Suspension effect and dynamic evaluation of the total surface bearing (TSB) trans-tibial prosthesis: a comparison with the patellar tendon bearing (PTB) trans-tibial prosthesis.

X-ray and cineradiography measurements were used to compare the suspension effect and stability of a TSB trans-tibial prosthesis with an Icelandic Roll-On Silicone Socket (ICEROSS) system to that of a PTB trans-tibial prosthesis. The suspension effect was measured by the distance between the tibia and the socket in both suspension position and weight-bearing position in both type of prostheses. The suspension effect of the TSB prosthesis (2.53 +/- 0.90 cm) was superior to that of the PTB prosthesis (3.60 +/- 0.56 cm) (p < 0.05) by x-ray measurement. The suspension effect of the TSB prosthesis (0.1, 0.4, 0.72 cm) was superior to that of the PTB prosthesis (0.3, 0.48, 1.03 cm) (p < 0.01, p < 0.05) by cineradiographic measurement. The stability was measured as the angle between the axis of the tibia and the prosthesis at the time of heel contact and toe off. The angle change of the TSB prosthesis was statistically smaller than that of the PTB prosthesis.