A new one-DOF fully parallel mechanism for modelling passive motion at the human tibiotalar joint

Knowledge on how ligaments and articular surfaces guide passive motion at the human ankle joint complex is fundamental for the design of relevant surgical treatments. The paper presents a possible improvement of this knowledge by a new kinematic model of the tibiotalar articulation. Passive motion, i.e. in virtually unloaded conditions, was captured in vitro in four lower leg specimens by means of a surgical navigation system with cluster of active markers attached to the tibia and talus. The anatomical geometry of the passive structures, i.e. articular surfaces and attachment areas of the ligaments, were taken by digitisation with a pointer. An equivalent spatial mechanism for the passive motion simulation was defined by three sphere-to-sphere contact points and two rigid links. These contact points were identified at the lateral talo-fibular articulation and at the medial and lateral aspects of the articulation between tibial mortise and trochlea tali. The two rigid links were identified by the isometric fibres at the calcaneofibular and tibiocalcaneal ligaments. An optimisation algorithm was developed for the identification of the final geometrical parameters resulting from an iterative refining process, which targets best matching between model predictions and corresponding experimental measurements of the spatial motion. The specimen-specific equivalent spatial mechanisms replicated the original passive motion very well, with mean discrepancies in position smaller than 2.5 mm and in rotation smaller than 1°. The study demonstrates that the articular surfaces and the ligaments, acting together as a mechanism, control the passive kinematics of the ankle joint.     

New aspects of the morphology and function of the human hip joint ligaments.

The capsular ligaments of the human hip joint were submitted to exact morphological analysis, and they proved to be multiple and numerous. We have described various ligamentous systems and their interconnections, and have suggested new terminologies and systematics. The ligaments were subjected to functional analysis by means of measuring strips to determine the positions in which the ligaments are taut. The ligament systems were all found to serve a restrictive function, and various parts of the apparatus restricted all possible movements in the hip joint. Extension is restricted by the medial iliofemoral complex, abduction by the pubofemoral ligament, and adduction by the posterior coxal ligaments and by the superior ischiofemoral ligament. Flexion is restricted by the inferior ischiofemoral ligaments, inward rotation by the superior ischiofemoral ligament, and outward rotation by the lateral iliofemoral complex. Only the ligament of the femoral head is unable to exert a restricting function, despite reaching a state of tension in extreme adduction.     

The collateral ligaments of the knee joint in the cat and man. Morphological and functional study of the internal arrangement of fibers

The present investigation of fiber arrangement in the collateral ligaments of the knee was carried out in cats and man in various positions of flexion and extension, without compression load. In all knee joint positions, the fibers of the collateral ligaments are twisted except for the fibers in the meniscal part of the medial collateral ligament which have a parallel arrangement. Furthermore, most of the fibers in the collateral ligaments are taut in all positions of the knee joint in both cat and man. By means of planar models representing different fiber arrangements, the kinematic behavior of the collateral ligaments was analyzed. It appears that a crossed (twisted) arrangement of the fibers is most effective in rotatory movements, whereas a parallel orientation is most effective in translation. Our data further indicate that, in measuring the changes in lengths of ligaments during joint motion, one cannot neglect the internal arrangement of fibers and the geometry of the articular surfaces and menisci.     

Cruciate ligaments of the avian knee: Insight into a complex system

The avian cruciate ligaments were examined in Gallus domesticus, Anas platyrhynchos, Meleagris gallopavo, and Struthio camelus australis. The ligaments proved to be deviated around the intercondylar groove (cranial cruciate) and around the medial femoral condyle (caudal cruciate). Four functionally different fiber groups could be differentiated: fibers taut only in maximal extension, fibers taut only in maximal flexion, fibers taut in ranges from an intermediate position to an extreme position, and fibers taut throughout the entire range of motion (guiding bundles). Hence the cruciates serve the guiding of the joint and the restriction of motion, whereby the majority of the cranial cruciate fibers are taut in extension while those of the caudal cruciate are in flexion. No differences were found between the species examined with respect to fiber arrangement and function. The avian mechanical model proved to be more complex than the relatively simple mammalian four-bar link model as the avian guiding bundles change their shape due to deflection during motion. © 1992 Wiley-Liss, Inc.     

