How to properly assess knee injuries during ski season
Ski season is upon us! And with that knee injuries usually increase. The reason for that is fairly simple to explain. Most of the year we don’t spend our times on ski slopes. Our knees are not used to the ,,abuse” icy hills and gnarly moguls can cause. Knee injuries come in many different shapes and forms. This blog will tell you how to properly asses knee injuries.
The pain in your knee may be acute, following an injury or overuse, or it may be chronic and evolve slowly over a period of time. Pain may occur in one or both knees. To provide a thorough assessment, there are a few important questions to ask, observations to make, and simple physical tests to perform. This process will help determine the type and severity of injury and guide you to the best treatment.
Let’s start with the basic knee anatomy. It will help you to understand why the knee is such an important instrument, and why knee injuries are so common when participating in any kind of winter sport.
There are two joints in the knee—the tibiofemoral and the patellofemoral. The knee also consists of:
Three bones: the femur, tibia, and patella. The femur and tibia line up evenly with each other, and the patella rests in a groove on the femur. A fourth bone, the fibula, is not involved in articulation but anchors some knee ligaments.
Two types of cartilage: articular and meniscal. The bone-to-bone contact surface of all three bones is covered by articular cartilage. Several millimeters thick, avascular, and roughly the texture of Formica, this cartilage follows the contours of the bone to which it adheres and provides strength and durability to the articulating portions of bones.
The space between the tibia and the femur is occupied by the meniscus. Four to five millimeters thick (but thinner in the middle), avascular, and similar in texture to hard rubber, this cartilaginous structure comprises two C-shaped disks (one medial, one lateral) and absorbs some of the forces knee bones must withstand.
Four major ligaments: two cruciate ligaments and two collateral ligaments. The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are found deep within the tibiofemoral joint. These two ligaments keep the femur from sliding forward or backward on the tibia. The knee has several smaller stabilizing ligaments as well.
Next we need to look at how we examine the knee. Appropriate radiologic tests will help further isolate and quantify any injuries. Your doctor should always perform tests on each leg separately and compare the results. To determine if knee motion is affected, your doctor should place his left hand over the knee joint, covering the patella, and grasp the ankle with his right hand. He should then slowly move the tibia up and down several times, bending and straightening the knee as far as comfort will allow.
While doing this, note any unusual noises or limitations of movement. Without pathology, the knee should swing easily and smoothly and elicit no pain or noise. Normal range of motion is at least 130° of flexion and 0° of extension.
Since hip joint pathology commonly results in referred to possible knee injuries, a quick check of the hip joint is important. With the knee bent to 90°, the left hand should be placed over the knee and pressed down lightly to stabilize the knee joint. Grasp the ankle with your right hand, and rock the tibia from side to side. This pendulum motion, which may cause some pain in the knee, is actually a test of the hip joint as it rocks the head of the femur in the hip socket. A normal hip will allow the tibia to swing at least 30° in each direction.
Palpation is a key component of every knee exam. Your doctor should sit on a stool facing the patient. With the knee flexed 90°, he moves his thumb across the joint line, feeling for the tibial plateau (a hard transverse ridge just below the patella) and the softer indentation just above it (where the meniscus lies). Note any painful areas.
Next, palpate in a circular motion with two fingers over the MCL and LCL, which extend more than an inch above and below the joint line. Note any areas of point tenderness or diffuse tenderness. If the patient is complaining of anterior or posterior knee pain, palpate there as well, identifying the precise area of maximal pain. Then, with the leg flat on the exam table, palpate around the edges of the patella, looking for any signs of discomfort or apprehension. Also place one hand on either side of the patella and press down with the fingers of one hand followed by the other. If you feel a fluid shift, the test is positive for an effusion. An effusion occurs with inflammation and usually points to underlying injury inside the joint capsule.
If the patient has described an acute injury accompanied by a popping noise, perform the following two tests to look for an ACL tear or a meniscal tear.
The anterior/posterior drawer test detects injury to the ACL or PCL. The patient reclines on the table with the injured leg bent to 90°. Rest your body against the patient’s foot to anchor it to the table, and grasp the injured leg with both hands just below the joint line. Firmly pull the tibia forward (toward yourself) in relation to the femur. Normal motion is <5 mm. Test for posterior motion by pushing the tibia backward (toward the patient) in relation to the femur. Any movement >5 mm usually indicates a tear of the ACL or PCL.
The Apley compression test helps detect a meniscal tear. The patient lies face down on the exam table. Gently grasp the injured leg and bend it to 90°. While maintaining downward pressure on the heel (pressing the patient’s knee against the table), slowly rotate the foot (hence the tibia) first internally then externally on the femur. Pain felt medially suggests a medial meniscus tear. Pain felt laterally suggests a lateral meniscus tear.
No matter what you do when you hit the snowy hills of Mammoth of Lake Tahoe this season, always keep in mind that your knees are delicate instruments that cannot be bend or stretched in every possible direction. Warm up properly, always ski within your abilities, and stop immediately when you feel a tweak or a sharp pain in your knee. We are here to help you assess the pain correctly, and to make sure you will be able to get out doing what you love to do. https://westcoastorthopedics.com/about-us/