An anatomic study of the triquetrum-hamate joint

PURPOSE: To investigate the articulating surface of the triquetrum-hamate joint (TqH). METHODS: The carpal bones of 46 wrist specimens were examined. The shape of the TqH joint surfaces were investigated, with focus on variations in the shape of the hamate and corresponding triquetrum and the presence and position of convex and concave surfaces. RESULTS: Two distinct patterns of hamate TqH articular surfaces were identified, designated type I (31 of 46) and type II (15 of 46). The triquetral TqH articular surface also was found to have 2 distinct patterns, designated type A (18 of 46) and type B (15 of 46). Of the triquetrums examined 13 of 46 had characteristics that were a variable mixture of the 2 identifiable triquetral surface types, but these did not have sufficient similarity to constitute a third triquetrum surface type. The corresponding articulation patterns of these joint surfaces showed a strong trend for a type A triquetrum to articulate with a type I hamate (18 of 46 of all joints) and for a type B triquetrum to articulate with a type II hamate (13 of 46 of all joints). No association was seen between lunate types and type I or type II hamates. CONCLUSIONS: These findings suggest the existence of 2 distinct TqH joint patterns, which have been termed TqH-1 and TqH-2. There appears to be a spectrum of variation between these 2 identifiable types. As a result, the TqH is best described as a spectrum, with TqH-1 at one end and TqH-2 at the other. A TqH-1 joint is a helicoidal configuration. It is double-faceted, with the hamate and the triquetrum articular surfaces possessing complementary concave and convex parts. A TqH-2 joint has a predominantly oval convex shape, whereas the primarily concave triquetrum is better described as a dish for the flatter hamate. It has no hamate groove or distal ridge.     

The in vivo kinematics of the rheumatoid wrist

The objectives of this study were to describe the three-dimensional in vivo kinematic behavior of wrists affected by rheumatoid arthritis, to correlate kinematic parameters and two radiographic indices of carpal disease, and to describe the in vivo kinematic behavior of the Swanson Silastic wrist implant. Fifteen normal wrists, 17 rheumatoid wrists, and 7 wrists with Silastic wrist implants were tested using a three-dimensional sonic digitizing system. The motion of the hand segment relative to the forearm segment, corresponding to the positions exhibited during flexion-extension motion (FEM) and radial-ulnar deviation (RUD), was described using the equivalent screw displacement (ESD) concept. The mean magnitudes of ESD rotation for both FEM and RUD were statistically different (p less than 0.05) among the normal, rheumatoid, and implant groups. The remaining ESD parameters (i.e., mean values for the translation, the direction angles of the ESD axis, and the intercepts of this axis with the planes of motion), the minimum separation between the FEM and RUD axes, and the coordinates of the midpoint of this separation were not statistically different (p greater than 0.05) among the normal, rheumatoid, and implant groups. The two radiographic indices (carpal collapse and carpal translation) did not correlate with the magnitude of rotation or with any other ESD parameter.     

Simulated radioscapholunate fusion alters carpal kinematics while preserving dart-thrower's motion

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.     

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.     

The scaphotrapezio-trapezoidal joint. Part 2: A kinematic study

Kinematics of the scaphotrapezio-trapezoidal joint during wrist flexion/extension motion (FEM) and radial/ulnar deviation (RUD) was investigated using a 3-dimensional dynamic motion analysis system. The scaphoid/trapezoid motion was found to be a rotational motion obliquely oriented relative to the sagittal plane of the wrist and described in an ulnoflexion/radial extension motion plane in both FEM and RUD of the wrist. The axis of rotation of the scaphoid/trapezoid motion during both FEM and RUD wrist motions was essentially the same and runs through the radiopalmar aspect of the distal scaphoid and the waist of the capitate. Motion analysis also revealed that the trapezium-trapezoid and trapezoid-capitate joints are essentially immobile. Hence, the scaphotrapezio-trapezoidal motion is considered to be a single degree of freedom that is essentially the same in both FEM and RUD of the wrist.     

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.     

Scaphoid kinematics in vivo

The purpose of this study was to quantify 3-dimensional (3-D) in vivo scaphoid kinematics during flexion-extension motion (FEM) and radial-ulnar deviation (RUD) of the hand. The right wrists of 11 healthy volunteers were imaged by spiral computed tomography during RUD and 5 of those wrists also during FEM. With a matching technique, relative translations and rotations of the scaphoids were traced. Our results showed a broad spectrum of kinematic patterns of the scaphoid during RUD, with small intercarpal motions within the proximal carpal row. Some scaphoids rotated basically around the flexion-extension axis only whereas others rotated almost entirely around the deviation axis during RUD. During FEM we found highly uniform scaphoid motion patterns with large intercarpal motions within the proximal carpal row. These findings suggest that current theories cannot sufficiently explain wrist kinematics and stress the need for more in vivo studies on 3-D carpal kinematics.     