3-D anatomically based dynamic modeling of the human knee to include tibio-femoral and patello-femoral joints

An anatomical dynamic model consisting of three body segments, femur, tibia and patella, has been developed in order to determine the three-dimensional dynamic response of the human knee. Deformable contact was allowed at all articular surfaces, which were mathematically represented using Coons' bicubic surface patches. Nonlinear elastic springs were used to model all ligamentous structures. Two joint coordinate systems were employed to describe the six-degrees-of-freedom tibio-femoral (TF) and patello-femoral (PF) joint motions using twelve kinematic parameters. Two versions of the model were developed to account for wrapping and nonwrapping of the quadriceps tendon around the femur. Model equations consist of twelve nonlinear second-order ordinary differential equations coupled with nonlinear algebraic constraint equations resulting in a Differential-Algebraic Equations (DAE) system that was solved using the Differential/Algebraic System Solver (DASSL) developed at Lawrence Livermore National Laboratory. Model calculations were performed to simulate the knee extension exercise by applying non-linear forcing functions to the quadriceps tendon. Under the conditions tested, both "screw home mechanism" and patellar flexion lagging were predicted. Throughout the entire range of motion, the medial component of the TF contact force was found to be larger than the lateral one while the lateral component of the PF contact force was found to be larger than the medial one. The anterior and posterior fibers of both anterior and posterior cruciate ligaments, ACL and PCL, respectively, had opposite force patterns: the posterior fibers were most taut at full extension while the anterior fibers were most taut near 90 degrees of flexion. The ACL was found to carry a larger total force than the PCL at full extension, while the PCL carried a larger total force than the ACL in the range of 75 degrees to 90 degrees of flexion.     

A new genus of crane (Aves: Gruiformes) from the Late Tertiary of the Balearic Islands, Western Mediterranean

A new genus and species of crane is described from Late Tertiary karstic deposits in Punta Nati-Cala's Pous, in the north-west of Menorca. The coracoid, the ends of the distal and proximal tibiotarsus, the proximal and distal ends of the tarsometatarsus (the latter is not well preserved) and the femur have been recovered, in what is one of the best osteological series of a crane pre-dating the Pleistocene. The morphology of the fossil is mainly coincident with the Gruinae, especially with recent Grus . However, its size and some symplesiomorphic features of the distal end of the tibiotarsus and of the coracoid are coincident with Balearica , and automorphic characters are also found mainly in the proximal end of the tibiotarsus. The combination of characters justifies the creation of a new genus that is considered basal in the Gruinae.     

Joint axes of rotation and body segment parameters of pig limbs

To enable a quantification of net joint moments and joint reaction forces, indicators of joint loading, this study aimed to locate the mediolateral joint axes of rotation and establish the body segment parameters of the limbs of pigs (Sus scrofa). To locate the joint axes of rotation the scapulohumeral, humeroradial, carpal complex, metacarpophalangeal, coxofemoral, femorotibial, tarsal, and metatarsophalangeal joints from 12 carcasses were studied. The joints were photographed in three positions, bisecting lines drawn at fixed landmarks with their intersection marking the joint axes of rotation. The body segment parameters, i.e. the segment mass, center of mass and moment of inertia were measured on the humerus, radius/ulna, metacarpus, forepastern, foretoe, femur, tibia, metatarsus, hindpastern, and hindtoe segments from five carcasses. The segments were weighed, and their center of mass was found by balancing them. The moments of inertia of the humerus, radius/ulna, femur and tibia were found by rotating the segments. The moments of inertia of the remaining segments were calculated. Generally, the joint axes of rotation were near the attachment site of the lateral collateral ligaments. The forelimb, with segments taken as one, was significantly lighter and shorter than the hindlimb (P < 0.001). In all segments the center of mass was located 31 to 50% distal to the proximal segment end. The segment mass decreased with distance from the trunk, as did the segment moment of inertia. The results may serve as reference on the location of the joint axes of rotation and on the body segment parameters for inverse dynamic modeling of pigs.     

