In-vivo three-dimensional carpal bone kinematics during flexion–extension and radio–ulnar deviation of the wrist: Dynamic motion versus step-wise static wrist positions

An in-vivo approach to the measurement of three-dimensional motion patterns of carpal bones in the wrist may have future diagnostic applications, particularly for ligament injuries of the wrist. Static methods to measure carpal kinematics in-vivo only provide an approximation of the true kinematics of the carpal bones. This study is aimed at finding the difference between dynamically and statically acquired carpal kinematics.For eight healthy subjects, static and a dynamic measurements of the carpal kinematics were performed for a flexion–extension and a radio–ulnar deviation movement. Dynamic scans were acquired by using a four-dimensional X-ray imaging system during an imposed cyclic motion. To assess static kinematics of the wrists, three-dimensional rotational X-ray scans were acquired during step-wise flexion–extension and radio–ulnar deviation. The helical axis rotations and the rotation components. i.e. flexion–extension, radio–ulnar deviation and pro–supination were the primary parameters. Linear mixed model statistical analysis was used to determine the significance of the difference between the dynamically and statically acquired rotations of the carpal bones.Small and in most cases negligible differences were observed between the dynamic motion and the step-wise static motion of the carpal bones. The conclusion is that in the case of individuals without any pathology of the wrist, carpal kinematics can be studied either dynamically or statically. Further research is required to investigate the dynamic in-vivo carpal kinematics in patients with dynamic wrist problems.     

A novel method to replicate the kinematics of the carpus using a six degree-of-freedom robot

Understanding the kinematics of the carpus is essential to the understanding and treatment of wrist pathologies. However, many of the previous techniques presented are limited by non-functional motion or the interpolation of points from static images at different postures. We present a method that has the capability of replicating the kinematics of the wrist during activities of daily living using a unique mechanical testing system. To quantify the kinematics of the carpal bones, we used bone pin-mounted markers and optical motion capture methods. In this paper, we present a hammering motion as an example of an activity of daily living. However, the method can be applied to a wide variety of movements. Our method showed good accuracy (1.0–2.6°) of in vivo movement reproduction in our ex vivo model. Most carpal motion during wrist flexion–extension occurs at the radiocarpal level while in ulnar deviation the motion is more equally shared between radiocarpal and midcarpal joints, and in radial deviation the motion happens mainly at the midcarpal joint. For all rotations, there was more rotation of the midcarpal row relative to the lunate than relative to the scaphoid or triquetrum. For the functional motion studied (hammering), there was more midcarpal motion in wrist extension compared to pure wrist extension while radioulnar deviation patterns were similar to those observed in pure wrist radioulnar deviation. Finally, it was found that for the amplitudes studied the amount of carpal rotations was proportional to global wrist rotations.     

The effect of tendon loading on in-vitro carpal kinematics of the wrist joint

Measurements of in-vitro carpal kinematics of the wrist provide valuable biomechanical data. Tendon loading is often applied during cadaver experiments to simulate natural stabilizing joint compression in the wrist joint. The purpose of this study was to investigate the effect of tendon loading on carpal kinematics in-vitro.A cyclic movement was imposed on 7 cadaveric forearms while the carpal kinematics were acquired by a 4-dimensional rotational X-ray imaging system. The extensor- and flexor tendons were loaded with constant force springs of 50 N, respectively. The measurements were repeated without a load on the tendons. The effect of loading on the kinematics was tested statistically by using a linear mixed model.During flexion and extension, the proximal carpal bones were more extended with tendon loading. The lunate was on the average 2.0° (p=0.012) more extended. With tendon loading the distal carpal bones were more ulnary deviated at each angle of wrist motion. The capitate was on the average 2.4° (p=0.004) more ulnary deviated.During radioulnar deviation, the proximal carpal bones were more radially deviated with the lunate 0.7° more into radial deviation with tendon loading (p<0.001). Conversely, the bones of distal row were more flexed and supinated with the capitate 1.5° more into flexion (p=0.025) and 1.0° more into supination (p=0.011).In conclusion, the application of a constant load onto the flexor and extensor tendons in cadaver experiments has a small but statistically significant effect on the carpal kinematics during flexion–extension and radioulnar deviation.     

