Tight hip abductor and/or adductor musculature can change the frontal plane posture of the pelvis, resulting in a scoliosis. Permission Joseph E. Muscolino. Kinesiology - The Skeletal System and Muscle Function, 3ed (Elsevier, 2017)

How Can Tight Muscles of the Hip Joint Cause a Scoliosis?

So, if hip abductor group on one side is tighter at baseline tone than the hip adductor group on that side, the pelvis will be pulled into depression on that side, resulting in a lumbar scoliosis that is convex on that side. Similarly, tight opposite-side hip adductor musculature can cause the same scoliotic curve.

Posterior views of the deep lateral rotator group (including the piriformis)

Muscles of the Pelvis

Pelvic musculature: 1. cross the LS joint onto the trunk 2. cross the hip joint onto the thigh/leg 3. pelvic floor muscles located wholly within the pelvis