Diagnostic Value of Stress Radiography and Arthrometer Measurement for Anterior Instability in Anterior Cruciate Ligament Injured Knees at Different Knee Flexion Position

摘要

Purpose: To evaluate diagnostic value of stress radiography and arthrometer measurements for anterior instability at different knee flexion angle positions. Methods: Forty-three patients with complete anterior cruciate ligament (ACL) rupture (group 1) and 37 normal subjects (group 2) were enrolled prospectively. Arthrometer (KT-1000) measurements and stress radiography by Telos were used to evaluate side-to-side differences. Results were recorded according to the knee position (30 degrees, 45 degrees, 60 degrees, and 90 degrees). Areas under the receiver operating characteristic curves (AUCs) were used to evaluate the diagnostic accuracy of each evaluation method. The calculated cutoff values at 30 degrees position were used to evaluate the sensitivity and specificity of combined evaluation with stress radiography and arthrometer measurements. Results: The side-to-side differences on stress radiography and arthrometer measurements were significantly different between groups (P < .05), except for the values at the 90 degrees position in arthrometer measurements (P = .844). The amount of anterior translation decreased in both arthrometer measurements and stress radiography between 30 degrees and 45 degrees positions (P < .000); however, no further decrease was observed beyond 45 degrees. The AUC of stress radiography at the 30 degrees position was significantly higher than other values (AUC = 0.955; P = .000). Moreover, the clinical cutoff value of 3 mm showed 86.0% sensitivity and 89.2% specificity in stress radiography at 30 degrees, which were higher than those in arthrometer measurements. Combined use of stress radiography and arthrometer measurements at the 30 degrees position showed 100% sensitivity and 59.5% specificity as a screening test. Conclusions: Evaluation at the 30 degrees knee position was significantly superior to that at other positions for both stress radiography and arthrometer measurements, whereas the 90 degrees knee flexion position was not meaningful for any measurements. Evaluation needs to be performed with a 3-mm cutoff value for stress radiography at the 30 degrees knee position; however, combined use of stress radiography and arthrometer measurements at the 30 degrees knee flexion can have a higher diagnostic value.