Mehrdimensionale Bewegungsanalyse des Handgelenks nach distaler Radiusfraktur

Distal radius fractures can cause wrist motion deficits. The purpose of this study was a motion analysis of the wrists in patients after complete fracture union and rehabilitation. A total of 28 patients with healed unilateral intra-articular distal radius fractures performed multiple circumferential motions of the wrist. Global wrist motion was captured by motion analysis based on electrogoniometry. All participants exhibited a low DASH score (16.7). The maximum motion boundaries of the wrists were reconstructed with a custom-made MatLab program. Maximum flexion-extension (FE), radial-ulnar deviation (RUD) and the area were calculated from the circumduction of the motion envelope. Differences between the fractured wrist and the unimpaired side were compared and analyzed with Student?s t-test. The circumduction boundaries of the wrists showed the typical kidney-shaped configuration with an oblique axis from radial/extension to ulnar/flexion. Compared to the uninjured side, a significant motion deficit was found for the orthogonal directions (FE, RUD) and the areas of the motion envelope (p?<?0.01). The results demonstrate that motion deficits can persist after complete union and rehabilitation of fractured wrists which can remain unidentified by manual methods of goniometry.     

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.     

Avascular necrosis of the hamate: A case report with reference to the hamate blood supply

Avascular necrosis of the hamate bone has not previously been reported. In this case the proximal fragment of the fractured hamate underwent avascular necrosis and prolonged healing. In an attempt to explain this sequela, angiography of the cadaver carpus followed by dissection of intact wrists and a study of enzyme-cleaned hamates showed that their wedge-shaped proximal segments were mostly enveloped by a distal extension of the midcarpal joint cavity and thus totally dependent on intraosseous nutrition. Consequently, the segment is at risk when a fracture line transects the body proximal to the base of the wedge. Clinically, this condition resulted in persistent discomfort and limitations of motion. A postinjury bone scan of the wrist indicated avascular changes in the proximal third of the hamate, and a delayed union was followed by later revascularization and a more normal scan image.     

Arthroscopic resection of arthrosis of the proximal hamate: a clinical and biomechanical study

PURPOSE: The purpose of this study was to present a series of patients with arthrosis of the proximal hamate treated by arthroscopic resection. To further investigate this condition a biomechanical study also was undertaken to document the effect this proximal hamate resection has on carpal loading. METHODS: Between 1991 and 2001 there were 23 patients who had arthroscopic proximal hamate resection for the treatment of proximal hamate arthrosis. Twenty-one patients were available for final follow-up evaluation (average, 4.7 y). Patients were evaluated by using a modified wrist score that examined pain relief, patient satisfaction, range of motion, and grip strength. Six cadaver wrists had resection of the proximal hamate. Loads across the carpal and midcarpal joints were documented with pressure-sensitive film before and after proximal hamate resection. RESULTS: Ninety-five percent of the patients had a type II lunate. Twenty-one of 23 wrists had lunotriquetral tears confirmed on arthroscopic examination. Follow-up evaluation revealed 14 excellent, 4 good, 1 fair, and 2 poor results. Biomechanical studies revealed that resection of 2.4 mm of the proximal hamate unloads the hamatolunate articulation without changing the load at the triquetrohamate joint. CONCLUSIONS: Arthrosis of the proximal pole of the hamate seems to be associated closely with tears of the lunotriquetral joint and may be part of the spectrum of ulnar-sided wrist degeneration. Arthroscopic resection of the proximal pole of the hamate appears to be a useful treatment in patients with symptomatic hamate arthrosis, even in those patients with lunotriquetral laxity.     

The use of medical imaging-based kinematic analysis in the evaluation of wrist function and outcome

The authors developed a 3D CT technique to analyze in vivo variations in carpal bone position based on 3D reconstruction of transverse CT data in 5 wrist positions. The subject groups analyzed consisted of 40 asymptomatic volunteers and 30 patients with various wrist disorders (fractures, instabilities). In 11 anatomic specimens, this kinematic analysis was completed by a radiographic morphologic study and an investigation of capsular ligament anatomy. Clinical applications showed that carpal bone motion in the injured wrist was not significantly different from contralateral, asymptomatic wrist motion. In both wrists of patients with unilateral pathology, however, significant differences were observed as compared with asymptomatic volunteers. Scaphoid motion was bilaterally altered, suggesting the existence of anatomic or kinematic factors predisposing to certain carpal pathologies.     

