A Clinical Device for Measuring Internal-External Rotational Laxity of the Knee

Background:The dial test can be improved by providing reproducible, accurate measurements to improve diagnosis and treatment comparisons.Purpose:Validation of a rotational measurement device (RMD) for measuring knee internal-external rotational laxity.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:The RMD consisted of 3 components: a femoral clamp and a tibial splint using paired inclinometers to measure rotations, and a boot to apply tibial internal-external rotation torque. A separate boot inclinometer allowed for foot rotations to be measured independently. The measurements were simultaneously compared with electromagnetic “nest of birds” (NOB) sensors. Sequential paired knee measurements were taken at 4, 6, and 8 N·m of torque at 30° and 90° of flexion in 46 volunteers.Results:The correlation coefficient was 0.92 (95% CI, 0.89 to 0.94) and 0.63 (95% CI, 0.54 to 0.70) between the NOB and RMD and between the NOB and boot inclinometer, respectively. Bland-Altman analysis revealed tha...