JointTracker: Real-time inertial kinematic chain tracking with joint position estimation.

In-field human motion capture (HMC) is drawing increasing attention due to the multitude of application areas. Plenty of research is currently invested in camera-based (markerless) HMC, with the advantage of no infrastructure being required on the body, and additional context information being available from the surroundings. However, the inherent drawbacks of camera-based approaches are the limited field of view and occlusions. In contrast, inertial HMC (IHMC) does not suffer from occlusions, thus being a promising approach for capturing human motion outside the laboratory. However, one major challenge of such methods is the necessity of spatial registration. Typically, during a predefined calibration sequence, the orientation and location of each inertial sensor are registered with respect to the underlying skeleton model. This work contributes to calibration-free IHMC, as it proposes a recursive estimator for the simultaneous online estimation of all sensor poses and joint positions of a kinematic chain model like the human skeleton. The full derivation from an optimization objective is provided. The approach can directly be applied to a synchronized data stream from a body-mounted inertial sensor network. Successful evaluations are demonstrated on noisy simulated data from a three-link chain, real lower-body walking data from 25 young, healthy persons, and walking data captured from a humanoid robot. The estimated and derived quantities, global and relative sensor orientations, joint positions, and segment lengths can be exploited for human motion analysis and anthropometric measurements, as well as in the context of hybrid markerless visual-inertial HMC.

Effects of technological running shoes versus barefoot running on the intrinsic foot muscles, ankle mobility, and dynamic control: a novel cross-sectional research.

BACKGROUND: Technological running shoes have become increasingly popular, leading to improvements in performance. However, their long-term effects on foot musculature and joint mobility have not been thoroughly studied. OBJECTIVE: To compare the activation of the intrinsic foot muscles between runners wearing technological footwear and barefoot runners. Secondary objectives included assessing ankle dorsiflexion (DF) range of motion (ROM) and dynamic postural control in both groups. METHODS: A cross-sectional study was conducted involving 22 technological footwear runners and 22 barefoot runners. Ultrasonography was used to measure the thickness of the plantar fascia (PF) and the quadratus plantae (QP), abductor digiti minimus (ADM), abductor hallucis (AH), and flexor hallucis longus (FHL) muscles. Ankle mobility and dynamic postural control were also recorded. RESULTS: Ultrasonography measurements showed statistically significant differences for PF thickness (mean difference [MD]: -0.10 cm; 95% CI: -0.13, -0.05 cm), QP cross-sectional area (CSA) (MD: -0.45 cm2; 95% CI: -0.77, -0.12 cm2), ADM CSA (MD: -0.49 cm2; 95% CI: -0.70, -0.17 cm2), and FHL thickness (MD: 0.82 cm; 95% CI: 0.53, 1.09 cm), with all measurements being lower in the group wearing technological footwear compared to the barefoot runners. Ankle DF ROM was also significantly greater for the barefoot runners (MD: -5.1°; 95% CI: -8.6, -1.7°). CONCLUSIONS: These findings suggest potential implications for the foot musculature and ankle mobility in runners using technological footwear.

Assessment of average femoral component rotation for balancing functionally aligned total knee replacement in varus deformity: Robotic image guidance study.

