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The strong genetic and clinical overlaps between spondyloarthritis (SpA) and inflammatory bowel disease (IBD) have placed much needed focus on the gut-joint axis of inflammation in SpA, leading to three key hypotheses that attempt to unravel this complex relationship. The arthritogenic peptide hypothesis and the aberrant cellular trafficking hypothesis have been put forth to rationalize the manner by which the innate and adaptive immune systems cooperate and converge during SpA pathogenesis. The bacterial dysbiosis hypothesis discusses how changes in the microbiome lead to architectural and immunological consequences in SpA. These theories are not mutually exclusive, but can provide an explanation as to why subclinical gut inflammation may sometimes precede joint inflammation in SpA patients, thereby implying a causal relationship. Such investigations will be important in informing therapeutic decisions which may be common to both SpA and IBD. However, these hypotheses can also offer insights for a coincident inflammatory relationship between the gut and the joint, particularly when assessing the immunological players involved. Insights from understanding how these systems might affect the gut and joint differently will be equally imperative to address where the therapeutic differences lie between the two diseases. Collectively, this knowledge has practical implications in predicting the likelihood of IBD development in SpA or presence of coincident SpA-IBD, uncovering novel therapeutic targets, and redesigning currently approved treatments. It is evident that a multidisciplinary approach between the rheumatology and gastroenterology fields cannot be ignored, when it comes to the care of SpA patients at risk of IBD or vice versa.

This study aims to solve problems caused by misalignments between exoskeleton systems and the human body. Misalignments interfere with the achievement of the wearer’s motion intention by generating unintended interaction forces between the wearer and the exoskeleton system. Therefore, this study attempts to overcome this problem by applying an additional degree of freedom (DOF) to the fixation of the human body. First, we analyzed a system of a human body and exoskeleton connected by serial chains. Second, we derived all possible DOF sets for a 7-DOF exoskeleton system and determined the final DOF set based on practical applicability. Finally, we measured the interaction forces generated during the operation of the exoskeleton system to verify the effects of the fixation mechanism. The significance of the results was confirmed by a t test with a significance level of p ≤ 0.05.

Background Thorough understanding of the morphometry of the ankle joint is crucial to optimize conservative and operative therapy of ankle joint disorders. Despite recent improvements, basic anatomic and biomechanical correlations of the ankle joint including the orientation of the ankle joint axis and joint morphology as its key biomechanical features are not sufficiently recorded to date. The aim of this study was the evaluation of the ankle morphometry to gain information about the ankle joint axis. Material and methods In this study 98 high-resolution CT-scans of complete Caucasian cadaver legs were analysed. Using the software Mimics and 3-Matic (Materialize) 22 anatomic parameters of the talocrural joint were assessed, including the length, width and surface area of the tibial and talar articular areas. Additionally, the radii of the articular areas, the medial distal tibial angle and the height of the talar dome were determined. Results The radius of the central trochlea tali was 44.6 ± 4.1 mm (mean ± SD). The central trochlea tali arc length was 40.8 ± 3.0 mm and its width was 27.4 ± 2.5 mm. Additionally we determined 47.0 ± 4.4 mm for the tibial sagittal radius, 27.6 ± 3.0 mm for the tibial arc length and 27.4 ± 2.5 mm for the central tibial width. Conclusion The present study describes the three-dimensional morphometry of Caucasian ankle joints in detail. This dimensional analysis of the ankle joint will inform the development and placements of implants and prostheses.

In this paper, a 7R spatial linkage for ankle rehabilitation was proposed. Thanks to its kinematic geometry, the output joint, which is accommodated by the patient’s ankle, of the linkage can possess an arbitrary joint axis at any configuration. This advantage allows the patient achieving a flexible ankle motion in 3-D space while performing the rehabilitation exercise. The design concept of the 7R linkage is explained, and the displacement and force relationships between the input and output joints (i.e., the motor and patient’s ankle) are analyzed through an equivalent RSSR linkage. A prototype is built to validate the proposed design concept.

The forefoot functions as the base of support during late stance, rotating about the dual-axis of the metatarsophalangeal joints. Previous research has shown that joint axis definition affects estimated joint moments about the forefoot. However, little is known about how metatarsophalangeal joint center definition affects estimated joint kinetics. This study compared moments about the metatarsophalangeal joint using four different defined joint centers. There was a significant difference (p .001) in peak moments between joint center definitions, differing by up to 0.488 N-m/kg for the slow and 0.878 N-m/kg for the fast running speeds tested. Additionally, there was a significant difference (p .001) for when peak plantar flexor moment occurred during the slower running condition. The more posteriorly oriented joint centers resulted in higher moments and earlier onset of the plantar flexor moment. In addition to careful modeling of the metatarsophalangeal joint axis, it is recommended that joint center definition should be considered as well.

