Prone Knee Bending Test (also known as reversed lasegue test) is used to evaluate the nerve roots of the midlumbar spine (L2 to L4).
How it’s Performed?
While the patient is prone, the examiner passively raises the leg, which is flexed at the knee joint.
Prone knee bending test (reversed lasegue test) can also be carried out with the patient in the lateral position. The patient lies on the unaffected side with the affected extremity slightly flexed at the hip and knee. The examiner fixes the pelvis with one hand and grasps the patient’s knee with the other and move the hip into a hyperextended position while increasingly flexing the knee.
What does a positive Prone Knee Bending Test mean?
Hyperextension of the hip with the knee flexed places traction on the femoral nerve.
Prone Knee Bending Test is positive if there is unilateral or bilateral radicular pain in the sacrum or anterior thigh and rarely in the lower leg is a sign of nerve root irritation, such as a herniated disk, in the L3/L4 spinal column segment.
As with the Lasegue test, symptoms may also occur on the opposite side, which is then referred to as a crossed femoral stretching test.
Pain in the groin and hip region radiating along the medial side of the thigh suggests an L3 origin, while pain over the anterior lower leg indicates an L4 problem.
Prone Knee Bending Test is similar to the Ober test used to evaluate a contracted, shortened iliotibial band. A tight iliotibial band does not allow the leg to adduct to any significant degree, and is often pain free. If pain is present, it is localized over the greater trochanter proximally and the lateral condyle distally.
Femoral nerve pain usually has a different history and is normally more distinct and dermatome-related.
In the case of a disk herniation at the L3/L4 level, there is weakness of the quadriceps muscle combined with an absent or weakened patellar tendon reflex.
Clinical Tests for the Musculoskeletal 3rd Ed. Book