Final answer:
The correct answer is c) Anteriorly rotated. This indicates that the innominate bone is pulled anteriorly, typically due to the action of the iliopsoas muscle, affecting leg length in different positions.
Step-by-step explanation:
The correct answer is c) Anteriorly rotated. When assessing leg length discrepancies, if a shorter leg in a supine position becomes longer in a sitting position, this typically suggests that the innominate bone on the side of the initially shorter leg is anteriorly rotated. An anterior rotation of the innominate can happen because of the action of the iliopsoas muscle, which attaches to the lesser trochanter of the femur and the lumbar spine, pulling the innominate anteriorly when tight or overactive.
In clinical practice, physiotherapists or chiropractors may assess the position of the innominate bones as part of a functional evaluation of the pelvis and lower extremities. It's important for them to understand the implications of innominate rotations, as these can influence leg length and possibly contribute to various musculoskeletal complaints.
If an innominate bone is posteriorly rotated, the opposite occurs: The leg on the affected side would appear longer in a supine position and shorter when the person sits up. Understanding these positional changes is crucial for proper diagnosis and treatment of musculoskeletal conditions involving the pelvis and spine.