This is what I believe to be the etiology of an ascending short leg syndrome based on several of my research projects (below cited):
Two abnormal genetically inherited foot structures (the PreClinical Clubfoot Deformity and Rothbarts Foot) force the feet to abnormally (gravity drive) pronate during ambulation (Rothbart 1988, 2002, 2006):
• Abnormal foot pronation drives the innominate bones anteriorly (1988, 2002, 2006).
• The more anteriorly rotated innominate bone being ipsilateral (same side) as the more pronated foot (2006).
• Anterior rotation of the innominate bone displaces its' acetabulum cephalad and posteriorly (Rothbart 2006).
• This functionally shortens both legs and hyperextends both knees.
• The resulting functional short leg being ipsilateral to the more anteriorly displaced innominate bone.
I view the anteriorly rotated innominate bones as one pathomechanical event in a series of pathomechanical events, initiated by an abnormal inherited foot structure.