A quantitative method was developed for defining manual socket modification
s, averaging these modifications over a series of amputees, and using the a
verage modifications as a template in commercial CAD/CAM systems. The CADVI
EW programme (i.e. software for viewing and analysing CAD sockets) was rewr
itten to provide comparison functions for aligning sockets to a common axis
, visualising the differences between sockets, generating modification outl
ines, assigning apex point values, and averaging the modification outlines.
A CAD template generated in this manner should be the best general represe
ntation of a prosthetist's modification style. To test this hypothesis, 13
people with trans-tibial amputations were fitted with both a manual and a C
AD/CAM socket. Questionnaires were completed by the subjects and by the pro
sthetist to obtain information on prosthetic comfort, function, and overall
satisfaction. Ground reaction force and stride parameter data were also co
llected for each prosthesis during gait laboratory testing. No significant
differences were found between the manually designed socket and the CAD/CAM
designed socket for all data except the vertical peak forces on the amputa
ted side. These results support the clinical application of this quantitati
ve technique for making the transition from manual to CAD/CAM prosthetic mo
dification procedures.