Introduction and purpose: Ensuring proper femoral component alignment post-Total Knee Arthroplasty (TKA) is crucial for normal patellofemoral (PF) kinematics. However, the customary 3° external rotation relative to the Posterior Condylar Axis (PC Axis) may not universally apply, and the expected final femoral component rotation remains unclear in functionally aligned knees. This study examines the relation between the Transepicondylar Axis (TEA) and PC axis, known as Posterior Condylar Angle (PCA) in Indian patients along with factors influencing PCA, and the feasibility of reproducing patient-specific PCA using image-guided Cuvis joint robot. Methods: Forty patients (52 Knees) with primary osteoarthritis and varus deformity were prospectively evaluated. Native PCA was determined using CT-based J planner. Pre-operative patellar shape, PF tilt, PF shift, final femoral component rotation (representing post-operative PCA), final patellar tracking, and post-operative functional and radiological assessment at 3 months were recorded. Results: Study participants averaged 64.3 years of age, with a female-to-male ratio of 23 to 17. Varus deformities varied, with IA2 being most prevalent, and sagittal plane deformities included fixed flexion (34.6 %) and hyperextension (44.2 %). The average PCA was 1.9° (range: 0°-7.3°), with most knees (41 out of 52) below 3°. The majority had Wiberg type 1 patellae, with pre-operative patellar tilt averaging 5.63°, reducing post-operatively to 4.43°. Most patients (37 out of 40) achieved excellent Knee Society functional scores at the 3-month mark. Complications included one case of delayed wound healing and one femoral array pin breakage. Notably, our study revealed a significant deviation in PCA from the commonly reported 3° in Western literature, underscoring the need for region-specific considerations in TKA planning. Conclusion: PCA of our population is statistically different from customary 3° followed with jig system. Image guided Robotics helps to identify patients specific PCA and reproducing the same was more commonly possible in patients with reducible Varus deformity.

Investigating the biomechanical behaviour of tendon-loaded wrist joint using web-like kinematic network model.

The complexity of wrist anatomy and mechanics makes it challenging to develop standardized measurements and establish a normative reference database of wrist biomechanics despite being studied extensively. Moreover, heterogeneity factors in both demographic characteristics (e.g. gender) and physiological properties (e.g. ligament laxity) could lead to differences in biomechanical behaviour even within healthy groups. We investigated the kinematic behaviour of the carpal bones by creating a virtual web-like network between the bones using electromagnetic (EM) sensors. Our objective was to quantify the changes in the carpal bones' biomechanical relative motions and orientations during active wrist motion in the form of orb-web architecture. Models from five cadaveric specimens at different wrist positions: (1) Neutral to 30° Extension, (2) Neutral to 50° Flexion, (3) Neutral to 10° Radial Deviation, (4) Neutral to 20° Ulnar Deviation, and (5) Dart-Throw Motion - Extension (30° Extension/10° RD) to Dart-Throw Motion Flexion (50° Flexion/20° UD), in both neutral and pronated forearm have been analyzed. Quantification analyses were done by measuring the changes in the network thread length, as well as determining the correlation between the threads at different wrist positions. We observed similarities in the kinematic web-network patterns across all specimens, and the interactions between the network threads were aligned to the carpal bones' kinematic behaviour. Furthermore, analyzing the relative changes in the wrist web network has the potential to address the heterogeneity challenges and further facilitate the development of a 3D wrist biomechanics quantitative tool.

Kinematic upper limb analysis outperforms electromyography at grading the severity of dystonia in children with cerebral palsy.

BACKGROUND: Severity of dyskinesia in children with cerebral palsy is often assessed using observation-based clinical tools. Instrumented methods to objectively measure dyskinesia have been proposed to improve assessment accuracy and reliability. Here, we investigated the technique and movement features that were most suitable to objectively measure the severity of dystonia in children with cerebral palsy. METHODS: A prospective observational study was conducted with 12 participants with cerebral palsy with a predominant motor type of dyskinesia, spasticity, or mixed dyskinesia/spasticity who had upper limb involvement (mean age: 12.6 years, range: 6.7-18.2 years). Kinematic and electromyography data were collected bilaterally during three upper limb tasks. Spearman rank correlations of kinematic or electromyography features were calculated against dystonia severity, quantified by the Dyskinesia Impairment Scale. FINDINGS: Kinematic features were more influential compared to electromyography features at grading the severity of dystonia in children with cerebral palsy. Kinematic measures quantifying jerkiness of volitional movement during an upper limb task with a reaching component performed best (|rs| = 0.78-0.9, p < 0.001). INTERPRETATION: This study provides guidance on the types of data, features of movement, and activity protocols that instrumented methods should focus on when objectively measuring the severity of dystonia in children with cerebral palsy.

