Adaptive stiffness energy return structure for orthopedics

An adaptive stiffness energy return structure, wherein the structure comprises:

• a first mount configured to mount with a first portion of a user's body;
• a second mount configured to mount to a second portion of the user's body;
• and
• a strut assembly with continuously variable stiffness, mechanically connecting the first mount and the second mount, wherein the strut assembly comprises:
• at least two strut layers;
• and
• two or more spacers displacing at least a strut layer of the at least two strut layers and affecting a gap between the at least two strut layers, wherein the two or more spacers comprise one or more of a static spacer configured to affect a constant gap distance and one or more of a dynamic spacer configured to selectively vary the gap distance, wherein the dynamic spacer comprises a threaded rod configured to adjust the gap distance between the at least two strut layers, wherein the threaded rod comprises right-hand and left-hand thread segments respectively engaged through threaded inserts to the at least two strut layers, such that rotation in a first direction increases the gap distance and rotation in a second direction decreases the gap distance.