Reliability of Different Methods for Measuring Stress Radiographs in Posterior Cruciate Ligament Insufficiency

Aims: This study aims to assess the intraobserver and interobserver reliability of various measurement methods of stress radiographs in PCL insufficiency.

Study Design: Descriptive study.

Place and Duration of Study: Department of Orthopaedics, at Rajavithi Hospital, Bangkok between December 2015 and June 2016.

Methodology: Three measurement methods including Mid-Mid Method, Blumensaat's Line-Posterior Tibia Method and Blumensaat's Line-Anterior Tibia Method were employed. Each technique performed twice by two orthopaedic surgeons. Patients were assessed at day 0 and at 4 weeks. Intrarater and interrater reliability of measurements in PCL Radiographs were observed.

Results: The findings indicate that the Blumensaat's line-posterior tibia method showed the highest intraobserver reliability. For intrarater agreement, each method produced high correlation (r > 0.9) at both week 0 and 4. Regarding interrater agreement between two surgeons, high correlation (r > 0.8) was found in Mid-Mid Method and Blumensaat's Line-Posterior Tibia Method, while the Blumensaat's Line-Anterior Tibia method gave medium level of correlation (r=0.528-0.675). Both surgeons indicated similar results for each pair of measurement. The Mid-Mid Method and Blumensaat's Line-Posterior Tibia Method showed positive correlation of measurement. Mid-Mid Method and Blumensaat's Line-Anterior Tibia Method, and Blumensaat's Line-Posterior Tibia Method and Blumensaat's Line-Anterior Tibia Method showed negative correlation of measurement.

Conclusion: The Blumensaat's line-anterior tibia method produced the highest intraobserver and interobserver reliability in measuring stress radiographs in posterior cruciate ligament insufficiency.