The triquetrum-hamate joint: an anatomic and in vivo three-dimensional kinematic study

Bilateral lunotriquetral coalition: a dynamic four-dimensional computed tomography technical case report

Lunotriquetral coalitions are the most common form of carpal coalition wherein the cartilage between the lunate and triquetrum ossification centers failed to undergo apoptosis. This technical case report examines the arthrokinematics of bilateral lunotriquetral coalitions with dissimilar Minnaar types in one participant with one asymptomatic wrist and one wrist with suspected distal radioulnar joint injury. Static and dynamic (four-dimensional) CT images during pronosupination were captured using a photon-counting detector CT scanner. Interosseous proximity distributions were calculated between the lunotriquetral coalition and adjacent bones in both wrists to quantify arthrokinematics. Interosseous proximity distributions at joints adjacent to the lunotriquetral coalition demonstrate differences in median and minimum interosseous proximities between the asymptomatic and injured wrists during resisted pronosupination. Altered kinematics from lunotriquetral coalitions may be a source of ulnar-sided wrist pain and discomfort, limiting the functional range of motion. This case report highlights potential alterations to wrist arthrokinematics in the setting of lunotriquetral coalitions and possible associations with ulnar-sided wrist pain, highlighting anatomy to examine in radiographic follow-up. Furthermore, this case report demonstrates the technical feasibility of four-dimensional CT using photon-counting detector technology in assessing arthrokinematics in the setting of variant wrist anatomy.

Carpal kinematics and morphological correlates of wrist ulnar deviation mobility in nonhuman anthropoid primates

OBJECTIVES

Primates employ wrist ulnar deviation during a variety of locomotor and manipulative behaviors. Extant hominoids share a derived condition in which the ulnar styloid process has limited articulation or is completely separated from the proximal carpals, which is often hypothesized to increase ulnar deviation range of motion. Acute angulation of the hamate's triquetral facet is also hypothesized to facilitate ulnar deviation mobility and mechanics. In this study, we test these longstanding ideas.

METHODS

Three-dimensional (3D) carpal kinematics were examined using a cadaveric sample of Pan troglodytes, Pongo sp., and five monkey species. Ulnar styloid projection and orientation of the hamate's triquetral facet were quantified using 3D models.

RESULTS

Although carpal rotation patterns in Pan and Pongo were uniquely similar in some respects, P. troglodytes exhibited overall kinematic similarity with large terrestrial cercopithecoids (Papio and Mandrillus). Pongo, Macaca, and Ateles had high wrist ulnar deviation ranges of motion, but Pongo did this via a unique mechanism. In Pongo, the triquetrum functions as a distal carpal rather than part of the proximal row. Ulnar styloid projection and wrist ulnar deviation range of motion were not correlated but ulnar deviation range of motion and the triquetrohamate facet orientation were correlated.

CONCLUSIONS

Increased ulnar deviation mobility is not the function of ulnar styloid withdrawal in hominoids. Instead, this feature probably reduces stress on the ulnar side wrist or is a byproduct of adaptations that increase supination. Orientation of the hamate's triquetral facet offers some potential to reconstruct ulnar deviation mobility in extinct primates.

The morphologic and morphometric features of the triquetrum

Fractures of the triquetrum are the second most common form of isolated carpal bone fracture after the scaphoid. However, data on triquetrum morphology and morphometry are sparse. The aim of this study was to describe the morphology of triquetrum using anatomical landmarks, evaluate its morphometric features, and determine its vascular entry points. The morphological and morphometrical features of 87 adult dry triquetral bones (39 left, 48 right) were determined by measuring length, width and thickness. The number and locations of nutrient foramina wider than 0.5 mm were recorded. Mean length, width and thickness were 17.37 mm (range, 14.26-22.13), 12.65 mm (range, 10.37-15.85) and 11.41 mm (range, 8.98-18.23), respectively. The facet articulating with the pisiform was oval in 40 bones, round in 8 and amorphous (neither round nor oval) in 39. The mean length of the interarticular ridge was 7.09 ± 0.9 mm. The mean number of nutrient foramina was significantly greater on the dorsal than on the other aspects. The dorsal predominance of nutrient foramina makes the bone weaker in the dorsal region, which could explain why fractures are more common in this region. Also, the dorsal aspect is rich in blood supply, which could explain why avascular necrosis is less common in triquetral fractures. As most of the vascularization is on the dorsal side, there is need for caution when performing triquetrum surgery. LEVEL OF EVIDENCE: Level 2.

The Intercalated Segment: Does the Triquetrum Move in Synchrony With the Lunate?

PURPOSE

To quantify the relative motion between the lunate and triquetrum during functional wrist movements and to examine the impact of wrist laxity on triquetral motion.