The impact of shoes versus ankle-restricted orthoses on sit-to-stand kinematics and centre of mass trajectories in adults with myelomeningocele.

BACKGROUND: Individuals with myelomeningocele (MMC) present with neurological and orthopaedic deficiencies, requiring orthoses during walking. Orthoses for counteracting dorsiflexion may restrict activities such as rising from a chair. RESEARCH QUESTION: How are sit-to-stand (STS) movements performed with ankle joint-restricted ankle-foot orthoses (AFO) and knee-ankle-foot orthoses with a free-articulated knee joint (KAFO-F)? METHODS: Twenty-eight adults with MMC, mean age 25.5 years (standard deviation: 3.5 years), were divided into an AnkleFree group (no orthosis or a foot orthosis) and an AnkleRestrict group (AFOs or KAFO-Fs). Study participants performed the five times STS test (5STS) while their movements were simultaneously captured with a three-dimensional motion system. Centre of mass (CoM) trajectories and joint kinematics were analysed using statistical parametric mapping. RESULTS: The AnkleRestrict group performed the STS slower than the AnkleFree group, median 8.8 s (min, max: 6.9, 14.61 s) vs 15.0 s (min, max: 7.5, 32.2 s) (p = 0.002), displayed reduced ankle dorsiflexion (mean difference: 6°, p = 0.044) (74-81 % of the STS cycle), reduced knee extension (mean difference: 14°, p = 0.002) (17-41 % of the STS cycle), larger anterior pelvic tilt angle (average difference: 11°, p = 0.024) (12-24 % of the STS cycle), and larger trunk flexion angle (on average 4°, p = 0.029) (6-15 % of the STS cycle). SIGNIFICANCE: The differences between the AnkleFree and AnkleRestrict groups in performing the STS seem consistent with the participants functional ambulation: community ambulation in the AnkleFree group, and household and nonfunctional ambulation with less hip muscle strength in the majority of the AnkleRestrict group. No differences in the 5STS CoM trajectories or the kinematics were found with respect to the AFO and KAFO-Fs groups. Because orthoses are constructed to enable walking, the environment needs to be adjusted for activities in daily living such as the STS movement.

Effects of different slopes on hip and ankle biomechanics of replaced and non-replaced limbs of patients with total knee arthroplasty during incline ramp walking.

Although knee biomechanics has been examined, hip and ankle biomechanics in incline ramp walking has not been explored for patients with total knee arthroplasty (TKA). The purpose of this study was to investigate the hip and ankle joint kinematic and kinetic biomechanics of different incline slopes for replaced limbs and non-replaced limbs in individuals with TKA compared to healthy controls. Twenty-five patients with TKR and ten healthy controls performed walking trials on four slope conditions of level (0°), 5°, 10° and 15° on a customized instrumented ramp system. A 3x4 (limb x slope) repeated analysis of variance was used to evaluate selected variables. The results showed a greater peak ankle dorsiflexion angle in the replaced limbs compared to healthy limbs. No significant interactions or limb main effect for other ankle and hip variables. The peak dorsiflexion angle, eversion angle and dorsiflexion moment were progressively higher in each comparison from level to 15°. The peak plantarflexion moment was also increased with each increase of slopes. Both the replaced and non-replaced limbs of patients with TKA had lower hip flexion moments than the healthy control limbs. Hip angle at contact and hip extension range of motion increased with each increase of slopes. Peak hip loading-response internal extension moment increased with each increase in slope and peak hip push-off internal flexion moment decreased with each increase of slope. Our results showed increased dorsiflexion in replaced limbs but no other compensations of hip and ankle joints of replaced limbs compared to non-replaced limbs and their healthy controls during incline walking, providing further support of using incline walking in rehabilitation for patients with TKA.

Instrumented Mouthguard Decoupling Affects Measured Head Kinematic Accuracy.

