Maximal Exercise Tolerance, Objective Trunk Strength, and Mobility Measurements in Axial Spondyloarthritis

OBJECTIVE

Although exercise therapy is safe, effective, and recommended as a nonpharmacological treatment for axial spondyloarthritis (axSpA), there is a lack of guidelines regarding type and dosage. Insufficient knowledge about physical and physiological variables makes designing effective exercise programs challenging. Therefore, the goal of this study was to simultaneously assess trunk strength, spinal mobility, and the cardiorespiratory fitness of patients with axSpA.

METHODS

In a cross-sectional study, 58 patients with axSpA (mean age 40.8 yrs, 50% male, mean symptom duration 10.3 yrs) performed maximal cervical and trunk mobility and isometric strength tests in all planes (using David Back Concept devices) and a maximal cardiopulmonary bicycle exercise test (n = 25). Mobility and strength data were compared to healthy reference data. Cut-off values for clinical cardiopulmonary exercise testing interpretation were used to judge normality. Patients were compared based on radiographic involvement and symptom duration.

RESULTS

Both strength (P ≤ 0.02) and mobility (P ≤ 0.001) were significantly lower for the patients with axSpA compared to the reference. Strength deficits were comparable between the radiographic and nonradiographic groups (P > 0.05, except trunk extension [P = 0.03]), whereas mobility showed higher deficits in the radiographic group (cervical extension [P = 0.02] and rotation [P = 0.01], and trunk extension [P = 0.03] and rotation [P = 0.03]), regardless of symptom duration. Similarly, symptom duration positively affected oxygen pulse (P = 0.03), relative anaerobic threshold (P = 0.02), and aerobic capacity (P = 0.02).

CONCLUSION

In patients with axSpA, strength is more affected than mobility when compared to healthy controls. Likewise, mainly the metabolic component of aerobic capacity is impaired, affecting cardiopulmonary fitness. These findings indicate that future personalized exercise programs in patients with axSpA should incorporate exercises for cardiopulmonary fitness next to strength and mobility training.

Three-Dimensional Upper Limb Movement Analysis in Children and Adolescents With Brachial Plexus Birth Injury: A Systematic Review

BACKGROUND

To synthesize the current evidence on clinical use of three-dimensional upper limb movement analysis (3D-ULMA) in children and adolescents with brachial plexus birth injury (BPBI).

METHODS

MEDLINE, Embase, and Web of Science were searched for relevant studies up to April 2022. An automatic e-mail alert was installed to ensure no eligible article was missed. Articles evaluating 3D-ULMA in children and adolescents with BPBI were included. Covidence web-based platform was used for blind screening of eligible articles. Twenty-one observational studies with a final sample size of 609, encompassing 493 BPBI cases, met the inclusion criteria. Data were extracted using a custom form to support standardized extraction conforming to the Cochrane Checklist of items. Risk of bias was assessed using the Newcastle-Ottawa Scale, the Strengthening the Reporting of Observational Studies in Epidemiology checklist, and a specifically established quality assessment form for kinematic analysis studies.

RESULTS

Study setups differed, including six different types of kinematic devices. Twelve studies used the (modified) Mallet positions for their 3D-ULMA. Throughout the studies, 3D-ULMA was used for various purposes. The Newcastle-Ottawa Scale scored 16 articles with five stars or more, indicating fair to moderate quality.

CONCLUSIONS

This systematic review summarizes the different 3D-ULMA kinematic devices, test protocols, and their clinical use for BPBI. The use of 3D-ULMA provides valuable, objective, and quantified data to clinicians with regard to movement strategies; it complements existing clinical scales and can be implemented to evaluate effectiveness of therapy interventions. Implications for future research and clinical practice are discussed.

