In the present work, the design, manufacture and testing of a developed type of shank which consists of two overlapping tubes and connected by hard rubber damper. The shank has stiffness value according to the patient data (weight and stump length ).The present shank has the ability to absorb shocks and overcome the problem of unevenness of the ground when walking, in addition it can store potential energy during the stance phase of walking and transformed into kinetic energy at the beginning of the swing phase to help for flexion and reduce effort on muscles . The modified prosthesis shank was tested with BK amputation patient and compared with traditional one by using force platform and treadmill . The results shows quite improvements in patient gait parameters and as the follows ;at stance phase it smoothen the GRF curve, at heel strike the loading rate increases by 1 22% indicating a good impact reduction .at pre swing it increases angul