METHODS

A digital database of wrist bone anatomy and carpal kinematics for 10 healthy volunteers in 10 different positions was used to study triquetral kinematics. The orientation of radiotriquetral (RT) and radiolunate rotation axes was compared during a variety of functional wrist movements, including radioulnar deviation (RUD) and flexion-extension (FE), and during a hammering task. The motion of the triquetrum relative to the radius during wrist RUD was compared with passive FE range of motion measurements (used as a surrogate measure for wrist laxity).

RESULTS

The difference in the orientation of the radiolunate and RT rotation axes was less than 20° during most of the motions studied, except for radial deviation and for the first stage of the hammering task. During wrist RUD, the orientation of the RT rotation axis varied as a function of passive FE wrist range of motion.

CONCLUSIONS

The suggestion that the lunate and triquetrum move together as an intercalated segment may be an oversimplification. We observed synchronous movement during some motions, but as the wrist entered RUD, the lunate and triquetrum no longer moved synchronously. These findings challenge the assumptions behind models describing the mechanical function of the carpals.

CLINICAL RELEVANCE

Individual-specific differences in the amount of relative motion between the triquetrum and lunate may contribute to the variability in outcomes following lunotriquetral arthrodesis. Variation in triquetral motion patterns may also have an impact on the ability of the triquetrum to extend the lunate, affecting the development of carpal instability.

Performance evaluation of surgical techniques for treatment of scapholunate instability in a type II wrist

We investigated the performance of three tenodesis techniques, modified Brunelli, Corella, and scapholunate axis (SLAM) methods in repairing scapholunate interosseous ligament (SLIL) disruption for a type II wrist using finite element-based virtual surgery and compared the results with those of a previous investigation for a type I wrist. In addition, a comparison of the carpal mechanics of type I and type II wrists was undertaken in order to elucidate the difference between the two types. For the type II wrist, following simulated SLIL disruption, the Corella reconstruction technique provided a superior outcome, restoring dorsal gap, volar gap, and SL angle to within 3.5%, 7.1%, and 8.4%, respectively, of the intact wrist. Moreover, application of the ligament reconstruction techniques did not significantly alter the motion pattern of the type II and type I wrists. For the type I wrist, SLIL disruption resulted in no contact between scaphoid-lunate cartilage articulation, whereas for the type II wrist, some contact was maintained. We conclude that the Corella ligamentous reconstruction technique is best able to restore SL gap, angle, and stability following SL ligament injury for both type II and type I wrists and is able to do so without altering wrist kinematics. Our findings also support the view that type I wrists exhibit row behaviour and type II wrists column behaviour. In addition, our analysis suggests that the extra articulation between the lunate and hamate in a type II wrist may help improve stability following SL ligament injury.

Morphological and positional changes of the carpal arch and median nerve associated with wrist deviations

BACKGROUND

Carpal tunnel and median nerve dynamically change with wrist motion. The purpose of this study was to investigate the morphological changes and positional migration of the carpal arch and median nerve, as well as nerve-arch positional relationship associated with wrist deviation in healthy volunteers.

METHODS

Twenty asymptomatic male volunteers performed wrist motion from neutral to deviated positions combining flexion-extension and radioulnar deviation. Ultrasound images of the carpal arch and median nerve at the distal carpal tunnel were collected during wrist motion. Morphological and positional parameters of the carpal arch and median nerve were derived from the ultrasound images.

FINDINGS

Carpal arch height, area, and palmar bowing of the transverse carpal ligament (TCL) increased with flexion related wrist motion and decreased with extension related motion (P < 0.05). Arch width increased with radial flexion and decreased with extension and ulnar extension (P < 0.05). Median nerve circularity increased with flexion and radial flexion but decreased with extension, ulnar extension, and ulnar deviation (P < 0.05). Nerve centroid displaced ulnarly with radial deviation, radial flexion, and radial extension and displaced radially with ulnar deviation, ulnar flexion, and ulnar extension (P < 0.05). Nerve centroid displaced in the dorsal direction with flexion and radial flexion, but in the palmar direction with extension (P < 0.05). Nerve-TCL distance increased with flexion related motion and decreased with extension relation motion (P < 0.05).

INTERPRETATION

The current study advances our understanding the effect of wrist motion on the carpal tunnel and its contents, which has implications for pathomorphological and pathokinematic changes associated with wrist disorders.

Biomechanical Comparison of Fifth Carpometacarpal Fusion Methods: Kirschner Wires Versus Plate and Screws

Background:

Fractures and dislocations of the base of the fifth metacarpal can lead to arthritis of the fifth carpometacarpal (CMC) joint. For patients who are symptomatic and fail conservative management, arthrodesis of the fifth CMC joint can be offered. The fusion can be performed using Kirschner wires (K-wires), but can lead to complications such as pin tract infection and pin migration. A low-profile locking plate may represent an attractive alternative. The purpose of this study was to compare the biomechanical stability of these 2 fusion techniques.

