Does Tester Experience Influence the Reliability of 3d-gait Analysis? a Comparison of the Functional and Predictive Approaches

INTRODUCTION: Anatomical marker placement reliability is an important consideration in 3D gait analysis given its influence on defining joint centers, anatomical coordinate systems (ACSs), and ultimately the resulting joint kinematic outputs. It has been postulated that gait kinematic reliability could be improved using a functional (FUN) method compared to a manual marker placement approach (MAN) [1,2]. This seems logical given that FUN methods would be less reliant on precise anatomical marker placement. However, two studies have reported minor or no differences in gait kinematic reliability when comparing FUN and MAN methods [1,2]. The authors in both studies speculated that similar reliability between the two techniques may have been due to the use of experienced testers. Specifically, an experienced tester may be able to locate anatomical landmarks with greater precision than a novice tester. Therefore, the purpose of the study was to determine whether tester experience influences the reliability of gait kinematics when using a FUN or MAN method. It was hypothesized that: 1) the experienced tester (EXP) would demonstrate greater within-tester reliability using the MAN technique compared to the novice (NOV) tester; 2) EXP and NOV testers would demonstrate similar reliability using the FUN technique; 3) Between-tester reliability would be greater in the FUN method compared to MAN.