Abstract
BackgroundSeveral clinical tests exist to assess knee laxity. Although these assessments are the predominant tools of diagnosis, they are subjective and rely on the experience of the clinician. The robotic knee testing (RKT) device has been developed to quantitatively and objectively measure rotational knee laxity. The purpose of this study was primarily to determine the intra-tester reliability of rotational knee laxity and slack, the amount of rotation occurring between the two turning points of the load deformation curve, measured by the RKT device and investigate the differences between female and male measurements.MethodsNinety-one healthy and moderately active volunteers took part in the study, of which twenty-five participated in the reliability study. Tibial rotation was performed using a servomotor to a torque of 6 N m, while measurements of motion in all 6° of freedom were collected. Reliability measurements were collected over 5 days at similar times of the day. Intra-class correlation coefficient (ICC) values and standard error of measurement (SEM) were determined across the load deformation curves. Linear mixed effects modelling was used to further assess the reliability of the measurement of external and internal tibial rotation using features of the curve (internal/external rotational laxity and slack). Measurements of internal/external rotational laxity and slack were compared between the sexes using the Student t test.ResultsPointwise axial rotation measurements of the tibia had good reliability [ICC (2,1) 0.83–0.89], while reliability of the secondary motions ranged between poor and good [ICC (2,1) 0.31–0.89]. All SEMs were less than 0.3°. Most of the variation of the curve features were accounted for by inter-subject differences (56.2–77.8%) and showed moderate to good reliability. Comparison of the right legs of the sexes revealed that females had significantly larger amounts of internal rotation laxity (females 6.1 ± 1.3° vs males 5.6 ± 0.9°, p = 0.037), external rotation laxity (females 6.0 ± 1.6° vs males 5.0 ± 1.2°, p = 0.002) and slack (females 19.2 ± 4.2° vs males 16.6 ± 2.9°, p = 0.003). Similar results were seen within the left legs.ConclusionsOverall, the RKT is a reliable and precise tool to assess the rotational laxity of the knee joint in healthy individuals. Finally, greater amounts of laxity and slack were also reported for females.
Highlights
Several clinical tests exist to assess knee laxity
The simple functional data analysis using Intra-class correlation coefficient (ICC) and standard error of measurement (SEM) pointwise reliability of the axial rotation of the tibia and of the other 5 degrees of freedom was calculated from the load deformation curves (Supplementary Fig. S1)
The ICC (2,1) axial rotation (Z rotation, primary motion; Supplementary Fig. S1A) values ranged between 0.83 and 0.89, while the SEM ranged between 0.14° and 0.18°
Summary
Several clinical tests exist to assess knee laxity. these assessments are the predominant tools of diagnosis, they are subjective and rely on the experience of the clinician. Increased anterior knee laxity and internal tibial rotation, as well as decreased tibial external rotation, have been associated with an increased risk of anterior cruciate ligament (ACL) injury [3, 4] These laxity measurements, together with other risk factors, could be used to identify high risk athletes and to inform decision making processes to prevent and reduce the risk of knee injuries, ACL injuries [5,6,7]. These rotational measurements are useful for the diagnosis of knee ligament injuries, as previous studies have shown that injury/transection of the ACL, the posterolateral bundles, and the anterolateral ligament affects measurements of rotational laxity [8, 9]. The availability of tools to measure these movements is important
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