Methods:

Twelve fresh frozen cadaver hands were divided into 2 groups. The first group underwent fixation of the fifth CMC joint using 2 1.6 mm (0.062 inches) diameter K-wires in a cross-pin configuration. The second group underwent fixation using a 2.0 mm locking plate with 2 locking screws in the hamate and 3 nonlocking screws in the fifth metacarpal shaft. The specimens were then loaded in extension until failure.

Results:

The stiffness was 15.0±7.2 N/mm for the K-wire group and 14.7±6.0 N/mm (mean±SD) for the plate group (P=0.9366). The peak loads were 62.5±40.0 N and 64.6±24.8 N for K-wire and plate groups, respectively (P=0.9181). The energy to peak load was 294±281 N mm for the K-wire group and 418±190 N mm for the plate group (P=0.3904).

Conclusions:

Fifth CMC fusion using either K-wires or plate and screws showed no significant difference in stiffness, peak load, and energy to peak load. These results suggest the 2 methods provide similar biomechanical stability.

Feasibility of a New Desktop Motion Analysis System with a Video Game Console for Assessing Various Three-Dimensional Wrist Motions

Background

The restriction of wrist motion results in limited hand function, and the evaluation of the range of wrist motion is related to the evaluation of wrist function. To analyze and compare the wrist motion during four selected tasks, we developed a new desktop motion analysis system using the motion controller for a home video game console.

Methods

Eighteen healthy, right-handed subjects performed 15 trials of selective tasks (dart throwing, hammering, circumduction, and winding thread on a reel) with both wrists. The signals of light-emitting diode markers attached to the hand and forearm were detected by the optic receptor in the motion controller. We compared the results between both wrists and between motions with similar motion paths.

Results

The parameters (range of motion, offset, coupling, and orientations of the oblique plane) for wrist motion were not significantly different between both wrists, except for radioulnar deviation for hammering and the orientation for thread winding. In each wrist, the ranges for hammering were larger than those for dart throwing. The offsets and the orientations of the oblique plane were not significantly different between circumduction and thread winding.

Conclusions

The results for the parameters of dart throwing, hammering, and circumduction of our motion analysis system using the motion controller were considerably similar to those of the previous studies with three-dimensional reconstruction with computed tomography, electrogoniometer, and motion capture system. Therefore, our system may be a cost-effective and simple method for wrist motion analysis.

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.

Reliability and responsiveness of a goniometric device for measuring the range of motion in the dart-throwing motion plane

Background: Dart-throwing motion (DTM) is an important component of wrist function and, consequently, has the potential to become an evaluation tool in rehabilitation. However, no measurement method is currently available to reliably measure range of motion (ROM) of the wrist in the DTM plane. Objectives: To determine the reliability and responsiveness of a goniometric device to measure wrist ROM in the DTM plane. Methods: ROM of the wrist in the DTM plane was measured in 70 healthy participants. The intra-class correlation coefficient (ICC) was used to evaluate the relative reliability of measurement, and a Bland-Altman analysis conducted to establish its absolute reliability, including the 95% limits of agreement (95% LOA). The standard error of the measurement (SEM) and minimal detectable change at the 95% confidence level (MDC₉₅) were calculated as measures of responsiveness. Results: The intra-rater ICC was 0.87, and an inter-rater ICC of 0.71. There was no evidence of a fixed or proportional bias. For intra- and inter-rater reliability, 95% LOA ranged from -13.83 to 11.12 and from -17.75 to 16.19, respectively. The SEM and MDC₉₅ were 4.5° and 12.4°, respectively, for intra-rater reliability, and 6.0° and 16.6°, respectively, for inter-rater reliability. Conclusion: The ROM of the wrist in the DTM plane was measured with fair-to-good reliability and responsiveness and, therefore, has the potential to become an evaluation tool for rehabilitation.

Analysis of displacement and deformation of the medial meniscus with a horizontal tear using a three-dimensional computer model

PURPOSE

The displacement and deformation of the knee meniscus significantly affect its roles; however, little is known about the displacement and deformation patterns of a torn medial meniscus. The objective of this study was to evaluate quantitatively the patterns of displacement and deformation in horizontally torn medial menisci during knee flexion.

METHODS

Twenty patients with horizontally torn medial menisci underwent three-dimensional (3-D) magnetic resonance imaging at varying degrees of knee flexion, and 3-D computer models of the tibia, tibial articular cartilage, and meniscus were generated. Based on these, the size of the horizontal tear (% tear) was evaluated and defined as the circumferential ratio between the length of the horizontal tear and that of the entire meniscus. The 3-D meniscus models were automatically superimposed over images taken at 0, 20, 40, and 60° of knee flexion by the voxel-based registration method. Meniscal motion and deformation during knee flexion were visualized and quantitatively calculated on the mid-sagittal plane. Correlations between the size of horizontal tear, displacement/deformation of torn menisci, and clinical symptoms were evaluated after conservative treatment for 3 months.

