2.6.2. Physical Exam Knee Flashcards
What do Menisci do for us in the knee?
Menisci (lateral and medial) provide shock absorption for the tibia and femur mashing together
What other features of the bones in the knee besides menisci help for smooth movement and shock absorption?
Both the tibia and femur are also both lined with Hyaline cartilage for more shock absorption. The femoral condyles provide a smooth rolling surface for the cup shaped tibial plateau
What are the ligaments of the knee and what do they help us with?
Medial (Tibial) and Lateral (fibular) collateral ligaments provide side-to-side stability while the cruciate ligaments (anterior and posterior) provide front-to-back stability
What does the ACL prevent? the PCL?
Anterior cruciate ligament prevents the tibia from sliding anteriorly on the femur. Posterior cruciate ligament prevents the tibia from sliding posteriorly on the femur
What is the oritentation of the ACL/PCL and what is a good way to remember this placement?
The ACL is always in front and goes from lateral to medial and the PCL is the opposite. Imagine crossing your middle finger over your index finger and then laying your crossed fingers over your knee (right hand over right knee and left hand over left knee). Your crossed fingers represent your cruciate ligaments, with the middle finger (ACL) going from the lateral femoral condyle to the front of tibia and your index finger (PCL) going from the medial femoral condyle to the posterior portion of the tibia plateau.
How does the knee provide further stability with extension?
Twist - As the knee swings into terminal extension, the tibia externally rotates on the femur to allow increased stability as the knee locks into full extension, predisposing the knee to injury.
What can occur with excessive rotation of the knee?
Excessive rotation can cause meniscus tears, cruciate ligament injury, and patellofemoral pain.
Which meniscus and region is more frequently injured?
posterior horns more commonly affected than anterior and medial more than lateral
Describe the differences between the presentation of an acute vs. a chronic knee injury.
Acute vs. Chronic - Acute injuries make obvious noises for the patient and are easy to track. Chronic typically are associated with vague pains, increased pain with increased activity, and often a history of recently increased physical activity
What are the points to address in your history?
- Mechanism of injury
- Swollen vs. Effusion
- Sounds or feelings during the event
- Effect injury has on activity
- Past medical.surgical history
- Location of Pain
- Provoking/alleviating factors
What is the important thing to know about a swollen knee?
You need to know how long after injury the swelling began
Discuss the difference between effusion and swelling.
Effusion is fluid inside the joint capsule. Large effusions are obvious. Small ones will require special tests like the Warm-cold-warm test or milking. Swelling can be from superficial structures like bursa becoming irritated.
What happens to skin dimples on the knee when effusion has occured?
Vanish
What does it mean to milk a knee?
For sounds and feelings during the injury, what are we looking for specifically?
- Pop or tear?
- Knee clicking, catching, or locking?
- Does the knee “give way” at all especially while walking?
What are we looking for on inspection?
- Observe gait (normal or limping, shuffling, or won’t walk).
- Swelling, ecchymosis, atrophy
- Alignment of the joint (Valgus vs. Varus, see below)
What is an antalgic gait?
Limping
What do we palpate for the knee exam?
- Lateral joint line
- Lateral Structures
- Medial joint line
- Medial Structures
- Popliteal fossa
- Pes Anserine
- IT Band
- Patella
What are our lateral structures that we are feeling for at the beginning of the palpation portion of the knee exam?
Walk lateral thumb back to popliteal fossa feeling for the anterior horn of the lateral meniscus, the lateral collateral ligament, and the posterior horn of the lateral meniscus.
What are our medial structures that we are feeling for during the palpation portion of the knee exam?
Run your thumb back medially from the medial joint line towards the popliteal fossa, feeling as before on the lateral side for the anterior horn, the medial collateral ligament and the posterior horn of the medial meniscus.
How can you distinguish the LCL and MCL on exam from their nearby structures?
For the LCL you can do a figure 4 arrangement.
For the MCL, it is very hard to find. Pretty much just do your best.
What structures are we feeling for in the popliteal fossa exam?
There are hamstrings that border medially and laterally. Laterally is the biceps femoris tendon and medially is the semimembranosus with the semitendonosus running within the borders of the semimembranosus and overtop of it.
A fullness in the popliteal fossa is a sign of what? What causes this?
A fullness in the popliteal fossa is a sign of a popliteal cyst or “baker’s cyst.” Usually caused by a meniscal tear, cartilage damage or arthritis.
How do we find the Pes Anserine on exam and what does tenderness indicate?
Find the anterior horn of the medial meniscus and then drop inferiorly down the tibia about two inches. Rub back and forth on the skin in this region, you’ll feel texture, this is the Pes. Tender to palpation even in normal folks, so compare each side.
What is the Pes Anserine? What is within it?
The Pes is a confluence of three tendons from the sartorius, gracillus, and semitendonosus, which has a bursa in it to cushion the tendons as they rub across the Tibia.
What part of the IT band are we concerned about for the knee exam and what other structures should we consider involving the IT band?
We’re only concerned about the part that comes across the lateral femoral condyle, which has a bursa between the band and the condyle for cushion. Irritation is common with frequent running. Palpate the condyle and band
Describe the palpation portion of the knee exam leading up to the patella starting with the tibial tuberosity.
Palpate the tibial tuberosity. Move superiorly up the patellar tendon which attaches the quads to your tibial tuberosity. Move up further to the kneecap (patella).