Development and validation of a computed tomography-based methodology to measure carpal kinematics

Motion of the wrist bones is complicated and difficult to measure. Noninvasive measurement of carpal kinematics using medical images has become popular This technique is difficult and most investigators employ custom software. The objective of this paper is to describe a validated methodology for measuring carpal kinematics from computed tomography (CT) scans using commercial software. Four cadaveric wrists were CT imaged in neutral, full flexion, and full extension. A registration block was attached to the distal radius and used to align the data sets from each position. From the CT data, triangulated surface models of the radius, lunate, and capitate bones were generated using commercial software. The surface models from each wrist position were read into engineering design software that was used to calculate the centroid (position) and principal mass moments of inertia (orientation) of (1) the capitate and lunate relative to the fixed radius and (2) the capitate relative to the lunate. These data were used to calculate the helical axis kinematics for the motions from neutral to extension and neutral to flexion. The kinematics were plotted in three dimensions using a data visualization software package. The accuracy of the method was quantified in a separate set of experiments in which an isolated capitate bone was subjected to two different known rotation/translation motions for ten trials each. For comparison to in vivo techniques, the error in distal radius surface matching was determined using the block technique as a gold standard. The motion that the lunate and capitate underwent was half that of the overall wrist flexion-extension range of motion. Individually, the capitate relative to the lunate and the lunate relative to the radius generally flexed or extended about 30 deg, while the entire wrist (capitate relative to radius) typically flexed or extended about 60 deg. Helical axis translations were small, ranging from 0.6 mm to 1.8 mm across all motions. The accuracy of the method was found to be within 1.4 mm and 0.5 deg (95% confidence intervals). The mean error in distal radius surface matching was 2.4 mm and 1.2 deg compared to the use of a registration block. Carpal kinematics measured using the described methodology were accurate, reproducible, and similar to findings of previous investigators. The use of commercially available software should broaden the access of researchers interested in measuring carpal kinematics using medical imaging.     

The insertion sites of selected human carpal ligaments. A quantitative morphological study using three-dimensional computer reconstructions

The shape and size of insertion sites associated to the relevant carpal ligaments are given in terms of outlines and surface areas. The sites are reconstructed as areas on the contours of the carpal bones with the use of three-dimensional reconstruction of serially sectioned wrists. The computer-models of the wrist-joint show accurately the sofar uncharted three-dimensional orientations of the insertions. The documentation of the surface areas is a first approach to the quantitative analysis of the bone-ligament complex of the wrist-joint. This is needed in future studies about the role of the ligament behavior in wrist-joint motion.     

In vivo motion of the scaphotrapezio-trapezoidal (STT) joint

It has previously been shown that the articulation of the scaphotrapezio-trapezoidal (STT) joint can be modeled such that the trapezoid and trapezium are tightly linked and move together on a single path relative to the scaphoid during all directions of wrist motion. The simplicity of such a model is fascinating, but it leaves unanswered why two distinct carpal bones would have a mutually articulating surface if there were no motion between them, and how such a simplistic model of STT joint motion translates into the more complex global carpal motion. We performed an in vivo analysis of the trapezoids and trapeziums of 10 subjects (20 wrists) using a markerless bone registration technique. In particular, we analyzed the centroid spacing, centroid displacements, kinematics, and postures of the trapezoid and trapezium relative to the scaphoid. We found that, on a gross level, the in vivo STT motion was consistent with that reported in vitro. In addition, we found that the magnitude of trapezoid and trapezium motion was dependent upon the direction of wrist motion. However, we also found that when small rotations and displacements are considered there were small but statistically significant relative motions between the trapezoid and trapezium (0.4 mm in maximum flexion, 0.3 mm in radial deviation and at least 10 degrees in flexion extension and ulnar deviation) as well as slight off-path rotations. The results of this study indicate that the STT joint should be considered a mobile joint with motions more complex than previously appreciated.     

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.     

In vivo kinematic behavior of the radio-capitate joint during wrist flexion-extension and radio-ulnar deviation.

The capitate is often considered the "keystone" of the carpus, not simply because of its central and prominent position in the wrist, but also because of its mechanical interactions with neighboring bones. The purpose of this study was to determine in vivo three-dimensional capitate kinematics. Twenty uninjured wrists were investigated using a recently developed, non-invasive markerless bone registration (MBR) technique. Surface contours of the capitate, third metacarpal and radius were extracted from computed tomography images of seven wrist positions and the three-dimensional motions of the capitate and third metacarpal were calculated with respect to the radius in wrist flexion-extension and radio-ulnar deviation. We found that in vivo capitate motion does not simply occur about a single pivot point like a universal joint, as demonstrated by non-intersecting rotation axes for different capitate motions. The distance between flexion and ulnar deviation axes was 3.9+/-2.0 mm, and the distance between extension and ulnar deviation axes was 3.9+/-1.4 mm. Furthermore, capitate axes for males tended to be located more distally than axes for females. However, we believe that this result is related to subject size and not to gender. We also found that there is minimal relative motion between the capitate and third metacarpal during these in vivo wrist motions. These findings demonstrate the complexity of capitate kinematics, as well as the different mechanisms through which wrist flexion, extension, radial deviation and ulnar deviation occur.     

