Validation of a quantitative method for defining CAD CAM socket modifications

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.