Sophie De Mits

A reliability study of biomechanical foot function in psoriatic arthritis based on a novel multi-segmented foot model

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.

Orthostatic intolerance and fatigue in the hypermobility type of Ehlers-Danlos Syndrome

OBJECTIVE To investigate whether orthostatic intolerance (OI) is a significant predictor for fatigue in Ehlers-Danlos Syndrome, hypermobility type (EDS-HT). METHODS Eighty patients with EDS-HT and 52 controls participated in the first part of the study, which consisted of questionnaires. Fatigue was evaluated using the Checklist Individual Strength (CIS). As possible fatigue determinants OI [Autonomic Symptom Profile (ASP)], habitual physical activity (Baecke), affective distress [Hospital Anxiety and Depression Scale (HADS)], pain (SF36), medication use and generalized hypermobility (5-point score of Grahame and Hakim regarding generalized joint hypermobility) were studied. Next, a 20 min head-up tilt (70°) was performed in a subsample of 39 patients and 35 controls, while beat-to-beat heart rate and blood pressure were monitored (Holter, Finometer Pro). Before and after tilt, fatigue severity was assessed using a numeric rating scale. RESULTS Patients scored significantly higher on the CIS [total score: EDS: 98.2 (18.63) vs controls: 45.8 (16.62), P < 0.001] and on the OI domain of the ASP [EDS: 22.78 (7.16) vs controls: 6.5 (7.78)]. OI was prevalent in EDS-HT (EDS: 74.4%, controls: 34.3%, P = 0.001), and frequently expressed as postural orthostatic tachycardia (41.0% of the EDS group). Patients responded to tilt with a higher heart rate and lower total peripheral resistance (p < 0.001; p = 0.032). This altered response correlated with fatigue in daily life (CIS). In the EDS-HT group, tilt provoked significantly more fatigue [numeric rating scale increase: EDS: +3.1 (1.90), controls: +0.5 (1.24), P < 0.001]. Furthermore, the factors OI, pain, affective distress, decreased physical activity and sedative use explained 47.7% of the variance in fatigue severity. CONCLUSION OI is an important determinant of fatigue in EDS-HT.

Foot orientation affects muscle activation levels of ankle stabilizers in a single-legged balance board protocol.

CONTEXT The main goal of balance training is regaining a normal neuromuscular control to a functional level. Although uniaxial balance boards are commonly used, no research has been done on the effect of foot orientation on muscle activation levels. OBJECTIVE To investigate the effect of foot orientation on muscle activation levels and modulation of the ankle stabilizing muscles in a single-legged balance protocol on a uniaxial balance board. METHODS Sixty-nine healthy subjects (age: 21.8±1.7years; mass: 67.5±11.9kg; body height: 174.7±8.6cm; BMI: 21.5±3.0) participated in this study. Subjects were asked to keep their balance during a single leg stance on a uniaxial balance board for four different foot orientations, aligning the boards rotation axis with frontal, sagittal, diagonal and subtalar axes of the foot, respectively. Surface electromyography registered muscle activity of peroneus longus, tibialis anterior, medial and lateral gastrocnemius muscles. RESULTS Highest muscle activation levels and modulation for the peroneus longus were registered exercising along the frontal axis; for the tibialis anterior along the diagonal axis; for the medial gastrocnemius along the sagittal axis; and for the lateral gastrocnemius along the diagonal axis. CONCLUSION Foot orientation modifications on a uniaxial balance board allows to differentially target specific ankle stabilizing muscles during balance training.

The effect of ankle muscle strength and flexibility on dolphin kick performance in competitive swimmers.