Associations between markers of inflammation and altered pain perception mechanisms in people with knee osteoarthritis: a systematic review

To provide an extensive review on the associations between knee inflammation and altered pain perception mechanisms in people with knee osteoarthritis (OA). MEDLINE, Web of Science, EMBASE and Scopus were searched up to 13 December 2022. We included articles reporting associations between knee inflammation (measured by effusion, synovitis, bone marrow lesions (BMLs) and cytokines) and signs of altered pain processing (assessed by quantitative sensory testing and/or questionnaire for neuropathic-like pain) in people with knee OA. Methodological quality was evaluated using the National Heart, Lung and Blood Institute Study Quality Assessment Tool. Level of evidence and strength of conclusion were determined using the Evidence-Based Guideline Development method. Nine studies were included, comprising of 1889 people with knee OA. Signs of greater effusion/synovitis may be positively associated with lower knee pain pressure threshold (PPT) and neuropathic-like pain. Current evidence could not establish an association between BMLs and pain sensitivity. Evidence on associations between inflammatory cytokines and pain sensitivity or neuropathic-like pain was conflicting. There are indications of a positive association between higher serum C reactive protein (CRP) levels and lower PPT and presence of temporal summation. Methodological quality varied from level C to A2. Signs of effusion/synovitis may be positively associated with neuropathic-like pain and pain sensitivity. There are indications of a possible positive association between serum CRP levels and pain sensitivity. Given the quality and the small amount of included studies, uncertainty remains. Future studies with adequate sample size and follow-up are needed to strengthen the level of evidence.PROSPERO registration number: CRD42022329245.

Statistical shape model-based tibiofibular assessment of syndesmotic ankle lesions using weight-bearing CT

Forced external rotation is hypothesized as the key mechanism of syndesmotic ankle injuries, inducing a three-dimensional deviation from the normal distal tibiofibular joint (DTFJ) alignment. However, current diagnostic imaging modalities are impeded by a two-dimensional assessment, without considering ligamentous stabilizers. Therefore, our aim is threefold: (1) to construct an articulated statistical shape model of the normal DTFJ with the inclusion of ligamentous morphometry, (2) to investigate the effect of weight-bearing on the DTFJ alignment, and (3) to detect differences in predicted syndesmotic ligament length of patients with syndesmotic lesions with respect to normative data. Training data comprised non-weight-bearing CT scans from asymptomatic controls (N = 76), weight-bearing CT scans from patients with syndesmotic ankle injury (N = 13), and their weight-bearing healthy contralateral side (N = 13). Path and length of the syndesmotic ligaments were predicted using a discrete element model, wrapped around bony contours. Statistical shape model evaluation was based on accuracy, generalization, and compactness. The predicted ligament length in patients with syndesmotic lesions was compared with healthy controls. With respect to the first aim, our presented skeletal shape model described the training data with an accuracy of 0.23 ± 0.028 mm. Mean prediction accuracy of ligament insertions was 0.53 ± 0.12 mm. In accordance with the second aim, our results showed an increased tibiofibular diastasis in healthy ankles after weight-bearing. Concerning our third aim, a statistically significant difference in anterior syndesmotic ligament length was found between ankles with syndesmotic lesions and healthy controls (p = 0.017). There was a significant correlation between the presence of syndesmotic injury and the positional alignment between the distal tibia and fibula (r = 0.873, p < 0,001). Clinical Significance: Statistical shape modeling combined with patient-specific ligament wrapping techniques can facilitate the diagnostic workup of syndesmosic ankle lesions under weight-bearing conditions. In doing so, an increased anterior tibiofibular distance was detected, corresponding to an "anterior open-book injury" of the ankle syndesmosis as a result of anterior inferior tibiofibular ligament elongation/rupture.

Statistical Shape Model-Based Tibiofibular Assessment of Syndesmotic Ankle Lesions using Weightbearing CT

Category:

Trauma; Ankle

Introduction/Purpose:

Forced external rotation is hypothesized as the key mechanism of syndesmotic ankle injuries, inducing a three-dimensional deviation from the normal distal tibiofibular joint alignment. These lesions, especially when subtle, present a deceitful diagnostic challenge. Current diagnostic imaging modalities are impeded by a two-dimensional assessment, without considering ligamentous stabilizers. Accurate diagnosis of syndesmotic lesions should involve 3D weightbearing osseous imaging in combination with - preferably automated- inclusion of patient-specific ligamentous information. Therefore, our aim is two-fold: (1) to construct a three-dimensional articulated statistical shape model of the normal distal tibiofibular joint with inclusion of ligamentous morphometry and (2) to detect differences in predicted syndesmotic ligament length of patients with syndesmotic lesions with respect to normative data.

