Validity of an inertial measurement unit for the assessment of range and quality of movement during head and thoracic spine movements.

BACKGROUND: Patients with spinal pain often exhibit movement limitations and altered motor control, which can be challenging to measure accurately in clinical practice. Inertial measurement sensors present a promising new opportunity to develop valid, low-cost, and easy-to-use methods for assessing and monitoring spinal motion in a clinical setting. AIM: This study aimed to investigate the agreement of an inertial sensor and a 3D camera system for assessing the range of motion (ROM) and quality of movement (QOM) in head and trunk single-plane movements. METHODS: Thirty-three healthy, pain-free volunteers were included. Each participant performed movements of the head (cervical flexion, extension, and lateral flexion) and trunk (trunk flexion, extension, rotation, and lateral flexion), which were simultaneously recorded by a 3D camera system and an inertial measurement unit (MOTI, Aalborg, Denmark). Agreement and consistency were analyzed for ROM and QOM by determining intraclass correlation coefficients (ICC), mean bias, and with Bland-Altman plots. RESULTS: The agreement between systems was excellent for all movements (ICC between 0.91 and 1.00) for ROM and good to excellent for the QOM (ICC between 0.84 and 0.95). The mean bias for all movements (0.1-0.8°) was below the minimum acceptable difference between devices. The Bland-Altman plot indicated that MOTI systematically measured a slightly greater ROM and QOM than the 3D camera system for all neck and trunk movements. CONCLUSION: This study showed that MOTI is a feasible and potentially applicable option to assess ROM and QOM for head and trunk movements in experimental and clinical settings.

Simulated Increase in Monoarticular Hip Muscle Strength Reduces the First Peak of Knee Compression Forces During Walking.

Reducing compressive knee contact forces (KCF) during walking could slow the progression and reduce symptoms of knee osteoarthritis. A previous study has shown that compensating for the hip flexion/extension moment could reduce the KCF peak occurring during early stance (KCFp1). Therefore, this study aimed to identify if monoarticular hip muscle could allow this compensation while considering different walking strategies. Gait trials from 24 healthy participants were used to make musculoskeletal models, and five load-cases were examined: (I) Normal, (II) with an applied external moment compensating for 100% of the hip flexion/extension moment, and (III-V) three conditions with isolated/combined 30% increase of peak isometric strength of gluteus medius and maximus. Knee contact forces, hip muscle forces, and joint moments were computed. A cluster analysis of the Normal condition was performed with hip and knee flexion/extension moment during KCFp1 as input to examine the influence of different walking strategies. The cluster analysis revealed two groups having significantly different hip and knee moments in early-stance (p < 0.01). The reduction in KCFp1 from the Normal condition, although present in both groups, was greater for the group with the highest hip and lowest knee flexion/extension moments for all conditions tested (II: -21.82 ± 8.71% versus -6.03 ± 6.68%, III: -3.21 ± 1.09% versus -1.59 ± 0.96%, IV: -3.00 ± 0.89% versus -1.76 ± 1.04%, V: -6.12 ± 1.69 versus -3.09 ± 1.95%). This reduction in KCFp1 occurred through a shift in force developed by the hamstrings during walking (biarticular) to the gluteus medius and maximus (monoarticular), whose isometric strength was increased. The differences between the groups suggest that this reduction depends on the walking strategy.

The impact of prolonged experimental neck pain on walking stability and gait kinematics - A parallel-group study.

BACKGROUND: Neck pain is a common problem in the general population, and movement adaptations are a natural response to pain. Previous studies have reported reduced trunk rotation during walking in those suffering from clinical neck pain. However, it is unknown how soon after the onset of pain, movement adaptations are adopted. This study investigated the effect of prolonged experimental neck pain four days after pain onset on gait kinematics during walking. METHODS: Forty healthy participants were randomized to receive injections of nerve-growth-factor or a control injection of isotonic saline into the right splenius capitis muscle at the end of days 0 and 2. Participants performed two walking tasks, walking and walking while reading on a smartphone, on days 0, 4, and 15. Gait kinematics, spatiotemporal parameters, and gait stability were measured using Xsens Awinda. FINDINGS: The nerve-growth-factor group reported increased neck pain intensity (median VAS 17.5 [IQR: 2.75-25.75]) on day 4 compared to day 0 and day 15. No pain intensity changes between days were reported for the isotonic-group. For gait kinematics, a main effect of the task was identified, showing that during the smartphone condition, participants had shorter stride lengths and reduced RoM for the trunk, hip, knee, and ankle compared to normal waking (P < 0.006). INTERPRETATION: Walking while reading on a smartphone, but not mild neck muscle pain, caused changes in the gait kinematics compared to normal walking without neck pain. This finding suggests that movement alterations during walking are not an early feature of prolonged experimental neck pain.

