Dart-throwing Motion Research Articles

Treatment of radiocarpal degenerative osteoarthritis by radioscapholunate arthrodesis: Long-term follow-up

Radioscapholunate arthrodesis is the treatment of choice for symptomatic, degenerative radioscapholunate osteoarthritis. We report on three patients after radioscapholunate arthrodesis with a follow-up of 22–28 years. There were no short-term postoperative complications; range of motion and strength were stable. All three patients showed radiological evidence of progressive, but clinically asymptomatic midcarpal osteoarthritis. The conversion rate for radioscapholunate to panarthrodesis of the wrist is reported at 31% with follow-ups of more than five years, invariably due to either non-union, or progressive, symptomatic midcarpal osteoarthritis. Primary excision of the distal pole of the scaphoid during radioscapholunate arthrodesis probably plays an important role in avoiding these conditions in the long-term. This measure allows a residual range of motion more than previously believed; considering that the dart thrower's motion is the physiological axis of wrist motion.

3차원 영상을 이용한 다트 던지기 운동에서의 주상골, 유두골, 월상골의 움직임 분석

The primary purpose of this study was to analyze the motion of the scaphoid, capitate, and lunate during dart-throwing motion by three-dimensional modeling. Five series of CT images of five normal right wrists were acquired from five motion steps from radial extension to ulnar flexion in the dart-throwing motion plane. Segmentation and three-dimensional modeling of bones from CT images was performed using Analyze. Distances among centroids of the scaphoid, capitate and lunate and angles between principal axes of three carpal bones were calculated to analyze the motion by using MATLAB. As the wrist motion changed from radial extension to ulnar flexion, the distance between two adjacent bones decreased. The scaphoid and lunate rotated less than the capitates during dart-throwing motion. This study reports the Three-dimensional in vivo measurement of carpal motion using CT images.

In Vivo Length Changes of Carpal Ligaments of the Wrist During Dart-Throwing Motion

The dart-throwing motion is an important movement pattern during most wrist actions. The aim of this study was to investigate length changes in the wrist ligaments in different positions of the dart-throw motion in vivo. We obtained computed tomography scans of the wrists of 6 volunteers at 5 positions of the wrist during the dart-throw motion: 20° of radial deviation with 60° of extension; 10° of radial deviation with 30° of extension; the neutral position of the carpus; 20° of ulnar deviation with 30° of flexion; and 40° of ulnar deviation with 60° of flexion. We reconstructed the 3-dimensional carpal and distal radioulnar joint structures with customized software and computed changes in length of 8 palmar and dorsal wrist ligaments. From wrist radial deviation with extension to ulnar deviation with flexion, the radioscaphocapitate, long radiolunate, ulnocapitate, and ulnotriquetral ligaments decreased significantly in length but the dorsal radiocarpal ligament and the dorsal intercarpal (DIC) ligament inserting on the trapezoid lengthened significantly; the ulnolunate ligament and the DIC ligament inserting on the scaphoid were shortest in neutral position. At wrist radial extension, the radioscaphocapitate, long radiolunate, ulnocapitate, and ulnotriquetral ligaments are lengthened and under increased tension. At wrist ulnar flexion, the dorsal radiocarpal ligament and the DIC ligament inserting on the trapezoid are lengthened and under increased tension. The ulnolunate ligament and the DIC ligament inserting on the scaphoid are the shortest and under the least tension in neutral position. These findings will help us understand the biomechanics of the carpus during the dart-throwing motion.

