Becky - I expect they are talking about the % of coverage the hip has. Normal I've been told is around 70%. My daughter currently has 72% coverage on the left hip which we have been told is normal and the right hip is at 67% which is considered mild. I wasn't told orginally what the coverage was but in 6 weeks the right hip has gone from severe to mild and the left from mild to normal. Georgie has been in a Pavlik Harness.