Measuring 3D Hand and Finger Kinematics—A Comparison between Inertial Sensing and an Opto-Electronic Marker System

Objective analysis of hand and finger kinematics is important to increase understanding of hand function and to quantify motor symptoms for clinical diagnosis. The aim of this paper is to compare a new 3D measurement system containing multiple miniature inertial sensors (PowerGlove) with an opto-electronic marker system during specific finger tasks in three healthy subjects. Various finger movements tasks were performed: flexion, fast flexion, tapping, hand open/closing, ab/adduction and circular pointing. 3D joint angles of the index finger joints and position of the thumb and index were compared between systems. Median root mean square differences of the main joint angles of interest ranged between 3.3 and 8.4deg. Largest differences were found in fast and circular pointing tasks, mainly in range of motion. Smallest differences for all 3D joint angles were observed in the flexion tasks. For fast finger tapping, the thumb/index amplitude showed a median difference of 15.8mm. Differences could be explained by skin movement artifacts caused by relative marker movements of the marker system, particularly during fast tasks; large movement accelerations and angular velocities which exceeded the range of the inertial sensors; and by differences in segment calibrations between systems. The PowerGlove is a system that can be of value to measure 3D hand and finger kinematics and positions in an ambulatory setting. The reported differences need to be taken into account when applying the system in studies understanding the hand function and quantifying hand motor symptoms in clinical practice.     

Feasibility of using a video-based motion analysis system for measuring thumb kinematics

While several different methods have been used to measure hand kinematics, fluoroscopy is generally considered to be the most accurate. Recently, video-based motion analysis has been developed for the measurement of joint kinematics. This method is versatile, easy to use, and can measure motions dynamically. Surface markers are most commonly used in the video-based motion systems. However, whether the surface markers placed on the thumb accurately represent the true kinematics of the underlying bony segment is questionable.In this study, the feasibility of surface markers to represent thumb kinematics was investigated by fluoroscopy. Both the positions of surface markers and bony landmarks were simultaneous recorded and then digitized. The Ra(2) values comparing the angular changes of the thumb interphalangeal, metacarpal and carpometacarpal joints derived using the surface markers or bony landmarks were 0.9986, 0.9730 and 0.9186 in the flexion/extension plane respectively, 0.8837, 0.9697 and 0.8775 in the abduction/adduction plane; and 0.9884, 0.9643 and 0.9431 in the opposition plane. The ranges, mean and standard deviation of the absolute differences between calculated angles of different marker sets were also compared. These data revealed that the similarities of the two different marker techniques throughout the motion cycle were high. The differences between the two methods were also within clinically allowable range of +/-5 degrees. It is concluded that the application of the video-based motion analysis system with surface markers to thumb kinematics is warranted.     

Simulation of extension,radial and ulnar deviation of the wrist with a rigid body spring model

A novel computational model of the wrist that predicts carpal bone motion was developed in order to investigate the complex kinematics of the human wrist.This rigid body spring model (RBSM) of the wrist was built using surface models of the eight carpal bones, the bases of the five metacarpal bones, and the distal parts of the ulna and radius, all obtained from computed tomography (CT) scans of a cadaver upper limb. Elastic contact conditions between the rigid bodies modeled the influence of the cartilage layers, and ligamentous structures were constructed using nonlinear, tension-only spring elements. Motion of the wrist was simulated by applying forces to the tendons of the five main wrist muscles modeled.Three wrist motions were simulated: extension, ulnar deviation and radial deviation. The model was tested and tuned by comparing the simulated displacement and orientation of the carpal bones with previously obtained CT-scans of the same cadaver arm in deviated (45°ulnar and 15°radial), and extended (57°) wrist positions. Simulation results for the scaphoid, lunate, capitate, hamate and triquetrum are presented here and provide credible prediction of carpal bone movement. These are the first reported results of such a model. They indicate promise that this model will assist in future wrist kinematics investigations. However, further optimization and validation are required to define and guarantee the validity of results.     