Carpal and Forearm Kinematics During a Simulated Hammering Task

Hammering is a functional task in which the wrist generally follows a path of motion from a position of combined radial deviation and extension to combined ulnar deviation and flexion, colloquially referred to as a dart thrower's motion. The purpose of this study was to measure wrist and forearm motion and scaphoid and lunate kinematics during a simulated hammering task. We hypothesized that the wrist follows an oblique path from radial extension to ulnar flexion and that there would be minimal radiocarpal motion during the hammering task. Thirteen healthy volunteers consented to have their wrist and distal forearm imaged with computed tomography at 5 positions while performing a simulated hammering task. The kinematics of the carpus and distal radioulnar joint were calculated using established markerless bone registration methods. The path of wrist motion was described relative to the sagittal plane. Forearm rotation and radioscaphoid and radiolunate motion were computed as a function of wrist position. All volunteers performed the simulated hammering task using a path of wrist motion from radial extension to ulnar flexion that was oriented an average of 41 degrees +/- 3 degrees from the sagittal plane. These paths did not pass through the anatomic neutral wrist position; rather, they passed through a neutral hammering position, which was offset by 36 degrees +/- 8 degrees in extension. Rotations of the scaphoid and lunate were not minimal but averaged 40% and 41%, respectively, of total wrist motion. The range of forearm pronation-supination during the task averaged 12 degrees +/- 8 degrees . The simulated hammering task was performed using a wrist motion that followed a coupled path of motion, from extension and radial deviation to flexion and ulnar deviation. Scaphoid and lunate rotations were greatly reduced, but not minimized, compared with rotations during pure wrist flexion/extension. This is likely because an extended wrist position was maintained throughout the entire task studied.

Wrist Tendon Forces During Various Dynamic Wrist Motions

A common treatment of arthritis of the thumb carpometacarpal joint requires all or a portion of the flexor carpi radialis tendon (FCR) to be used as an interpositional graft. The purpose of this study was to examine the in vitro tendon forces in 6 wrist flexors and extensors to determine whether their force contribution changes during various dynamic wrist motions along with a specific application to the FCR. We tested 62 fresh-frozen cadaver wrists in a wrist joint motion simulator. During wrist flexion-extension, radioulnar deviation, dart throwing, and circumduction motions, the peak and average tendon forces were determined for the extensor carpi ulnaris, extensor carpi radialis brevis and longus, abductor pollicis longus, flexor carpi radialis, and flexor carpi ulnaris. During a dart-throwing motion, the mean and peak FCR forces were statistically less than during the other 3 motions. Conversely, the mean and peak flexor carpi ulnaris forces were statistically greater during the dart-throwing motion than during the other 3 motions. Patients who have undergone a surgical procedure in which all or a portion of the FCR has been harvested may experience a decrease in wrist strength with wrist motion, as the FCR tendon normally applies force during wrist motion. The motion least likely to be affected by such surgery is the dart-throwing motion when the force on the remaining FCR is minimized.

The Advantage of Throwing the First Stone: How Understanding the Evolutionary Demands of Homo sapiens Is Helping Us Understand Carpal Motion

Unlike any other diarthrodial joint in the human body, the "wrist joint" is composed of numerous articulations between eight carpal bones, the distal radius, the distal ulna, and five metacarpal bones. The carpal bones articulate with each other as well as with the distal radius, distal ulna, and the metacarpal bases. Multiple theories explaining intercarpal motion have been proposed; however, controversy exists concerning the degree and direction of motion of the individual carpal bones within the two carpal rows during different planes of motion. Recent investigations have suggested that traditional explanations of carpal bone motion may not entirely account for carpal motion in all planes. Better understanding of the complexities of carpal motion through the use of advanced imaging techniques and simultaneous appreciation of human anatomic and functional evolution have led to the hypothesis that the "dart thrower's motion" of the wrist is uniquely human. Carpal kinematic research and current developments in both orthopaedic surgery and anthropology underscore the importance of the dart thrower's motion in human functional activities and the clinical implications of these concepts for orthopaedic surgery and rehabilitation.