RESULTS

The % tear was 35.7 ± 12.5 % (range 13.7-55.5 %). During knee flexion, all torn menisci moved posteriorly, with gradual widening of horizontal and vertical gaps (p < 0.05). A direct correlation was observed between % tear and change in the vertical tear gap during knee flexion (p < 0.05). There was an inverse correlation between Lysholm score and % tear (p < 0.05).

CONCLUSION

Medial meniscal horizontal tears widen and deform during knee flexion, and % tear correlates with the change in the vertical gap. Patients with a lower % tear are more capable of performing activities of daily living after conservative treatment. This method may help clarify the cause of pain in patients with medial meniscus tears as well as facilitate the selection of an appropriate treatment plan.

LEVEL OF EVIDENCE

Case series, Level IV.

Volar dislocation of the triquetrum - case report and review of literature

In contrast to triquetral fractures, dislocations of the triquetrum are very uncommon because of the very strong ligamentous support. They occasionally occur in association with complex wrist injuries, isolated dislocations however are extremely rare. We report a case of a male athlete who sustained an isolated volar dislocation of the triquetrum. The injury was treated by open reduction, fixation with Kirschner-wires and direct repair of torn ligaments. Kirschner-wires were removed after 6 weeks and physiotherapy was started. At 3 years follow-up he reported to be free of pain and showed only slightly restricted grip strength and range of motion when compared to his uninjured hand. A review of the literature indicates that final outcomes are usually satisfactory if prompt diagnosis and treatment occurs. However persistent pain and impaired hand function may result because of delayed diagnosis or insufficient repair of associated ligament injuries.

DECOMPRESSION EFFECT OF PARTIAL CAPITATE SHORTENING FOR KIENBOCK'S DISEASE: A BIOMECHANICAL STUDY

Although capitate shortening for Kienbock's disease decompresses the radiolunate joint, the distal carpal row migrates proximally postoperatively and the carpal alignment subsequently collapses. We hypothesised that partial capitate shortening, in which only the lunate facet of the capitate is shortened and the scaphocapitate joint is preserved, could achieve adequate decompression without carpal collapse. Using 11 cadavers, we measured the intra-articular pressure with an axial load on the radioscaphoid, radiolunate and ulnocarpal joints before and after resection. We also investigated whether the decompression effect is related to the presence of the lunohamate articulation. After resection, the radioscaphoid joint mean pressure was significantly increased by an average of 39%, the radiolunate joint mean pressure was significantly decreased by an average of 53% and the ulnocarpal joint mean pressure was unchanged. The radiolunate joint mean pressure significantly decreased irrespective of the lunohamate articulation status.

In vivo triquetrum-hamate kinematics through a simulated hammering task wrist motion

BACKGROUND

The shape and kinematics of the triquetrum-hamate joint have been the subject of continued research, as its articulation provides wrist stability and motion. The purpose of this study was to measure the in vivo articulation of the triquetrum-hamate joint as the wrist moves along an important functional wrist motion, the dart thrower's path.

METHODS

The right wrist of six male and six female volunteers (average age [and standard deviation], 24.8 ± 3.8 years) were imaged with computed tomography in five positions along a simulated hammering task. Three-dimensional kinematics of the third metacarpal, triquetrum, hamate, and radius were analyzed with use of the rotation axis and the path of contact areas.

RESULTS

As the wrist ulnar-flexed with respect to the radius, the triquetrum translated 3.7 ± 1.7 mm distally on the hamate. Approximately midway through this distal course, when the triquetrum appeared to engage the distal ridge of the hamate, the triquetrum began translating volarly. Total volar translation was 2.6 ± 1.1 mm. As the wrist ulnar-flexed, there was also a decrease in the distance and variability in the location of the triquetrum-hamate rotation axis from the hamate centroid: it decreased from 11.7 ± 4.1 mm to 3.3 ± 1.4 mm (p < 0.0001).

CONCLUSIONS

Our findings support the concept that the triquetrum rotates on the convex ellipsoid surface of the hamate and that the helicoidal description of the triquetrum's motion on the hamate may be an oversimplification.

A pilot trial on kinematic magnetic resonance imaging using a superconducting, horizontally opened, 1.2 T magnetic resonance system

Purpose

This study was performed to introduce and evaluate the potential of kinematic magnetic resonance imaging (KMRI) using a high-field open-magnet magnetic resonance (MR) system.