Many recent studies have used boil-and-bite style instrumented mouthguards to measure head kinematics during impact in sports. Instrumented mouthguards promise greater accuracy than their predecessors because of their superior ability to couple directly to the skull. These mouthguards have been validated in the lab and on the field, but little is known about the effects of decoupling during impact. Decoupling can occur for various reasons, such as poor initial fit, wear-and-tear, or excessive impact forces. To understand how decoupling influences measured kinematic error, we fit a boil-and-bite instrumented mouthguard to a 3D-printed dentition mounted to a National Operating Committee on Standards for Athletic Equipment (NOCSAE) headform. We also instrumented the headform with linear accelerometers and angular rate sensors at its center of gravity (CG). We performed a series of pendulum impact tests, varying impactor face and impact direction. We measured linear acceleration and angular velocity, and we calculated angular acceleration from the mouthguard and the headform CG. We created decoupling conditions by varying the gap between the lower jaw and the bottom face of the mouthguard. We tested three gap conditions: 0 mm (control), 1.6 mm, and 4.8 mm. Mouthguard measurements were transformed to the CG and compared to the reference measurements. We found that gap condition, impact duration, and impact direction significantly influenced mouthguard measurement error. Error was higher for larger gaps and in frontal (front and front boss) conditions. Higher errors were also found in padded conditions, but the mouthguards did not collect all rigid impacts due to inherent limitations. We present characteristic decoupling time history curves for each kinematic measurement. Exemplary frequency spectra indicating characteristic decoupling frequencies are also described. Researchers using boil-and-bite instrumented mouthguards should be aware of their limitations when interpreting results and should seek to address decoupling through advanced post-processing techniques when possible.

Unicompartmental knee arthroplasty approximates healthy knee kinematics more closely than total knee arthroplasty.

Total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) are effective surgeries to treat end-stage knee osteoarthritis. Clinicians assume that TKA alters knee kinematics while UKA preserves native knee kinematics; however, few studies of in vivo kinematics have evaluated this assumption. This study used biplane radiography to compare side-to-side tibiofemoral kinematics during chair rise, stair ascent, and walking in 16 patients who received either TKA or UKA. We hypothesized that TKA knees would have significant kinematic changes and increased asymmetry with the contralateral knee, while UKA knee kinematics would not change after surgery and preoperative knee symmetry would be maintained. Native bone and implant motion were tracked using a volumetric model-based tracking technique. Six degrees of freedom kinematics were calculated throughout each motion. Kinematics were compared between the operated and contralateral knees pre- and post-surgery using a linear mixed-effects model. TKA knees became less varus with the tibia more medial, posterior, and distal relative to the femur. UKA knees became less varus with the tibia less lateral on average. Postoperative TKA knees were in less varus than UKA knees on average and at low flexion angles, with an internally rotated tibia during chair rise and stair ascent. At high flexion angles, the tibia was more medial and posterior after TKA than UKA. Side-to-side kinematic symmetry worsened after TKA but was maintained or improved after UKA. Greater understanding of kinematic differences between operated and contralateral knees after surgery may help surgeons understand why some patients remain unsatisfied with their new knees.

Dyadic body competence predicts movement synchrony during the mirror game.

The process of synchronizing our body movements with others is known to enhance rapport, affect, and prosociality. Furthermore, emerging evidence suggests that synchronizing activities may enhance cognitive performance. Unknown, by contrast, is the extent to which people's individual traits and experiences influence their ability to achieve and maintain movement synchrony with another person, which is key for unlocking the social and affective benefits of movement synchrony. Here, we take a dyad-centered approach to gain a deeper understanding of the role of embodiment in achieving and maintaining movement synchrony. Using existing data, we explored the relationship between body competence and body perception scores at the level of the dyad, and the dyad's movement synchrony and complexity while playing a 2.5-min movement mirroring game. The data revealed that dyadic body competence scores positively correlate with movement synchrony, but not complexity, and that dyadic body perception scores are not associated with movement synchrony or complexity. Movement synchrony was greater when the more experienced member of the dyad was responsible for copying movements. Finally, movement synchrony and complexity were stable across the duration of the mirror game. These findings show that movement synchrony is sensitive to the composition of the dyad involved, specifically the dyad's embodiment, illuminating the value of dyadic approaches to understanding body movements in social contexts.