Discuss the patella and what it runs against/issues we can face with it.
Kneecap sits on the trochlear groove created by the femur. If the patella derails off of this groove (dislocation), the patient will have a lot of patellafemoral pain.
What ROM movements do we do for the knee exam?
Flexion and Extension - Active and passive
Discuss the Strength and Neurovascular portion of the Knee exam.
Strength: Flexion and Extension - Active and passive
Sensation
Distal pulses - Dorsalis pedis and posterior tibial
What categories of special tests do we have for the knee?
Effusion tests
Menisci tests
ACL/PCL Tests
MCL/LCL tests
Patella Tests
What tests do we use to test for knee joint effusion?
Warm-Cold-Warm
Milking
Recall what the warm-cold-warm test is
Place the back of your hand on your thigh a few inches above the knee. The thigh will feel slightly warm to touch. Now place the back of your hand on the kneecap or just medial to the kneecap. This region is relatively cool to the touch. Finally place the back of your hand on the lateral calf: warm again
What do the results of the warm-cold-warm test imply?
Warm-Cold Warm = Normal
Warm-Warm-Warm = Irritation of some kind
Warm-Hot-Warm - Usually joint infection and is usually accompanied by swelling, redness, and other signs of inflammation
What Meniscus tests do we have?
McMurray’s
Thessaly Test
Discuss the McMurray’s Test and what a positive sign indicates
One hand on the plantar foot the other on the joint line on the knee. Flex the knee and then externally rotate the tibia so that the heel moves medially. While keeping this rotation, extend the knee slowly. Add “Varus” force if more compression desired (medial force from the lateral knee). This is for the medial meniscus. Repeat this with internal rotation and Valgus force is needed (lateral meniscus) A pop in the medial or lateral joint line under your hand suggests a meniscus tear
Discuss the Thessaly Test and what the positive signs indicate
Patient stands on one leg bent at 20 degrees. Instruct patient to twist their hips/trunk back and forth three times to rotate the femur on the tibia, using body weight and rotation to grind on the menisci. Help hold the patient upright. Positive test if there is pain at the medial or lateral joint line
Discuss the anterior and posterior drawer tests and what they indicate.
- Have the patient lie back on the table with their knees flexed at 90 degrees and foot planted. Sit on the patient’s foot.
- Verify the starting position of the tibial tuberosity.
- Grasp the superior tibia and push posteriorly and anteriorly to assess the function of the ACL and PCL. Tibia coming too far forward is a sign of ACL sprain or tear. Same goes for PCL
Why do we verify the position of the tibial tuberosity with the drawer test and what are we verifying?
Verify the starting position of the tibial tuberosity, it should be anterior to the femoral condyles. If the PCL is town, gravity will pull the tibia posteriorly when the knee is in the starting position for this test. This posterior tibial sag can fool you into thinking that there is anterior tibial laxity when in fact you are just pulling the tibia back into neutral position.
What is the Lachman’s Test used for?
ACL injury
Discuss the Lachman Test and what a positive finding is.
Grasp thigh with the hand closest to the patient’s to relax thigh muscles and stabilize. Flex the knee to 15-20 degrees and allow slight external rotation of the hip. Place your other hand on the medial knee and pull upwards in the anterior direction. A torn ACL has no discrete end point and allows more motion than the uninjured side.
What is a modified Lachman test?
Same as Lachman but with your thigh under the patient’s knee to help with the first 15-20 degrees of flexion
What tests do we use to test the ACL/PCL?
- Anterior and Posterior Drawer Tests
- Lachman’s Test
- Modified Lachman’s Test
How do we test the LCL and MCL?
Have the patient flex the knee to 20-30 degrees. Use the hand closest to the patient while between their legs or lateral to the patient (you can be in either position) to brace under their knee. Grasp the lateral ankle with the other hand and push medially to test the LCL and grasp the medial ankle and push laterally to test the MCL. Pain or difference in laxity between sides can indicate an issue.
Varus vs. Valgus pressure
Varus is when you push laterally from the medial side of the knee. Valgus is when you push medially from the lateral side of the knee
What patella special tests do we have?
Patella Apprehension
Patella Grind
Retropatellar Test
Clarke’s Test (Patellar Shrug)
Discuss the Patellar Apprehension test and when we typically use it:
Usually when dislocated, the patella moves laterally. Lay the patient’s knee on your thigh and with your hands, push the patella laterally. Pain or feeling that the patella will come off is a positive apprehension test
Discuss the patellar Grind Test
With the knee in full extension, place your thumbs on the anterior surface and press the patella inwards. Pain with this test is a positive sign of irritation under the patella.
Discuss the retropatellar test
Knee in full extension and as before, push the patella laterally. With one thumb, feel the lateral upper underside of the patella. Do the same medially for the medial upper underside of the patella (lateral and medial patellar facets respectively). Pain on either facet is a positive test.
Discuss the Clarke’s Test (Patellar Shrug Test)
Knee in full extension. Wrap your hands around the knee so that the hand closest to the patient is on top, wrapped around the base of the quads and pushing the patella downwards. Have the patient contract the quadriceps while you maintain pressure. The patella should rise, and if there is pain when contracting retropatellarly, you have a positive test.
When do we consider x-ray for a patient for a knee exam?
- 55 or older with acute trauma
- Isolated tenderness of the patella after an injury
- Tenderness at the head of the fibula
- Inability to flex to 90 degrees following trauma
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