Background Revision rates after total ankle replacements (TARs) are higher compared with other total joint replacements. The present study aimed to establish a new patient-specific implantation (PSI) technique for TAR. Material and methods A total of 10 complete Caucasian cadaver legs had whole leg computed tomography scans. The individual geometrical ankle joint axis was determined, and based on this axis, the position of the prosthesis was planned. We assessed prosthesis placement, guiding block position, and preoperative and postoperative ankle rotational axes. Results The guiding block position interobserver reliability was 0.37 mm 0.45 (mean ± SD) for the tibial guiding block. The value for the first talar guiding block was 1.72 ± 1.3 mm and for the second talar guiding block, 0.61 ± 0.39 mm. The tibial slope as well as the frontal angles of the anatomical tibial axis compared to the tibial and talar articular surfaces showed no statistically relevant differences with numbers available. The deviation of the assessed preoperative joint axis to the postoperative joint axis was 14.6° ± 7.8. Conclusion The present study describes the results of an establishing process of a new PSI technique for TAR. The reliability of guiding block positioning and, thereby, prosthesis placement is sufficient. Level of Evidence: Biomechanical study

Estimating the functional knee axis (FKA) is crucial to correctly implanting a prosthesis and accessing joint kinematics. The correct estimation of the patient-specific joint axis of the knee is crucial for achieving a reliable assessment of musculoskeletal kinematics and dynamics Researchers have reported on the KFA mainly with regard to manual management of flexion-extension movements performed passively without any voluntary actions. Active touch and movement refer to what is ordinarily called touching—variations in skin stimulation caused by surfaces are altered together by motor activity variations. This fact is worth noting because it is often neglected that locomotion and its surfaces form an inseparable pair. The objective of this study was to confirm the distinction between touching and being touched. We were particularly interested in measuring the instantaneous axes of the knee (IAK) during locomotion. We propose the invariant structure of the knee as an attempt to distill a kind of higher-order simplification of a knee model relative to the enormous complexities of the biological systems of a human joint. This principle attempted to distill a kind of higher-order simplification relative to the enormous complexities of analytical anatomical objects and the practice of biomechanical engineering, which are sometimes confused.

The Salto Talaris Total Ankle System prosthesis is an anatomically designed fixed-bearing prosthesis available in the United States based on the successful design of the Salto Mobile Version prosthesis available outside the United States. The Salto Talaris XT Primary and Revision Total Ankle System prosthesis is a flat-top version of the Salto Talaris Total Ankle System talar component and also includes thicker ultra-high molecular weight polyethylene insert options to allow for complicated primary and revision total ankle replacements to be performed. For each system, the original mobile-bearing morphology has been redesigned and mobile-bearing concept was transferred to the precision instrumentation at the trial phase evaluation for the fixed-bearing version. Instrumentation and technique allow the surgeon to determine the functional joint axis prior to final implantation. Both systems have updated instrumentation to reduce operating room time, an extended XL tibial tray to provide complete tibial plafond coverage, and a size 0 talar component for smaller individuals. The Salto Talaris Total Ankle System and Salto Talaris XT Primary and Revision Total Ankle System designs blend minimal bone resection and optimize surface area, cortical contact, and ultra-high molecular weight polyethylene conformity. In this chapter, the surgical techniques for both systems are reviewed step-by-step and pearls for successful application of both systems are provided.

Through the realization of complex trajectory motions and multi-layer material shooting, camera robot can be an important tool for film and television shooting. At present, the trajectory planning of camera robot needs to be plotted in advance by professions, and it has not been easy to adjust on site. In addition, on the actual shooting scene, it’s required to adjust running speed of the robot to meet the performance and rhythm of the actors. This paper presents a robot control schema using real-time tracking for unknown trajectories, and real-time stepless speed regulation for existing trajectories. It mainly includes data reading strategies and motion parameter protection algorithms. The response time is within 25 ms. When the real-time target position exceeds the limit of the joint axis servo capability, the robot approaches the target at the maximum speed that can be realized on its own. Furthermore, the schema for tracking functions and speed regulated reproduction have been already realized on the camera robot physical prototype.

Transfemoral prosthetic users have motor functional impairments during running. A major impairment is unintended prosthetic knee flexion during weight bearing on the prosthetic side. Therefore, the present study aims to develop a passive mechanism for a transfemoral prosthetic knee to prevent flexion during the prosthetic stance phase. The proposed mechanism has a single axis for prosthetic knee flexion–extension. The shaft that functions as the prosthetic knee joint axis can move 3 mm along the long axis of the shank part to change functions between the stance and the swing phase. The prosthetic knee joint limits only flexion and allows extension possible during the stance phase. However, it rotates freely (flexion–extension) during the prosthetic swing phase. These functions of the proposed mechanism were verified using a rough prototype. The he participant with the attached prosthetic limb prototype performed level walking with habitual gait velocity on a 10 m straight walkway. The result shows that the kinematic data of the hip, knee, and ankle were similar to able-bodied gait. Moreover, the mechanism was able to mechanically limit only the flexion with compression force acting along the shank part. These proposed mechanisms and results of the preliminary trial suggest that transfemoral amputees can run safely.

Functional methods usually allow for a flexible and accurate representation of joint kinematics and are increasingly implemented both for clinical and biomechanics research purposes. This paper presents a quantitative comparison between two widely adopted methods for functional axis estimation, that is, the helical axis theory and the symmetrical axis of rotation approach (SARA). To this purpose, a multi-body model was developed to simulate the lower limb of a subject. This model was designed to reproduce different motion patterns, that is, by selecting the active degrees of freedom of the simulated ankle joint. Thanks to virtual markers attached to each segment, the multi-body model was used to generate simulated motion capture data that were then analyzed by instantaneous helical axes and SARA algorithms. To achieve a synthetic representation of joint kinematics, a mean helical axis and an average SARA functional axis were estimated, along with dispersion parameters and rms distance data that were used to quantitatively assess the performance of each method. The sensitivity of each algorithm to different combinations of range and speed of motion, scattering of marker clusters, sampling rate, and additive noise on markers’ trajectories, was finally evaluated.