Kinematics and coordination of moth flies walking on smooth and rough surfaces.

The moth fly, Clogmia albipunctata, is a common synanthropic insect with a worldwide range that lives in nearly any area with moist, decaying organic matter. These habitats comprise both smooth, slippery substrates (e.g., bathroom drains) and heterogeneous, bumpy ground (e.g., soil in plant pots). By using terrain of varying levels of roughness, we focus specifically on how substrate roughness at the approximate size scale of the organism affects kinematics and coordination in adult moth flies. Finally, we compare and contrast our characterizations of locomotion in C. albipunctata with previous work of insect walking in naturalistic environments.

Comparison of the in vivo kinematics between robotic-assisted Bi-cruciate retaining and Bi-cruciate stabilised total knee arthroplasty.

BACKGROUND: Up to 20% of patients remain unsatisfied after total knee arthroplasty (TKA), prompting the development of new implants. Bi-Cruciate Retaining (BCR) TKA preserves both the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), with the ACL beneficial for its proprioceptive qualities. The Bi-Cruciate Stabilised (BCS) TKA substitutes the ACL and PCL with a unique dual cam-post mechanism. Robotics improve accuracy and facilitate technically demanding TKA. METHODS: This was a retrospective case-control study recruited from two centres. Measured outcomes included kinematic analysis, proprioception, and functional outcomes. RESULTS: There was a significantly larger maximum flexion angle and range of flexion to extension in sit-to-stand and stairs in BCR when compared to BCS. Further analysis revealed more similarities between BCR and normal native knees. Proprioception and functional scores did not have any statistical difference. CONCLUSION: BCR TKA demonstrated better knee flexion in weight-bearing active range of motion and showed similarities with normal knee kinematics.

Comparing the Drop Vertical Jump Tracking Performance of the Azure Kinect to the Kinect V2.

Traditional motion analysis systems are impractical for widespread screening of non-contact anterior cruciate ligament (ACL) injury risk. The Kinect V2 has been identified as a portable and reliable alternative but was replaced by the Azure Kinect. We hypothesize that the Azure Kinect will assess drop vertical jump (DVJ) parameters associated with ACL injury risk with similar accuracy to its predecessor, the Kinect V2. Sixty-nine participants performed DVJs while being recorded by both the Azure Kinect and the Kinect V2 simultaneously. Our software analyzed the data to identify initial coronal, peak coronal, and peak sagittal knee angles. Agreement between the two systems was evaluated using the intraclass correlation coefficient (ICC). There was poor agreement between the Azure Kinect and the Kinect V2 for initial and peak coronal angles (ICC values ranging from 0.135 to 0.446), and moderate agreement for peak sagittal angles (ICC = 0.608, 0.655 for left and right knees, respectively). At this point in time, the Azure Kinect system is not a reliable successor to the Kinect V2 system for assessment of initial coronal, peak coronal, and peak sagittal angles during a DVJ, despite demonstrating superior tracking of continuous knee angles. Alternative motion analysis systems should be explored.

The Kinematic Models of the SINS and Its Errors on the SE(3) Group in the Earth-Centered Inertial Coordinate System.