Methods

We attempted to perform KMRI of healthy volunteers’ lumbar spine and knee in the lateral position and ankle in the supine position utilizing the superconducting, horizontally opened, 1.2 T MR system (OASIS, HITACHI, Tokyo, Japan). For the KMRI of the lumbar spine, the volunteer had to lie on one side while maintaining maximally anteflexed, neutral, and maximally retroflexed positions and remain still for the duration of the acquisition time for each posture. In the same way, KMRI of the knee was performed with the volunteer's knee flexed at 0°, 30°, 60°, 90°, and 120° in the lateral position, and KMRI of the ankle was performed with the volunteer's ankle in maximally dorsiflexed, neutral, and maximally plantarflexed positions while lying in the supine position.

Results

We could acquire higher quality kinematic MR images than those acquired using low-field MR systems. The spinal canal, intervertebral discs and foramina, and facet joints in lumbar spine KMRI; the ligaments, menisci and patellofemoral joint in knee KMRI; and the tibiotalar articulation and peroneal tendon in ankle KMRI were clearly depicted.

Conclusion

The results of our pilot trial indicated that a superconducting horizontally opened, 1.2 T MR system offers high-quality KMRI images and can be utilized for the kinematic diagnosis and evaluation of sports injuries.

Evaluation of translation in the normal and dysplastic hip using three-dimensional magnetic resonance imaging and voxel-based registration

OBJECTIVE

To elucidate in vivo hip instability by comparing normal hips to hips with acetabular dysplasia by evaluating three-dimensional (3D) translations of the femoral head center (FHC) at different hip positions using magnetic resonance imaging (MRI).

DESIGN

Forty normal hips and 22 dysplastic female hips were examined. MRI was performed at four different positions bilaterally: neutral, 45° of flexion, 15° of extension, and the Patrick position. Femoral and pelvic bones were separately extracted at the neutral position and superimposed over the images of each different position using voxel-based registration. The distance between the acetabular center and FHC at neutral position was defined as 3D-migration. The distance between FHC at neutral position and that at each different position was defined as 3D-translation. Two-way repeated measures analysis of variance was performed to consider the dependency between right and left-side data, and multiple linear regression analyses were performed to assess independent relationships.

RESULTS

The center-edge (CE) angle was the determinant for 3D-migration (β=-0.415, P=0.001), and there was a statistical significant difference in 3D-migration between normal female hips and dysplastic hips (P=0.047). From neutral to the Patrick position, the FHC of normal and dysplastic hips translated postero-infero-medially by 1.12±0.39mm (0.45-1.85mm) and 1.97±0.84mm (0.95-4.34mm), respectively, and the difference between the groups was statistically significant (P=0.005). CE angle was the determinant for 3D-translation from neutral to the Patrick position (β=-0.730, P<0.001). The average root mean square error in 3D-translation was 0.172mm and 0.193mm for intra- and interobserver reproducibility, respectively.

CONCLUSIONS

Hip instability was increased in proportion to the severity of acetabular dysplasia. A 3D MRI voxel-based registration technique can show in vivo morphology and kinematics of the native hip without exposure to radioactivity.

Direct anterior cruciate ligament insertion to the femur assessed by histology and 3-dimensional volume-rendered computed tomography

PURPOSE

The purpose of this study was to histologically identify the direct and indirect insertion of the femoral anterior cruciate ligament (ACL) insertion. Furthermore, we quantitatively measured the direct femoral insertion area by use of the 3-dimensional (3D) volume-rendered (VR) computed tomography (CT) model.

METHODS

By use of 8 intact cadaveric knees, the lateral femoral condyle including the ACL attachment was sectioned for histologic examination in 3 oblique-axial planes parallel to the roof of the intercondylar notch and in the sagittal planes. Before sectioning, these knees had been subjected to CT to obtain 3D VR images of the femur. Once the direct insertion of the ACL was identified on each histologic section, the corresponding image was superimposed on the corresponding CT image.

RESULTS

The direct ACL insertion, in which dense collagen fibers were connected to the bone by the fibrocartilaginous layer, was microscopically identified at the region between the posteromedial articular cartilage margin of the lateral femoral condyle and the linear bony ridge 7 to 10 mm anterior to the articular cartilage margin. Meticulous comparison of histologic analysis and the 3D VR CT model showed that the ACL direct insertion coincided with a crescent-shaped hollow just behind the linear bony ridge. The direct insertion measured 17.4 +/- 0.9 mm (mean +/- SD) in length, 8.0 +/- 0.5 mm in width, and 128.3 +/- 10.5 mm(2) in area.

CONCLUSIONS

The direct insertion of the ACL is located in the depression between the resident's ridge and the articular cartilage margin on the lateral femoral condyle. It measured 17.4 +/- 0.9 mm in length, 8.0 +/- 0.5 mm in width, and 128.3 +/- 10.5 mm(2) in area.