Change in functional biomechanics following a targeted exercise intervention in patients with acetabular retroversion and femoroacetabular impingement syndrome.

BACKGROUND: Acetabular retroversion is a form of hip dysplasia that may cause femoroacetabular impingement syndrome (FAIS), leading to pain and restricted hip range of motion. An exercise intervention aiming at altering pelvis tilt and related functional biomechanics may be a useful first-line intervention for patients who are not eligible for surgical repositioning. RESEARCH QUESTION: Does squat and gait biomechanics change following an 8-week targeted exercise program in individuals with symptomatic acetabular retroversion and FAIS? METHODS: This prospective intervention study used participants as their own controls. Examinations were conducted at three time-points: T1 baseline; T2 following an 8-week control period; T3 after 8 weeks' intervention. At each time-point, three-dimensional motion analysis of a deep squat and level gait was performed, and pain intensity was recorded using a numerical rating scale (NRS 0-10). The intervention consisted of a home-exercise program to improve core stability and pelvic movement. Differences in waveforms between time-points across pelvis and lower-limb biomechanics were evaluated using statistical parametric mapping. Delta (Δ, differences between T1-T2 and T2-T3) was used to evaluate changes in spatiotemporal gait parameters and pain. RESULTS: Nineteen patients (18 females), mean age 22.6 (SD 4.5) years, BMI (kg/m2) 23.0 (SD 4.1), were included. Changes (Δ T1-T2 vs. Δ T2-T3) in squat biomechanics were observed as: (i) decreased anterior pelvic tilt, (ii) deeper vertical pelvis position, and (iii) increased knee flexion angle. Contrary, no significant changes in gait biomechanics, Δ walking speed, Δ step length, or NRS for pain were found. SIGNIFICANCE: Following a targeted exercise intervention, participants were able to squat deeper, potentially allowing better hip function. The deepened squat position was accompanied by increased knee flexion and reduced anterior pelvic tilt. Gait biomechanics and patient-reported pain remained unchanged post-intervention. These findings are important for future design of exercise interventions targeting pelvic tilt in symptomatic individuals.

Reliability of Running Economy Measurements: Influence of Shoe Familiarisation.

The purpose was to investigate differences in reliability of running economy measurements between familiar and unfamiliar shoes. Thirty-seven runners were included who all ran in familiar and unfamiliar running shoes while running economy was measured at steady state using a treadmill. Each participant was tested on two different visits (three sessions in total), with two trials in each of the three shoe conditions completed at each visit. Coefficient of variation, standard deviation of differences, and limits of agreement of running economy were used to quantify the repeatability (within-visit variation) and reproducibility (between-visit variation). The coefficient of variation showed a marginal difference in reproducibility across shoe conditions, whereas no differences were seen in coefficient of variation, standard deviation of the differences, or limits of agreement for repeatability across shoes. All three shoe conditions showed greater repeatability than reproducibility for running economy, and enhanced repeatability at visit 3 compared to visit 2. Our results indicate that familiarisation to shoes might not be needed for reliable measurements of running economy. Based on our results, when evaluating benefits in running shoes we suggest that running economy be assessed within the same day. Further, our data suggest a beneficial effect of using multiple familiarisation sessions if small differences between shoe conditions are expected.

A 3-Dimensional Gait Analysis of the Effects of Fatigue-Induced Reduced Foot Adductor Muscle Strength on the Walking of Healthy Subjects.

Dysfunction of the tibialis posterior muscle is the most common cause of adult acquired flat foot. Tibialis posterior muscle weakness has been observed in several patient populations, including those in the early stages of rheumatoid arthritis. However, the influence of tibialis posterior weakness on gait mechanics is not fully understood, although gait instability has been reported. In 24 healthy participants, 3-dimension lower limb kinematics and kinetics during walking were evaluated bilaterally, before and after, a muscle fatigue protocol aiming to decrease the right foot adductor muscles strength, including the tibialis posterior muscle. The 3-dimension gait kinematics and kinetics were analyzed with statistical parametric mapping. The stance phase duration was increased for the right side. The right ankle external rotation moment decreased, and the left hip extension moment increased with reduced muscle strength compared with normal strength conditions. These changes are similar in patients with dysfunction in the tibialis posterior muscle, indicating that compensatory strategies observed in these patients might be related to the loss of tibialis posterior muscle strength. Such strategies may involve the unaffected side.

The effect of foot orthoses on gait biomechanics and pain among people with rheumatoid arthritis: A quasi-experimental study.

