Knee Physical Exam

Lachman (Torg JS, Am J Sports Med. 1976;4:84-93)

best test for ACL laxity.  Knee placed in 20-30 degress of flexion, the femur is stabilized, and an anteriorly directed force  applied to proximal calf.    Compare to uninjured side. Grade 1+ = 1-5mm increased translation; 2+= 6-10mm ; 3+=>10mm.

Confirms complete ACL tear. Based on very early flexion causing anterior subluxation of the tibia that is reduced with further flexion (20-40 degrees) due to the posterior pull of the iliotibial tract.  Relocation event graded as 0(absent), 1+ (pivot glide), 2+(pivot shift), 3+(momentary locking) (Galway HR, JBJS 1972;54Br:763)

• Most accurate test for PCL tear.
• Patient in supine postion with knee flexed 90°.
• Palpate the medial tibial plateau and appreciate its position relative to the medial femoral condyle.
• Apply a posteriorly directed force to proximal tibia.
• Note the change in the distance (the step-off) from the medial tibial plateau and medial femoral condyle.

Figure: Normal Posterior Drawer
Step-off between medial femoral condyle and medial tibial plateau is maintained when posteriorly directed force is applied to proximal tibia.

1. Medial femoral condyle
2. Medial tibial plateau

• Grade I = palpable but diminished stepoff (0-5mm).
• Grade II = lost their stepoff, but the medial tibial plateau cannot be pushed beyond the medial femoral condyle (5-10mm). 
• Grade III = complete PCL injuries stepoff is lost, and the tibia can be pushed beyond the medial femoral condyle (>10mm) and has an obvious positive posterior sag.

Figure: Grade II Posterior Drawer
Step-off between medial femoral condyle and medial tibial plateau is lost (5-10mm of subluxation) when posteriorly directed force is applied to proximal tibia.

1. Medial femoral condyle
2. Medial tibial plateau

• Prone postion. Measure thigh-foot angle with external rotation stress applied both at 30° and 90°. Compare to normal side. External rotation of the tibia >10° compared to normal side indicates posterolateral corner injury. Increased ER at 30° but not at 90° indicates isolated posterolateral corner injury. Increased ER at both 30° and 90° indicates combined PLC, PCL injury. (Bleday RM, Arthroscopy 1998;14:489-94) (Larsen MW, J Knee Surg 2005;18:146-50).

Valgus Laxity

• Indicates MCL injury or posteromedial corner injury. 

Varus Laxity

• Indicates LCL injury or posterolateral corner injury.

• patient lying supine with the hip and knee flexed 90°. Apply axial compression while ER and IR the leg.
• Reproduction of pain +/- clicking indicates meniscal tear.

• Posterior tanslation and external rotation forces are applied to the knee at 30° of flexion. Posterolateral subluxation of the proximal tibia indicates PLC injury.

• Lift the patients extended leg by the great toe and observe for any side to side differences in hyperextension, varus and tibial external rotation. (Hughston JC, CORR 1980;147:82-7).

• (Hughston JC, CORR 1980;147:82-7), adduction stress test, dynamic posterior shift test, Reverse pivot shift test.

anterior force applied at 90 degrees of  flexion.  Least reliable.

• Place feet 8-10 inches appart with feet pointed outward (medial meniscus) or inward (lateral meniscus.
• Patient squates down with feet flat of the floor. Pain or a click when the knee approaches 90 indicates meniscal tear.
• 71% accuracy, 67% sensitivity, 81% specificity for medial meniscal lesions (Akseki D, Arthroscopy, 2004;20:951).