Methods:

Training data comprised non-weightbearing CT scans from asymptomatic controls (N= 76, Mean age 63 +/- 19 years), weightbearing CT scans from patients with syndesmotic ankle injury (N = 13, Mean Age 35 +/- 15 years) and their weightbearing healthy contralateral side (N = 13). CT scan segmentation was used to generate 3D bone models in the control and patient group. All ankles were aligned based on the tibia. Path and length of the syndesmotic ligaments were predicted using a discrete element model, wrapped around bony contours. Statistical shape model evaluation was based on accuracy, generalization and compactness. The predicted ligament length in patients with syndesmotic lesions was compared to healthy controls by use of two-tailed Two- Sample student's t-test.

Results:

Our presented skeletal shape model described the training data with an accuracy of 0.23 +/- 0.028 mm. Mean prediction accuracy of ligament insertions was 0.53 +/- 0.12 mm. Mean length of the Anterior inferior tibiofibular ligament was 12.26 +- 1.89mm for the control cases, 12.32 +- 1.58 mm for the contralateral cases and 14.13 +- 1.48 mm for the cases with syndesmotic lesions. Statistically significant differences were found between the latter two (95% CI [ 0.323.29], p = 0.017) There was a significant correlation between presence of syndesmotic injury and the positional alignment between the distal tibia and fibula (r = 0.873, p < 0,001).

Conclusion:

Statistical shape modelling combined with patient-specific ligament wrapping techniques can facilitate the diagnostic workup of syndesmotic ankle lesions under weightbearing conditions. In doing so, an increased anterior tibiofibular distance was detected, corresponding to an 'anterior open-book injury' of the ankle syndesmosis as a result of anterior inferior tibiofibular ligament elongation/rupture (Figure 1).

Repetitive Knee Bending and Synovitis in Individuals at Risk of and With Knee Osteoarthritis: Data From the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium

OBJECTIVE

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.

METHODS

We included baseline data from 594 participants (mean ± SD age 61.5 ± 8.9 years, 61% had Kellgren/Lawrence grade ≥2; 59% were female; mean ± SD body mass index was 30.7 ± 4.8 kg/m² ) of the Osteoarthritis Biomarker Consortium Foundation for the National Institutes of Health project. Knee bending activities were queried by a standard questionnaire, and the severity of Hoffa synovitis and effusion synovitis (surrogate outcomes of synovitis) were graded using the MRI OsteoArthritis Knee Scoring system. Logistic regression was used, unadjusted and adjusted, for metabolic syndrome, physical activity level, and sex. A grade ≥1 defined synovitis prevalence, with a grade ≥2 cutoff implemented in sensitivity analyses.

RESULTS

The prevalence of grade ≥1 Hoffa synovitis and effusion synovitis equaled 59% (n = 353) and 62% (n = 366), respectively. Adjusted for confounders, kneeling for ≥30 minutes during a single day was associated with grade ≥1 Hoffa synovitis prevalence (odds ratio [OR] 1.65 [95% confidence interval (95% CI) 1.11-2.47]). Participants engaging in this activity ≤1 day per week had greater odds for prevalent Hoffa synovitis than those who did not perform the activity (OR 1.88 [95% CI 1.11-3.18]). No other significant associations were found. Sensitivity analyses yielded similar findings.

CONCLUSION

In this selected sample with a preponderance of grade ≥1 Hoffa and/or effusion synovitis on noncontrast MRI, only prolonged kneeling was associated with Hoffa synovitis prevalence. Replication in other samples is warranted.

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.

A Nationwide Survey on Patient's versus Physician´s Evaluation of Biological Therapy in Rheumatoid Arthritis in Relation to Disease Activity and Route of Administration: The Be-Raise Study

Objectives

Biological treatment of rheumatoid arthritis (RA) is one of the cornerstones of current treatment strategies for the disease. Surprisingly little information exists on whether the route of administration affects patients’ treatment satisfaction. It is equally unclear whether rheumatologists are able to accurately perceive their patients’ appreciation. Thus, the Belgian Be-raise survey aimed to examine whether RA patient’s experience of their current biological treatment coincided with the treating physician’s perception.