BACKGROUND: Foot pain is frequent among people with rheumatoid arthritis (RA). Foot orthoses (FO) are commonly prescribed with the intention to reduce pain symptoms and improve function. RESEARCH QUESTION: How do a custom-made FO affect pain, gait biomechanics and daily activity among people with RA? METHODS: Twenty-five participants with RA and foot pain completed this quasi-experimental study using a control insole for four weeks and then a custom-made FO in the following four weeks. The foot orthoses were customized by plantar foot shape targeting optimal restoration of normal arch height. A visual analog scale was used to monitor changes in ankle/foot, knee, hip joints, and global arthritis pain. In addition, the perceived pain area was measured using a body chart analysis. Kinematics and kinetics of the hip, knee and ankle joints during gait were analyzed using 3D-motion capture. Daily steps were measured with a wrist-based activity tracker for both the control insole and custom-made FO period, respectively. RESULTS: In comparison to the control insole, the custom-made FO reduced ankle/foot pain intensity (p < 0.001) in addition to a reduction of the perceived pain areas in the feet (p < 0.001), legs (p = 0.012), as well as the arms and hands (p = 0.014). Ankle plantar flexion and eversion moments were also reduced (p < 0.001). No difference in daily steps was observed between the two periods (p = 0.657). SIGNIFICANCE: This study has demonstrated an ankle/foot pain-relieving effect in conjunction with alterations of the ankle joint moments in people with RA using custom-made FO. The pain relief is plausibly attributed to alterations of the ankle joint moments when using the custom-made FO. However, future studies are needed to explore further into therapeutic implication of custom-made FO in pain management of people with RA.

Different types of foot orthoses effect on gait mechanics in patients with rheumatoid arthritis.

Foot orthoses are a first line conservative treatment for foot impairments in patients with rheumatoid arthritis (RA), however their effect on gait mechanics is poorly understood. We aimed to compare changes in lower limb and foot mechanics between two types of commonly used foot orthoses (FO) with a control. Twenty-seven patients with rheumatoid arthritis participated in this crossover study. Two different types of FO (a medially wedged custom-made FO and a prefabricated FO with a metatarsal dome, respectively), were compared against a control insole. During gait, lower limb mechanics were analyzed using 3D motion capture, force plates, and an in-shoe pressure system. Inverse dynamics models were created in the Anybody Modeling System to calculate joint angles and joint moments during gait. Gait variables were analyzed using statistical parametric mapping. Compared to the control, the prefabricated FO had limited effect on gait mechanics. Compared to the control the custom-made FO reduced ankle plantarflexion moment with 0.4 %body weight * body height (BW * BH) between 66 and 76% of stance and ankle eversion moment was reduced 0.16% BW*BH between 3 and 40% of stance. Furthermore, it also reduced the average forefoot plantar pressure by 9 kPa between 20 and 62% of stance compared to the control. Changes in foot pressure distribution, joint moments and angles were most pronounced for custom-made FO compared to the prefabricated FO. The findings suggest that patients with RA and foot impairments may benefit more from an individualized FO strategy, if the aim of the treatment is to alter gait mechanics. (NCT03561688).

Foot and Ankle Problems in Patients With Rheumatoid Arthritis in 2019: Still an Important Issue.

OBJECTIVE: To study the prevalence of foot pain in patients with rheumatoid arthritis (RA) and whether including a 12-joint foot count in addition to the 28-joint count (from the Disease Activity Score 28 [DAS28]) improved detection of foot or ankle pain. In addition, the association between the self-reported foot and ankle score (SEFAS), patient-reported function, and disease-specific factors was studied. METHODS: Physician-reported data (swollen/tender 12-joint foot count, DAS28, and medication) and patient-reported data (foot/ankle pain, physical function, global health, and SEFAS) were assessed during a clinical visit. Data were analyzed with t test, χ2 tests, and regression analysis. RESULTS: A total of 320 patients with RA were included (mean age 63 years, SD 13 years; 73% women), of whom 69% reported foot or ankle pain. Patients who reported foot or ankle pain had a lower mean age and worse disease activity, general pain, function, and global health (P ≤ 0.016), and fewer were in remission (50% versus 75%; P < 0.001) compared with patients without foot pain. The 12-joint foot count identified 3.2% and 9.5% additional patients with swollen and tender joints, respectively, compared with the 28-joint count. The SEFAS was associated with walking problems (ß = -2.733; 95% confidence interval [CI] = -3.963 to -1.503) and worse function (ß = -3.634; 95% CI = -5.681 to -1.587) but not with joint inflammation severity. CONCLUSION: The prevalence of foot or ankle pain in patients with RA is high. The 12-joint foot count had minor effects on detecting patients with foot pain. However, the SEFAS contributed additional information on foot problems that was not identified by joint examinations alone.

Validation of different stepping counters during treadmill and over ground walking.