CLINICAL RELEVANCE

Delineation of the ACL femoral direct insertion by 3D VR CT could be a useful tool for planning of accurate femoral tunnel positioning in anatomic ACL reconstruction.

Studying primate carpal kinematics in three dimensions using a computed-tomography-based markerless registration method

The functional morphology of the wrist pertains to a number of important questions in primate evolutionary biology, including that of hominins. Reconstructing locomotor and manipulative capabilities of the wrist in extinct species requires a detailed understanding of wrist biomechanics in extant primates and the relationship between carpal form and function. The kinematics of carpal movement, and the role individual joints play in providing mobility and stability of the wrist, is central to such efforts. However, there have been few detailed biomechanical studies of the nonhuman primate wrist. This is largely because of the complexity of wrist morphology and the considerable technical challenges involved in tracking the movements of the many small bones that compose the carpus. The purpose of this article is to introduce and outline a method adapted from human clinical studies of three-dimensional (3D) carpal kinematics for use in a comparative context. The method employs computed tomography of primate cadaver forelimbs in increments throughout the wrist's range of motion, coupled with markerless registration of 3D polygon models based on inertial properties of each bone. The 3D kinematic principles involved in extracting motion axis parameters that describe bone movement are reviewed. In addition, a set of anatomically based coordinate systems embedded in the radius, capitate, hamate, lunate, and scaphoid is presented for the benefit of other primate functional morphologists interested in studying carpal kinematics. Finally, a brief demonstration of how the application of these methods can elucidate the mechanics of the wrist in primates illustrates the closer-packing of carpals in chimpanzees than in orangutans, which may help to stabilize the midcarpus and produce a more rigid wrist beneficial for efficient hand posturing during knuckle-walking locomotion.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Imaging recognition of morphological variants at the midcarpal joint

PURPOSE

To compare the imaging methods for identifying the various morphological variations of the articular surfaces at the midcarpal joint.

METHODS

Thirteen cadaveric wrists were examined by plain neutral anteroposterior radiographs; 2-dimensional computed tomography (CT); 3-dimensional CT reconstruction, and 3-tesla magnetic resonance imaging (MRI). Carpal measurements were performed, and the parameters that defined the scaphoid, lunate, hamate, and capitate morphological types were investigated, with dissection being used as the definitive measure of morphology. The dissection findings were compared to the results of each imaging technique to determine the accuracy of morphological determination from each technique.

RESULTS

Lunate type was the most accurately identified morphological variant amongst all imaging techniques. Lunate type was most accurately determined from coronal MRI. A lunate with a small, cartilaginous ulnar facet (intermediate type) could be differentiated only by coronal MRI and dissection. Scaphoid type could not be determined accurately using any of the imaging modalities described. Capitate type was most accurately determined from coronal MRI. However, flat and spherical-type capitates could not be routinely differentiated from V-shaped capitates. Hamate type was most accurately determined from 3-dimensional CT reconstruction.

CONCLUSIONS

Accurate identification of carpal bone morphology is required to improve our understanding of carpal mechanics and pathology. Not all morphological features can be identified radiographically. Direct visualization is required to differentiate types of scaphoid, and to differentiate V-type capitates. MRI provides the most accurate identification of lunate type, and 3-dimensional CT provides the best method of differentiating hamate types.

Three-dimensional in vivo kinematics of the subtalar joint during dorsi-plantarflexion and inversion-eversion

BACKGROUND

It is difficult to determine the kinematics of the subtalar joint because of its anatomical and functional complexity. The purpose of the study was to clarify the 3D kinematics of the subtalar joint in vivo.

MATERIALS AND METHODS

Subjects were four healthy female volunteers. Magnetic resonance imaging (MRI) sequences were acquired in seven positions during dorsi-plantarflexion (DPF) and in 10 positions during inversion-eversion (IE) at intervals of 10 degrees. MRI data of the talus and calcaneus in the neutral position were superimposed on images of the other positions using voxel-based registration, and relative motions and axes of rotation were visualized and quantitatively calculated.

RESULTS

The calcaneus always rotated from dorsolateral to medioplantar during DPF and IE, and the motion plane was very similar to that of the entire foot in IE. The axes of rotation of the calcaneus relative to the talus during DPF and IE had a very close spatial relationship, running obliquely from antero-dorso-medial to postero-planto-lateral and penetrating the talar neck. The rotation angle around each of these calcaneal axes tended to be greater in IE (20 degrees +/- 2 degrees) than in DPF (16 degrees +/- 3 degrees). In DPF, motion of the calcaneus relative to the talus occurred predominantly around maximum dorsiflexion and plantarflexion, with little movement observed at intermediate positions. During IE, the calcaneus exhibited uninterrupted motion related to foot movement.

