This paper describes the theoretical background of Dynamic Flamingo Therapy (DF therapy) . DF therapy is a method based on Wolff's laws and Pauwels' lever arm theory for increasing the bone mineral density at the femoral neck. According to Pauwels' theory, during one-leg standing the femoral head receives 2.75 times the load applied during two-leg standing. Our photoelasticity results show that the maximum concentration of stress in the inner side of the femoral neck was 0.706kg/mm2 for the one-leg standing posture and 0.212kg/mm2 for the two-leg standing posture. When the patient stands on one leg the femur is subjected to a mechanical stress approximately 3-fold that of a normal standing posture without any increase in body weight. According to Peizer's walking cycle, 95% of the maximum stress applied to the femoral head of one leg (the supporting leg) equals 1.5/80 of the walking cycle. The time necessary to complete this number of cycles is 2987× (60/56) =3200 seconds (53.3minutes) .