Dynamic motion analysis of dart throwers motion visualized through computerized tomography and calculation of the axis of rotation

Trabecular bone structure of the proximal capitate in extant hominids and fossil hominins with implications for midcarpal joint loading and the dart-thrower's motion

OBJECTIVES

This research examines whether the distribution of trabecular bone in the proximal capitates of extant hominids, as well as several fossil hominin taxa, is associated with the oblique path of the midcarpal joint known as the dart-thrower's motion (DTM).

MATERIALS AND METHODS

We analyzed proximal capitates from extant (Pongo n = 12; Gorilla n = 11; Pan n = 10; fossil and recent Homo sapiens n = 29) and extinct (Australopithecus sediba n = 2; Homo naledi n = 1; Homo floresiensis n = 2; Neandertals n = 3) hominids using a new canonical holistic morphometric analysis, which quantifies and visualizes the distribution of trabecular bone using relative bone volume as a fraction of total volume (rBV/TV).

RESULTS

Homo sapiens and Neandertals had a continuous band of high rBV/TV that extended across the scaphoid, lunate, and hamate subarticular regions, but other fossil hominins and extant great apes did not. A. sediba expressed a distinct combination of human-like and Pan-like rBV/TV distribution. Both H. floresiensis and H. naledi had high rBV/TV on the ulnar-side of the capitate but low rBV/TV on the radial-side.

CONCLUSION

The proximal capitates of H. sapiens and Neandertals share a distinctive distribution of trabecular bone that suggests that these two species of Homo regularly load(ed) their midcarpal joints along the full extent of the oblique path of the DTM. The observed pattern in A. sediba suggests that human-like stress at the capito-scaphoid articular surface was combined with Pan-like wrist postures, whereas the patterns in H. floresiensis and H. naledi suggest their midcarpal joints were loaded differently from that of H. sapiens and Neandertals.

Examination of the traction effect in an artificial muscle-type dynamic traction orthosis using computed tomography

BACKGROUND

Dart-throwing motion from radial dorsiflexion to palmar flexion has recently attracted attention as a functional movement direction of the wrist joint. We developed a novel artificial muscle-type dynamic traction orthosis (DTSaM) that includes these movements. This prospective crossover controlled study aimed to compare the traction effects in the presence and absence of DTSaM using computed tomography.

METHODS

Healthy participants with no history of finger disease (6 men: 6 fingers, 4 women: 4 fingers; average age [range]: 29.4 [34-24] years) were examined. The distance and area of the joint space between the radiolunate (RL) and capitolunate (CL) joints were evaluated using 2 types of computed tomography: automatic movement and DTSaM.

RESULTS

Participants with DTSaM showed more dilated joint space distance on the dorsal and central sides (p < 0.05) and larger joint space areas on the dorsal side (p < 0.05) of the RL and CL joints than those without orthosis. Significant differences in the magnitude of change in each joint were observed between the RL and CL joints regarding the joint space distance on the dorsal (p = 0.021) and central (p = 0.038) sides and the joint space area on the dorsal side (p = 0.044).

CONCLUSIONS

The movement of the CL joint is important in the dorsiflexion direction. Our results suggest that the dilated CL joint allows dorsiflexion and that combined traction and dart-throwing motion exercises may be possible for wrist joint contracture.

Wrist Arthritis and Arthrodesis: Preserving Function, Minimizing Problems

Wrist arthritis is a common condition with numerous causes and presentations. Several management options exist, and treatment should be individualized based on patient age, comorbidities, occupation, duration of symptoms, and failed treatment modalities. Arthroscopy and denervation are appealing because of shorter recovery time and preservation of motion, but duration of effectiveness varies between patients. Patients who fail these smaller procedures or those with pancarpal arthrosis are treated effectively with total wrist arthrodesis or total wrist arthroplasty in lower-demand patients. This article reviews causes and patterns of wrist arthritis and discusses treatment strategies aimed at preserving function and minimizing complications.

Dynamic three-dimensional computed tomographic imaging facilitates evaluation of the equine cervical articular process joint in motion

BACKGROUND

Dynamic computed tomography (CT) imaging has been introduced in human orthopaedics and is continuing to gain popularity. With dynamic CT, video sequences of anatomical structures can be evaluated in motion.

OBJECTIVES

To investigate the feasibility of dynamic CT for diagnostic imaging of the equine cervical articular process joints (APJs) and to give a detailed description of the APJ movement pattern.

STUDY DESIGN

Descriptive cadaver imaging.

METHODS

Cervical specimens of twelve Warmblood horses were included. A custom-made motorised testing device was used to position and manipulate the neck specimens and perform dynamic 2D and 3D CT imaging. Images were obtained with a 320-detector-row CT scanner with a 160 mm wide-area (2D) solid-state detector design that allows image acquisition of a volumetric axial length of 160 mm without moving the CT couch. Dynamic videos were acquired and divided into four phases of movement. Three blinded observers used a subjective scale of 1 (excellent) to 4 (poor) to grade the overall image quality in each phases of motion cycle.

