Clinical meaningfulness of the Oxford Foot Model to assess foot deformity during gait

Abstract

AIM of THESIS The primary aim of this thesis was to establish the clinical role of the Oxford Foot Model to assess foot deformity during gait. To achieve this, we evaluated the OFM’s clinimetric properties and created and tested a new outcome measure based on the OFM kinematics: the Foot Profile Score. A secondary aim was to explore a potential relationship between altered foot structure/ function during gait and perceived disability in a clinical population. CHAPTER OUTLINES The following chapters culminate to address the overall aims of this thesis. Chapter II is a repeatability study to justify the use of the OFM in populations with known foot deformity. Intra and inter-rater repeatability of marker placement was assessed in children with clubfoot and in children with hemiplegia cerebral palsy and compared to a typically developing population. This study was completed at the Oxford Gait Laboratory in Oxford, UK. Chapter III builds on previous research completed in Oxford evaluating the repeatability of the hindfoot marker in the OFM. Two jigs were created to improve the repeatability of the heel marker placement. Two gait analysts (one beginner and one experienced with the foot model) completed this repeatability study comparing the two jigs to the traditional method of eyeballing marker placement on 10 healthy adult subjects. This study was completed at VU Medical Centre in Amsterdam, Netherlands. Chapter IV is a validation study of a new summary score of dynamic foot motion during gait based on the OFM kinematics- the Foot Profile Score (FPS). THE FPS was defined, then studied for its properties and design, and analysed against a clinical assessment of foot deformity. This study was completed at the Oxford Gait Laboratory in Oxford, UK. Chapter V defines a minimal clinically important difference (MCID) for the Foot Profile Score based on the regression of the FPS on the Clinical Foot Deformity Scale (CFDS) presented in Chapter IV. The FPS was then assessed for its responsiveness in children with hemiplegia, cerebral palsy who underwent gait analysis pre-and post-surgery for correction of their foot deformities. Chapter VI utilises the FPS to analyse recurrent foot deformities in children previously treated for clubfoot deformity, presenting at the Oxford Gait Laboratory for consideration of further treatment due to ongoing symptoms. Foot function was assessed by the OFM kinematics and plantar pressure and correlated with parent-reported outcome measures including the Oxford Ankle Foot Questionnaire, the Disease Specific Index for clubfoot and the Pediatric Quality of Life Inventory 4.0. Chapter VII discusses the overall aim of this thesis and considerations for future research are given.