Question

For internal rotation (IR) and external rotation (ER), we look for an arc of at least ______ degrees between the two. If we don't get this, it is a mobility deficit at the hip.

a) 60
b) 90
c) 120
d) 180

Answer 1

For hip internal and external rotation, an arc of at least 180 degrees is usually needed; anything less suggests a mobility deficit. The hip joint's multiaxial nature allows for this range of rotation, critical for stability and functional movements.

Step-by-step explanation:

For internal rotation (IR) and external rotation (ER) at the hip, an arc of at least 180 degrees is generally sought between the two types of movements. If this degree of motion is not achieved, it typically indicates a mobility deficit at the hip joint. The hip joint is a multiaxial ball-and-socket joint, composed of the head of the femur and the acetabulum of the hip bone.

It requires sufficient mobility to perform weight-bearing functions with stability during activities such as standing and walking. Medial (internal) rotation moves the anterior surface of the thigh toward the midline, whereas lateral (external) rotation moves it away. These rotations are exclusive to the multiaxial joints such as the hip, distinguishing them from circumduction, which can occur at biaxial or multiaxial joints.