RESULTS

With an overall median score of 1 the image quality, a significantly lower score was observed in the dynamic 3D videos over the four phases by the three observers compared with the 2D videos for both flexion (3D 95% CI: 1-2 and 2D 95% CI: 1-3; P = .007) and extension movement (3D 95% CI: 1-2 and 2D 95% CI: 1-3; P = .008). Median Translational displacement of the APJ surface was significantly greater in flexion than in extension movement (P = .002).

MAIN LIMITATIONS

The small number of specimens included. Excision of spines and removal of musculature.

CONCLUSIONS

The study is a first step in the investigation of the potential of dynamic 3D CT in veterinary medicine, a technique that has only begun to be explored and leaves much room for refinement prior to its introduction in routine practice. CT with a detector coverage of 16 cm and a rotation speed of 0.32 seconds provides high-quality images of moving objects and gives new insight into the movement pattern of equine cervical APJs.

Radiographic Evaluation of Carpal Mechanics and the Scapholunate Angle in a Clenched Fist with Dynamic Computed Tomography Imaging

Purpose

The long-term consequences of injuries to the scapholunate joint can severely limit hand function, and the potential for posttraumatic deformity makes early recognition of these injuries important. The purpose of this study was to evaluate the motion of the scapholunate joint in normal wrists through the radial and ulnar deviation using novel dynamic computed tomography (CT) imaging.

Methods

Fifteen participants consented to have their uninjured wrists scanned. A protocol was designed to ensure adequate time, yet limited exposure, for volunteers. Participants began with the hand in a relaxed fist position and then proceeded to clench the hand in a full fist and relax. Once relaxed again, the wrist was maximally ulnarly deviated and then maximally radially deviated in a fluid motion. Dynamic CT imaging was captured throughout the range of motion.

Results

The scapholunate angle was measured on dynamic wrist images. The mean range of the scapholunate angle that the wrists moved through was 37.2°-45.9°, and the mean midpoint angle was 41.2° ± 0.4°. All wrists had small, measurable differences in the scapholunate angle when moving from the maximum ulnar deviation to the maximal radial deviation. The average maximum angle change through the range is 11.7°, whereas the average minimum angle change was 0.9°.

Conclusions

In this study, scapholunate angle calculations using dynamic wrist CT scans were within the range of accepted normal for the angle in uninjured wrists. With the increased focus on dynamic imaging for wrist motion, it may be possible to derive a standardized protocol for mapping the carpal motion that is clinically applicable and reproducible.

Type of study/level of evidence

Diagnostic IV.

Twenty-four-channel high-impedance glove array for hand and wrist MRI at 3T

PURPOSE

To present a novel 3T 24-channel glove array that enables hand and wrist imaging in varying postures.

METHODS

The glove array consists of an inner glove holding the electronics and an outer glove protecting the components. The inner glove consists of four main structures: palm, fingers, wrist, and a flap that rolls over on top. Each structure was constructed out of three layers: a layer of electrostatic discharge flame-resistant fabric, a layer of scuba neoprene, and a layer of mesh fabric. Lightweight and flexible high impedance coil (HIC) elements were inserted into dedicated tubes sewn into the fabric. Coil elements were deliberately shortened to minimize the matching interface. Siemens Tim 4G technology was used to connect all 24 HIC elements to the scanner with only one plug.

RESULTS

The 24-channel glove array allows large motion of both wrist and hand while maintaining the SNR needed for high-resolution imaging.

CONCLUSION

In this work, a purpose-built 3T glove array that embeds 24 HIC elements is demonstrated for both hand and wrist imaging. The 24-channel glove array allows a great range of motion of both the wrist and hand while maintaining a high SNR and providing good theoretical acceleration performance, thus enabling hand and wrist imaging at different postures to extract kinematic information.

Four-dimensional computed tomography evaluation of shoulder joint motion in collegiate baseball pitchers

The purpose of this study is to evaluate the glenohumeral contact area, center of glenohumeral contact area, and center of humeral head during simulated pitching motion in collegiate baseball pitchers using four-dimensional computed tomography (4D CT). We obtained 4D CT data from the dominant and non-dominant shoulders of eight collegiate baseball pitchers during the cocking motion. CT image data of each joint were reconstructed using a 3D reconstruction software package. The glenohumeral contact area, center of glenohumeral contact area, center of humeral head, and oblateness of humeral head were calculated from 3D bone models using customized software. The center of glenohumeral contact area translated from anterior to posterior during maximum external rotation to maximum internal rotation (0.58 ± 0.63 mm on the dominant side and 0.99 ± 0.82 mm on the non-dominant side). The center of humeral head translated from posterior to anterior during maximum external rotation to maximum internal rotation (0.76 ± 0.75 mm on the dominant side and 1.21 ± 0.78 mm on the non-dominant side). The increase in anterior translation of the center of glenohumeral contact area was associated with the increase in posterior translation of the center of humeral head. Also, the increase in translation of the center of humeral head and glenohumeral contact area were associated with the increase in oblateness of the humeral head. 4D CT analyses demonstrated that the center of humeral head translated in the opposite direction to that of the center of glenohumeral contact area during external rotation to internal rotation in abduction in the dominant and non-dominant shoulders. The oblateness of the humeral head may cause this diametric translation. 4D CT scanning and the software for bone surface modeling of the glenohumeral joint enabled quantitative assessment of glenohumeral micromotion and be used for kinematic evaluation of throwing athletes.