Monteggia and Monteggia variant injuries are a rare entity in the adolescent trauma patient. They are still a challenge for the orthopedic surgeon because of the combination of fracture and joint dislocation in the complex anatomical and biomechanical area of the elbow. The elbow function as well as forearm rotation is dependent on anatomic fracture fixation, restoration of the bone and joint axis, and stable humeroulnar, humeroradial, and ulnoradial joints.

Objective. To analyze the results of application of modified procedure in the correction osteotomy of the shin lateral small bone in a falsely consolidated its fractures without significant destructive-dystrophic changes in tramatized ankle joint. Materials and methods. The investigation was conducted in 37 patients, 16 - men and 21 - women, with average age (38 ± 7) yrs. From the trauma moment 6-15 mo passed, (7.8 ± 1.9) mo at average. During roentgenological examination in patients with posttraumatic osteoarthrosis of ankle joint the Stages I-II in accordance to Kellgren and Lawrence were established. Correctional osteotomy have included a transverse osteotomy of lateral small bone of the shin on the level of the joint fissure, what made possible to perform a three-dimensional correction of the bone localization and to restore the interrelationship in ankle joint. Functional results were estimated in accordance to the AOFAS (American Orthopaedic Foot and Ankle Society Score) scale for ankle joint and posterior part of foot before and after surgical treatment. The progression degree of osteoarthrosis were determined in accordance to result of roentgenography with loading in accordance to classification of Kellgren-Lawrence. Average term of observation with the results analysis have constituted (1.9 ± 0.6) yrs. Results. Estimation of functional results in accordance to the AOFAS scale in borders of the follow-up term have increased from (58.7 ± 2.4) to (86.2 ± 1.8) points. During roentgenological examination in all the patients a restoration of the ankle joint axis was observed, but in 8 (21%) patients the osteoporosis Stage III was revealed, what have witnessed its progress. Conclusion. Modified procedure of the correction osteotomy of the shin lateral small bone in a its falsely consolidated fractures gives possibility to restore a congruence and biomechanical axis of the joint injured, to improve significantly its functional capacity and to slow down a progress of posttraumatic osteoarthrosis.

In this paper, we present a hybrid exoskeletal-soft glove for the application of on-axis angle sensors that can be placed close to the center of rotation of the digit joints. 3D printed exoskeletal digit segments that run medially on most digits connect to low friction bearings. Exoskeletal segments and bearings provide rigid fixation points for a variety of traditional angle sensors, while a combination of textile and rigid structure fixate exoskeletal digits to the digits and hand. Exoskeletal digits are designed modularly so that only required digits are used and to reduce difficulty in donning and doffing. On-axis measurement may prove useful in control or assessment tasks in rehabilitation. The articulation of the digits while wearing the glove is demonstrated, albeit without sensors, showing little restriction at an early stage of the design process. Exoskeletal metacarpophalangeal joints of the 3rd and 4th digits require more work as the flexion/extension joint axis is inaccessible and moves when he digits are articulated. The proposed device must be customized for an individual and will facilitate an alternative approach to existing hand posture monitoring techniques.

Background: Misalignment of an articulated ankle-foot orthosis joint axis with the anatomic joint axis may lead to discomfort, alterations in gait, and tissue damage. Theoretical, two-dimensional models describe the consequences of misalignments, but cannot capture the three-dimensional behavior of ankle-foot orthosis use. Objectives: The purpose of this project was to develop a model to describe the effects of ankle-foot orthosis ankle joint misalignment in three dimensions. Study design: Computational simulation. Methods: Three-dimensional scans of a leg and ankle-foot orthosis were incorporated into a link segment model where the ankle-foot orthosis joint axis could be misaligned with the anatomic ankle joint axis. The leg/ankle-foot orthosis interface was modeled as a network of nodes connected by springs to estimate interface pressure. Motion between the leg and ankle-foot orthosis was calculated as the ankle joint moved through a gait cycle. Results: While the three-dimensional model corroborated predictions of the previously published two-dimensional model that misalignments in the anterior -posterior direction would result in greater relative motion compared to misalignments in the proximal -distal direction, it provided greater insight showing that misalignments have asymmetrical effects. Conclusions: The three-dimensional model has been incorporated into a freely available computer program to assist others in understanding the consequences of joint misalignments. Clinical relevance Models and simulations can be used to gain insight into functioning of systems of interest. We have developed a three- dimensional model to assess the effect of ankle joint axis misalignments in ankle-foot orthoses. The model has been incorporated into a freely available computer program to assist understanding of trainees and others interested in orthotics.