CONCLUSION

The subtalar joint is essentially a uniaxial joint with a motion plane almost identical to that of IE of the entire foot.

CLINICAL RELEVANCE

Knowledge of normal subtalar kinematics may be helpful when evaluating pathologic conditions.

Analysis of radiocarpal and midcarpal motion in stable and unstable rheumatoid wrists using 3-dimensional computed tomography

PURPOSE

The kinematic evaluation of carpal motion, especially midcarpal motion, in rheumatoid arthritis (RA) has been extremely difficult because of limited imaging techniques previously available. The purpose of this study was to evaluate the amount of radiocarpal and midcarpal motion in the flexion-extension plane in both stable and unstable rheumatoid wrists using three-dimensional computed tomography.

METHODS

We acquired in vivo kinematic data on 30 wrists with RA by three-dimensional computed tomography with the wrist in 3 positions: neutral, maximum flexion, and maximum extension. All cases were radiographically classified into 1 of 2 subtypes, the stable form or unstable form, according to the classification by Flury et al. We evaluated the precise range of radiocarpal and midcarpal motion using a markerless bone registration technique and calculated the individual contributions to the total amount of wrist motion in the flexion-extension plane in the different radiographic subtypes of RA.

RESULTS

The average range of motion of radiocarpal and midcarpal joint was 27 degrees +/-15 and 32 degrees +/-17, respectively. The average contribution of midcarpal motion to the total amount of wrist motion was 54%. The average contribution of midcarpal motion in the unstable form was 67%, which was significantly higher than 47% (p< .05) in the stable form.

CONCLUSIONS

Midcarpal motion of rheumatoid wrists in the flexion-extension plane was better preserved than previously thought. The contribution of midcarpal motion to the total amount of wrist motion was significantly greater (p< .05) in the unstable form than in the stable form of RA.

Assessment of the "functional length" of the three bundles of the anterior cruciate ligament

The objectives of the present study are to compare "functional length" between the three bundles of the anterior cruciate ligament (ACL) from extension to deep flexion and to perform a sensitivity study on the patterns of "functional length" change due to deviations in insertion site selection. Nine knees of healthy volunteers were examined using a horizontal open magnetic resonance apparatus with the knee at 0 degrees -150 degrees of flexion and created three-dimensional (3D) virtual models of the knee. The femoral and tibial attachment sites of the three ACL bundles were determined, and the distance between the attachment sites was automatically calculated as the "functional length" of each bundle in each position. After changing the attachment sites, computer simulation was performed to investigate in vivo "functional length" changes for the three bundles of the ACL in normal knee kinematics from extension to deep flexion. Three bundles statistically significantly changed in "functional length" during flexion/extension, while they were longest at full extension, and decreased with increasing knee flexion to 100 degrees . They were smallest at flexion of 100 degrees , with increase lengths with flexion deeper than 100 degrees . Deviation of 6 mm of insertion site beyond attachment area caused significant alteration in the pattern of "functional length" change of each bundle, while deviation of 3 mm within attachment area caused no significant difference. The "functional length" of the three ACL bundles was not isometric, not even the antero-medial bundle. The "functional length" might be of major importance in terms of the site of the ACL insertion. The "functional length" of multiple bundles of the ACL and the pattern of their changes are useful for not only graft choice and preparation but also knee angle and initial tension at graft fixation during multiple-bundle ACL reconstruction surgery.

2007 IFSSH committee report of wrist biomechanics committee: biomechanics of the so-called dart-throwing motion of the wrist

The dart-throwing motion (DTM) plane can be defined as a plane in which wrist functional oblique motion occurs, specifically from radial extension to ulnar flexion. Most activities of daily living are performed using a DTM. The DTM utilizes the midcarpal joint to a great extent. Scaphotrapezio-trapezoidal anatomy and kinematics may be important factors that cause a DTM to be a more stable and controlled motion. During a DTM, there is less scaphoid and lunate motion than during pure flexion-extension or radioulnar deviation. Clinically, a DTM at the plane approximately 30 degrees to 45 degrees from the sagittal plane allows continued functional wrist motion while minimizing radiocarpal motion when needed for rehabilitation.

In vivo three-dimensional skeletal alignment analysis of the hindfoot valgus deformity in patients with rheumatoid arthritis

The purpose of this study was to analyze the skeletal alignment of the hindfoot valgus deformity in patients with rheumatoid arthritis using bone models reconstructed from three-dimensional computerized tomography data. Computed tomography was performed on 21 feet of patients with rheumatoid arthritis, and magnetic resonance imaging was taken of 10 normal feet of eight volunteers. An image processing system was used to create bone models and analyze the three-dimensional displacement of the calcaneus, talus, navicular, and cuboid bones. With a standard coordinate system in the distal tibia and a local coordinate system in each bone of the hindfoot, three rotational parameters and three translational parameters were used to evaluate the relative displacement. The talus showed plantar flexion. Both the calcaneus and navicular bones had valgus and lateral shift displacements. However, the cuboid had no displacement relative to the calcaneus, and the navicular showed no displacement relative to the cuboid. The calcaneus, navicular, and cuboid bones have the same pattern of deformity in patients with rheumatoid arthritis. This three-dimensional image-based technique successfully quantified the hindfoot valgus deformity resulting from rheumatoid arthritis and is beneficial for better understanding the deformity pathomechanism.