Anatomy of the squirrel wrist: bones, ligaments, and muscles

Anatomical differences among squirrels are usually most evident in the comparison of flying squirrels and nongliding squirrels. This is true of wrist anatomy, probably reflecting the specializations of flying squirrels for the extension of the wing tip and control of it during gliding. In the proximal row of carpals of most squirrels, the pisiform articulates only with the triquetrum, but in flying squirrels there is also a prominent articulation between the pisiform and the scapholunate, providing a more stable base for the styliform cartilage, which supports the wing tip. In the proximal wrist joint, between these carpals and the radius and ulna, differences in curvature of articular surfaces and in the location of ligaments also correlate with differences in degree and kind of movement occurring at this joint, principally reflecting the extreme dorsal flexion and radial deviation of the wrist in flying squirrels when gliding. The distal wrist joint, between the proximal and distal rows of carpals, also shows most variation among flying squirrels, principally in the articulations of the centrale with the other carpal bones, probably causing the distal row of carpal bones to function more like a single unit in some animals. There is little variation in wrist musculature, suggesting only minor evolutionary modification since the tribal radiation of squirrels, probably in the early Oligocene. Variation in the carpal bones, particularly the articulation of the pisiform with the triquetrum and the scapholunate, suggests a different suprageneric grouping of flying squirrels than previously proposed by McKenna (1962) and Mein (1970). J. Morphol. 246:85-102, 2000. Published 2000 Wiley-Liss, Inc.     

Mobility of the subtalar joint in the intact ankle complex

A previous study by these authors showed that the calcaneus follows a unique path of unresisted coupled motion relative to the tibia during passive flexion and that most of this motion occurred at the ankle level. Subtalar motion in the intact ankle complex was observed only when perturbations from this path were induced by the application of force to the calcaneus. Relative motion of the bones of the ankle complex was tracked by stereophotogrammetry in seven specimens. Anatomical landmarks, reference frames and joint angles were defined by standard techniques. Sequential moments were applied to the calcaneus about the long axis of the tibia. Measured movements at subtalar level demonstrated plantarflexion coupled to supination and internal rotation (inversion) and dorsiflexion coupled to pronation and external rotation (eversion). These movements were resisted and were fully recovered when the external load was removed. Subtalar motion diminished as the ankle approached maximal dorsi- and plantarflexion. Two clearly distinguished mean axes of rotation were observed for inversion and eversion runs. The axes of inversion and eversion of the subtalar complex changed orientation along a preferred and repeatable path. The subtalar joint complex occupied only a single stable position in the unloaded state and with no range of unresisted motion. It is inferred that mobility was possible only by the stretching and lengthening of the ligaments and the indentation of the articular surfaces, requiring the application of loads. The subtalar joint complex behaves like a flexible structure.     

Transarticular bony defects after trauma and sepsis: arthrodesis using vascularized fibular transfer

Ten male patients with previously infected bony defects involving both sides of an articulation underwent arthrodesis using a vascularized fibular transfer. The average age of these patients was 38 years (range, 20 to 60 years). The size of the bony defect averaged 9 cm (range, 3 to 21 cm). The ankle was involved in five patients, the knee in two patients, the wrist in two patients, and the elbow in one patient. Nine cases represented septic pseudarthroses (eight after trauma and one after attempted ankle arthrodesis). One patient had a defect across the wrist after debridement of a chronic infection. The patients were followed for an average of 71 months (range, 26 to 144 months). Nine patients healed after the index vascularized fibular transfer, and one patient (ankle arthrodesis) required a second cancellous bone-grafting procedure for delayed union at the junction of the fibula with the talus. Four of seven patients with lower limb involvement had residual leg length discrepancies averaging 5 cm (range, 3 to 8 cm), and one had a persistent 20-degree internal rotation deformity. Two of the patients with upper limb involvement had stiff digits. Five of the nine previously employed patients returned to their former occupation (including heavy labor in four cases). Complications included two wound separations, one case of instability of the donor ankle after removal of a large fibular graft (related in part to a prior injury), and one fracture at the junction of the fibular graft with the local bone 10 months after the index procedure, which united after plate fixation and application of autogenous cancellous bone graft. Arthrodesis using a transfer of vascularized fibular bone represents a viable option for limb salvage in the face of an infected transarticular bony defect.     