Three-Dimensional Kinematics of the Rheumatoid Wrist After Partial Arthrodesis

Partial arthrodesis of the wrist, such as radiolunate and radioscapholunate arthrodesis, is intuitively more appealing for the treatment of the rheumatoid wrist than total arthrodesis is because it preserves some motion. However, wrist kinematics after partial arthrodesis are incompletely understood. The purpose of the present study was to evaluate the kinematics of the radiocarpal and midcarpal joints of rheumatoid wrists with use of three-dimensional computed tomography before and after partial arthrodesis. We selected ten wrists that were affected by rheumatoid arthritis in which the radiolunate joint was severely damaged but the midcarpal joint congruities were relatively well preserved. Six radiolunate and four radioscapholunate arthrodeses were then performed, with preservation of the joint congruity between the scaphoid, lunate, and capitate. We acquired in vivo three-dimensional kinematic data during wrist flexion-extension preoperatively and postoperatively with use of computed tomography and a markerless bone-registration technique. Postoperative midcarpal joint congruity and range of motion were compared with preoperative values. The mean range of global wrist motion was 48 degrees +/- 21 degrees after radiolunate arthrodesis and 47 degrees +/- 14 degrees after radioscapholunate arthrodesis. Midcarpal joint congruities and motion between the scaphoid, lunate, and capitate were well preserved in all ten wrists. The postoperative range of capitate motion relative to the lunate was 109% of the preoperative value after radiolunate arthrodesis and 88% after radioscapholunate arthrodesis. The directions of capitate motion relative to the lunate after both types of partial arthrodesis were significantly more oblique than before the arthrodeses, changing from radiodorsal to ulnopalmar along the so-called dart-throwing motion plane (p < 0.05). The results of this kinematic analysis, which showed that midcarpal motion occurred in the dart-throwing motion plane, may support the use of radiolunate and radioscapholunate arthrodeses as an alternative to total wrist arthrodesis in patients with symptomatic rheumatoid arthritis of the wrist.

The Non-Dissociative Clunking Wrist: A Personal View

Clunking of the wrist is often the result of a combined radiocarpal and midcarpal ligament insufficiency, coupled with inadequate neuromuscular coordination. When symptomatic, these wrists may benefit from splinting, isometric exercising of specific muscles and advice on activity modification. Failing this, different surgical strategies have been proposed, depending on the location of dysfunction. When the clunking derives from an isolated injury of one joint, reconstruction of its inadequate ligaments may be an effective solution. However, soft tissue procedures tend to fail when clunking results from multilevel instability. In these cases, partial carpal arthrodesis is an alternative. Although effective in eliminating the clunking, midcarpal fusion is associated with alteration of the so-called "dart-throwing" motion, the most common rotation in daily activities, and hence is not recommended. Radiolunate fusion, by contrast, appears to be a less morbid alternative, with the benefit of eliminating the painful clunking while preserving a good range of dart-throwing motion.

Change in the Length of the Ulnocarpal Ligaments During Radiocarpal Motion: Possible Impact on Triangular Fibrocartilage Complex Foveal Tears

The fovea of the ulnar head is the primary attachment site for both the distal radioulnar and the ulnocarpal ligaments. Thus, both ligaments should be simultaneously affected by the traumatic avulsion of the triangular fibrocartilage complex from its ulnar attachment. Little attention, however, has been directed toward the role of the ulnocarpal ligaments in the mechanics of this type of injury. The purpose of this study was to investigate the changes in length of the ulnocarpal ligaments during various radiocarpal motions and to determine the type of radiocarpal motion that makes the ulnocarpal ligament taut and that could cause foveal avulsion if it were excessive. The 3-dimensional kinematics of the wrist joint were investigated noninvasively using a markerless bone registration technique in vivo. Magnetic resonance images of the wrists of 15 healthy volunteers were acquired in at least 5 positions during each wrist flexion-extension motion, radioulnar deviation, or the so called dart-throwing motion (radial extension-ulnar flexion motion). The 3-dimensional ligament paths of the ulnotriquetral, ulnolunate, ulnocapitate, and palmar radioulnar ligaments were modeled as the shortest paths between the fovea and the insertion point of each ligament. Changes in the 3-dimensional ligament length of each ligament between the neutral position and each wrist position were then calculated. The lengths of the ulnotriquetral and ulnocapitate ligaments increased the most on wrist radial extension, and the length of the ulnolunate ligament increased the most on wrist extension. The length of the palmar radioulnar ligament changed minimally during any motion. The ulnocarpal ligaments are likely to be stretched tensely in wrist radial extension and wrist extension. This study supports the hypothesis that one of the mechanisms responsible for a triangular fibrocartilage complex foveal tear is excessive traction of the ulnocarpal ligament caused by a fall on the outstretched hand.