In this paper, the kinematic models of the Strapdown Inertial Navigation System (SINS) and its errors on the SE(3) group in the Earth-Centered Inertial frame (ECI) are established. On the one hand, with the ECI frame being regarded as the reference, based on the joint representation of attitude and velocity on the SE(3) group, the dynamic of the local geographic coordinate system (n-frame) and the body coordinate system (b-frame) evolve on the differentiable manifold, respectively, and the high-order expansion of the Baker-Campbell-Haussdorff equation compensates for the non-commutative motion errors stimulated by strong maneuverability. On the other hand, the kinematics of the left- and right-invariant errors of the n-frame and the b-frame on the SE(3) group are separately derived, where the errors of the b-frame completely depend on inertial sensor errors, while the errors of the n-frame rely on position errors and velocity errors. In this way, the errors brought by the inconsistency of the reference coordinate system are tackled, and a novel attitude error definition is introduced to separate and decouple the factors affecting the dynamic of the n-frame errors and the b-frame errors for better attitude estimation. Through a turntable experiment and a car-mounted field experiment, the effectiveness of the proposed kinematic models in estimating attitude has been verified, with a remarkable improvement in yaw angle accuracy in the case of large initial misalignment angles, and the models developed have better robustness compared to the traditional SE(3) group-based model.

Biomechanical Investigation of Lower Limbs during Slope Transformation Running with Different Longitudinal Bending Stiffness Shoes.

BACKGROUND: During city running or marathon races, shifts in level ground and up-and-down slopes are regularly encountered, resulting in changes in lower limb biomechanics. The longitudinal bending stiffness of the running shoe affects the running performance. PURPOSE: This research aimed to investigate the biomechanical changes in the lower limbs when transitioning from level ground to an uphill slope under different longitudinal bending stiffness (LBS) levels in running shoes. METHODS: Fifteen male amateur runners were recruited and tested while wearing three different LBS running shoes. The participants were asked to pass the force platform with their right foot at a speed of 3.3 m/s ± 0.2. Kinematics data and GRFs were collected synchronously. Each participant completed and recorded ten successful experiments per pair of shoes. RESULTS: The range of motion in the sagittal of the knee joint was reduced with the increase in the longitudinal bending stiffness. Positive work was increased in the sagittal plane of the ankle joint and reduced in the keen joint. The negative work of the knee joint increased in the sagittal plane. The positive work of the metatarsophalangeal joint in the sagittal plane increased. CONCLUSION: Transitioning from running on a level surface to running uphill, while wearing running shoes with high LBS, could lead to improved efficiency in lower limb function. However, the higher LBS of running shoes increases the energy absorption of the knee joint, potentially increasing the risk of knee injuries. Thus, amateurs should choose running shoes with optimal stiffness when running.

Squatting biomechanics following physiotherapist-led care or hip arthroscopy for femoroacetabular impingement syndrome: a secondary analysis from a randomised controlled trial.