Ankle joint kinematics is mainly stabilized by the morphology of the talar dome and the articular surface of tibiofibular mortise as well as the medial and lateral ligament complexes. Because of this the bicondylar geometry of talus dome is believed to be crucial for ankle implant design. However, little data exist describing the precise anatomy of the talar dome and the talocrural joint axis. The aim of this study is to document the anatomy of the talar dome and the axis of the talocrural joint using three-dimensional (3D) computed tomographic (CT) modeling. Seventy-one participants enrolled for CT scanning and 3D talar model reconstruction. All the ankles were held in a neutral position during the CT scanning. Six points on the lateral and medial crest of the talar dome were defined. The coordinate of the six points; radii of lateral-anterior (R-LA), lateral-posterior (R-LP), medial-anterior (R-MA), and medial-posterior (R-MP) sections; and inclination angle of the talar dome were measured, and the inclination and deviation angles of the talocrural joint axis were determined. The mean values of R-LA, R-LP, R-MA, and R-MP were 19.23 ± 2.47 mm, 18.76 ± 2.90 mm, 17.02 ± 3.49 mm, and 22.75 ± 3.04 mm. The mean inclination angle of the talar dome was 9.86 ± 3.30 degrees. Gender variation was found in this parameter. The mean inclination and deviation angles were 8.60 ± 0.07 and 0.76 ± 0.69 degrees for the dorsiflexion axis and −7.34 ± 0.07 and 0.09 ± 0.18 degrees for the plantarflexion axis. Bilateral asymmetries between the medial and lateral crest of the talar dome were found, which resulted in different dorsiflexion and plantarflexion axes of the talocrural joint. Currently, no ankle implants replicate this talar anatomy, and these findings should be considered in future implant designs.

The aim was to clarify the effect of differences in the number of fiber bundles of the anterior tibial ligament (ATFL) on ankle braking function. The study sample included 81Japanese cadavers. ATFLs were categorized as: Type I with one fiber bundle; Type II with two fiber bundles that were completely separated; and Type III with three fiber bundles. Three-dimensional reconstructions of a single specimen from each category were then created. These were used to simulate and calculate ATFL strain during dorsiflexion (20°) and plantarflexion (30°) on the talocrural joint axis and inversion (20°) on the subtalar joint axis. Almost all types of superior fiber lines were stretched with dorsiflexion and plantarflexion. Regardless of Type, the inferior fiber line was shortened with plantarflexion and stretched with dorsiflexion. The inferior fiber bundle of Type III was shortened only at plantarflexion 30° and inversion 20°, but in all others it was stretched. The results suggest that Type III was weaker than Type I and Type II in terms of ankle plantarflexion and inversion braking function.

The paper presents research on one DOF (Degree of Freedom) hip joint of an exoskeleton regarding the possibilities and effects of rotation axis misalignment in the hip joint. By rotation axis misalignment, we understand the difference of alignment between the hip joint axis of rotation in human and exoskeleton; we also consider only parallel, not angular axis misalignments in our model. The proposed approach for the development of exoskeletons is to take into consideration inherent axis misalignments and analyze the possibilities to reduce their effects on the ergonomics of the device. The first step in this approach is the quantification of effects of rotation axis misalignments in exoskeletons and to achieve this, we developed the kinematic model which is presented in this paper. Most approaches focus on perfectly aligned axis of rotation, while this is not the case in our study, we focus on an acceptable misalignment for the user.

Background Despite intensive research there is no consensus about the talocrural joint axis. The aim of the present study is a new method to determinate the geometric rotational axis of the talocrural joint. Methods We analyzed 98 CT-scans of full cadaver Caucasian legs. We generated three-dimensional reconstruction models of the talus. A best fitting cone was orientated to the talar articular surface. The geometric rotational axis was defined to be the axis of this cone. Results The geometric rotational axis of the talocrural joint is orientated from lateral–distal to medial–proximal (85.6°±10 compared to anatomical tibial axis in torsional plane), from posterior–distal to anterior–proximal (81.43°±44.35 compared to anatomical tibial axis in sagittal plane) and from posterior–medial to anterior–lateral (169.2°±5.91 compared to intermalleolar axis in axial plane). Conclusions The consideration of our results might be helpful for better understanding of ankle biomechanics.

Background In the present study, CFLs harvested from cadavers were categorized according to the differences in the angle of the CFL with respect to the long axis of the fibula and their shape, and then three-dimensional reconstructions of the CFLs were used to simulate and examine the differences in the angles of the CFLs with respect to the long axis of the fibula and how they affect CFL function. Methods The study sample included 81 ft from 43 Japanese cadavers. CFLs were categorized according to their angle with respect to the long axis of the fibula and the number of fiber bundles. Five categories were subsequently established: CFL20° (angle of the CFL with respect to the long axis of the fibula from 20° to 29°); CFL30° (range 30–39°); CFL40° (range 40–49°); CFL50° (range 50–59°); and CFL2 (CLFs with two crossing fiber bundles). Three-dimensional reconstructions of a single specimen from each category were then created. These were used to simulate and calculate CFL strain during dorsiflexion (20°) and plantarflexion (30°) on the talocrural joint axis and inversion (20°) and eversion (20°) on the subtalar joint axis. Results In terms of proportions for each category, CFL20° was observed in 14 ft (17.3%), with CFL30° in 22 ft (27.2%), CFL40° in 29 ft (35.8%), CFL50° in 15 ft (18.5%), and CFL2 in one foot (1.2%). Specimens in the CFL20° and CFL30° groups contracted with plantarflexion and stretched with dorsiflexion. In comparison, specimens in the CFL40°, CFL50°, and CFL2 groups stretched with plantarflexion and contracted with dorsiflexion. Specimens in the CFL20° and CFL2 groups stretched with inversion and contracted with eversion. Conclusions CFL function changed according to the difference in the angles of the CFLs with respect to the long axis of the fibula.