Home exercise in the dart-throwing motion plane after distal radius fractures: A pilot randomized controlled trial

INTRODUCTION

During daily functions, our wrist moves through an oblique plane, named the dart-throwing motion (DTM) plane. This plane is considered a more stable plane because the proximal carpal row remains relatively immobile. However, rehabilitation programs that incorporate exercising in the DTM plane have yet to be explored.

PURPOSE OF THE STUDY

The purpose of this study was to evaluate the rehabilitation outcomes after treatment in the DTM plane compared with outcomes after treatment in the sagittal plane after distal radius fracture.

STUDY DESIGN

This is a pilot randomized controlled trial.

METHODS

Subjects after open reduction internal fixation were assigned into a research group (N = 12; ages 48.7 ± 7.3) and a control group (N = 12; ages 50.8 ± 15). The control group activated the wrist in the sagittal plane, whereas the research group activated the wrist in the DTM plane. Range of motion, pain levels, functional hand motor skills tests, and satisfaction from self-training exercise were measured before and after a 12-session intervention.

RESULTS

The outcome measures were similar between the treatment groups. The research group reported significantly higher satisfaction rates than the control group on topics such as general satisfaction (research group: 3.4 ± 0.7, control group: 2. 5 ± 1.2, P = .030), motivation to exert oneself (research group: 2.8 ± 1.0, control group: 2.3 ± 1.2, P = .009), progressed function (research group: 3.4 ± 0.7, control group: 2.4 ± 1.1, P = .012), and self-training contribution to the daily function (research group: 3.4 ± 0.7, control group: 2.5 ± 1.2, P = .030).

DISCUSSION AND CONCLUSION

Pilot results do not favor one treatment method over the other. However, exercising in the DTM plane may contribute to the satisfaction of the client and increase self-training motivation.

Four-dimensional CT analysis of carpal kinematics: An explorative study on the effect of sex and hand-dominance

Wrist pathology is often diagnosed by using the contralateral wrist as a comparison of baseline motion and strength. However, recent range of motion studies suggest that females have different carpal motion patterns compared to males and that the dominant carpal bones have different motion patterns. The purpose of this study is to evaluate the effect of sex and hand dominance on in vivo kinematics of the scaphoid, lunate and capitate using four-dimensional computed tomography (4D-CT) analysis in healthy uninjured volunteers. In this prospective study, both wrist of 20 uninjured Caucasian volunteers (11 men and 9 women) were assessed using 4D-CT during active flexion-extension and radial-ulnar deviation. A linear mixed model was used to compare the carpal motion patterns. Sex had no influence on carpal kinematics. Hand-dominance in males did have a significant effect on carpal kinematics. During flexion-extension of the male wrist, more radial-ulnar deviation of the lunate, scaphoid and capitate of the non-dominant hand was seen. During radial-ulnar deviation of the male wrist, radial-ulnar deviation and pro-supination of the lunate was more in the dominant hand. This study provides a better understanding of carpal kinematics and the effect of sex and hand-dominance on the scaphoid, lunate and capitate in uninjured wrists.

Analysis of a New Artificial Muscle Type Dynamic Orthosis for Wrist Joint Disease Using a Three-dimensional Motion Analyzer

Objectives:

Recently, the dart-throwing motion (DTM) has attracted attention as a functional direction of wrist joint motion. Consequently, we devised a new artificial muscle-type dynamic orthosis (Dynamic Traction Splint by Artificial Muscle, DTSaM) to reproduce DTM. This study analyzed the automatic motion of the wrist joint using a three-dimensional motion analysis system to assess how closely the DTSaM replicates DTM.

Methods:

The DTSaM orthosis incorporates two McKibben-type rubber artificial muscles, and measurements were performed using image analysis software and a three-dimensional motion analysis system. The wrist radial angle (WRA) was defined as the angle between the line connecting the head of the index finger metacarpal to the radial styloid process and the line connecting the radial styloid process to the lateral epicondyle of the humerus. WRAs were investigated from 60° of palmar flexion to 60° of dorsiflexion.

Results:

For dorsiflexion, comparisons of radial deviation and wrist ulnar angle (WUA) between the motion obtained using the DTSaM orthosis and active DTM showed a significant difference (P <0.05) at 30° and 60°, respectively. For palmar flexion, the same comparison showed a significant difference for both the ulnar and radial deviations (30°, P <0.05; and 60°, P <0.01, respectively). Furthermore, WUA showed a significant difference at 50° (P <0.05). Intraclass correlation coefficient analyses yielded good reliability with an average value of ≥0.8.

Conclusion:

The DTSaM orthosis produces a motion similar to the DTM. It is hoped that the use of the DTSaM orthosis will help to shorten the treatment period for patients with wrist disease.