Background: Femoroacetabular impingement syndrome (FAIS) can cause hip pain and chondrolabral damage that may be managed non-operatively or surgically. Squatting motions require large degrees of hip flexion and underpin many daily and sporting tasks but may cause hip impingement and provoke pain. Differential effects of physiotherapist-led care and arthroscopy on biomechanics during squatting have not been examined previously. This study explored differences in 12-month changes in kinematics and moments during squatting between patients with FAIS treated with a physiotherapist-led intervention (Personalised Hip Therapy, PHT) and arthroscopy. Methods: A subsample (n = 36) of participants with FAIS enrolled in a multi-centre, pragmatic, two-arm superiority randomised controlled trial underwent three-dimensional motion analysis during squatting at baseline and 12-months following random allocation to PHT (n = 17) or arthroscopy (n = 19). Changes in time-series and peak trunk, pelvis, and hip biomechanics, and squat velocity and maximum depth were explored between treatment groups. Results: No significant differences in 12-month changes were detected between PHT and arthroscopy groups. Compared to baseline, the arthroscopy group squatted slower at follow-up (descent: mean difference -0.04 m∙s-1 (95%CI [-0.09 to 0.01]); ascent: -0.05 m∙s-1 [-0.11 to 0.01]%). No differences in squat depth were detected between or within groups. After adjusting for speed, trunk flexion was greater in both treatment groups at follow-up compared to baseline (descent: PHT 7.50° [-14.02 to -0.98]%; ascent: PHT 7.29° [-14.69 to 0.12]%, arthroscopy 16.32° [-32.95 to 0.30]%). Compared to baseline, both treatment groups exhibited reduced anterior pelvic tilt (descent: PHT 8.30° [0.21-16.39]%, arthroscopy -10.95° [-5.54 to 16.34]%; ascent: PHT -7.98° [-0.38 to 16.35]%, arthroscopy -10.82° [3.82-17.81]%), hip flexion (descent: PHT -11.86° [1.67-22.05]%, arthroscopy -16.78° [8.55-22.01]%; ascent: PHT -12.86° [1.30-24.42]%, arthroscopy -16.53° [6.72-26.35]%), and knee flexion (descent: PHT -6.62° [0.56- 12.67]%; ascent: PHT -8.24° [2.38-14.10]%, arthroscopy -8.00° [-0.02 to 16.03]%). Compared to baseline, the PHT group exhibited more plantarflexion during squat ascent at follow-up (-3.58° [-0.12 to 7.29]%). Compared to baseline, both groups exhibited lower external hip flexion moments at follow-up (descent: PHT -0.55 N∙m/BW∙HT[%] [0.05-1.05]%, arthroscopy -0.84 N∙m/BW∙HT[%] [0.06-1.61]%; ascent: PHT -0.464 N∙m/BW∙HT[%] [-0.002 to 0.93]%, arthroscopy -0.90 N∙m/BW∙HT[%] [0.13-1.67]%). Conclusion: Exploratory data suggest at 12-months follow-up, neither PHT or hip arthroscopy are superior at eliciting changes in trunk, pelvis, or lower-limb biomechanics. Both treatments may induce changes in kinematics and moments, however the implications of these changes are unknown. Trial registration details: Australia New Zealand Clinical Trials Registry reference: ACTRN12615001177549. Trial registered 2/11/2015.

Ex vivo biomechanical investigations of combined extra- and intracapsular stabilization in canines with cranial cruciate ligament deficiency.

Intracapsular reconstruction (ICR) has long been recommended as a treatment for cranial cruciate ligament deficiency (CCLD) in dogs, but it has fallen out of favor due to its inferior long-term functional outcomes. These outcomes may be attributed to the poor stiffness and strength of the graft in the early period before ligamentization is completed. Additional placement of extracapsular sutures to mechanically protect the graft during the ligamentization process may be a viable method to address this problem. However, the biomechanical effect of this combined surgical approach remains unknown. This study aimed to evaluate the 3D kinematics of the CCLD stifle in dogs in response to ICR and combined extra- and intracapsular reconstruction (CEICR). Twelve hindlimbs were collected from nine cadavers of mature dogs. The limbs were tested using a custom-made testing apparatus that reproduces their sagittal plane kinematics during the stance phase. Four statuses of stifle joints were tested, namely, (a) cranial cruciate ligament (CCL) intact; (b) CCLD; (c) CCLD stifle stabilized by CEICR; and (d) CCLD stifle stabilized by ICR only. Three-dimensional stifle kinematics at the 5 instances of the stance phase were measured with an optoelectronic system. The results showed that ICR marginally corrects the increased adduction, internal rotation, and caudodistal stifle joint center displacement that occur as a result of CCLD. CEICR led to better restoration of the stifle kinematics, especially with respect to the internal rotation and cranial translation stabilities. Furthermore, CEICR only resulted in minor excessive restraints on other motion components. The findings indicated that the additional lateral fabellotibial suture offers immediate stability to the stifle, consequently lowering the risk of graft over-elongation in the short term postoperatively. Considering the propensity for the extracapsular suture to degrade over time, further in vivo studies are warranted to explore the long-term effects of the CEICR procedure.

Walking and Running of Children with Decreased Femoral Torsion.