The direct problem of researching the load capacity of segment gas-static bearing is being discussed. In calculation the movement of the shaft in the bearing is considered slow comparing than the rotational velocity. Vibrations and the influence of non-stationarity are neglected. The given geometry of the bearing and the pressure of lubrication supply in the gap between the bearing and the shaft are considered initial data. The result of the calculation is the value of the resultant pressure force, applied to the bearing segments. Summing the forces the value of the static load capacity can be found. For segments that may spontaneously rotate about the joint axis, described a method of calculating the rotation angle, at which the main moment of pressure forces applied to the segment is equal to zero and the segment’s position is stable.

Unilateral sagittal split fracture (USSF) of the C1 lateral mass (LM) has been recently recognized as a rare variant of C1 atlas fracture. To date, there has been no study to investigate whether radiologic criteria can be applied to determine the presence or absence of transverse atlantal ligament (TAL) injury in USSF of the C1 LM. Twenty six consecutive cases of USSF of the C1 LM were included in this study. According to Dickman classification, 16 cases were TAL injury, and 10 cases were TAL intact. Radiologic parameters were measured and compared between the 2 groups. Total LM displacement (LMD) of the 2 sides (5.9 ± 2.0 mm vs 1.2 ± 2.0 mm), unilateral LMD of the fracture side (4.3 ± 1.2 mm vs 1.0 ± 1.1 mm), atlanto-dental interval (ADI) (2.0 ± 0.9 mm vs 1.5 ± 0.4 mm), and fracture gap (6.9 ± 2.7 mm vs 2.1 ± 1.1 mm) were statistically higher in the TAL injury group than the TAL intact group. However, basion-dental interval, clivus canal angle, and atlanto-occipital joint axis angle were not different between the 2 groups. Total LMD and unilateral LMD positively correlated with ADI and fracture gap. The incidence of fracture gap larger than 7 mm was statistically higher in the TAL injury group than the TAL intact group (81% vs 30%). In conclusion, total LMD > 5.9 mm or unilateral LMD > 4.3 mm suggests the presence of TAL injury in USSF of the C1 LM. The possibility of diagnostic error for TAL injury can be further reduced in USSF of the C1 LM by considering the fracture gap larger than 7 mm.

This paper proposes a simple spatial rehabilitation mechanism that aims to exert the desired flexion motion with adjustable load and also to provide an objective measure of recovery status, in terms of mobilization, force, and torque, on the affected part. This is to verify the condition of therapeutic exercise to support physiotherapists, as well as to establish selfrehabilitation by patients themselves. In this work, the composition of the mechanism is first determined by extending Oldham’s coupling mechanism. Next, a kinetostatic analysis of the mechanism is performed for two purposes. One is to determine a reasonable link dimension that achieves a suitable range of motion for the practical rehabilitation treatment of human ankle joints. The other is to calculate the magnitude of the shearing load on the ankle joint, caused by gravity and the friction of the cylindrical joints. A validation experiment demonstrates the effectiveness of the proposed mechanism and of the kinetostatic analysis. Shearing load is also compensated for through the introduction of springs to certain joints. The optimum location, spring constant, and initial offset of each spring are determined through the proposed kinetostatic analysis scheme.

The Salto Talaris total ankle replacement is an anatomically designed fixed bearing prosthesis available in the United States based on the successful design of the mobile-bearing Salto prosthesis available outside the United States. The original mobile-bearing design was modified and the mobile-bearing was transferred to the precision instrumentation at the trial phase evaluation. Instrumentation and technique allow the surgeon to determine the functional joint axis before final implantation. The Salto Talaris total ankle replacement design blends minimal bone resection and optimizes surface area, cortical contact, and ultra-high molecular weight polyethylene conformity. The authors present an overview of the Salto Talaris total ankle replacement surgical technique and pearls for successful application.

Conventionally joint axis corrections are achieved with the use of bare hands or bone distraction devices, both of which result in considerable time and effort. This article proposes the design of a new device for improved efficiency of these joint axis correction surgeries. The proposed device was analyzed by finite element methods to investigate its static structure, thus providing a reference for device fabrication. Results indicated that the displacement deformation of PEI (Ultem) was greater than that of aluminum, while both designs met necessary safety requirements.

Most of the known six-revolute linkages are hybrid in character. The six simplest of these synthesised loops arise by combining a pair of four-bars along a common joint axis. Because displacement–closure equations have not been previously developed for all of them, the task is undertaken in this article. Contributing to the examination is a scrutiny of the single motion screw reciprocal to the joint screws of a resultant loop. It is an unconventional approach, but one that is flexible and offers useful insights into the nature of a kinematic chain's mobility.