Simulated Radioscapholunate Fusion Alters Carpal Kinematics While Preserving Dart-Thrower's Motion

Midcarpal degeneration is well documented after radioscapholunate fusion. This study tested the hypothesis that radioscapholunate fusion alters the kinematic behavior of the remaining lunotriquetral and midcarpal joints, with specific focus on the dart-thrower's motion. Simulated radioscapholunate fusions were performed on 6 cadaveric wrists in an anatomically neutral posture. Two 0.060-in. carbon fiber pins were placed from proximal to distal across the radiolunate and radioscaphoid joints, respectively. The wrists were passively positioned in a custom jig toward a full range of motion along the orthogonal axes as well as oblique motions, with additional intermediate positions along the dart-thrower's path. Using a computed tomography-based markerless bone registration technique, each carpal bone's three-dimensional rotation was defined as a function of wrist flexion/extension from the pinned neutral position. Kinematic data was analyzed against data collected on the same wrist prior to fixation using hierarchical linear regression analysis and paired Student's t-tests. After simulated fusion, wrist motion was restricted to an average flexion-extension arc of 48 degrees , reduced from 77 degrees , and radial-ulnar deviation arc of 19 degrees , reduced from 33 degrees . The remaining motion was maximally preserved along the dart-thrower's path from radial-extension toward ulnar-flexion. The simulated fusion significantly increased rotation through the scaphotrapezial joint, scaphocapitate joint, triquetrohamate joint, and lunotriquetral joint. For example, in the pinned wrist, the rotation of the hamate relative to the triquetrum increased 85%. Therefore, during every 10 degrees of total wrist motion, the hamate rotated an average of nearly 8 degrees relative to the triquetrum after pinning versus 4 degrees in the normal state. Simulated radioscapholunate fusion altered midcarpal and lunotriquetral kinematics. The increased rotations across these remaining joints provide one potential explanation for midcarpal degeneration after radioscapholunate fusion. Additionally, this fusion model confirms the dart-thrower's hypothesis, as wrist motion after simulated radioscapholunate fusion was primarily preserved from radial-extension toward ulnar-flexion.

The Dart-Throwing Motion of the Wrist: Is It Unique to Humans?

Kinematic analysis has shown a near-stationary proximal carpal row during the dart-thrower's motion, which is believed to provide a stable platform for the generation of force and accuracy during certain power and precision grip activities. This finding is consistent with evidence in the human hand of adaptations that enabled effective manipulation of stones, cylindric wood, and bone tools for throwing and clubbing. There are at least two possible explanations for the observed human proximal carpal row kinematics. One is that it is retained from a previous common ancestor with great apes and previously adapted to some form of foraging or locomotor behavior involving the hands, but was recruited for tool use after we diverged from the apes. The second is that it evolved after our divergence from apes, in synchrony with adaptations in the human hand to the manipulation of tools, and central to the development of the human's unique ability to aim and accelerate tools and weapons.

In Vivo Three-Dimensional Kinematics of the Midcarpal Joint of the Wrist

The human carpus is a complex joint system. Many problems that arise in the wrist are the result of an alteration of intercarpal motion. Although the midcarpal joint is a major component of the wrist joint, the global kinematics of the midcarpal joint have not been described. The purpose of this study was to provide a simplified description of the motion and function of the midcarpal joint. We studied the in vivo three-dimensional kinematics of the midcarpal joint with use of a markerless bone-registration technique. Magnetic resonance images of the wrists of twenty-four healthy volunteers were acquired during a dart-throwing motion or flexion-extension motion of the wrist. Three-dimensional animations of the isolated midcarpal joint were created. Relative midcarpal motions were investigated qualitatively and quantitatively. The direction of the capitate motion relative to the scaphoid was always similar: it was oblique and it extended from radiodorsal to ulnopalmar in radioulnar deviation, in the dart-throwing motion, and in the flexion-extension motion. The directions of the capitate motions relative to the lunate and triquetrum inclined in a similar way, while the ranges of motion were almost unchanged. As the wrist motion changed from radioulnar deviation to flexion-extension motion, the range of the capitate rotation relative to the scaphoid decreased while the range of the lunate rotation relative to the scaphoid increased. Regardless of the type of wrist motion, the loci of the displacement of all of the joint surfaces of the midcarpal joint were located within a midcarpal ovoid space, and a line connecting the centers of the joint surfaces of the midcarpal joint could be schematized as a letter "C" entwining the midcarpal ovoid. Midcarpal motion is essentially the combined motion of three types of joint systems: (1) the uniaxial joint between the scaphoid and the distal row; (2) the biaxial joint between the lunate and triquetrum and the distal row; and (3) the intercarpal joints of the proximal row, which have an adaptive mechanism that accommodates the above-mentioned two types of joint systems in the midcarpal joint. We advocate use of the "ovoid/C" concept to describe the function of the midcarpal joint that contributes to both the stability and the mobility of the wrist, to assist clinicians in achieving a better understanding of the kinematics of the wrist joint.