The velocity of a swimmer is determined by biomechanical and bioenergetics factors. However, little is known about the effect of ankle flexibility on dolphin kick performance. Next to this, scientific evidence is lacking concerning the influence of ankle muscle strength. Therefore, the aim of this study was to investigate the effect of ankle flexibility and muscle strength on dolphin kick performance in competitive swimmers. Ankle range of motion (ROM) and ankle muscle strength were measured in 26 healthy competitive swimmers. The effect of both was assessed on the swimmers velocity and lower extremity joint angles during three maximal dolphin kick trials. Additionally, the effect of a flexibility restriction by a tape on the dolphin kick performance was assessed. Correlations were calculated between the flexibility, muscle strength and dolphin kick performance and differences were investigated between the unrestricted and restricted condition. Muscle strength of dorsal flexors and internal rotators were positively significantly correlated with the velocity. Active and passive plantar flexion ROM and internal rotation ROM were not significantly correlated. A plantar flexion-internal rotation restriction during the dolphin kick showed a significant decrease in velocity. This restriction was associated with a changed movement pattern in the knee towards more flexion. The results suggest that dolphin kick velocity might be enhanced by ankle muscle strength exercises and that subjects with a restricted ankle flexibility might profit from a flexibility program.

Reliability and Validity of the INFOOT Three-dimensional Foot Digitizer for Patients with Rheumatoid Arthritis

BACKGROUND Abnormal foot posture and deformities are identified as important features in rheumatoid arthritis. There is still no consensus regarding the optimum technique(s) for quantifying these features; hence, a foot digitizer might be used as an objective measurement tool. We sought to assess the validity and reliability of the INFOOT digitizer. METHODS To investigate the validity of the INFOOT digitizer compared with clinical measurements, we calculated Pearson correlation coefficients. To investigate the reliability of the INFOOT digitizer, we calculated intraclass correlation coefficients, SEMs, smallest detectable differences, and smallest detectable difference percentages. RESULTS Most of the 38 parameters showed good intraclass correlation coefficients, with values greater than 0.9 for 30 parameters and greater than 0.8 for seven parameters. The left heel bone angle expressed a moderate correlation, with a value of 0.609. The SEM values varied between 0.31 and 3.51 mm for the length and width measures, between 0.74 and 5.58 mm for the height data, between 0.75 and 5.9 mm for the circumferences, and between 0.78° and 2.98° for the angles. The smallest detectable difference values ranged from 0.86 to 16.36 mm for length, width, height, and circumference measures and from 2.17° to 8.26° for the angle measures. For the validity of the INFOOT three-dimensional foot digitizer, Pearson correlation coefficients varied between 0.750 and 0.997. CONCLUSIONS In this rheumatoid arthritis population, good validity was demonstrated compared with clinical measurements, and most of the obtained parameters proved to be reliable.

Reliability and validity of the Infoot 3D foot digitizer for normal healthy adults

Introduction: Abnormal foot posture and foot deformities have been identified as important factors in several foot and lower limb dysfunctions and pathologies. There is still no consensus over the optimum technique(s) to quantify these; hence a foot digitizer might be used as an objective measurement tool. The objective of this study is to check for the validity and the reliability of the Infoot digitizer. Methods: To investigate the validity of the Infoot digitizer in comparison with weight bearing X-rays and clinical measurements, both used in daily clinical practice, Pearson correlation coefficients were calculated and Bland-Altman plots were analysed. To investigate the reliability of the Infoot digitizer ICC, SEM, SDD and SDD% were calculated. Results and conclusions: Within this healthy population good validity could be demonstrated comparing the linear measurements from the Infoot 3D foot digitizer with the data from X-rays and clinical measurements. The majority of the obtained parameters proved to be very reliable.

Intratest Reliability in Determining the Subtalar Joint Axis Using the Palpation Technique Described by K. Kirby

BACKGROUND Exact determination and classification of the spatial position of the subtalar joint axis could be a predictive clinical variable in biomechanical analysis and a valuable tool in the design of functional foot orthoses. METHODS Three clinicians with different levels of experience determined and classified the subtalar joint axis location, three times, on 52 individuals, using the clinical palpation, allocation and interpretation technique, as described by K. Kirby. RESULTS High intratester precision (ICC 0.72 to 0.93) was found for determining the axis location (SEM, 3.72° for angle/0.27 cm for X-axis); however, classification of the spatial position of the axis has large intertester variation (κ = 0.243 to 0.494) CONCLUSIONS The clinical palpation technique itself is reliable; the consistent attribution of a classification, in other words, interpretation, is weak.