Simplifying orthotic fabrication in the clinic is of value to both therapists and patients. This author describes a technique of using thermoplastic material to create a hinge, thus eliminating the task of lining up hinges with the joint axis of motion. Three different orthotic designs using this technique are described in this article.—Victoria Priganc, PhD, OTR, CHT, CLT, Practice Forum Editor

The paper discusses the work carried out over the past 7 years within RILEM Technical Committee 190-SBJ Service Life Prediction of Sealed Building and Construction Joints towards the development of RILEM Technical Recommendations (RTR) on durability test methods for wet-applied (gun-grade) curtain-wall sealants. This paper is published along with the two draft RTR methods to provide some insight into the discussions within the committee during the development and early evaluation of both methods. The two draft RTR methods define test and evaluation protocols for accelerated artificial weathering and natural outdoor weathering. Both draft RTR methods are based on a novel test specimen configuration that allows simultaneous exposure of the sealant to compression and extension during movement cycles. Because of the special test joint configuration, the sealant is exposed to variable extension and compression amplitudes along the joint axis, allowing an evaluation of the effect of different movement amplitudes on the sealant when taking weatherability considerations into account. The results of the initial evaluations indicate that the test methods are capable of differentiating between products with regard to their resistance to accelerated or outdoor weathering and mechanical cycling. The type of failure and the changes in surface appearance observed during the test regimes are similar to those observed in actual service conditions. It is hoped that exposure studies based on these two new RTR methods will provide the underpinnings for the development of future ISO and ASTM durability test standards for building sealants.

A simple and easy method of CT-measurement of humeral torsion is proposed. This requires a transverse section of the proximal and distal epiphyses. The optimal site of cross-sectioning with reliable construction of the joint axis was determined in ten humeral bones. The variability of the angle was 2 to 3 degrees. Comparing CT-measurements in 50 humeri with anthropometry showed excellent correlation. Varation in humeral torsion on either side was approx. 50 degrees with the same mean value in right and left humeri of our specimens. Deviations in bone positioning within the gantry of up to 15 degrees in two different planes had little effect on the measurements. Habitual dislocation of the shoulder as well as assessment of postfractural malrotation of the humerus might be indications for measurement of humeral torsion.

Glued-in rods are an increasingly used technical solution for numerous structural applications in timber engineering, and demonstrate the potential of adhesively bonded connections. During the insertion process the adhesive fills a very narrow gap over significant anchorage contact area, raising concerns that manufacturing defects may impact the structural performance of the bonded joint, namely the possible lack of adhesion resulting from inadequate preparation of the joint on site. Previous studies on the effect of bonding defects on the capacity of bonded joints identified a nuanced relationship that depends on the ductility of the adhesive. This paper presents experimental evidence that sheds light on the relationship between defects and capacity of glued timber joints. Joints composed of softwood glulam members and mild steel glued-in threaded rods were manufactured with two types of defects likely to be encountered on-site: i) rods placed at an angle inside drill hole instead of aligned with the joint axis, and ii) rod placed against the side of the drill hole instead of fully centered. To establish performance benchmarks a first phase studied the influence of the anchorage length and the rod diameter using three different adhesives. The effect of these defects on joint capacity was investigated with three different adhesives in combination with three different rod anchorage lengths. The investigations demonstrated that joints with sufficient rod anchorage (herein 10 times the rod diameter) do not exhibit a statistically significant loss of capacity, if compared to defect free joints. These results can contribute towards better understanding of the influence that the studied parameters have on the performance on timber joints with glued-in rods, as well as to translate this information to promote the development of further applications.

Figure 7.1 shows a spatial chain of three bodies 0, 1 and 2 interconnected by two joints 1 and 2. Body 0 is referred to as frame and body 2 as terminal body. Joints are either revolute (R) or prismatic (P) or cylindric (C). Throughout Sects. 7.1 and 7.2 cylindrical joints are excluded. Chains with revolute and prismatic joints are classified by the sequence of joints (joint 1, joint 2 ) as RR, RP, PR, PP. Since each joint has a single joint variable, the degree of freedom of the terminal body is two.

The Salto Talaris Total Ankle Prosthesis is an anatomically designed fixed-bearing prosthesis available in the United States based on the successful design of the Salto Mobile Version prosthesis available outside the United States. The original mobile-bearing morphology has been redesigned, and mobile-bearing concept was transferred to the precision instrumentation at the trial phase evaluation for the fixed-bearing version. Instrumentation and technique allow the surgeon to determine the functional joint axis prior to final implantation. The Salto Talaris Total Ankle Prosthesis design blends minimal bone resection and optimizes surface area, cortical contact, and ultrahigh molecular weight polyethylene conformity. In this chapter, the surgical technique is reviewed step by step, and pearls for successful application are provided.

Knowledge of the location of the subtalar joint axis in individual patients would permit clinical assessment of the forces and moments that produce frontal-plane foot and ankle deformities. Biomechanical analysis of the subtalar joint is hindered, however, by the inaccessibility of the talus, which makes locating the joint axis difficult, and by the high degree of intersubject anatomic variation. This article discusses work done with cadaver specimens and using invasive methods in vivo that has enhanced our understanding of the mechanics of the subtalar joint and its function during gait. Also reviewed are investigations of the actions of muscles that cross the subtalar joint.