In Vivo Radiocarpal Kinematics and the Dart Throwerʼs Motion

Wrist motion is dependent on the complex articulations of the scaphoid and lunate at the radiocarpal joint. However, much of what is known about the radiocarpal joint is limited to the anatomically defined motions of flexion, extension, radial deviation, and ulnar deviation. The purpose of the present study was to determine the three-dimensional in vivo kinematics of the scaphoid and lunate throughout the entire range of wrist motion, with special focus on the dart thrower's wrist motion, from radial extension to ulnar flexion. The three-dimensional kinematics of the capitate, scaphoid, and lunate were calculated from serial computed tomography scans of both wrists of fourteen healthy male subjects (average age, 25.6 years; range, twenty-two to thirty-four years) and fourteen healthy female subjects (average age, 23.6 years; range, twenty-one to twenty-eight years), which yielded data on a total of 504 distinct wrist positions. The scaphoid and lunate primarily flexed or extended in all directions of wrist motion, and their rotation varied linearly with the direction of wrist motion (R2= 0.90 and 0.82, respectively). Scaphoid and lunate motion was significantly less along the path of the dart thrower's motion than in any other direction of wrist motion (p < 0.01 for both carpal bones). The scaphoid and lunate translated radially (2 to 4 mm) when extended, but they did not translate appreciably when flexed. The dart thrower's path defined the transition between flexion and extension rotation of the scaphoid and lunate, and it identified wrist positions at which scaphoid and lunate motion approached zero. These findings indicate that this path of wrist motion confers a unique degree of radiocarpal stability and suggests that this direction, rather than the anatomical directions of wrist flexion-extension and radioulnar deviation, is the primary functional direction of the radiocarpal joint.

Changes in Patterns of Scaphoid and Lunate Motion During Functional Arcs of Wrist Motion Induced by Ligament Division

To determine the in vitro motion of the scaphoid and lunate during wrist circumduction and wrist dart-throw motions and to see how these motions change after the ligamentous stabilizers of the scaphoid and lunate are sectioned in a manner simulating scapholunate instability. Twenty-one fresh-frozen cadaver forearms were moved through a dart-throw motion and a circumduction motion using a wrist joint simulator. Scaphoid and lunate motion were measured with the wrist ligaments intact and after sectioning of the scapholunate interosseous ligament, the scaphotrapezium ligament, and the radioscaphocapitate ligament. In the intact wrist the scaphoid and lunate moved more during circumduction than during the dart-throw motion. With ligamentous sectioning the scaphoid flexed more and the lunate extended more during both the circumduction and dart-throw motions. During the circumduction motion both before and after sectioning the global motion of the scaphoid was greater than that of the lunate. After sectioning the scaphoid motion increased and the lunate motion decreased. The scaphoid and lunate motions were observed to change remarkably after ligamentous sectioning. The observed changes in carpal motion correlate with the clinical observation that after ligamentous injury arthritic changes occur in the radioscaphoid joint and not in the radiolunate joint. Analysis of the injured wrist in positions that combine flexion-extension and radial-ulnar deviation may allow noninvasive diagnosis of specific wrist ligament injuries.

In vivo three-dimensional wrist motion analysis using magnetic resonance imaging and volume-based registration

This study represents a new attempt to non-invasively analyze three-dimensional motions of the wrist in vivo. A volume-based registration method using magnetic resonance imaging (MRI) was developed to avoid radiation exposure. The primary aim was to evaluate the accuracy of volume-based registration and compare it with surface-based registration. The secondary aim was to evaluate contributions of the scaphoid and lunate to global wrist motion during flexion–extension motion (FEM), radio-ulnar deviation (RUD) and radial-extension/ulnoflexion, “dart-throwing” motion (DTM) in the right wrists of 12 healthy volunteers. Volume-based registration displayed a mean rotation error of 1.29° ± 1.03° and a mean translation error of 0.21 ± 0.25 mm and was significantly more accurate than surface-based registration in rotation. Different patterns of contribution of the scaphoid and lunate were identified for FEM, RUD, and DTM. The scaphoid contributes predominantly in the radiocarpal joint during FEM, in the midcarpal joint during RUD and almost equally between these joints during DTM. The lunate contributes almost equally in both joints during FEM and predominantly in the midcarpal joint during RUD and DTM.

