11 research outputs found
Markerless motion capture through visual hull and articulated icp using subject specific models
No full textAn approach for accurately measuring human motion through Markerless Motion Capture (MMC) is presented. The method uses multiple color cameras and combines an accurate and anatomically consistent tracking algorithm with a method for automatically generating subject specific models. The tracking approach employed a Levenberg-Marquardt minimization scheme over an iterative closest point algorithm with six degrees of freedom for each body segment. Anatomical consistency was maintained by enforcing rotational and translational joint range of motion constraints for each specific joint. A subject specific model of the subjects was obtained through an automatic model generation algorithm (Corazza et al. in IEEE Trans. Biomed. Eng., 2009) which combines a space of human shapes (Anguelov et al. in Proceedings SIGGRAPH, 2005) with biomechanically consistent kinematic models and a pose-shape matching algorithm. There were 15 anatomical body segments and 14 joints, each with six degrees of freedom (13 and 12, respectively for the HumanEva II dataset). The overall method is an improvement over (Mundermann et al. in Proceedings of CVPR, 2007) in terms of both accuracy and robustness. Since the method was originally developed for a parts per thousand yen8 cameras, the method performance was tested both (i) on the HumanEva II dataset (Sigal and Black, Technical Report CS-06-08, 2006) in a 4 camera configuration, (ii) on a series of motions including walking trials, a very challenging gymnastic motion and a dataset with motions similar to HumanEva II but with variable number of cameras
Automatic generation of a subject specific model for accurate markerless motion capture and biomechanical applications
No full textA markerless motion capture system to study musculoskeletal biomechanics: visual hull and simulated annealing approach
No full textHuman motion capture is frequently used to study musculoskeletal biomechanics and clinical problems, as well as to provide realistic animation for the entertainment industry. The most popular technique for human motion capture uses markers placed on the skin, despite some important drawbacks including the impediment to the motion by the presence of skin markers and relative movement between the skin where the markers are placed and the underlying bone. The latter makes it difficult to estimate the motion of the underlying bone, which is the variable of interest for biomechanical and clinical applications. A model-based markerless motion capture system is presented in this study, which does not require the placement of any markers on the subject's body. The described method is based on visual hull reconstruction and an a priori model of the subject. A custom version of adapted fast simulated annealing has been developed to match the model to the visual hull. The tracking capability and a quantitative validation of the method were evaluated in a virtual environment for a complete gait cycle. The obtained mean errors, for an entire gait cycle, for knee and hip flexion are respectively 1.5 degrees (+/-3.9 degrees ) and 2.0 degrees (+/-3.0 degrees ), while for knee and hip adduction they are respectively 2.0 degrees (+/-2.3 degrees ) and 1.1 degrees (+/-1.7 degrees ). Results for the ankle and shoulder joints are also presented. Experimental results captured in a gait laboratory with a real subject are also shown to demonstrate the effectiveness and potential of the presented method in a clinical environment
Balance and gait adaptations in patients with early knee osteoarthritis
No full textAbstractGait adaptations in people with severe knee osteoarthritis (OA) have been well documented, with increased knee adduction moments (KAM) the most commonly reported parameter. Neuromuscular adaptations have also been reported, including reduced postural control. However these adaptations may be the result of morphological changes in the joint, rather than the cause. This study aimed to determine if people with early OA have altered gait parameters and neuromuscular adaptations. Gait and postural tasks were performed by 18 people with early medial knee OA and 18 age and gender-matched control subjects. Parameters measured were kinematics and kinetics during gait and postural tasks, and centre of pressure and electromyographic activity during postural tasks. OA subjects showed no differences in the gait parameters measured, however they demonstrated postural deficits during one-leg standing on both their affected and unaffected sides and altered hip adduction moments compared with controls. Increased activity of the gluteus medius of both sides (p<0.05), and quadriceps and hamstrings of the affected side (p<0.05) during one-leg standing compared with controls were also noted. This study has demonstrated that gait adaptations commonly associated with OA do not occur in the early stages, while neuromuscular adaptations are evident. These results may be relevant for early interventions to delay or prevent osteoarthritis in its early stages
Self-reported adult footwear and the risks of lower limb osteoarthritis : the GOAL case control study
No full textBackground: Biomechanical factors may play a role in osteoarthritis (OA) development and progression. Previous biomechanical studies have indicated that types of footwear may modulate forces across the knee joint, and high heeled womens’ shoes in particular are hypothesised to be detrimental to lower limb joint health. This analysis of data from a case control study investigated persistent users of different adult footwear for risks of knee and hip OA. Our underlying hypotheses were that high heeled, narrow heeled, and hard soled shoe types were putative risk factors for lower limb OA.