BACKGROUND: Commercially available physical activity trackers are very popular in the general population and are increasingly common in clinical and research settings. The marketfor activity trackers are rapidly expanding, requiring them to be validated on an ongoing basis. Different approaches have been used for validating these devices. Studies using treadmills shows good step-counting accuracy although test performed in field tests settings are limited. RESEARCH QUESTION: Does step-counting validity differ between a field test and a treadmill protocol for different types of activity trackers? METHODS: Thirty healthy subjects participated in this study, mean age was 28.2 (± 4.33) years, body mass 78.9 (± 12.9) kg, and height 178.5 (± 9.7) cm. A treadmill protocol with three different walking speeds (2, 3 and 4 km/h) and a 982 m field test was used. During the tests, participants' feet were filmed using a waist-mounted camera. The number of steps were extracted from the video data and used for comparison with four different step counters: a) Polar M200; b) Polar A300; c) Dunlop pedometer; d) Samsung Galaxy S9 smartphone. Validity and agreement determined was determined with the use of Bland-Altman plot and Spearman's correlation. RESULTS: Validity was higher for the field test compared to the 4 km/h treadmill test for all tested devices. The smartphone was the most accurate in terms of error, validity and agreement for both the treadmill and field test. All devices performed poorly for the 2 km/h treadmill test and only the smartphone performed well at 3 km/h. SIGNIFICANCE: The results of this study show that step counting validity and error obtained during treadmill walking is not similar to a field test. Future validation studies of activity trackers should consider this when designing a protocol. The smartphone had the lowest mean bias during the field test.

A parametric study of effect of experimental tibialis posterior muscle pain on joint loading and muscle forces-Implications for patients with rheumatoid arthritis?

BACKGROUND: Foot pain and deformities are commonly encountered in patients with rheumatoid arthritis (RA). Likewise, Posterior tibial tendon dysfunction (PTTD) is commonly involved in development of foot and ankle abnormalities and has been reported with a prevalence in two-thirds of the RA patients. RESEARCH QUESTION: Redundancy in the physiological function between different muscles provides the central nervous system multiple options to perform the same movement but which muscles compensate for the impairment of the tibialis posterior (TP) muscle? And how does these changes affect ankle joint loading? METHODS: Experimental and computational disciplines were applied to investigate changes in muscle forces as result of induced pain in the right TP muscle. Twelve healthy subjects were enrolled in the study. Experimental pain was induced in the TP by a single ultrasound graphically guided injection of 1 mL hypertonic saline (5.0% Sodium Chloride). The participants' gait was assessed by skin marker-based motion capture and force plates. Musculoskeletal models were used to investigate compensation mechanisms systematically in the lower under extremity when TP muscle was recruited less as a consequence of the induced pain. RESULTS: Experimental TP muscle pain and simulated reduced strength caused altered muscle recruitment and made the flexor digitorum longus and flexor hallucis longus muscles compensated for the impairment of the TP muscle. Further, the resultant ankle joint force was increased as the strength of the TP muscle was reduced. SIGNIFICANCE: The compensation mechanism observed in the present study indicate that alterations in muscle recruitment and muscle force distribution as a result of the underlying disease inflammation itself may contribute to development of chronic foot pain and deformities in patients with RA. Further studies are required to understand the role of PTTD in occurrence of those late adverse musculoskeletal manifestations aiming at search for early preventive strategies.

Tibialis posterior muscle pain effects on hip, knee and ankle gait mechanics.

BACKGROUND: Tibialis posterior (TP) dysfunction is a common painful complication in patients with rheumatoid arthritis (RA), which can lead to the collapse of the medial longitudinal arch. Different theories have been developed to explain the causality of tibialis posterior dysfunction. In all these theories, pain is a central factor, and yet, it is uncertain to what extent pain causes the observed biomechanical alterations in the patients. The aim of this study was to investigate the effect of experimental tibialis posterior muscle pain on gait mechanics in healthy subjects. METHODS: Twelve healthy subjects were recruited for this randomized crossover study. Experimental pain was induced by ultrasound-guided injection of 1 mL hypertonic saline into the upper part of the right tibialis posterior muscle with the use of isotonic saline as non-pain-inducing control. Subsequently, kinematic data during three self-paced over ground walking for each condition were collected. Ground reaction forces and external moments were measured from force plates installed in the floor. Painful areas were evaluated using body charts and pain intensity scoring via a verbal numerical rating scale. FINDINGS: Decreased hip internal rotation was observed during the pain condition at the end of the stance phase. There were no changes in gait velocity and duration of stand phase between the pain and no pain conditions. Reduced external joint moment was found for external knee rotation and for external hip rotation. INTERPRETATION: The study has demonstrated that induced pain in the TP muscle evokes kinematic alteration in the hip and the knee joints, but not in the ankle, which suggest an underlying early stage joint compensatory mechanism. These findings suggest the need to include those joints in current physical evaluations of tibialis posterior dysfunction.