Stance and gait in the hindlimb of a therocephalian mammal-like reptile

The ilium, femur, tibia, fibula, astragalus and calcaneum of the therocephalian therapsid Regisaurus jacobi Mendrez are described. Functional consideration of the bones and particularly the nature of the hip, knee and ankle joints indicate that this animal was capable of at least two distinct gaits, a primitive, sprawling type and an advanced upright type. The ankle joint had a moveable articulation between the astragalus and the calcaneum analogous to that of the crocodiles. The possibility of such a multi-gaited intermediate stage having occurred in the course of the evolution of the mammalian locomotory pattern is suggested.     

采用同种异体腓骨植骨重建肱骨近端内侧柱的临床应用及疗效

目的:探讨同种异体腓骨移植重建肱骨近端内侧柱联合锁定钢板治疗肱骨近端骨折的临床疗效。方法:回顾性分析2011年3月至2013年9月于我院行同种异体腓骨移植联合锁定钢板治疗肱骨近端骨折患者38例。根据Neer分型:三部分骨折26例,四部分骨折12例;随访期间测量肱骨头内翻角度、肱骨头高度;患肩功能评分采用Constant肩关节评分标准、美国肩肘协会评分系统(ASES)及加州大学肩关节评分系统(UCLA),同时记录患者并发症。结果:患者随访时间平均15.5±1.8个月;末次随访Constant肩关节评分平均89.0±3.2分;美国肩肘协会评分系统(ASES)评分为平均81.2±14.5分;加州大学肩关节评分系统(UCLA)平均27.6±5.3;根据UCLA评分系统,患者术后优良率为89.4%。患侧肩关节前屈、外展、外旋及内旋运动范围分别是143±20°、138±9°、44±12°、42±9°。影像学结果显示:末次随访肱骨头高度平均丢失1.9 mm,颈干角度平均为128±16°。根据Paavolainen方法,末次随访优30例、良7例、差1例。结论:同种异体腓骨移植重建肱骨近端骨折内侧柱,术中联合肱骨近端锁定钢板能有效支撑肱骨头,预防肱骨头塌陷及螺钉穿出,短期临床疗效满意。     

Variation in fibular robusticity reflects variation in mobility patterns

During hominin plantigrade locomotion, the weight-bearing function of the fibula has been considered negligible. Nevertheless, studies conducted on human samples have demonstrated that, even if less than that of the tibia, the load-bearing function of the fibula still represents a considerable portion of the entire load borne by the leg. The present study assesses whether variation in habitual lower limb loading influences fibular morphology in a predictable manner. To achieve this, both fibular and tibial morphology were compared amongst modern human athletes (field hockey players and cross-country runners) and matched sedentary controls. Peripheral quantitative computed tomography was used to capture two-dimensional, cross-sectional bone images. Geometric properties were measured at the midshaft for each bone. Results show a trend of increased fibular rigidity from control to runners through to field hockey players. Moreover, relative fibular robusticity (fibula/tibia) is significantly greater in hockey players compared with runners. These results are likely the consequence of habitual loading patterns performed by these athletes. Specifically, the repeated directional changes associated with field hockey increase the mediolateral loading on the lower leg in a manner that would not necessarily be expected during cross-country running. The present study validates the use of the fibula in association with the tibia as a mean to provide a more complete picture of leg bone functional adaptations. Therefore, the fibula can be added to the list of bones generally used (tibia and femur) to assess the correspondence between mobility patterns and skeletal morphology for past human populations.     

A geometric model of the human ankle joint.

A two-dimensional four-bar linkage model of the ankle joint is formulated to describe dorsi/plantarflexion in unloaded conditions as observed in passive tests on ankle complex specimens. The experiments demonstrated that the human ankle joint complex behaves as a single-degree-of-freedom system during passive motion, with a moving axis of rotation. The bulk of the movement occurred at the level of the ankle. Fibres within the calcaneofibular and tibiocalcaneal ligaments remained approximately isometric. The experiments showed that passive kinematics of the ankle complex is governed only by the articular surfaces and the ligaments. It was deduced that the ankle is a single-degree-of-freedom mechanism where mobility is allowed by the sliding of the articular surfaces upon each other and the isometric rotation of two ligaments about their origins and insertions, without tissue deformation. The linkage model is formed by the tibia/fibula and talus/calcaneus bone segments and by the calcaneofibular and tibiocalcaneal ligament segments. The model predicts the path of calcaneus motion, ligament orientations, instantaneous axis of rotation, and conjugate talus surface profile as observed in the experiments. Many features of ankle kinematics such as rolling and multiaxial rotation are elucidated. The geometrical model is a necessary preliminary step to the study of ankle joint stability in response to applied loads and can be used to predict the effects of changes to the original geometry of the intact joint. Careful reconstruction of the original geometry of the ligaments is necessary after injury or during total ankle replacement.     