Predicting Carpal Bone Kinematics Using an Expanded Digital Database of Wrist Carpal Bone Anatomy and Kinematics

The wrist can be considered a 2 degrees‐of‐freedom joint with all movements reflecting the combination of flexion–extension and radial–ulnar deviation. Wrist motions are accomplished by the kinematic reduction of the 42 degrees‐of‐freedom of the individual carpal bones. While previous studies have demonstrated the minimal motion of the scaphoid and lunate as the wrist moves along the dart‐thrower's path or small relative motion between hamate‐capitate‐trapezoid, an understanding of the kinematics of the complete carpus across all wrist motions remains lacking. To address this, we assembled an open‐source database of in vivo carpal motions and developed mathematical models of the carpal kinematics as a function of wrist motion. Quadratic surfaces were trained for each of the 42‐carpal bone degrees‐of‐freedom and the goodness of fits were evaluated. Using the models, paths of wrist motion that generated minimal carpal rotations or translations were determined. Model predictions were best for flexion–extension, radial–ulnar deviation, and volar–dorsal translations for all carpal bones with R ² > 0.8, while the estimates were least effective for supination‐pronation with R ² < 0.6. The wrist path of motion's analysis indicated that the distal row of carpal bones moves rigidly together (<3° motion), along the anatomical axis of wrist motion, while the bones in the proximal row undergo minimal motion when the wrist moves in a path oblique to the main axes. The open‐source dataset along with its graphical user interface and mathematical models should facilitate clinical visualization and enable new studies of carpal kinematics and function. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2661–2670, 2019     

Evolution of arthritis of the wrist

Degenerative arthritis of the wrist follows very specific patterns from onset to terminal severe bone and joint destruction. About 95% of them occur as periscaphoid area problems: SLAC (scapholunate advanced collapse pattern) wrist (55%), triscaphe arthritis (26%), and a combination of the two (14%). In SLAC wrist, the repeating sequence of degenerative change is based on and caused by articular alignment problems between the scaphoid and the radius. Changes then progress between the capitate and the lunate that are secondary to carpal collapse. In triscaphe arthritis, the degenerative change is limited to between the trapezium, trapezoid, and distal scaphoid. SLAC procedure (fusion of the capitate, lunate, hamate, and triquetrum along with silastic scaphoid implant) for SLAC wrists and triscaphe arthrodesis (fusion of the scaphoid, trapezium, and trapezoid) for triscaphe arthritis, are designed to make maximum use of undamaged structures and to maintain full-power, painless, mobile human wrists.     

In vivo scaphoid, lunate, and capitate kinematics in flexion and in extension

Carpal kinematics have been previously limited to in vitro models with cadaveric specimens. Using a newly developed markerless bone registration algorithm, we noninvasively studied the in vivo kinematics of the capitate, scaphoid, and lunate during wrist extension and flexion in both wrists of 5 men and 5 women. Computed tomography volume images were acquired in neutral and in 2 positions in both extension and flexion. The 3-dimensional kinematics of the capitate, scaphoid, and lunate relative to the radius were the determined. Scaphoid and lunate rotations differed for flexion and extension but were found to vary linearly with capitate rotation. In flexion the scaphoid contributed 73% of capitate motion and the lunate contributed 46%. In extension the scaphoid contributed 99% of capitate motion and the lunate contributed 68%. Contributions of the scaphoid and lunate to wrist extension were 15% greater than values reported in previous in vitro studies, while scaphoid and lunate contributions to wrist flexion were more similar to previous studies. The findings support a relative "engagement" of the scaphoid, capitate, and lunate during wrist extension. The only difference between male and female kinematics was a more distal location of the rotation axes; we believe this was due to a difference in carpal bone size, not gender. This study reports the 3-dimensional in vivo measurement of carpal motion using a noninvasive technology. This technique may prove useful in the study of more complex motions of the hand and wrist and of the abnormal kinematics that occur following ligamentous injury.     