The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in the ACL

This study investigated the effect of hamstring co-contraction with quadriceps on the kinematics of the human knee joint and the in-situ forces in the anterior cruciate ligament (ACL) during a simulated isometric extension motion of the knee. Cadaveric human knee specimens (n = 10) were tested using the robotic universal force moment sensor (UFS) system and measurements of knee kinematics and in-situ forces in the ACL were based on reference positions on the path of passive flexion/extension motion of the knee. With an isolated 200 N quadriceps load, the knee underwent anterior and lateral tibial translation as well as internal tibial rotation with respect to the femur. Both translation and rotation increased when the knee was flexed from full extension to 30 of flexion; with further flexion, these motion decreased. The addition of 80 N antagonistic hamstrings load significantly reduced both anterior and lateral tibial translation as well as internal tibial rotation at knee flexion angles tested except at full extension. At 30 of flexion, the anterior tibial translation, lateral tibial translation, and internal tibial rotation were significantly reduced by 18, 46, and 30%, respectively (p<0.05). The in-situ forces in the ACL under the quadriceps load were found to increase from 27.8+/-9.3 N at full extension to a maximum of 44.9+/-13.8 N at 15 of flexion and then decrease to 10 N beyond 60 of flexion. The in-situ force at 15 was significantly higher than that at other flexion angles (p<0.05). The addition of the hamstring load of 80 N significantly reduced the in-situ forces in the ACL at 15, 30 and 60 of flexion by 30, 43, and 44%, respectively (p<0.05). These data demonstrate that maximum knee motion may not necessarily correspond to the highest in-situ forces in the ACL. The data also suggest that hamstring co-contraction with quadriceps is effective in reducing excessive forces in the ACL particularly between 15 and 60 of knee flexion.     

Elbow helical axes of motion are not the same in physiologic and kinetic joint simulators

Physiologic and kinetic joint simulators have been widely used for investigations of joint mechanics. The two types of simulator differ in the way joint motion is achieved; through prescribed motions and/or forces in kinetic joint simulators and by tendon loads in physiologic joint simulators. These two testing modalities have produced important insights, as in elucidating the importance of soft tissue structures to joint stability. However, the equivalence of the modalities has not been tested. This study sequentially tested five cadaveric elbows using both a physiologic simulator and a robot/6DOF system. Using position data from markers on the humerus and ulna, we calculated and compared the helical axes of motion of the specimens as the elbows were flexed from full extension. Six step size increments were used in the helical axis calculation. Marker position data at each test's full extension and full flexion point were also used to calculate a datum (overall) helical axis. The angles between the datum axis and step-wise movements were computed and stored. Increasing step size monotonically decreased the variability and the average conical angle encompassing the helical axes; a repeated measures ANOVA using test type (robot or physiologic simulator) and step size found that both type and step caused statistically significant differences (p<0.001). The large changes in helical axis angle observed for small changes in elbow flexion angle, especially in the robot tests, are a caveat for investigators using similar control algorithms. Controllers may need to include increased joint compliance and/or C(1) continuity to reduce variability.     

Scapular kinematics during unloaded and maximal loaded isokinetic concentric and eccentric shoulder flexion and extension movements

Characterization of scapular kinematics under demanding load conditions might aid to distinguish between physiological and clinically relevant alterations. Previous investigations focused only on submaximal external load situations. How scapular movement changes with maximal load remains unclear. Therefore, the present study aimed to evaluate 3D scapular kinematics during unloaded and maximal loaded shoulder flexion and extension. Twelve asymptomatic individuals performed shoulder flexion and extension movements under unloaded and maximal concentric and eccentric loaded isokinetic conditions. 3D scapular kinematics assessed with a motion capture system was analyzed for 20° intervals of humeral positions from 20° to 120° flexion. Repeated measures ANOVAs were used to evaluate kinematic differences between load conditions for scapular position angles, scapulohumeral rhythm and scapular motion extent. Increased scapular upward rotation was seen during shoulder flexion and extension as well as decreased posterior tilt and external rotation during eccentric and concentric arm descents of maximal loaded compared to unloaded conditions. Load effects were further seen for the scapulohumeral rhythm with greater scapular involvement at lower humeral positions and increased scapular motion extent under maximal loaded shoulder movements. With maximal load applied to the arm physiological scapular movement pattern are induced that may imply both impingement sparing and causing mechanisms.     