An improved OpenSim gait model with multiple degrees of freedom knee joint and knee ligaments

Musculoskeletal models are widely used to investigate joint kinematics and predict muscle force during gait. However, the knee is usually simplified as a one degree of freedom joint and knee ligaments are neglected. The aim of this study was to develop an OpenSim gait model with enhanced knee structures. The knee joint in this study included three rotations and three translations. The three knee rotations and mediolateral translation were independent, with proximodistal and anteroposterior translations occurring as a function of knee flexion/extension. Ten elastic elements described the geometrical and mechanical properties of the anterior and posterior cruciate ligaments (ACL and PCL), and the medial and lateral collateral ligaments (MCL and LCL). The three independent knee rotations were evaluated using OpenSim to observe ligament function. The results showed that the anterior and posterior bundles of ACL and PCL (aACL, pACL and aPCL, pPCL) intersected during knee flexion. The aACL and pACL mainly provided force during knee flexion and adduction, respectively. The aPCL was slack throughout the range of three knee rotations; however, the pPCL was utilised for knee abduction and internal rotation. The LCL was employed for knee adduction and rotation, but was slack beyond 20° of knee flexion. The MCL bundles were mainly used during knee adduction and external rotation. All these results suggest that the functions of knee ligaments in this model approximated the behaviour of the physical knee and the enhanced knee structures can improve the ability to investigate knee joint biomechanics during various gait activities.     

A reciprocal connection factor for assessing knee-joint function

In the knee joint, interactions between instantaneous kinetics and kinematics associated with ligamentous and articular tissues are not fully understood. These structures may be represented by the instantaneous screw axis ($) (ISA) and static force vectors ($'). Geometric changes to the joint structure affecting motion have not been fully explained, especially after surgical reconstruction and replacement procedures. The ISA offers a joint-characterisation approach, which is dependent on the combined forces of ligaments, articular contacts and muscles. The standard four-bar linkage model in the sagittal plane demonstrates that the normal contact force and the lines of action of the cruciate ligaments always intersect at the centre of rotation of the joint. A kinematic knee model in which the articular surfaces in the lateral and medial compartments as well as the isometric fascicles in the engaged ligaments may be represented as five constraints in a one-degree-of-freedom parallel spatial mechanism. This study provides a theoretical foundation to elucidate the role of each of these elements in the control of the ISA. A recourse to the principle of virtual work explained through d'Alembert's principle for reducing a dynamics problem to an instantaneous static scenario allows screws to be applied to the biomechanics of human motion. The principle of reciprocity links these approaches together to explain the transmitting load between the tibia and the femur as well as the relative motion within the knee joint. A principal clinical implication of this study is the introduction of the reciprocal connection factor to evaluate knee kinematics and kinetics in one simple term, allowing the quantitative assessment of the outcome of knee-joint treatment and rehabilitation methods.     

Two-dimensional dynamic modelling of human knee joint

A mathematical dynamic model of the two-dimensional representation of the knee joint is presented. The profiles of the joint surfaces are determined from X-ray films and they are represented by polynomials. The joint ligaments are modelled as nonlinear elastic springs of realistic stiffness properties. Nonlinear equations of motion coupled with nonlinear constraint conditions are solved numerically. Time derivatives are approximated by Newmark difference formulae and the resulting nonlinear algebraic equations are solved employing the Newton-Raphson iteration scheme. Several dynamic loads are applied to the center of mass of the tibia and the ensuing motion is investigated. Numerical results on ligament forces, contact point locations between femur and tibia, and the orientation of tibia relative to femur are presented. The results are shown to be consistent with the anatomy of the knee joint.     