Evaluation of Four-Dimensional Computed Tomography as a Technique for Quantifying Carpal Motion

Delayed diagnosis of dynamic carpal instability often occurs because early changes in bone alignment and movement are difficult to detect and manifest mainly during a dynamic/functional task. Current diagnostic tools are only able to examine the carpal bones under static or sequential-static conditions. Four-dimensional (three dimensions + time) computed tomography (4DCT) enables quantification of carpal mechanics through 3D volume sequences of the wrist in motion. A comprehensive understanding of carpal mechanics is needed to define normal function and structure and provide targets for treatment of carpal injuries. In this study, measurements of scaphoid translation and joint congruency were taken by creating models from the CT scans of the carpals in extreme frames of motion, registering those models to the neutral position, transforming the models into a local coordinate system, and using software to calculate the joint surface areas (JSA). Results indicated that the centroid of the scaphoid translated 6.4 ± 1.3 mm and extended from extreme radial to extreme ulnar deviation. Results are consistent with the literature. An additional study was performed to measure the responsiveness of the 4DCT technique presented. Bone models from each frame of motion for radio ulnar deviation (RUD) and flexion extension (FE) were created and distinct differences between their JSA were measured qualitatively and quantitatively. The results show that there was statistically significantly different JSA within carpal joints between RUD and FE. These studies provide the first step in developing the methodology when using 4DCT scanning to measure subtle abnormalities in the wrist.

A Reference Range of Dart-Thrower's Motion at the Wrist in a Healthy Adult Population

PURPOSE

Dart-thrower's motion (DTM) is a functional wrist movement from maximum radial extension to maximum ulnar flexion. This study defines a reference range of DTM in a healthy population.

METHODS

Goniometric measurements were collected from both wrists of 200 healthy volunteers. Mean age was 21.1 years (range, 18-25 years), 126 volunteers (63%) were female, and 177 (89%) were right-handed. Volunteers also reported perceived difficulty of performing DTM.

RESULTS

For male subjects, the mean arc of motion was 126° (range, 83°-166°) for dominant and 114° (range, 62°-148°) for nondominant wrists. For female subjects, the mean values were 129° (range, 79°-170°) and 126° (range, 70°-167°), respectively. On multiple regression analysis, female subjects had a significantly increased range of dominant and nondominant arc of motion compared with males. Older subjects had significantly increased dominant but reduced nondominant arc of motion. High inter- and intrarater reliability was observed for goniometric measurement of DTM (intraclass correlation coefficients, 0.93-0.98).

CONCLUSIONS

This study quantified a reference range of DTM in normal individuals.

CLINICAL RELEVANCE

This study provides a reference range for DTM in a young adult population, which may aid clinical comparison of measurements of wrist movement and evaluation of conditions and treatments that impact DTM.

The forearm and hand musculature of semi-terrestrial rhesus macaques (Macaca mulatta) and arboreal gibbons (fam.Hylobatidae). Part II. Quantitative analysis

Nonhuman primates have a highly diverse locomotor repertoire defined by an equally diverse hand use. Based on how primates use their hands during locomotion, we can distinguish between terrestrial and arboreal taxa. The 'arboreal' hand is likely adapted towards high wrist mobility and grasping, whereas the 'terrestrial' hand will show adaptations to loading. While the morphology of the forearm and hand bones have been studied extensively, functional adaptations in the forearm and hand musculature to locomotor behaviour have been documented only scarcely. In this paper, we investigate the forelimb musculature of the highly arboreal gibbons (including Hylobates lar,Hylobates pileatus,Nomascus leucogenys,Nomascus concolor and Symphalangus syndactylus) and compare this with the musculature of the semi-terrestrial rhesus macaques (Macaca mulatta). Anatomical data from previous dissections on knuckle-walking bonobos (Pan paniscus) and bipedal humans (Homo sapiens) are also included to further integrate the analyses in the scope of catarrhine hand adaptation. This study indicates that the overall configuration of the arm and hand musculature of these primates is very similar but there are some apparent differences in relative size which can be linked to differences in forelimb function and which might be related to their specific locomotor behaviour. In macaques, there is a large development of wrist deviators, wrist and digital flexors, and m. triceps brachii, as these muscles are important during the different phases of palmi- and digitigrade quadrupedal walking to stabilize the wrist and elbow. In addition, their m. flexor carpi ulnaris is the most important contributor to the total force-generating capacity of the wrist flexors and deviators, and is needed to counteract the adducting torque at the elbow joint during quadrupedal walking. Gibbons show a relatively high force-generating capacity in their forearm rotators, wrist and digital flexors, which are important muscles in brachiation to actively regulate forward movement of the body. The results also stress the importance of the digital flexors in bonobos, during climbing and clambering, and in humans, which is likely linked to our advanced manipulation skills.

Effects of axial load on in vivo scaphoid and lunate kinematics using four-dimensional computed tomography

This in vivo study investigated the effect of axial load on lunate and scaphoid kinematics during flexion-extension and radial-ulnar deviation of the uninjured wrist using four-dimensional computed tomography. We found that applying axial load to the wrist results in a more flexed, radially deviated and pronated position of the lunate and scaphoid during flexion-extension of the wrist compared with when no load is applied. A larger pronation and supination range of the lunate and scaphoid was seen when the wrist was flexed and extended under axial load, whereas a larger flexion and extension range of the lunate and scaphoid occurred during radial-ulnar deviation of the wrist when axial load was applied.

