Alignment of trans–tibial prostheses based on roll–over shape principles

The authors examined the roll‐over shape alignment hypothesis, which states that prosthetic feet are aligned by matching their rollover shapes with an “ideal” shape. The “ideal” shape was considered to be the roll‐over shape of the able‐bodied foot‐ankle system. An alignment algorithm and computational alignment system were developed to set trans‐tibial alignments based on this hypothesis. Three prosthetic feet with considerably different roll‐over shapes were either aligned using the alignment system or not aligned (i.e. used previous foot's alignment), and then were aligned by a team of prosthetists. No significant differences were found between roll‐over shapes aligned by the computational alignment system and those based on standard clinical techniques (p = 0.944). Significant differences were found between the “no alignment” shapes and the prosthetist alignment shapes (p = 0.006), and between the “no alignment” shapes and the computational alignment system shapes (p = 0.024). The results of the exper...