Insects have an elaborate sense of touch. Their most important source for tactile information is the pair of feelers on the head: the antennae (Figure 1; singular: antenna). The stick insect Carausius morosus is one of four major study organisms for the insect tactile sense. Open image in new window Figure 1 The stick insect Carausius morosus (de Sinety 1901) carries a pair of long and straight feelers, or antennae. They are the main sensory organs for touch and smell

This chapter will discuss the unique nature of this approach and fixation that allow it to be minimally invasive and yet highly effective in achieving surgical goals. Its etiology as an Investigational Review Board (IRB) hospital study will be discussed as well as limitations based on the lack of current FDA approval for implanting instrumentation in the longitudinal axis of the sacroiliac joint (SIJ). The indications, contraindications, and specific technical challenges to this procedure will be discussed as well as relative outcomes. Lastly, the method of salvaging this procedure in the event of failure will be discussed as well as using this approach for SIJ aspiration and biopsy in the event of suspected joint infection or other pathologic process.

In this paper, the solutions to closure equations of the original general line-symmetric Bricard 6R linkage are derived through matrix method. Two independent linkage closures are found in the original general line-symmetric Bricard 6R linkage, which are line-symmetric in geometry conditions, kinematic variables and spatial configurations. The revised general line-symmetric Bricard 6R linkage differs from the original linkage with negatively equaled offsets on the opposite joints. Further analysis shows that the revised linkage is equivalent to the original linkage with different setups on joint axis directions. As a special case of the general line-symmetric Bricard linkage, the line-symmetric octahedral Bricard linkage also has two forms in the closure equations. Their closure curves are not independent but joined into a full circle. This work offers an in-depth understanding about the kinematics of the general line-symmetric Bricard linkages.

A 6-DOF articulated robot (PUMA 560) is calibrated by using a laser tracking system according to the multiple positioning method and the effectiveness of this system is certified. A method which calibrates only angle parameters is newly proposed, since there is a possibility that true values of length parameters are directly measured by some other methods. The relationship between sensibility index and the number of measurement are simulated and it is inferred that 10 random measurements with fixed orientation is enough in case of calibrating only angle parameters and 20 random measurements with random orientation is enough in case of calibrating both angle and length parameters. The combination method which obtains length parameters by the joint axis estimating method and calibrates angle parameters by the multiple positioning method is experimentally developed. The accuracy of the combination method and that of the normal multiple positioning method are experimentally investigated. From the results, the effectiveness of the strategy of how to select parameters, number and pose (position and orientation) of measurement, which is mentioned above, is experimentally confirmed. The accuracy of 0.12mm is achieved in wide area and this value is better than already reported ones about PUMA 560.

Measurement of lateral rotation range of motion (ROM) is frequently performed during shoulder evaluation. The purpose of this study was to determine the intratester and intertester reliability of goniometric measurement of passive lateral rotation ROM of the shoulder. Two experienced PTs performed the testing in a randomized block design. They were blinded to all clinical information and to their goniometric readings. Passive lateral rotation ROM of the shoulder was assessed in 34 patients with a variety of shoulder pathologies. Patients were placed in the supine position with the arm abducted approximately 20 degrees to 30 degrees. A standard goniometer, placed along the joint axis by the therapist, was red by an independent assistant. Intraclass correlation coefficients (ICCs) and their associated 95% confidence intervals were calculated. Intratherapist ICCs (0.88 and 0.93) and intertherapist ICCs (0.85 and 0.80) were high. These findings suggest that reliable measures of passive lateral rotation ROM of the shoulder can be obtained from patients with shoulder pathology using standard goniometry and by placing the patient in a supine position.

To fully understand the research literature on the efficacy of various clinical procedures, the physical therapist must be knowledgeable in the anatomy and biomechanics of the synovial joints. This paper presents detailed information on the bony, lligamentous, muscular, and vascular anatomy of the subtalar joint. In addition, there is a discussion of the joint axis as well as the joint motions about this axis. This information will prove valuable to the clinician as new examination and treatment procedures are considered for inclusion in the management of patients with foot-ankle dysfunction.

Category:AnkleIntroduction/Purpose:The total ankle replacement (TAR) is increasingly used in cases of severe ankle arthritis. Although the knowledge about joint kinematics is crucial for designing ...

It is well known that tendons have to be able to move if the muscle contracts. It is still not generally known that any structure in the body has to be able to move passively against other structures. This is especially important for the movement of limbs. In a monoaxial joint like the humero-ulnar joint only structures in the plane of the joint axis remain fixed. Structures in a certain distance to the flexion or to the extension side have to be able to move against other structures in different levels. The amount of passive motion is dependent on the distance to the plane of the joint axis. Tissues which provide a frictionless passive motion are discussed.

A study of industrial robotic systems is provided, for the case of contact-free operation. This part of the book includes the dynamic and kinematic analysis of rigid-link robotic manipulators, and expands towards more specialized topics, such as dynamic and kinematic analysis of flexible-link robots, and control of rigid-link and flexible-link robots in contact-free operation.

The orientations of the joint axes of the talocalcaneal and talonavicular joints were investigated by roentgen stereophotogrammetric analysis under full body load in 8 healthy volunteers. The positions examined were internal and external rotation of the leg as well as pronation, supination, plantar flexion and dorsiflexion of the foot. Resulting rotations about the joint axes were also calculated. The talonavicular joint showed consistently higher values of resulting rotation and a greater variation in joint axis deviation and inclination than the talocalcaneal joint, while the joint axes observed were more transverse and more steeply inclining in the talocalcaneal than in the talonavicular joint. The large amounts of rotation registered in the talonavicular joint under in vivo conditions point to the great importance of this joint in the function of the ankle/foot complex.

