Inverse kinematic total knee arthroplasty using conventional instrumentation restores constitutional coronal...

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Imaging Analysis

Background:

• Restricted inverse kinematic alignment (iKA) is a modern approach for total knee arthroplasty (TKA).
• While kinematic alignment strategies show clinical benefits, registry data do not confirm improved survivorship with robotic assistance.
• This study investigates a conventionally instrumented iKA technique for precise patient-specific alignment.

Purpose of the Study:

• To evaluate the efficacy of a restricted, instrumented iKA technique in achieving patient-specific alignment during TKA.
• To compare preoperative and postoperative lower limb alignment parameters using AI-driven radiographic analysis.
• To assess the technique's ability to restore constitutional alignment profiles.

Main Methods:

• Eighty-four TKAs in 79 patients were analyzed for alignment changes.
• Artificial intelligence was used for preoperative and postoperative radiographic measurements.
• The Coronal Plane Alignment of the Knee (CPAK) system classified alignment profiles, with subanalyses for different preoperative states.

Main Results:

• Postoperative joint-line convergence angle (JLCA) improved significantly, reducing from 2.5° to -0.1°.
• While the lateral distal femoral angle (LDFA) remained stable, the medial proximal tibial angle (MPTA) increased by 2.5° (p=0.001).
• The hip knee ankle angle (HKA) shifted from 3.5° varus to 1.2° valgus, with 63% of patients showing a change in CPAK classification.

Conclusions:

• A restricted, conventionally instrumented iKA technique can successfully restore constitutional lower limb alignment in TKA.
• This method offers a viable alternative for achieving patient-specific alignment without necessarily requiring robotic assistance.
• The findings support the use of kinematic-type TKA strategies with conventional instrumentation.