Errors in visual estimation of flexion contractures during total knee arthroplasty.

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Surgical Outcomes

Background:

• Accurate assessment of knee flexion contractures is crucial for successful total knee arthroplasty (TKA).
• Visual estimation of knee flexion contractures can be unreliable, leading to potential surgical inaccuracies.
• Existing methods for intraoperative measurement may lack precision or ease of use.

Purpose of the Study:

• To quantify the errors inherent in the visual estimation of knee flexion contractures during TKA.
• To develop and validate a novel device for improving the accuracy of intraoperative knee flexion contracture measurement.
• To enhance feedback on sagittal alignment during TKA procedures.

Main Methods:

• Quantification of visual estimation error involved 3 orthopedic surgeons assessing knee flexion contractures from digital images of 23 patients before and after surgical draping, compared to goniometer measurements.
• A dual inclinometer device was developed to improve intraoperative measurement accuracy.
• The device's reliability and impact on knee extension measurement were assessed during 146 TKA cases using intraclass correlation coefficients (ICC) and paired t tests.

Main Results:

• Surgeons significantly overestimated contractures pre-draping and underestimated them post-draping (P = 0.003).
• The developed inclinometer device demonstrated high test-retest reliability (ICC = 0.98).
• The device measured a loss of 2.7° ± 2.2° knee extension with a 2 mm thicker tibial liner, though it failed to detect this in 6.2% of cases.

Conclusions:

• Significant errors are associated with visual estimation of knee flexion contractures in TKA.
• A simple, reliable inclinometer device and method were successfully developed to enhance intraoperative feedback on sagittal alignment.
• The device shows promise for improving accuracy and consistency in TKA procedures.