Proven accuracy for a new dynamic gap measurement in navigated TKA

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Surgical Navigation

Background:

• Total knee arthroplasty (TKA) clinical outcomes remain unsatisfactory in 20% of patients.
• Conventional gap balancing in TKA is static, assessing only extension and 90° flexion.
• Existing navigation systems improve alignment accuracy but show limited clinical outcome improvement.

Purpose of the Study:

• To evaluate the accuracy and reliability of a novel dynamic navigation software for intraoperative gap assessment.
• To determine the software's effectiveness in facilitating gap-balanced TKA throughout the entire range of motion (ROM).

Main Methods:

• Sixty-five TKA procedures were performed using a tibia-first, gap-balanced technique with new computer-assisted surgery (CAS) software.
• Inter-observer and intra-observer reliability were assessed through repeated gap measurements by different surgeons.
• Dynamic stress testing was employed to measure gaps throughout the entire ROM.

Main Results:

• The CAS system achieved correct coronal alignment in 96.4% of cases (within 3° of mechanical alignment).
• Both inter-observer and intra-observer reliability for gap values across the entire ROM were excellent.
• Specific bias and limits of agreement were reported for inter-observer (-2.1 to +2.21 mm) and intra-observer (-2.27 to +2.44 mm) measurements.

Conclusions:

• The new CAS software and dynamic gap measurement provide accurate and reproducible gap assessments.
• This technique facilitates effective knee balancing during TKA.
• The system demonstrates robustness and reproducibility across multiple surgeons and repeated measurements.