Methods: Data on footwear were initially obtained from participants during the Genetics of Osteoarthritis and Lifestyle (GOAL) hospital-based, case control study using standardised interview-delivered questionnaires. An additional questionnaire was later sent to GOAL study participants to verify findings and to further investigate specific shoe use per decade of life. Persistent users of footwear types (high or narrow heel; sole thickness or hardness) were identified from early adulthood. Participants were grouped into single sex knee OA, hip OA or control groups. Adjusted odds ratios (aOR) and 95% confidence interval (CI) were calculated.
Results: Univariate analysis of persistent users of women’s high heeled and narrow heeled shoes during early adulthood showed negative associations with knee OA and hip OA. After logistic regression, persistent narrow heel users were associated with less risk of OA (knee OA aOR 0.59, 95% CI 0.35 – 1.00 and hip aOR: 0.50, 95% CI 0.30 – 0.85), and other analyses were not statistically significant. Further analysis suggested that women with hip OA may have stopped wearing high and narrow heeled footwear to attenuate hip pain in early adulthood. Consistent associations between shoe soles and OA were not found.
Conclusions: In general, persistent users of high and narrow heeled shoes during early adulthood had a negative association with knee or hip OA. This does not necessarily imply a causal relationship, as changing footwear during early adulthood to modulate index joint pain may provide a possible explanation. Despite the findings of previous biomechanical studies of high heels, we did not find a positive association between women’s shoes and lower limb osteoarthritis
2D Markerless Gait Analysis
No full textWe present a 2D gait analysis system which is completely markerless and extracts kinematic information by analyzing video sequences obtained from an RGB video camera. These properties make the proposed approach particularly suitable in medical contexts where visual gait observation is still a recognised procedure or the invasiveness and high costs of marker-based systems can not be afforded. Markerless motion estimation literature for medical gait analysis is generally 2D oriented, since the majority of joints dysfunctions related to gait occur in the sagittal plane. Most of the approaches are based on time consuming human body models or need human-intervention. Conversely, the method we present this contribution is silhouette-based, completely automatic and uses information on the human body anthropometric proportions for the estimation of the lower limbs’ pose in the sagittal plane with good accuracy and low computational cost. Tests on a large number of synthetic and real video sequences with normal gait have been performed. Different frame rates, image resolutions and noises have been considered. The obtained results, in terms of sagittal joint angles, have been compared with the typical trends found in biomechanical studies. The performance of the proposed method is particularly encouraging for its appliance in the real medical context. Keywords— Mar
Improvement of walking speed and gait symmetry in older patients after hip arthroplasty: a prospective cohort study
No full textBACKGROUND: Retraining walking in patients after hip or knee arthroplasty is an important component of rehabilitation especially in older persons whose social interactions are influenced by their level of mobility. The objective of this study was to test the effect of an intensive inpatient rehabilitation program on walking speed and gait symmetry in patients after hip arthroplasty (THA) using inertial sensor technology.
METHODS: Twenty-nine patients undergoing a 4-week inpatient rehabilitation program following THA and 30 age-matched healthy subjects participated in this study. Walking speed and gait symmetry parameters were measured using inertial sensor device for standardized walking trials (2*20.3 m in a gym) at their self-selected normal and fast walking speeds on postoperative days 15, 21, and 27 in patients and in a single session in control subjects. Walking speed was measured using timing lights. Gait symmetry was determined using autocorrelation calculation of the cranio-caudal (CC) acceleration signals from an inertial sensor placed at the lower spine.
RESULTS: Walking speed and gait symmetry improved from postoperative days 15-27 (speed, female: 3.2 and 4.5 m/s; male: 4.2 and 5.2 m/s; autocorrelation, female: 0.77 and 0.81; male: 0.70 and 0.79; P <0.001 for all). After the 4-week rehabilitation program, walking speed and gait symmetry were still lower than those in control subjects (speed, female 4.5 m/s vs. 5.7 m/s; male: 5.2 m/s vs. 5.3 m/s; autocorrelation, female: 0.81 vs. 0.88; male: 0.79 vs. 0.90; P <0.001 for all).