Toward a realistic optoelectronic-based kinematic model of the hand: representing the transverse metacarpal arch reduces accessory rotations of the metacarpophalangeal joints

A kinematic model representing the versatility of the human hand is needed to evaluate biomechanical function and predict injury risk in the workplace. We improved upon an existing optoelectronic-based kinematic hand model with grouped metacarpals by defining segmented metacarpals and adding the trapeziometacarpal joint of the thumb. Eight participants performed three static postures (neutral pose, cylinder grip, cap grip) to evaluate kinematic performance of three different models, with one, two, and four metacarpal segment(s). Mean distal transverse metacarpal arch angles in the four-segment metacarpal model were between 22.0° ± 3.3° (neutral pose) and 32.1° ± 3.7° (cap grip). Representation of the metacarpals greatly influenced metacarpophalangeal joint rotations. Both the two- and four-segment metacarpal models displayed significantly lower metacarpophalangeal joint ‘supination’ angles (than the one-segment model) for the fourth and fifth fingers. However, the largest reductions were for the four- versus one-segment models, with mean differences ranging from 9.3° (neutral pose) to 17.0° (cap grip) for the fourth finger and 16.3° (neutral pose) to 33.0° (cylinder grip) for the fifth finger. MCP joint abduction/adduction angles of the fourth and fifth fingers also decreased with segmentation of the metacarpals, although the lowest magnitudes generally occurred in the four-segment model. Overall, the four-segment metacarpal model produced the lowest accessory rotations in non-dominant axes, and best matched previous radiological studies that found MCP joint pronation/supination angles were typically less than 10°. The four-segment metacarpal model, with improved anatomic fidelity, will better serve future studies of detailed actions of the hand in clinical or work applications.     

An automatic 2D–3D image matching method for reproducing spatial knee joint positions using single or dual fluoroscopic images

Fluoroscopic image technique, using either a single image or dual images, has been widely applied to measure in vivo human knee joint kinematics. However, few studies have compared the advantages of using single and dual fluoroscopic images. Furthermore, due to the size limitation of the image intensifiers, it is possible that only a portion of the knee joint could be captured by the fluoroscopy during dynamic knee joint motion. In this paper, we presented a systematic evaluation of an automatic 2D–3D image matching method in reproducing spatial knee joint positions using either single or dual fluoroscopic image techniques. The data indicated that for the femur and tibia, their spatial positions could be determined with an accuracy and precision less than 0.2 mm in translation and less than 0.4° in orientation when dual fluoroscopic images were used. Using single fluoroscopic images, the method could produce satisfactory accuracy in joint positions in the imaging plane (in average up to 0.5 mm in translation and 1.3° in rotation), but large variations along the out-plane direction (in average up to 4.0 mm in translation and 2.2° in rotation). The precision of using single fluoroscopic images to determine the actual knee positions was worse than its accuracy obtained. The data also indicated that when using dual fluoroscopic image technique, if the knee joint outlines in one image were incomplete by 80%, the algorithm could still reproduce the joint positions with high precisions.     

Locomotion in the quail (Coturnix japonica): the kinematics of walking and increasing speed

Hindlimb segmental kinematics and stride characteristics are quantified in several quail locomoting on a treadmill over a six-fold increase in speed. These data are used to describe the kinematics of a walking stride and to identify which limb elements are used to change stride features as speed increases. In quail, the femur does not move during locomotion and the tarsometatarsus-phalangeal joint is a major moving joint; thus, quail have lost the most proximal moving joint and added one distally. The tibiotarsus and tarsometatarsus act together as a fixed strut swinging from the knee during stance phase (the ankle angle remains constant at a given speed) and the tarsometatarsus-phalangeal joint appears to have a major role in increasing limb length during the propulsive phase of the stride. Speed is increased with greater knee extension and by lengthening the tibiotarsus/tarsometatarsus via increased ankle extension at greater speeds. Because the femur is not moved and three distal elements are, quail move the limb segments through a stride and increase speed in a way fundamentally different from other nonavian vertebrates. However, the three moving joints in quail (the knee, ankle, and tarsometatarsophangeal joint) have strikingly similar kinematics to the analogous moving joints (the hip, knee, and ankle) in other vertebrates. Comparisons to other vertebrates indicate that birds appear to have two modes of limb function (three- and four-segment modes) that vary with speed and locomotory habits.