Modeling the ankle joint during amputee locomotion is difficult since a definitive joint axis may not exist. Gait analysis estimates joint center positions and defines body segment motions by placing reflective markers on anatomical landmarks. Inverse dynamics techniques then estimate joint kinetics (forces and moments) and mechanical energy expenditure using data from ground reaction forces (GRFs) and the most distal joint (usually the ankle) to make calculations for proximal joints.

1. During unilateral leg movements performed while standing, it is necessary to displace the center of gravity toward the other leg to maintain equilibrium. In addition, the orientation of particular segments, such as the head and trunk, which are used as reference values for organizing the motor act, needs to be preserved. The aim of the present study was to investigate the coordination between movement, equilibrium, and local posture. 2. Experiments were carried out on standing subjects who were instructed to raise one leg laterally to an angle of 45 degrees in response to a light. Two sources of light placed in front of the subject indicated the side on which the movement was to be performed. Three main aspects of the posturokinetic sequence were investigated in two populations, naive subjects and dancers: 1) The body weight transfer toward the supporting leg was found to have two components: first, a "ballistic" one, initiated by a thrust exerted by the moving leg; and second, an "adjustment" component during which the displacement of the center of gravity (CG) reaches a final position (steady state). An early burst in the gastrocnemius medialis of the moving leg often precedes the onset of the center of pressure change. Two differences between naive subjects and dancers were observed: first, the new CG position was almost reached in one step very near to the end of the ballistic component and required only a short adjustment in dancers, whereas in naive subjects it was reached in two steps, including a much longer adjustment component. Second, the dancers were able to minimize the CG displacement toward the supporting side; this might be because they form a better internal representation of the biomechanical limits of stability because of their long training. 2) The onset of the lateral displacement of the malleolus marker of the moving leg always occurred when the body weight had almost completed its transfer to above the support foot. This shows that the positioning of the CG in a new position compatible with equilibrium maintenance was a prerequisite for the leg movement to be performed. The relative timing of events during the posturokinetic sequence was fairly fixed in the dancers, whereas it varied from one trial to another in the naive subjects. 3) The coordination between movement, equilibrium, and head-trunk orientation involves two control strategies. An "inclination" strategy was used by the naive subjects; this consisted of an external rotation of the supporting leg around the anteroposterior ankle joint axis. A counter-rotation at the neck level ensured the stability of the interorbital line in the horizontal plane.(ABSTRACT TRUNCATED AT 400 WORDS)

Background Robot-assisted therapy offers a promising approach to neurorehabilitation, particularly for severely to moderately impaired stroke patients. The objective of this study was to investigate the effects of intensive arm training on motor performance in four chronic stroke patients using the robot ARMin II. Methods ARMin II is an exoskeleton robot with six degrees of freedom (DOF) moving shoulder, elbow and wrist joints. Four volunteers with chronic (≥ 12 months post-stroke) left side hemi-paresis and different levels of motor severity were enrolled in the study. They received robot-assisted therapy over a period of eight weeks, three to four therapy sessions per week, each session of one hour. Patients 1 and 4 had four one-hour training sessions per week and patients 2 and 3 had three one-hour training sessions per week. Primary outcome variable was the Fugl-Meyer Score of the upper extremity Assessment (FMA), secondary outcomes were the Wolf Motor Function Test (WMFT), the Catherine Bergego Scale (CBS), the Maximal Voluntary Torques (MVTs) and a questionnaire about ADL-tasks, progress, changes, motivation etc. Results Three out of four patients showed significant improvements (p < 0.05) in the main outcome. The improvements in the FMA scores were aligned with the objective results of MVTs. Most improvements were maintained or even increased from discharge to the six-month follow-up. Conclusion Data clearly indicate that intensive arm therapy with the robot ARMin II can significantly improve motor function of the paretic arm in some stroke patients, even those in a chronic state. The findings of the study provide a basis for a subsequent controlled randomized clinical trial.

In this paper an analysis concerning dynamical couplings between manipulator links is proposed. In order to detect nonlinearities we utilize equations of motion in terms of unnormalized quasi-velocities (UQV) introduced originally by Jain and Rodriguez (1995). Based on the equations some observations which are helpful for nonlinearity investigation and reduction were made. The presented strategy was tested by simulation on a 3 d.o.f. spatial manipulator.

Recent advances in tissue-engineered cartilage open the door to new clinical treatments of joint lesions. Common to all therapies with in-vitro-engineered autografts is the need for optimal fit of the construct to allow screwless implantation and optimal integration into the live joint. Computer-assisted surgery (CAS) techniques are prime candidates to ensure the required accuracy, while at the same time simplifying the procedure. A pilot study has been conducted aiming at assembling a new set of methods to support ankle joint arthroplasty using bioengineered autografts. Computer assistance allows planning of the implant shape on a computed tomography (CT) image, manufacturing the construct according to the plan, and interoperatively navigating the surgical tools for implantation. A rotational symmetric model of the joint surface was used to avoid segmentation of the CT image; new software was developed to determine the joint axis and make the implant shape parameterizable. A complete cycle of treatment from planning to operation was conducted on a human cadaveric foot, thus proving the feasibility of computer-assisted arthroplasty using bioengineered autografts