The use of two-dimensional motion analysis and functional performance tests for assessment of knee injury risk behaviours in athletes

AbstractDynamic knee valgus and limb asymmetry havebeen linked to greater riskof anterior cruciate ligament (ACL) or patellofemoral joint (PFJ) injury. Two-dimensional (2D) frontal plane projection angle (FPPA)is more clinically useful than three-dimensional (3D) motion analysis techniques used toassess dynamic knee valgus in the literature. Further, hop for distance tests and the star excursion balance test (SEBT)offer a clinically useful assessmentof limb symmetry.1.Reliability and validity of 2D FPPAWithin-day and between-session reliability of 2DFPPA during the drop jump (DJ), single legland (SLL) and single leg squat (SLS) tasks was fair to good.Intra-and inter-tester reliabilitywas excellent.Significant correlations were found between 2D FPPA and 3Dmeasures ofdynamic knee valgus. These results indicate that 2D FPPA is areliable andvalid measure ofdynamic knee valgus.2.Reliability of hop for distance tests and the SEBTBetween-session reliability of the hop for distance tests and SEBT was good.Errormeasurementvalueswere calculated toevaluate future performance.3.Investigation of factors contributing to 2D FPPASignificant correlations were found between DJ FPPA and isometric hip abduction, externalrotation and combined abduction/external rotation (clam) strength. Clam strengthaccountedfor 20% of the variance in 2D FPPA. No significant correlations were found for SLL FPPA.4.Use of feedback to modify movement patternsAugmented feedback was shown to significantly improve landing patterns during the drop DJand SLL tasks. In theDJ task a significant reduction in FPPA and increase in contact timewere found post-feedback. A significant reduction in FPPA and vertical ground reactionforces were found for the SLL task.5.Prospective assessment of ACL injury risk in women’s sportOnewomen’s footballer suffered an ACL injury and was found to demonstrate greater FPPAduring the DJ, SLL and SLS tasks and lower crossover hop for distance scores than her peers.Limb asymmetry did not appear to predict ACL injury risk in this athlete