Functional Dart-Throwing Motion: A Clinical Comparison of Four-Corner Fusion to Radioscapholunate Fusion Using Inertial Motion Capture

Background  Dart-throwing motion (DTM) is an important functional arc of the wrist from radial extension to ulna flexion. An aim of partial fusion surgery of the wrist is to maintain maximal functional motion while addressing the pathology. The radioscapholunate (RSL) fusion, accompanied with partial resection of the distal scaphoid, is thought to allow better DTM than other partial wrist fusions such as the four-corner fusion (4CF). Question  Does an RSL fusion allow better functional DTM than 4CF, and how does this range compare with healthy wrists and the patient's contralateral wrist? Patients and Methods  Patients who have undergone an RSL fusion or 4CF at our tertiary center were identified and invited to present to have their DTM arc measured. To accurately measure DTM, a previously validated inertial measurement device was used. Patient's functional DTM arc was measured in both unrestrained (elbow and shoulder free to move) and restrained (elbow and shoulder immobilized) fashions. This was compared with their contralateral wrist and a group of healthy control volunteers. Results  Overall five RSL fusions, 10 4CF and 24 control patients were enrolled in the study. There was no significant difference between functional DTM when 4CF and RSL fusion were compared. Both had significantly reduced functional DTM arc than control patients. There was no significant difference between the operated wrist compared with the patient's contralateral unoperated wrist. Conclusion  RSL fusion is not significantly better at maintaining functional DTM when compared with 4CF. Both surgeries result in decreased functional DTM arc when compared with control patients. This is a cohort study and reflects a level of evidence IV. Level of Evidence  This is a Leve IV, cohort study.

The use of 4D-CT in assessing wrist kinematics and pathology

The wrist is a complex joint involving many small bones and complicated kinematics. It has, therefore, been traditionally difficult to image and ascertain information about kinematics when making a diagnosis. Although MRI and fluoroscopy have been used, they both have limitations. Recently, there has been interest in the use of 4D-CT in imaging the wrist. This review examines the literature regarding the use of 4D-CT in imaging the wrist to assess kinematics and its ability to diagnose pathology. Some questions remain about the description of normal ranges, the most appropriate method of measuring intercarpal stability, the accuracy compared with established standards, and the place of 4D-CT in postoperative assessment.

Cite this article: Bone Joint J 2019;101-B:1325–1330.

Does Object Height Affect the Dart Throwing Motion Angle during Seated Activities of Daily Living?

Complex wrist motions are needed to complete various daily activities. Analyzing the multidimensional motion of the wrist is crucial for understanding our functional movement. Several studies have shown that numerous activities of daily livings (ADLs) are performed using an oblique plane of wrist motion from radial-extension to ulnar-flexion, named the Dart Throwing Motion (DTM) plane. To the best of our knowledge, the DTM plane angle performed during ADLs has not been compared between different heights (e.g. table, shoulder and head height), as is common when performing day-to-day tasks. In this study, we compared DTM plane angles when performing different ADLs at three different heights and examined the relationship between DTM plane angles and limb position. We found that height had a significant effect on the DTM plane angles - the mean DTM plane angle was greater at the lower level compared to the mid and higher levels. A significant effect of shoulder orientation on mean DTM plane angles was shown in the sagittal and coronal planes. Our findings support the importance of training daily tasks at different heights during rehabilitation following wrist injuries, in order to explore a large range of DTM angles, to accommodate needs of common ADLs.

Dynamic CT Scan of the Normal Scapholunate Joint in a Clenched Fist and Radial and Ulnar Deviation

BACKGROUND

Injuries to the scapholunate can have severe long-term effects on the wrist. Early detection of these injuries can help identify pathology. The purpose of this study was to evaluate the motions of the scapholunate joint in normal wrists in a clenched fist and through radial and ulnar deviation using novel dynamic computed tomography (CT) imaging.

METHODS

Fifteen participants below 40 years of age consented to have their wrist scanned. Eight participants were randomized to have the right wrist scanned and 7 the left wrist. Volunteers were positioned at the back of the gantry with the wrist placed on the table, palmar side down. Participants began with the hand in a relaxed fist position and then proceeded through an established range of motion protocol. Dynamic CT imaging was captured throughout the range of motion.

RESULTS

The movement in the healthy scapholunate joint through a clenched fist and radial and ulnar deviation is minimal. The averages were 1.19, 1.01, and 0.95 mm, representing the middle, dorsal, and volar measurements, respectively.

CONCLUSIONS

This novel dynamic CT scan of the wrist is a user-friendly way of measuring of the scapholunate distance, which is minimal in the normal wrist below 40 years of age.