Capitate-based kinematics of the midcarpal joint during wrist radioulnar deviation: an in vivo three-dimensional motion analysis

Purpose The purpose of this study was to obtain qualitative and quantitative information regarding in vivo 3-dimensional (3D) kinematics of the midcarpal joint during wrist radioulnar deviation (RUD). Methods We studied the in vivo kinematics of the midcarpal joint during wrist RUD in the right wrists of 10 volunteers by using a technology without radioactive exposure. The magnetic resonance images were acquired during RUD. The capitate was registered with the scaphoid, the lunate, and the triquetrum by using a volume registration technique. Animations of the relative motions of the midcarpal joint were created and accurate estimates of the relative orientations of the bones and axes of rotation (AORs) of each motion were obtained. Results The scaphoid, lunate, and triquetrum motions relative to the capitate during RUD were found to be similar, describing a rotational motion around the axis obliquely penetrating the head of the capitate in almost a radial extension/ulnoflexion plane of motion of the wrist. The AORs of the scaphoid, the lunate, and the triquetrum were located closely in space. In the axial plane the AORs of the scaphoid, lunate, and triquetrum formed a radially and palmarly opening angle of 43° ± 7°, 41° ± 11°, and 42° ± 14° with the wrist flexion/extension axis, respectively. Conclusions This study reports the in vivo 3D measurements of midcarpal motion relative to the capitate. Isolated midcarpal motion during RUD could be approximated to be a rotation in a plane of a radiodorsal/ulnopalmar rotation of the wrist, which may coincide with a motion plane of one of the most essential human wrist motions, known as the dart-throwing motion.

Scaphoid and lunate motion during a wrist dart throw motion 1,2

Purpose The primary purpose of this study was to measure the in vitro scaphoid and lunate motion during 9 different variations of a wrist dart throw motion. Another goal was to determine the specific dart throw motion that minimized scaphoid and lunate motion. Methods Scaphoid and lunate motion were recorded in 7 cadaver forearms during various combinations of wrist dart throw motions caused by a wrist joint motion simulator. Results During wrist flexion and extension the scaphoid and lunate motions follow the wrist motion. During wrist radial and ulnar deviation the scaphoid and lunate correspondingly flex and extend. During intermediate motions the scaphoid and lunate move as little as 26% of the total third metacarpal motion and do not necessarily follow a planar motion. Conclusions These findings suggest that there may be a dart throw motion during which there may be minimal scaphoid and lunate motion. If a subject’s wrist motion could be clinically restricted to this dart throw motion, early hand mobility might be possible after surgery on the scaphoid and lunate.

The effects of wrist distraction on carpal kinematics

Changes in carpal kinematics under wrist distraction were studied in fresh cadaveric specimens. A magnetic tracking device measured kinematic motions of the scaphoid, lunate, and third metacarpal relative to the fixed radius in 3 planes of passive motion (coronal, sagittal, and "dart throwers") under progressive distraction loads. The change in percent contribution of the radiocarpal and midcarpal joints was calculated. Radiocarpal motion during extension was decreased as increasing traction was applied, but it increased with flexion. Motion of the scaphoid relative to the lunate was smaller in the oblique plane, resulting in less radiocarpal motion than in the sagittal plane. In the coronal plane, traction had little effect on radial deviation, but ulnar angulation of the scaphoid was greater with ulnar deviation of the wrist. These results suggest that different degrees of tension exist in the palmar and dorsal ligaments with the wrist under traction and during different planes of wrist motion. If wrist motion is desired during fixed traction, such as used clinically with external fixation, the dart-throwers motion (wrist extension with radial deviation and wrist flexion with ulnar deviation) appears to have the least impact on radiocarpal motion. If greater radiocarpal motion is desired, however, such as during postoperative mobilization, flexion-extension and radioulnar deviation will create more radiocarpal motion than the dart-thrower's motion.