The three-dimensional motions of glenohumeral joint under semi-loaded condition during arm abduction using vertically open MRI

BACKGROUND

Magnetic resonance imaging is an accurate non-invasive tool for visualizing muscles, tendons, and bones. It also provides 3D coordinate values. The purpose of the present study was to visualize and quantify the 3D positions of the glenohumeral joint during isometric abduction of the arm using vertically open magnetic resonance imaging.

METHODS

We examined 14 shoulders of seven healthy volunteers. Magnetic resonance images were obtained in a seated position and in seven static positions of the arm from 0 degrees to maximum abduction using vertically open magnetic resonance imaging. 3D surface models were created and 3D movements of each bone in the glenohumeral joint were calculated using a computer algorithm. We analyzed the translation and contact pattern of the glenohumeral joint.

FINDINGS

In supero-inferior direction, the humeral head translated slight inferiorly from +1.9 (SD 1.0) mm at 0 degrees to +0.8 (SD 1.8) mm at the maximum abduction. In antero-posterior direction, the humeral head translated anteriorly from 0 degrees to 90 degrees (mean +2.4, SD 2.6 mm) and posteriorly from 90 degrees to 150 degrees of abduction (mean -1.4, SD 2.7 mm). Furthermore, the humeral head had a unique contact patterns with the glenoid; the contact part of the humeral head with the glenoid changed from the central part to the posterior in the midrange of abduction.

INTERPRETATION

The humeral head showed a small translation in the antero-posterior direction between 90 degrees and 150 degrees of abduction. In addition, the posterior part of the humeral head contacted the glenoid in this range of abduction. These findings of motion patterns in asymptomatic subjects will be necessary when comparing the kinematics with pathologic condition such as the glenohumeral instability and rotator cuff tear.

3D kinematic analysis of the acromioclavicular joint during arm abduction using vertically open MRI

Many researchers have evaluated the motions of the shoulder girdle, especially scapular and humeral motion. However, few reports exist that describe motions of the acromioclavicular joint. The purpose of the present study was to analyze the 3D kinematics of the acromioclavicular joint during arm abduction using 3D MR images obtained by a vertically open MRI. Fourteen shoulders of seven volunteers were examined in seven static positions from 0 degrees to the maximum abduction in a seated position. 3D surface models of the clavicle and scapula were created, and the movements of the acromioclavicular joint from 0 degrees to each position were calculated using the volume-based registration technique. From these calculations, the translations were evaluated and the rotational motions were analyzed using the concept of the screw axis. In the anteroposterior direction, the clavicle translated most posteriorly (-1.9 +/- 1.3 mm) at 90 degrees of abduction and most anteriorly (1.6 +/- 2.7 mm) at maximum abduction. In the superoinferior direction, the clavicle translated slightly superiorly (0.9 +/- 1.9 mm). When analyzing relative motion of the scapula with respect to the clavicle, the scapula generally rotated about a specific screw axis passing through the insertions of both the acromioclavicular and the coracoclavicular ligaments on the coracoid process. The average rotation was 34.9 +/- 8.4 degrees.

Operative technique of a new decompression procedure for Kienböck disease: partial capitate shortening

A new decompression procedure for Kienböck disease, namely "partial capitate shortening," was developed. Patients in Lichtman stages 2 and 3A, independent of the ulnar variance, are candidates for this procedure. This procedure can dramatically reduce compressive forces on the lunate almost as much as a traditional decompression procedure of the capitate (capitate shortening combined with capitate-hamate fusion) and much more than the decompression procedure of the forearm bone such as radial shortening. We surmise that our procedure will allow better lunate revascularization. Although the scaphoid progressively adopts an abnormal palmarflexed position after capitate shortening combined with capitate-hamate fusion, partial capitate shortening can maintain normal carpal alignment, resulting in better joint congruency around the scaphoid and range of motion of the wrist. Moreover, partial capitate shortening allows minimal invasion and is an easy technique without bone grafting. Both operating and immobilizing time are shortened, and there are no secondary problems in the distal radioulnar and/or ulnocarpal joint often seen after radial osteotomy procedures.

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 degrees +/-1.03 degrees 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 degrees +/- 7 degrees, 41 degrees +/- 11 degrees, and 42 degrees +/- 14 degrees 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.