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

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Medical device technology

Background:

• Total knee replacement (TKR) aims to restore the knee's mechanical axis for optimal function.
• Patient-specific instrumentation (PSI) has emerged as a potential method to improve TKR accuracy.
• Conventional alignment guides are the standard for bone preparation in TKR.

Observation:

• This study investigated the accuracy of PSI in TKR using computer navigation.
• The precision of PSI jigs was found to be highly dependent on accurate fixation to the distal femur and proximal tibia.
• Malpositioning of PSI jigs, even slightly, directly resulted in malalignment of bone cuts.

Findings:

• PSI jigs are accurate for restoring the mechanical axis in TKR, but only when precisely positioned.
• Computer navigation confirmed that accurate pinning of PSI jigs is critical for achieving correct bone cuts.
• Inaccurate jig placement leads to significant malalignment, compromising the intended benefits of PSI.

Implications:

• Precise intraoperative verification, potentially via computer navigation, is essential for ensuring the accuracy of PSI in TKR.
• Surgeons must be vigilant about jig placement to avoid errors that could negate the advantages of PSI.
• Further research may focus on improving PSI jig design or fixation methods to enhance robustness against minor positional errors.