Improved tibial component rotation in TKA using patient-specific instrumentation.

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Radiology

Background:

• Patient-specific instrumentation (PSI) aims to minimize positional errors in total knee arthroplasty (TKA).
• The hypothesis was that PSI could enhance the rotational alignment of tibial components during TKA.

Purpose of the Study:

• To evaluate the effectiveness of PSI in achieving optimal rotational alignment of tibial components in TKA.
• To compare the rate of rotational outliers between PSI and conventional instrumentation methods.

Main Methods:

• Magnetic resonance imaging (MRI) analysis of 58 TKA patients (30 PSI, 28 conventional).
• Tibial component rotation assessed using dorsal tibial condyle tangent, epicondylar line, and tibial tubercle as references.
• Outliers defined as >9° deviation or >1° internal rotation; statistical analysis via Chi-squared test.

Main Results:

• PSI significantly reduced rotational outliers compared to conventional instrumentation (6.7% vs. 21.4-28.6%).
• Reliable rotational measurements were achieved using dorsal condyle and epicondylar lines; tibial tubercle reference showed poor reproducibility.
• Statistical significance (p < 0.05) confirmed the efficacy of PSI in reducing outliers.

Conclusions:

• PSI effectively reduces outliers in tibial component rotational alignment in TKA.
• Inconsistent anatomical landmarks on the proximal tibia pose challenges for MRI analysis, jig production, and intraoperative placement.