Methods

A nationwide cross-sectional survey was conducted by 67 Belgian rheumatologists providing data obtained from 550 RA patients. Patients under stable dose of biologics for at least 6 months, were enrolled consecutively and all completed questionnaires. Separate questionnaires were completed by the treating rheumatologist which evaluated their patient’s perception of the route of treatment administration. This study therefore evaluates whether a treating physician perceives the satisfaction with the route of administration to the same degree as the patient.

Results

Completed questionnaires were obtained from 293 and 257 patients who obtained treatment via the intravenous (IV) or subcutaneous (SC) route of administration, respectively. 58.4% of patients were in DAS28-CRP(3) remission. Patient satisfaction with disease control was higher (44% scored ≥ 9) than that of the treating physician (35%), regardless of the route of administration (p< 0.01). No differences were seen for the patients treated with an IV as opposed to a SC route of administration. The physician´s perception of patient’s satisfaction with disease control was markedly lower for IV treated patients as opposed to SC treated patients (p< 0.001).

Conclusions

Patients’ satisfaction with biological treatment is high, but there is a considerable mismatch between patients´ and rheumatologists´ appreciation on the route of administration of biological therapy in RA. Physicians consistently consider IV biological therapy to be less satisfactory. Patient´s appreciation is largely dependent on disease control, irrespective of the route of administration. Therefore, and encouraging shared decision making, we suggest that physicians and patients discuss the route of administration of biologicals in an open way.

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. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1969-1976, 2016.

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 swimmer's 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.

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 board's 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.

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.

Quantitative assessment of foot structure in rheumatoid arthritis by a foot digitizer: detection of deformities even in the absence of erosions

OBJECTIVE

Foot involvement is a major feature in rheumatoid arthritis (RA), leading to structural deformities. Methods to allow a 3-dimensional (3-D) evaluation of foot structure in RA to be applicable in daily clinical practice have not been evaluated. This study assessed the use of a foot digitizer, a noninvasive 3-D scanner collecting objective quantitative data of the feet, to evaluate the presence of foot structure abnormalities in an RA outpatient cohort.

METHODS

Foot digitizer data of RA patients were compared with healthy controls. Subanalyses were performed to find relationships with erosive disease and the presence of swollen and/or tender joints. Linear mixed models were applied with correction, including sex, age, body weight and height, foot length, Disease Activity Score in 28 joints, and disease duration.

RESULTS

Forty-one percent of the patients showed >1 abnormal parameter, measured with the 3-D foot scanner. Most differences found were located in the forefoot, the most frequently affected area of the RA foot. Strikingly, even in the absence of joint erosions, marked alterations were found. Comparable differences were also observed between the patients with and without swollen and/or tender joints. Additionally, alterations were not strongly related to foot pain and disability, suggesting the capacity of the foot digitizer to detect early changes in foot structure.

CONCLUSION

The results highlight the impact of RA on foot structure, even in the absence of clinical signs of swelling or radiographic erosions. The foot digitizer offers a valuable tool to screen for such foot deformities before the presence of erosions.

A clinically applicable six-segmented foot model

We describe a multi-segmented foot model comprising lower leg, rearfoot, midfoot, lateral forefoot, medial forefoot, and hallux for routine use in a clinical setting. The Ghent Foot Model describes the kinematic patterns of functional units of the foot, especially the midfoot, to investigate patient populations where midfoot deformation or dysfunction is an important feature, for example, rheumatoid arthritis patients. Data were obtained from surface markers by a 6 camera motion capture system at 500 Hz. Ten healthy subjects walked barefoot along a 12 m walkway at self-selected speed. Joint angles (rearfoot to shank, midfoot to rearfoot, lateral and medial forefoot to midfoot, and hallux to medial forefoot) in the sagittal, frontal, and transverse plane are reported according to anatomically based reference frames. These angles were calculated and reported during the foot rollover phases in stance, detected by synchronized plantar pressure measurements. Repeated measurements of each subject revealed low intra-subject variability, varying between 0.7° and 2.3° for the minimum values, between 0.5° and 2.1° for the maximum values, and between 0.8° and 5.8° for the ROM. The described movement patterns were repeatable and consistent with biomechanical and clinical knowledge. As such, the Ghent Foot model permits intersegment, in vivo motion measurement of the foot, which is crucial for both clinical and research applications.

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.

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.