Clinical measurement of the dart throwing motion of the wrist: variability, accuracy and correction

Despite being functionally important, the dart throwing motion is difficult to assess accurately through goniometry. The objectives of this study were to describe a method for reliably quantifying the dart throwing motion using goniometric measurements within a healthy population. Wrist kinematics of 24 healthy participants were assessed using goniometry and optical motion tracking. Three wrist angles were measured at the starting and ending points of the motion: flexion-extension, radial-ulnar deviation and dart throwing motion angle. The orientation of the dart throwing motion plane relative to the flexion-extension axis ranged between 28° and 57° among the tested population. Plane orientations derived from optical motion capture differed from those calculated through goniometry by 25°. An equation to correct the estimation of the plane from goniometry measurements was derived. This was applied and differences in the orientation of the plane were reduced to non-significant levels, enabling the dart throwing motion to be measured using goniometry alone.

Trabecular bone patterning across the human hand

Hand bone morphology is regularly used to link particular hominin species with behaviors relevant to cognitive/technological progress. Debates about the functional significance of differing hominin hand bone morphologies tend to rely on establishing phylogenetic relationships and/or inferring behavior from epigenetic variation arising from mechanical loading and adaptive bone modeling. Most research focuses on variation in cortical bone structure, but additional information about hand function may be provided through the analysis of internal trabecular structure. While primate hand bone trabecular structure is known to vary in ways that are consistent with expected joint loading differences during manipulation and locomotion, no study exists that has documented this variation across the numerous bones of the hand. We quantify the trabecular structure in 22 bones of the human hand (early/extant modern Homo sapiens) and compare structural variation between two groups associated with post-agricultural/industrial (post-Neolithic) and foraging/hunter-gatherer (forager) subsistence strategies. We (1) establish trabecular bone volume fraction (BV/TV), modulus (E), degree of anisotropy (DA), mean trabecular thickness (Tb.Th) and spacing (Tb.Sp); (2) visualize the average distribution of site-specific BV/TV for each bone; and (3) examine if the variation in trabecular structure is consistent with expected joint loading differences among the regions of the hand and between the groups. Results indicate similar distributions of trabecular bone in both groups, with those of the forager sample presenting higher BV/TV, E, and lower DA, suggesting greater and more variable loading during manipulation. We find indications of higher loading along the ulnar side of the forager sample hand, with high site-specific BV/TV distributions among the carpals that are suggestive of high loading while the wrist moves through the 'dart-thrower's' motion. These results support the use of trabecular structure to infer behavior and have direct implications for refining our understanding of human hand evolution and fossil hominin hand use.

Psychometric properties of the goniometric assessment of the Dart Thrower’s Motion

Introduction

The Dart Thrower’s Motion is an important movement for hand function. A goniometric clinical measure of Dart Thrower’s Motion has been developed. However, its validity and reliability in people with wrist and hand injury is not known. This study investigated the inter-rater and test–retest reliability and criterion validity of the Dart Thrower’s Motion measure.

Methods

A cross-sectional design was used. Thirty-five participants with hand or wrist injury completed the goniometric assessment of the Dart Thrower’s Motion and goniometric wrist active range of motion assessment three times in a hand clinic. Two assessors and a reader to record the results were involved. Participants also completed the patient-rated wrist and hand evaluation.

Results

The intraclass correlation coefficients were 0.70–0.83 and 0.91–0.92, respectively for inter-rater and test–retest reliability in the injured hands indicating moderate to high reliability. The Pearson correlation coefficients between the Dart Thrower’s Motion measure and wrist active range of motion assessment ranged from 0.45 to 0.73, and with patient-rated wrist and hand evaluation ranged from −0.36 to −0.53. The results indicate that goniometric assessment of the Dart Thrower’s Motion has acceptable criterion validity.

Conclusion

The goniometric assessment of Dart Thrower’s Motion can be considered a valid and reliable clinical measure for measuring the impact of the injury to one’s hand and wrist range of motion and function. It shows its clinical utility in people with hand and wrist injury. It is hoped this simple measure can be eventually implemented in clinical settings, allowing for an increased understanding of an individual’s functional use of the hand and wrist.

Rehabilitation for scapholunate injury: Application of scientific and clinical evidence to practice

In this article, the development of a rehabilitation approach is describe using scapholunate injury as a model. We demonstrate how scientific and clinical evidence is applied to a treatment paradigm and modified based on emerging evidence. Role of the scapholunate interosseous ligament within the pathomechanics of the carpus, along with the progression of pathology, and specific rehabilitation algorithms tailored to the stage of injury. We review the recent and current evidence on the kinematics of wrist motion during functional activity, role of the muscles in providing dynamic stability of the carpus, and basic science of proprioception. Key relevant findings in each of these inter-related areas are highlighted to demonstrate how together they form the basis for current wrist rehabilitation. Finally, we make recommendations for future research to further test the efficacy of these approaches in improving functional outcomes.

Early controlled mobilization using dart-throwing motion with a twist for the conservative management of an intra-articular distal radius fracture and scapholunate ligament injury: A case report

This case describes an early controlled mobilization (ECM) approach that uses dart-throwing motion (DTM) with a twist orthoses as an alternative to immobilization for conservative management of a minimally displaced and intra-articular distal radius styloid fracture with an associated scapholunate ligament injury in a 47-year-old female health care administrator (JP). Pain-free active DTM began at day 10 (5 times/d) with a dynamic DTM with a twist orthosis worn during the day from weeks 3 to 6. At 6 weeks, JP had pain-free functional mobility and strength with minimal limitation in household and occupational activities, returning to her normal sporting activities by 3 months. ECM led to rapid return of normal functioning in the short term with no apparent impact on intermediate outcomes at 8 months. This case allows hand therapists to consider a similar ECM approach for the management of similar injuries in their patients.

