Innovative Clinical Tools for Objectively Measuring Longitudinal Changes in Knee Arthroplasty Patient Gait Kinematics Awaiting Surgery

Abstract

Current clinical management of end-stage knee OA lacks objective functional assessments of patients. Markerless motion capture systems are a new technology that have the potential to facilitate efficient, well-integrated kinematic gait analyses within space-limited clinical environments, which previously limited the clinical uptake of standard technologies. Gait changes associated with end-stage knee OA have been identified, and there has been a growing recognition of functional and symptomatic variability within the patient population presenting for TKA. Extensive pre-operative waitlists for joint replacements contribute to greater patient pre-operative decline of PROMs, including pain, function, and quality of life. Understanding of the variability in patient pre-TKA function and the persistent functional deficits post-TKA will aid in targeting patient-specific improvements in gait and mobility throughout the TKA decision making process. This thesis was a sub-study within a longitudinal research program focused on investigating the association of patient characteristics with declines in patient function awaiting TKA. The overarching goal is to optimize patient-specific objective joint function and mechanics post-TKA by tailoring robotic surgery to the patient’s anatomy and function. The goals of this thesis were to facilitate the efficient collection of gait kinematics within a hospital clinic hallway, to analyze and define the repeatability of knee OA and TKA related kinematic gait metrics captured using this system, and to investigate the association of changes in gait kinematics over the TKA wait period in a cohort of end-stage knee OA patients with baseline patient factors. A novel installation of a markerless motion capture system within a confined clinical hallway environment was successfully completed. A test-retest study of clinically relevant discrete knee angle gait outcomes collected with this system showed good-to-excellent repeatability. The clinical cohort study component of this thesis was the first to investigate changes in gait biomechanics of end-stage knee OA patients awaiting TKA. No significant changes in gait kinematics were observed on a group level, however, significant worsening of gait kinematics was found in one third of the patients. Patients with worsening gait presented with lower sagittal plane kinematics and higher knee adduction angle magnitudes at baseline, but no demographic or self-reported differences, highlighting the added sensitivity of an objective gait assessment during the wait period. Results of this initial investigation support the usage of longitudinal patient gait analysis over the TKA wait-period to potentially aid in surgical triage and prioritization. The results from this thesis will allow for the increased clinical implementation of objective assessments of joint-level mechanics within end-stage knee OA populations. This serves as a valuable tool which can be used throughout the overarching research program and facilitate the high-volume collection of gait data on clinical cohorts, ultimately allowing for a better understanding of patient biomechanical deterioration or impact of treatment interventions. End-stage knee OA patients who demonstrated a worsening of their joint-level kinematics while awaiting surgery were not distinguishable at baseline by demographics or PROMs yet displayed biomechanical differences in their gait with stiffer sagittal plane angles and increased adduction magnitudes. These findings have implications regarding the clinical use of objective assessment tools to monitor patient function, especially in situations where long surgical wait periods are endured, as standard qualitative functional or patient-perceived outcomes may not capture this variability.