Treatment of distal radioulnar disorders

Twenty-nine wrists of 29 patients were treated with three procedures: distal ulnar resection (Darrach's procedure), distal ulnar recession, or hemiresection-interposition arthroplasty. The indications were pain and limitation of motion associated with primary osteoarthritis of the distal radioulnar joint, derangement after distal forearm bone fracture, Madelung's deformity, and distal radioulnar sprain. The age of the patients averaged 48.3 years. Follow-up averaged 1 year and 9 months. Radiographic evaluations were done preoperatively and postoperatively. Relief of pain was good in the wrists treated by Darrach's procedure; however, diminished grip strength and wrist instability occurred. Relief of pain in the wrists treated by distal ulnar recession and hemiresection-interposition arthroplasty was inferior to that of Darrach's procedure; however, postoperative grip strength increased and wrist instability did not occur.     

Motion analysis in two dimensions of radial-ulnar deviation of type I versus type II lunates

The motions of 2 different types of lunate (type I, no medial hamate facet; type II, medial hamate facet) were evaluated and compared during radial-ulnar deviation of the wrist using radiography and magnetic resonance imaging. Ten right wrists (5 type I and 5 type II lunates) were studied using posteroanterior and lateral x-rays. Six of the 10 normal volunteers (3 type I and 3 type II lunates) were studied using magnetic resonance imaging in 6 positions of radial-ulnar deviation. In the radiographic study the ulnar shift ratio of the lunate (USR), the shortest distance between the proximal ulnar tip of the lunate and the distal ulnar edge of the sigmoid notch of the radius (R-L), the closest distance between the distal ulnar tip of the lunate and the proximal pole of the hamate (L-H), the radius of curvature of the proximal head of the capitate (Cr) on posteroanterior view, and the radiolunate angle on lateral view were measured in each wrist in each of the 6 positions. There were statistically significant differences between type I and II lunates with regard to average maximum ulnar deviation of USR and R-L, total change of USR, R-L distance and L-H distance, average L-H distance and Cr distance in all positions, and average radiolunate angle in neutral and 15 degrees ulnar deviation. In the magnetic resonance imaging study the wrists with a type I lunate did not have contact between the lunate and hamate in any position; the wrists with a type II lunate did have contact between the hamate and the lunate, but only in ulnar deviation. The results of this study demonstrate that the kinematics of a type I lunate are different from those of a type II lunate during radial-ulnar deviation of the wrist.     

Three-dimensional kinematic analysis of the second through fifth carpometacarpal joints

The kinematics of the 2nd through 5th carpometacarpal (CMC) joints was investigated by using a 3-dimensional dynamic motion analysis system to delineate flexion-extension motion, radial-ulnar deviation, and pronation-supination motion. Analysis of the axes of rotation revealed that the axes of rotation for flexion-extension motion are located within the base of each respective metacarpal bone. The axis of rotation for radial-ulnar deviation passes through the distal carpal bone of each CMC joint except in the 3rd CMC joint where the axis of rotation is located within the base of the 3rd metacarpal. The axis of rotation for pronation-supination motion passes through the base of the respective metacarpal except in the 3rd CMC joint where it is located within the hamate. The overall flexion-extension motions of the 2nd and 3rd carpometacarpal (CMC) joints were found to be more limited than those of the 4th and 5th CMC joints (11 degrees, 7 degrees to 20 degrees, 27 degrees, respectively) and even more so in radial-ulnar deviation (2 degrees, 4 degrees to 7 degrees, 13 degrees, respectively) and pronation-supination motion (5 degrees, 5 degrees to 27 degrees, 22 degrees, respectively). The 5th CMC joint has the greatest overall range of motion with the flexion-extension motion found to be greatly reduced by 40% to 28 degrees when the 4th CMC joint was immobilized. Maximum range of motion in flexion-extension of the 5th CMC joint is dependent on and contributed by the 4th CMC joint motion.     

Kinematic considerations of the wrist

Mechanically the wrist is the most complex joint in the body, providing a large range of motion in the flexion-extension and radial-ulnar deviation planes. By virtue of the constraints at the radiocarpal level, strong torque may be delivered to the grasping hand for work in the grasping mode through the rotational axis of the forearm. The intrinsic forces acting on the wrist are well distributed around the perimeter, while the extrinsic forces for the fingers are centralized to affect wrist position minimally. The stability of the wrist in which the proximal carpal row presents an inherently unstable intercalated segment is provided by a complex osseoligamentous arrangement. The scaphoid performs a unique function as a mechanical link between the carpal rows, interacting with two arcs of oblique ligamentous support for the radiocarpal area. This allows synchronous angulation of the proximal and distal carpal rows and, by virtue of conjunct angulation, adaptive geometric change to encourage radial-ulnar deviation. The distal radioulnar joint functions both as the support of the carpus on the ulnar aspect of the joint and as a primary pivot for forearm rotation through a unique anatomic arrangement.