Evaluation of the psychophysical detection threshold level for vibrotactile and pressure stimulation of prosthetic limbs using bone anchorage or softtissue support

In the present study the psychophysical detection threshold levels for mech anical stimulation of 32 prosthetic limbs were determined. Prosthetic limbs were anchored to the hone by means of an implant (n=17) or supported by a socket enclosing the amputation stump (n=15). Detection threshold levels we re assessed fur pressure and vibrator stimulation of the prosthesis and the limb at the contralateral side (control). Following vibratory stimulation, thresholds wt re increased on an avarage 20% for socket prostheses, but ap proached those of the control for bone-anchored prostheses. For pressure st imulation, thresholds were increased up to 60% for socket prostheses and 40 % for bone-anchored prostheses compared to the control. While bone-anchored prostheses yielded significantly lower threshold levels than socket prosth eses, there was no significant difference between both treatments regarding pressure stimulation. Results were applicable to both upper and lower limb amputees. It could be concluded that detection thresholds for pressure and especially vibratory stimulation of prosthetic limbs were generally higher than for control limbs. The outcome was related to the prosthetic limb des ign with bone-anchored prostheses yielding better perception than socket pr ostheses.