Hip dyslpasia (abnormal development) or dislocation is one of the characteristics of one of Kabuki's cardinal manifestations (skeletal anomalies). According to published literature, 20-30+ percent have hip dysplasia or dislocation. Most individuals with Kabuki have some sort of skeletal abnormality which may include spinal anomalies, lax joints, scoliosis, shortened finger bones or dislocated hips, patellas, or other joints.
Virtually every genetic article mentions hip dislocations. There have not yet been studies done to specifically examine the possible causes. It's often mentioned that there is incomplete development of the acetabulum (the cup-shaped cavity in the lateral surface of the hipbone in which the head of the femur fits) and that the lax ligaments (ligaments attach bone to bone) may play a role. Some authors have speculated on whether it's due to a collagen (the main protein or part of connective tissue, skin, tendons, cartilage, and bone) alteration.
INFO ON THE WEB
http://www.drhull.com/EncyMaster/H/hip_dysplasia.html
http://www.chw.edu.au/parents/factsheets/developj.htm