Soft Tissue Balance Profiles Differ Between Manual and Robotically Assessed Gaps in Total Knee Arthroplasty.

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Surgical Technology

Background:

• Assessing knee joint gaps is crucial in total knee arthroplasty (TKA).
• Manual gap assessment is subjective and can vary between surgeons.
• Robotic systems offer objective measurements for soft-tissue tensioning.

Purpose of the Study:

• To compare manual and robotic gap assessments in TKA.
• To evaluate the agreement and error between manual and robotic mediolateral (ML) balance.
• To analyze surgeon-specific variations in gap measurements.

Main Methods:

• Retrospective review of 517 robotic-assisted TKAs across six surgeons.
• Comparison of manual and robotic ML balance and gap measurements using Intraclass Correlation Coefficient (ICC).
• Analysis of differences in ML balance (ΔML) between right and left knees.

Main Results:

• Poor agreement between manual and robotic ML balance (ICC = 0.368).
• Low to moderate correlations (ICC range: 0.152-0.633) and significant differences in gaps throughout flexion.
• Significant ΔML balance differences between leg sides (p < 0.05) with surgeon-specific variations.

Conclusions:

• Manual ML balance assessment in TKA shows poor correlation and significant differences compared to robotic assessment.
• Surgeon-specific variations in gap measurements are notable.
• Surgeons must recognize the discrepancy between subjective manual and objective robotic gap assessments.