T2* Mapping of subtalar cartilage: Precision and association between anatomical variants and cartilage composition

Hindfoot arthritis is an important contributor to foot pain and physical disability. While the subtalar joint (STJ) is most frequently affected, anatomical variants such as facet configuration were suggested to further STJ cartilage deterioration. T2* mapping enables detection of ultra‐structural cartilage change, particularly in thin cartilage layers, but its feasibility in the STJ has not yet been evaluated. The purpose of this study was to evaluate segmentation consistency and inter‐scan short‐term precision error of T2* mapping of talocalcaneal cartilage and to investigate the relationship between facet configuration and STJ T2* values. Using 3Tesla morphological magnetic resonance imaging, STJ configuration was categorized according to the degree of fusion between anterior, medial, or posterior facets. Subsequently, two repeats of multi‐echo gradient recalled echo sequences were performed to obtain T2* maps with repositioning. Segmentation consistency of T2* values attained an ICC of 0.90 (95%CI 0.69–0.99). Precision errors comprised a coefficient of variation (CV) ranging 0.01–0.05, corresponding to a root mean square CV of 0.03–0.04. A 2‐joint configuration type (i.e., fused anterior‐medial facets) was significantly associated with a decrease in posterior facet T2* values (β = −0.6, p = 0.046). STJ T2* mapping is a reliable method requiring at least a 4% difference within people to enable detection of significant change. Anatomical variants in STJ configuration were associated with T2* values with the more stable 3‐joint types exhibiting more favorable cartilage outcomes. Longer‐term larger‐scaled studies focusing on arthritis pathology are needed to further support the use of T2* mapping in hindfoot disease monitoring.

Effect of mechanical stress on magnetic resonance imaging of the sacroiliac joints: assessment of military recruits by magnetic resonance imaging study

Objective To assess the baseline condition of the SI joints (SIJs) in healthy individuals without symptoms of back pain and to study the effect of mechanical stress caused by intense physical training on MRI of the SIJs. Methods Twenty-two military recruits underwent an MRI of the SIJs before and after 6 weeks of intense standardized physical training. Bone marrow oedema and structural lesions were scored based on the Spondyloarthritis Research Consortium of Canada (SPARCC) method, by three trained readers blinded for time sequence and clinical findings. Additionally, fulfilment of the Assessment of SpondyloArthritis international Society (ASAS) definition of a positive MRI was evaluated. Results At baseline, 9/22 recruits (40.9%) already presented a SPARCC score ⩾1; this number increased to 11/22 (50.0%) at week 6 (P = 0.625). In these patients, the mean (SD) SPARCC score was 2.4 (0.4) at baseline, compared to 3.7 (1.3) at week 6. Overall, the mean (SD) change in SPARCC score over time in all 22 patients was 0.9 (0.6) (P = 0.109). A positive MRI according to the ASAS definition was present in 5/22 recruits (22.7%) at baseline, which increased to 8/22 (36.4%) at follow-up (P = 0.375). Structural lesions were present in 6/22 subjects (27.3%), both at baseline and after 6 weeks of training. Conclusion A substantial proportion of healthy active individuals without any symptoms of back pain displayed bone marrow oedema lesions on MRI at baseline. However, MRI lesions did not increase significantly after 6 weeks of intensive physical training. Our study underscores the necessity to interpret MRI findings of the SIJs in the appropriate clinical context, even in a young active population.

Repetitive knee bending and synovitis in people at risk and with knee osteoarthritis: Data from the FNIH Osteoarthritis Biomarkers Consortium

To investigate associations between engagement in knee bending (stair climbing, kneeling, squatting, heavy lifting, getting in/out of a squatting position) and synovitis prevalence on noncontrast magnetic resonance imaging (MRI) in individuals at risk of and with knee osteoarthritis.