CONCLUSIONS: While patients with THA improved their walking capacity during a 4-week inpatient rehabilitation program, subsequent intensive gait training is warranted for achieving normal gait symmetry. Inertial sensor technology may be a useful tool for evaluating the rehabilitation process during the post-inpatient period
Standardized loads acting in knee implants
No full textThe loads acting in knee joints must be known for improving joint replacement, surgical procedures, physiotherapy, biomechanical computer simulations, and to advise patients with osteoarthritis or fractures about what activities to avoid. Such data would also allow verification of test standards for knee implants. This work analyzes data from 8 subjects with instrumented knee implants, which allowed measuring the contact forces and moments acting in the joint. The implants were powered inductively and the loads transmitted at radio frequency. The time courses of forces and moments during walking, stair climbing, and 6 more activities were averaged for subjects with I) average body weight and average load levels and II) high body weight and high load levels. During all investigated activities except jogging, the high force levels reached 3,372–4,218N. During slow jogging, they were up to 5,165N. The peak torque around the implant stem during walking was 10.5 Nm, which was higher than during all other activities including jogging. The transverse forces and the moments varied greatly between the subjects, especially during non-cyclic activities. The high load levels measured were mostly above those defined in the wear test ISO 14243. The loads defined in the ISO test standard should be adapted to the levels reported here. The new data will allow realistic investigations and improvements of joint replacement, surgical procedures for tendon repair, treatment of fractures, and others. Computer models of the load conditions in the lower extremities will become more realistic if the new data is used as a gold standard. However, due to the extreme individual variations of some load components, even the reported average load profiles can most likely not explain every failure of an implant or a surgical procedure
Der Zusammenhang von Knorpelmarkerkinetik und subjektiver Bewegungseinschränkung mit körperlicher Aktivität in prä-RA und RA-Patienten.
No full textHintergrund und Ziele
Rheumatoide Arthritis (RA) ist eine häufige und gesundheitspolitisch relevante Erkrankung (Smolen et al., 2016a). Trotz sich weiterentwickelnder Therapieoptionen ist eine Heilung bisher nicht möglich. Frühe oder der RA vorausgehende Stadien zu diagnostizieren, ist ein wichtiger Ansatz, um das Verständnis der Pathophysiologie zu verbessern und neue Therapie-möglichkeiten zu schaffen (Greenblatt et al., 2020). Eine von der European Alliance of Associations for Rheumatology (EULAR) beschriebene Gruppe mit Risiko für eine spätere RA-Erkrankung sind Menschen, die positiv für RA-assoziierte Antikörper (AK) sind (Gerlag et al., 2012). Hierzu zählen AK gegen citrullinierte Peptide (ACPAs) (Sokolove et al., 2012). Die Relevanz von ACPAs für Knochenschäden ist bekannt und eine mögliche Auswirkung auf Knorpelgewebe wird diskutiert (Kleyer et al., 2014, Renner et al., 2014). ACPA-positive Personen ohne klinische RA-Manifestation werden in dieser Arbeit als prä-RA bezeichnet.
Zur Untersuchung von Knorpelstoffwechsel werden verschiedene Biomarker verwendet. Cartilage Oligomeric Matrix Protein (COMP) ist ein wichtiger Vertreter der im Serum nachweisbaren Knorpelmarker. Seine Mechanosensitivität ist bekannt (Giannoni et al., 2003). Ein möglicher prognostischer Wert für spätere Knorpelschäden wird diskutiert (Neidhart et al., 2000). Hinweise auf Unterschiede im Knorpelstoffwechsel zwischen RA und prä-RA sollen mit der Analyse der COMP-Level weiter untersucht werden. Bei bekannter Mechanosensitivität von COMP sind hierbei standardisierte Untersuchungsbedingungen essenziell und die Analyse des körperlichen Aktivitätslevels der Probanden sinnvoll (Niehoff et al., 2010).
Ziel der vorliegenden Arbeit ist die Untersuchung der Unterschiede zwischen den Diagnosegruppen RA und prä-RA in Bezug auf die körperliche Aktivität und die COMP-Werte. Weiter wird die Abhängigkeit der COMP-Level von der körperlichen Aktivität, der Krankheitsaktivität und der empfundenen Bewegungseinschränkung evaluiert.