In vitro analysis of kinematics and elastostatics of the human rib cage during thoracic spinal movement for the validation of numerical models

Neither kinematic nor stiffness properties of the rib cage during thoracic spinal motion were investigated in previous studies, while being essential for the accurate validation of numerical models of the whole thorax. The aim of this in vitro study therefore was to quantify the kinematics and elastostatics of the human rib cage under defined boundary conditions. Eight fresh frozen human thoracic spine specimens (C7-L1, median age 55 years, ranging from 40 to 60 years) including entire rib cages were loaded quasi-statically in flexion/extension, lateral bending, and axial rotation using pure moments of 5 Nm. Relative motions of ribs, thoracic vertebrae, and sternal structures as well as strains on the ribs were measured using optical motion tracking of 150 reflective markers per specimen, while specimens were loaded displacement-controlled with a constant rate of 1°/s for 3.5 cycles. The third full cycle was used to determine relative angles and strains at full loading of the spine for all motion directions. Largest relative angles were found in the main loading directions with only small motions at the mid-thoracic levels. Highest strains of the intercostal spaces were detected in the anterior section of the lowest fourth of the rib cage, showing compressions and elongations of more than 10% in all spinal motion planes. Elastostatic rib deformation was generally less than 1%. Rib-sternum relative motions exhibited complex motion patterns, overall showing relative angles below 2°. The results indicate that rib cage structures are not macroscopically deformed during spinal motion, but exhibit characteristic reproducible kinematics patterns.     

Effects of data smoothing on the reconstruction of helical axis parameters in human joint kinematics

In biomechanical joint-motion analyses, the continuous motion to be studied is often approximated by a sequence of finite displacements, and the Finite Helical Axis (FHA) or "screw axis" for each displacement is estimated from position measurements on a number of anatomical or artificial landmarks. When FHA parameters are directly determined from raw (noisy) displacement data, both the position and the direction of the FHA are ill-determined, in particular when the sequential displacement steps are small. This implies, that under certain conditions, the continuous pathways of joint motions cannot be adequately described. The purpose of the present experimental study is to investigate the applicability of smoothing (or filtering) techniques, in those cases where FHA parameters are ill-determined. Two different quintic-spline smoothing methods were used to analyze the motion data obtained with Roentgenstereophotogrammetry in two experiments. One concerning carpal motions in a wrist-joint specimen, and one relative to a kinematic laboratory model, in which the axis positions are a priori known. The smoothed and non-smoothed FHA parameter errors were compared. The influences of the number of samples and the size of the sampling interval (displacement step) were investigated, as were the effects of equidistant and nonequidistant sampling conditions and noise invariance.     

The mole's thumb -- evolution of the hand skeleton in talpids (Mammalia)

Osteological specimens representing 15 out of the 16 currently recognized talpid genera were examined and scored for seven discrete morphological characters of the hand. The phylogenetic distribution of these characters was studied in the context of alternative hypotheses of talpid relationships, using three species of shrews and a hedgehog as outgroups. All talpids show a similar number and arrangement of carpal bones. The most obvious differences concern the presence of additional sesamoid bones, the relative size of the os falciforme when present, and the degree of fusion of the scaphoid and lunate in the proximal carpal row. Marked differences in the relative length and proportions of the metacarpals also exist. The development of the carpals in Talpa europaea was studied through examination of histological sections of the hand of an embryo and a neonate. Whereas carpal anatomy in the neonate mirrors the arrangement and proportions of the adult, in the embryo the scaphoid and lunate are still separate, there are no signs of the os falciforme, and the size proportions of metacarpals to carpals are obviously different to those of the adult. A prehallux or tibial sesamoid, serial homologue to the os falciforme or prepollex (a radial sesamoid), does not have an obvious functional role, and its presence might be the result of a common epigenetic control in the hand and the foot resulting in a non-adaptive structure in the latter.     

Radio-ulnar deviation of the primate carpus: an X-ray study

The lack of contact between the ulna and first row of carpals characterizes the wrist morphology of hominoids as compared to other primates. This distinctive feature--generally interpreted as a significant synapomorphy between humans and other hominoids--was a priori considered to be an indication of an increased capacity for ulnar deviation, allowing a greater diversity of hand movements. This X-ray study aimed to test this hypothesis by comparing the shifting of the carpals throughout radioulnar deviation in eight extant genera endowed with ulno-carpal contact or lacking it. The results show that the amplitude of ulnar deviation is not directly correlated with the presence or absence of an ulno-carpal contact: most ulnar deviation takes place at the antebrachio-carpal joint in those primates that lack an ulno-carpal contact (hominoids), instead of at the mid-carpal joint in primates whose ulna articulates with the triquetral (cercopithecoids, platyrrhines, most strepsirrhines). Analysis of the X-ray suggests that the loss of ulno-carpal contact improved the ability to supinate at the radio-ulnar joints, with correlated unfitness for palmigrade/semidigitigrade walking. This evolutive change, associated with a considerable reduction of the share of body weight carried on the forelimbs, likely cleared the way for either knuckle walking or bipedalism and handiness.