Patient-specific instrumentation for total knee replacement verified by computer navigation: a case report.

Patient-specific instrumentation (PSI) enables better restoration of the mechanical axis in total knee replacement (TKR) than conventional instrumentation (alignment guides) does. We verified the accuracy of the PSI by computer navigation. The PSI jigs were accurate only if they were pinned accurately onto the distal femur and proximal tibia. Any slight malposition of the jigs leads to malalignment of the bone cuts. In the absence of computer navigation, the accuracy of the jig alignments cannot be checked and may result in malalignment.