and key to a successful surgery is for the ACL graft to be placed exactly where your original ACL was on the femur and tibia. I recommend that younger, active people have an auto-graft tendon, meaning a tendon from you, used to reconstruct your ACL, as allograft or donor tendon grafts tear at a higher rate.
I typically recommend using a portion of a patient's hamstring or quadriceps tendons. Another graft choice is bone-patellar tendon-bone auto-graft, but I typically recommend a quadriceps graft over a patellar tendon graft, as it is thicker and less painful.
Following ACL reconstruction surgery, pending other necessary repairs, we allow patients to walk on the knee right away, full weight bearing through the surgical lower extremity locked in a telescoping knee brace for two weeks. Crutches may be required for the first few days following surgery, and a cold-compression unit is often recommended.
Pain medications are prescribed initially post surgically for pain control, and physical therapy can begin right away to work on range of motion and joint mobilization. The knee brace is discontinued approximately two weeks from the date of surgery, or when the quadriceps muscle demonstrates good activation while walking.
We anticipate full range of motion of the knee by six weeks post-operatively, at which time patients can increase their strengthening program with the guidance of a skilled physical therapist. Formal therapy is recommended over a time frame of approximately three to four months, in addition to a home exercise program.
A patient may begin jogging at 3 ½ months post-op and begin to increase their activities as tolerated with pain and swelling as their guide; however, we continue to recommend avoidance of cutting and pivoting sports such as soccer, skiing, football or basketball until approximately eight to nine months post-operatively. At that time, we fit our patients for a functional knee brace for full clearance to return to sport.
Have you experienced a twisting injury to your knee? Do you think you've torn your ACL? We're happy to see you. For more information regarding ACL injury and my surgical technique, feel free to visit our website at http://www.vailknee.com, watch one of our YouTube videos at http://www.vailknee.com/videos or give our office a call to schedule an appointment at 970-569-3240 (Edwards) or 970-668-3633 (Frisco).
Victoria Stanislawski, certified athletic trainer, contributed to this article. Dr. Rick Cunningham is a knee and shoulder sports medicine specialist with Vail-Summit Orthopaedics. He is a physician for the U.S. Ski Team and president of Vail-Summit Orthopaedics. Do you have a sports medicine question you'd like him to answer in this column? Visit his website at http://www.vailknee.com to submit your topic idea. For more information about Vail-Summit Orthopaedics, visit http://www.vsortho.com.