title: A reliability study of biomechanical foot function in psoriatic arthritis based on a novel multi-segmented foot model.
abstract: The objective of this study was to determine the within-and between-day reliability of spatio-temporal, plantar pressure, kinematic and kinetic measurements based on a novel, seven segment foot model applied in patients with Psoriatic Arthritis (PsA). Nine PsA patients and matched healthy adult controls underwent three-dimensional gait analysis on two occasions, one week apart using a seven segment foot model. A core-set of functional variables including inter-segment kinematics, kinetics, spatio-temporal and plantar pressure distribution were analysed using the coefficient of multiple correlation (CMC), Bland-Altman plots, intraclass correlation coefficients (ICC) and the standard error of measurement (SEM). Results showed excellent within- and between-day reliability for intersegment kinematic and kinetic data patterns with CMC values typically greater than 0.950 in a clinically stable cohort of PsA patients. Between-day reliability ranged from poor to excellent for absolute CMC values. Corrected CMC values were consistently higher across all variables ranging from fair-to-good to excellent. ICC values indicated excellent reliability for discrete spatio-temporal, plantar pressure, and ankle moment and power variables for both groups. Reliability for ground reaction forces and kinematic discrete variables ranged from fair-to-good to excellent. Standard error of measurement values ranged from 0.7° to 3.0° for discrete kinematic variables across both groups with greater variability in the PsA patients. In conclusion, intersegment kinematics and kinetics as well as spatio-temporal and plantar pressure can be reliably measured in PsA patients using a novel seven segment foot model. Some discrete kinematic variables have poor reliability and should not be used in prospective cohort and intervention studies.
authors.affiliation: School of Health, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA, UK.
authors.forename: Elaine
authors.initials: E
authors.lastname: Hyslop
authors.forename: James
authors.initials: J
authors.lastname: Woodburn
authors.forename: Iain B
authors.initials: IB
authors.lastname: McInnes
authors.forename: Ruth
authors.initials: R
authors.lastname: Semple
authors.forename: Lisa
authors.initials: L
authors.lastname: Newcombe
authors.forename: Gordon
authors.initials: G
authors.lastname: Hendry
authors.forename: Danny
authors.initials: D
authors.lastname: Rafferty
authors.forename: Sophie
authors.initials: S
authors.lastname: De Mits
authors.forename: Deborah E
authors.initials: DE
authors.lastname: Turner
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology; D015535:Arthritis, Psoriatic / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D005260:Female; D005528:Foot / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D016059:Range of Motion, Articular; D015203:Reproducibility of Results