Understanding the implications of decreased femoral torsion on gait and running in children and adolescents might help orthopedic surgeons optimize treatment decisions. To date, there is limited evidence regarding the kinematic gait deviations between children with decreased femoral torsion and typically developing children, as well as the implications of the same on the adaptation of walking to running. A three-dimensional gait analysis study was undertaken to compare gait deviations during running and walking among patients with decreased femoral torsion (n = 15) and typically developing children (n = 11). Linear mixed models were utilized to establish comparisons within and between the two groups and investigate the relationship between clinical examination, spatial parameters, and the difference in hip rotation between running and walking. Patients exhibited increased external hip rotation during walking in comparison to controls, accompanied by higher peaks for the same as well as for knee valgus and external foot progression angle. A similar kinematic gait pattern was observed during running, with significant differences noted in peak knee valgus. In terms of variations from running to walking, patients internally rotated their initially externally rotated hip by 4°, whereas controls maintained the same internal hip rotation. Patients and controls displayed comparable kinematic gait deviations during running compared to walking. The passive hip range of motion, torsions, and velocity did not notably influence the variation in mean hip rotation from running to walking. This study underlines the potential of 3D gait kinematics to elucidate the functional implications of decreased FT and, hence, may contribute to clinical decision making.

The Use of Head-Mounted Display Systems for Upper Limb Kinematic Analysis in Post-Stroke Patients: A Perspective Review on Benefits, Challenges and Other Solutions.

In recent years, there has been a notable increase in the clinical adoption of instrumental upper limb kinematic assessment. This trend aligns with the rising prevalence of cerebrovascular impairments, one of the most prevalent neurological disorders. Indeed, there is a growing need for more objective outcomes to facilitate tailored rehabilitation interventions following stroke. Emerging technologies, like head-mounted virtual reality (HMD-VR) platforms, have responded to this demand by integrating diverse tracking methodologies. Specifically, HMD-VR technology enables the comprehensive tracking of body posture, encompassing hand position and gesture, facilitated either through specific tracker placements or via integrated cameras coupled with sophisticated computer graphics algorithms embedded within the helmet. This review aims to present the state-of-the-art applications of HMD-VR platforms for kinematic analysis of the upper limb in post-stroke patients, comparing them with conventional tracking systems. Additionally, we address the potential benefits and challenges associated with these platforms. These systems might represent a promising avenue for safe, cost-effective, and portable objective motor assessment within the field of neurorehabilitation, although other systems, including robots, should be taken into consideration.

Smartpaddle® as a New Monitoring Feature: A Comparison Between Inertial Measurement Unit- and Strain Gauge-Based Devices on Tethered Swimming Forces.

Smartpaddle® is a novel wearable device based on inertial measurement units (IMU) for in-field arm-stroke kinetics and kinematics analysis in swimming. However, the lack of data regarding its agreement and reliability, coupled with restricted access to raw data, emphasizes the need to evaluate it against a well-established strain gauge (SG) reference method for assessing swimming forces. Thus, this study aimed to investigate the agreement and reliability between the Smartpaddle® and strain gauge in a 30-s all-out arms-only tethered swimming test. Twelve trained young adult swimmers performed a test-retest 30-s all-out arms-only tethered swimming trial. Peak and mean forces were obtained from IMU (PFIMU and MFIMU) and SG (PFSG and MFSG) simultaneously. Statistical differences and correlations were found in both peak (PFSG = 158.46 ± 48.85 N, PFIMU = 75.47 ± 12.05 N, p < 0.001, r = 0.88) and mean (MFSG = 69.62 ± 16.36 N, MFIMU = 30.06 ± 5.42 N, p < 0.001, r = 0.84) forces between devices, presenting elevated systematic errors for both variables. No differences were found in IMU data between test-retest conditions in both peak (PFIMU = 75.47 ± 12.05 N, PFIMU = 75.45 ± 11.54 N, p = 0.99, ICC = 0.96) and mean (MFIMU = 30.06 ± 5.42 N, MFIMU = 30.21 ± 5.83 N, p = 0.80, ICC = 0.95) forces, with negligible systematic errors. In conclusion, although the Smartpaddle® device is not directly comparable to the strain gauge reference method, it has demonstrated high reliability levels in test-retest trials.