Ask a Vail Sports Doc column: Types of knee injuries, and ways to examine your knee
August 29, 2017
The knee is one of the most injured joints in the body.
In the office, I first look at a patient's leg alignment. Is the patient knock kneed (in valgus) or bow legged (in varus). Alignment has a significant impact on how we wear down cartilage in our knee's over time, similar to how tread on your tires may wear if your tires have not been properly balanced.
Next, I assess the musculature in the lower extremities for any atrophy — a decline due to underuse. If there is pain in the knee, then there is typically atrophy of the musculature in that limb as one favors the other limb, and the degree of atrophy speaks to the disability a patient has with their injured knee. Furthermore, atrophy can increase pain in the knee.
Range of motion, localizing pain
Next, range of motion of the knee is inspected and compared to the uninjured knee. Several different conditions can cause decreased range of motion of the knee.
Palpating various areas of the knee is key to establishing the correct diagnosis.
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When I see an injured knee in the office, I ask where the pain is located. This seems like an obvious question, but it is important to determine if the pain can be localized in a definite area or whether the pain location migrates to different areas around the knee.
Knee conditions localize pain to around the knee itself and pain is not referred down to the foot, for instance.
However, spine or hip conditions can refer pain down from their respective joint to the foot (spine issue) or to the knee (hip issue).
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Patella maltracking and subsequent arthritis is a common source of pain, so I next examine how the patella moves in the groove of the femur bone. I look for any increased swelling in the knee and check for a Baker's cyst in the back of the knee. Patellar pain typically is localized over the medial or lateral side of the patella and commonly refers pain to the back of the knee as well.
Patella pain is classically increased with stair climbing or descending hills and swelling is common.
Meniscus tears classically cause very localized pain directly over the joint line where the tear is located. Patients report a catching sensation and there can be sudden sharp pain in the knee when doing certain activities such as squatting down. A good test you can do to determine if you have a meniscus tear is to squat down and rotate on the knee.
If you experience pain that you can localize with one finger on the inside or outside of the knee, you probably have a meniscus tear.
Quadriceps or patellar tendon tears usually occur from landing awkwardly. Much like an ACL tear, patients feel like their knee gave way. Unlike an ACL tear, patients with a quad or patellar tendon tear are unable to lock their knee straight and raise it.
They may also be able to palpate a defect in their tendon when comparing to how their other knee feels. Patients with this may be able to walk with their knee locked straight, but the knee collapses when they try to walk with the knee bending normally.
When one tears a ligament, such as the ACL or MCL, there is a specific injury that occurred. This is usually not the case with meniscus tears or arthritis flares that occur insidiously.
In a future article, I will address the physical exam tests you could do on your own to evaluate your knee for a ligament injury.
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. Visit http://www.vailknee.com to submit your sports medicine question. For more information about Vail-Summit Orthopaedics, visit http://www.vsortho.com.
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