LEVEL OF EVIDENCE

Level 5 and case report.

The Role of Dynamic (4D) CT in the Detection of Scapholunate Ligament Injury

Background Scapholunate (SL) interosseus ligament injuries detected at an early stage could allow the surgeon to prevent progression through the spectrum of injury that leads to instability, and eventually osteoarthritis. We contend that early instability following injury can be detected by visualizing the relative motions and distances between the involved carpal bones (scaphoid and lunate) during wrist movement in vivo. The purpose of this study is to demonstrate the utility of dynamic CT (i.e., 4DCT) in diagnosing SL interosseus ligament injuries in two patients with clinical suspicion of SL interosseus ligament injury during flexion-extension (FE), radial-ulnar (RU) deviation, and dart thrower's (DT) motions. Case Description 4DCT images obtained from two individual cases were analyzed to assess the proximity between the scaphoid and lunate during wrist motion using standard image processing techniques. Proximity maps representing the distances between the scaphoid and lunate bones during each phase of wrist motion were determined. These maps provide insight into the severity of diastasis (large separation) and location of diastasis at the SL joint. The patients' proximity maps indicated dorsal diastasis and subtle uniform diastasis. Literature Review Complex musculoskeletal abnormalities, such as wrist joint instabilities, elude diagnosis during 2D fluoroscopy due to the 3D geometry of the anatomy and the inherent 3D nature of the bony kinematics. Even the most recent advances with MR arthrography lack good correlation with wrist arthroscopy. Wrist arthroscopy remains the gold standard for diagnosis to assess for intercarpal laxity. However, arthroscopy is an invasive procedure subjecting patients to the risk of infection, nerve injury, pain, and stiffness. Clinical Relevance 4DCT allows noninvasive characterization of where ligament injuries likely occur; this may allow for a more selective surgical treatment directed at the specific location of the tear.

Carpal Kinematics and Kinetics

The complex interaction of the carpal bones, their intrinsic and extrinsic ligaments, and the forces in the normal wrist continue to be studied. Factors that influence kinematics, such as carpal bone morphology and clinical laxity, continue to be identified. As imaging technology improves, so does our ability to better understand and identify these factors. In this review, we describe advances in our understanding of carpal kinematics and kinetics. We use scapholunate ligament tears as an example of the disconnect that exists between our knowledge of carpal instability and limitations in current reconstruction techniques.

Evidence-based recommendations for musculoskeletal kinematic 4D-CT studies using wide area-detector scanners: a phantom study with cadaveric correlation

PROPOSE

To establish evidence-based recommendations for musculoskeletal kinematic 4D-CT on wide area-detector CT.

MATERIALS AND METHODS

In order to assess factors influencing image quality in kinematic CT studies, a phantom consisting of a polymethylmethacrylate rotating disk with round wells of different sizes was imaged with various acquisition protocols. Cadaveric acquisitions were performed on the ankle joint during motion in two different axes and at different speeds to allow validation of phantom data. Images were acquired with a 320 detector-row CT scanner and were evaluated by two readers.

RESULTS

Motion artefacts were significantly correlated with various parameters (movement axis, distance to centre, rotation speed and volume acquisition speed) (p < 0.0001). The relation between motion artefacts and distance to motion fulcrum was exponential (R² 0.99). Half reconstruction led to a 23 % increase in image noise and a 40 % decrease in motion artefacts. Cadaveric acquisitions confirmed phantom data. Based on these findings, high tube rotation speed and half reconstruction are recommended for kinematic CT. The axis of motion significantly influences image artefacts and should be considered in patient training and evaluation of acquisition protocol suitability.

CONCLUSION

This study provides evidence-based recommendations for musculoskeletal kinematic 4D-CT.

KEY POINTS

• Motion artefacts can hamper the quality and interpretation of dynamic joint studies • The recommendations presented here help increase image quality • Patient training and preparation can be improved • The artefact-free distance concept helps protocol adaptation and comparison.

A study to investigate the intra-rater and inter-rater reliability of goniometric measurements of dart throwers motion of asymptomatic wrists

Introduction

This study investigated the intra-rater and inter-rater reliability of measuring dart throwers motion of asymptomatic wrists with a handheld manual goniometer typical of that used in the clinical setting.

Method

Working in pairs, each rater took three repeated measures of radial extension and of ulnar flexion of both wrists using a goniometer positioned on the radiodorsal aspect of the radius proximally and the second metacarpal distally. Both raters and subjects were blinded, and measurements were read by an independent observer. Subjects were of varied age, gender and with no history of wrist pathology. Subjects rated how difficult they found the dart throwers motion to perform using a 5-point Likert scale.