Teilergebnisse der vorliegenden Arbeit wurden veröffentlicht in: Bleckwedel-Rolack L, Tascilar K, Nees V, Hühne J, Hueber A, Rech J, Schett G, Kleyer A, Liphardt A M (2021) Patients at risk for RA show the same amount of acute soluble cartilage degradation markers after physi-cal activity compared to patients with established RA. Annals of the Rheumatic Diseases, 80: 420-421 sowie beim EULAR 2021 als Poster (POS0381) präsentiert. Ein weiteres Abstract mit dem Titel „Acute response of a soluble cartilage degradation marker to a 30-minute walking exercise is similar in patients at risk of RA compared to patients with established RA“ wurde für den Deutschen Rheumatologiekongress 2021 (Abstract-Nr. 204) angenommen. Die Veröffentlichungen des Abstracts und des zugehörigen Posters (Nr. RA 44) stehen noch aus.
Methoden
Die untersuchte Kohorte bestand aus 28 RA und 22 prä-RA-Patienten. Die Probanden wurden zu jeweils drei Visiten geladen, bei denen sie eine 30-minütige Bewegungsintervention auf dem Laufband in selbst gewähltem Tempo durchführten. In bestimmten Abständen zur Inter-vention erfolgten Blutentnahmen. Aus dem gewonnenen Serum wurde mittels Sandwich-Enzyme-linked Immunosorbent Assay (ELISA) die Bestimmung der COMP-Level vorgenom-men. Zur Verifizierung der körperlichen Aktivität im Alltag füllten die Probanden bei den Visiten einen Fragebogen, den International Physical Activity Questionnaire (IPAQ), aus und trugen im Anschluss einen Aktivitätsmonitor für die folgenden sieben Tage. Die Krankheitsaktivität wurde mittels Disease Activity Score 28 (DAS 28) und die subjektive Bewegungseinschrän-kung im Health Assessment Questionnaire-Disability Index (HAQ-DI) erfasst.
Ergebnisse und Beobachtungen
Die Diagnosegruppen prä-RA und RA unterschieden sich im Untersuchungszeitraum nicht bezüglich der COMP-Level oder der -Kinetik. Während sich kein Zusammenhang zwischen COMP-Level und DAS 28 zeigte, war ein steigender HAQ-DI mit niedrigeren COMP-Werten assoziiert. RA-Patienten hatten in der Aktivitätsmonitor-Datenauswertung eine um 22,3 % hö-here mittlere körperliche Aktivitätsdauer als prä-RA-Patienten. Ein positiver Zusammenhang der körperlichen Gesamtaktivitätsdauer mit dem COMP-Level war nur für prä-RA nachweisbar.
Schlussfolgerungen und Diskussion
Keinen Unterschied zwischen den Diagnosegruppen bezüglich der allgemeinen COMP-Level und deren Reaktion auf die Bewegungsintervention nachweisen zu können, deutet eventuell auf einen Knorpelstoffwechsel hin, der Parallelen zum ACPA-abhängigem Knochenverlust zeigt. Hierbei ist allerdings zu berücksichtigen, dass sich die COMP-Level in prä-RA- und RA- nicht deutlich von denen in gesunden Probanden oder Osteoarthritis (OA)-Patienten aus an-deren Studien unterscheiden (Mundermann et al., 2009). Ob sich mögliche, durch ACPA-Positivität bedingte Veränderungen im Knorpelstoffwechsel wirklich auf die COMP-Reaktion nach einer Gehbelastung auswirken, sollte daher in künftigen Untersuchungen mit einer ge-sunden Vergleichsgruppe evaluiert werden. Dass lediglich Individuen mit prä-RA eine positive Korrelation von COMP und Gesamtaktivitätsdauer zeigen, lässt sich eventuell auf eine sich unterscheidende Knorpelvitalität zwischen prä-RA- und RA-Diagnosegruppen zurückführen. Bilddatenauswertungen zur Knorpeldicke der Probanden könnten diese Annahme überprüfen. Ein weiterer möglicher Untersuchungsgegenstand wäre eine möglicherweise zwischen den Gruppen verschiedene qualitative Gelenkbelastung. Dies könnte mittels einer Videoanalyse der Bewegungsabläufe während der Gehbelastung überprüft werden
