Here we are discussing about test to identify knee joint dislocation and diseases
1. Collateral ligament instability tests (valgus & varus stress tests):
- Aim of the test: Identifies collateral ligaments laxity.
- Patient position: Patient is supine, the entire lower extremity is supported & knee placed in 20-30° of flexion. Valgus force placed through knee to test medial collateral ligament. Varus force placed through knee to test lateral collateral ligament.
- Positive sign: Primary finding is laxity, but pain may be noted.
2. Lachman stress test:
- Aim of the test: Indicates integrity of anterior/posterior cruciate ligament (ACL/ PCL).
- Patient position: Patient supine with testing knee flexed 20-30°. Stabilize femur and passively try to glide tibia anterior (posterior).
- Positive sign: finding is excessive anterior (posterior) glide of tibia.
3. Anterior (posterior) drawer test
- Aim of the test: Indicates integrity of anterior (posterior) cruciate ligament.
- Patient position: Patient supine and testing hip flexed to 45 degree and knee flexed to 90 degree. Passively glide tibia anteriorly (posteriorly) following the joint plane.
- Positive sign: Positive finding is excessive anterior (posterior) glide.
4. McMurray test
- Aim of the test: Identifies meniscal tears.
- Patient position: Patient supine with testing knee is in maximal flexion. Passively internally rotate and extend the knee. This tests lateral meniscus. Test the medial meniscus with the same procedure except rotate the tibia into lateral rotation.
- Positive sign: Positive finding is reproduction of click and/ or pain in the knee joint.
5. Clarke’s sign
- Aim of the test: Indicates Patellofemoral dysfunction.
- Patient position: Patient supine with knee in extension resting on table. Push posterior on superior pole of patella then ask patient to perform active contraction of the quadriceps muscle.
- Positive sign: Pain is produced in knee as a result of the test.
6. Apley test:
- Aim of the test: Helps to differentiate between meniscal tears and ligamentous lesions.
- Patient position: Patient prone with testing knee flexed to 90 degrees. Stabilize patient’s thigh to table with your knee. Passively distract the knee joint then slowly rotate tibia internally and externally. Next step is to apply a compressive load to knee joint and once again slowly rotate tibia internally and externally.
- Positive sign: Pain or decreased motion during compression indicates a meniscal dysfunction. If pain or decreased motion occurs during the distraction then it is most likely a Ligamentous dysfunction.
Patellar tap test (Ballotable patella)
- Aim of the test: Indicates infrapatellar effusion.
- Patient position: Patient supine with knee in extension resting on table. Apply a soft tap over the central patella.
- Positive sign: Positive finding is perception of the patella floating (dancing patella sign).
8. Patellar apprehension test
- Aim of the test: indicate past history of patella dislocation.
- Patient position: patient supine &patella is passively glided laterally
- Positive sign: patient does not allow &/or doesn’t like patella to move in lateral direction to stimulate sub laxation /dislocation.
Also read :Intro to types of joints in human body