Results

Measurements were collected from both wrists of 37 subjects (74 wrists). The intraclass correlation coefficient for intra-rater measurements of radial extension was 0.89 (95% CI 0.86–0.92) and for ulnar flexion was 0.92 (95% CI 0.90–0.94). Standard deviation for radial extension was 4.2° and for ulnar flexion 3.6°. The intraclass correlation coefficient for inter-rater measurements of radial extension was 0.83 (95% CI 0.74–0.89) and for ulnar flexion was 0.81 (95% CI 0.72–0.88). Subjects rated the movement more difficult to perform with the non-dominant side (P=0.006), and standard deviation was greater when the subject found dart throwers motion difficult to perform. No significant associations were found (P<0.05) to suggest that reliability is influenced by hand dominance, gender, age, level of perceived difficulty or data collection site.

Discussion

Our study confirms good reliability when using this method to measure dart throwers motion. It is suggested that dart throwers motion can be measured to compare different subjects and monitor change; however, studies need to be undertaken with a symptomatic population.

Functional kinematics of the wrist

The purpose of this article is to review past and present concepts concerning functional kinematics of the healthy and injured wrist. To provide a context for students of the wrist, we describe the progression of techniques for measuring carpal kinematics over the past century and discuss how this has influenced today's understanding of functional kinematics. Next, we provide an overview of recent developments and highlight the clinical relevance of these findings. We use these findings and recent evidence that supports the importance of coupled motion in early rehabilitation of radiocarpal injuries to develop the argument that coupled motion during functional activities is a clinically relevant outcome; therefore, clinicians should develop a framework for its dynamic assessment. This should enable a tailored and individualized approach to the treatment of carpal injuries.

In Vivo Contact Characteristics of Distal Radioulnar Joint With Malunited Distal Radius During Wrist Motion

PURPOSE

To determine whether distal radioulnar joint (DRUJ) contact characteristics were altered in patients with malunited distal radius fractures.

METHODS

We obtained computed tomography scans at 5 positions of both wrists of 6 patients who had unilateral malunited distal radius fractures with dorsal angulation from 10° to 20° and ulnar variance less than 3 mm. We reconstructed 3-dimensional images and mapped contact regions of DRUJ by calculating the shortest distance between the 2 opposing bones. The contact areas of the DRUJ were measured and the contact region centers were calculated and analyzed. The values of the malunited side were compared with those of the contralateral uninjured side.

RESULTS

In the uninjured wrist, the contact areas of the DRUJ increased slightly from wrist flexion to extension and ulnar deviation. In the malunited wrist, we found the contact areas of DRUJ to be progressively reduced from 20° flexion to neutral, 40° extension, and 20° extension, to ulnar deviation. The centroid of this area on the sigmoid notch moved to distal from flexion to extension. Compared with the contralateral uninjured wrist, the contact area significantly decreased during wrist extension and ulnar deviation, and significantly increased during wrist flexion. The centroids of this area on sigmoid notch all moved volarly in all selected wrist positions.

CONCLUSIONS

The contact areas of the DRUJ and the centroid of contact area on sigmoid notch are altered in patients with malunited distal radius fractures. The contact area of the DRUJ increases during wrist flexion and decreases during wrist extension and ulnar deviation. The centroids of the contact area on sigmoid notch move volarly during wrist flexion-extension and ulnar deviation.

CLINICAL RELEVANCE

The in vivo findings suggest that alterations in joint mechanics may have an important role in the dysfunction associated with these injuries.

The treatment of arthritis of the wrist

Arthritis of the wrist is a painful disabling condition that has various causes and presentations. The traditional treatment has been a total wrist fusion at a price of the elimination of movement. However, forms of treatment which allow the preservation of movement are now preferred. Modern arthroplasties of the wrist are still not sufficiently robust to meet the demands of many patients, nor do they restore normal kinematics of the wrist. A preferable compromise may be selective excision and partial fusion of the wrist using knowledge of the aetiology and pattern of degenerative change to identify which joints can be sacrificed and which can be preserved. This article provides an overview of the treatment options available for patients with arthritis of the wrist and an algorithm for selecting an appropriate surgical strategy.

A technique for quantifying wrist motion using four-dimensional computed tomography: approach and validation

Accurate quantification of subtle wrist motion changes resulting from ligament injuries is crucial for diagnosis and prescription of the most effective interventions for preventing progression to osteoarthritis. Current imaging techniques are unable to detect injuries reliably and are static in nature, thereby capturing bone position information rather than motion which is indicative of ligament injury. A recently developed technique, 4D (three dimensions + time) computed tomography (CT) enables three-dimensional volume sequences to be obtained during wrist motion. The next step in successful clinical implementation of the tool is quantification and validation of imaging biomarkers obtained from the four-dimensional computed tomography (4DCT) image sequences. Measures of bone motion and joint proximities are obtained by: segmenting bone volumes in each frame of the dynamic sequence, registering their positions relative to a known static posture, and generating surface polygonal meshes from which minimum distance (proximity) measures can be quantified. Method accuracy was assessed during in vitro simulated wrist movement by comparing a fiducial bead-based determination of bone orientation to a bone-based approach. The reported errors for the 4DCT technique were: 0.00-0.68 deg in rotation; 0.02-0.30 mm in translation. Results are on the order of the reported accuracy of other image-based kinematic techniques.