Explanation of  HD Values as per "The W K Hirschfeld Stichting":

 

HD Values: HD- (= negative) X-ray is free of HipDysplasia
HD Tc (= on the point of change ) X-ray show slight diviation
HD +/- (= slight positive) X-ray shows a diviation
HD + (=  Positive) X-ray shows clear diviation
HD + + (Positive in optima forma) X-ray shows serious diviation

 

Norberg Value:

HOW TO CALCULATE THE NORBERG VALUE: 

Take the centre of each femoral head (hip ball) and draw a line between them. Then take the centre of the femoral head and draw a line to the outerpoint of the pelvis. The angle between these lines minus 90º (3), gives the Norbergwaarde for each hip. Ad those 2 numbers and you have the Norbergwaarde used on the evaluation. The higher the Norbergwaarde the better.

Values for both hips are added to give the "Norberg waarde".  A normal hip should score at least 15.  The sum of the Norberg Waarde (Value) should therefore be at least 30.