The effect of methodological sources ofvariability on the interpretation of change of direction kinematic and kinetic metrics following anterior cruciate ligament reconstruction.

Abstract

Change of direction (CoD) movements are the most common mechanism of anterior cruciate ligament (ACL) rupture during multi-directional field-based sports. ACL-reconstruction (ACLR) is the recommended treatment for athletes intent on returning to sport participation. A high incidence of secondary ACL injury is reported following return to sport. The relationship between technique and knee joint loading during movement tasks associated with injury has been studied extensively in an attempt to identify risk factors for primary and secondary ACL injury. However, there have been limited analyses of CoD in this context. One possible explanation for this is that concurrent methodological and task-specific issues make CoD a challenging movement to study experimentally. This thesis aimed to examine the effect of methodological sources of variability on the interpretation of kinematic and kinetic metrics during a CoD task following ACLR. A cohort of ACLR patients and a non-injured control group completed a 90° CoD task while optical motion capture and ground reaction force data were recorded. Four experimental studies examining issues related to marker placement error, variability in approach velocity and CoD angle during task completion, and calculations of normative kinematic and kinetic inter-limb differences were conducted. Simulated systematic marker placement error within previously reported inter-tester variability ranges caused significant differences in knee abduction moment, hip rotation angle, knee rotation angle, ankle abduction and ankle rotation angle across various periods of stance. Simulated random marker placement error caused large changes in inter-limb difference measures in several variables including hip rotation angle, knee abduction angle and knee abduction moment, severely limiting the ability to monitor these variables and identify ACLR patients with large inter-limb differences relative to a control group. Variability in approach velocity and CoD angle explained 3–60% of the variance in kinematic and kinetic inter-limb differences during CoD stance phase. No method for identifying systematic inter-limb differences in non-injured control groups was successfully identified. Considerable challenges exist in the assessment of CoD as small methodological variation can have a large effect on kinematic and kinetic metrics, altering the subsequent clinical interpretation of data. This thesis can serve as a framework informing best practice in the analysis of CoD tasks following ACLR.

Date of Award	22 Aug 2022
Original language	English
Awarding Institution	University of Roehampton
Sponsors	Sports Medicine Research Department, Sports Surgery Clinic, Santry Demesne, Dublin, Ireland; Department of Life Sciences, Roehampton University, UK. Electronic address: [email protected].
Supervisor	Siobhan Strike (Director of Studies) & Katherine Daniels (Co-Supervisor)