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Biomedical subjects

S F Viegas

Publications and source records attributed to S F Viegas.

At least 19 recordsLinked to original sources
PubMed2001

Type I versus type II lunates: Ligament anatomy and presence of arthrosis.

One hundred-seventy embalmed cadaver wrists were dissected. The type of lunate (type I, no medial hamate facet; type II, medial hamate facet), the incidence and location of arthrosis (exposed subchondral bone) in the lunohamate joint, and the anatomic relationship of the volar triquetrocapitate (T-C) and the volar triquetrohamate (T-H) ligaments were identified and measured. The relationship between the T-C and T-H ligaments was classified into 3 types. In type A the T-C ligament was completely separate from the T-H ligament, in type B the T-C ligament overlapped the T-H ligament, and in type C the T-C ligament had an additional ligament from the triquetrum to the proximal pole of the hamate. Eighty-two percent of type I lunates were associated with a type A relationship between the T-C and the T-H ligaments and 96% of type II lunates were associated with a type C relationship between the T-C and the T-H ligaments. Arthrosis at the proximal pole of the hamate was more commonly associated with the type II lunates (49%) and with the type C relationship (57%) of the T-C and T-H ligaments. The incidence of arthrosis in the lunohamate joint was also significantly greater in the type II lunate with a medial facet of 3 mm or more.

Adult↗
PubMed2001

The ligament and skeletal anatomy of the second through fifth carpometacarpal joints and adjacent structures.

A detailed and comprehensive study of the anatomy of the 2nd through 5th carpometacarpal (CMC) joints and adjacent structures and clinical relevance is reported. Multiple dorsal ligaments were identified, including 2 from the 5th metacarpal (MC), 2 from the 4th, 3 from the 3rd, and 2 from the 2nd. There were also multiple volar ligaments, 1 from the 5th MC, 1 from the 4th, 4 from the 3rd, and 1 from the 2nd. There was only 1 intra-articular ligament, which was located between the 3rd/4th MC and the capitate/hamate and provided stability even when the dorsal and volar CMC ligaments were cut. There was more variability and often multiple distinct joint surfaces or facets forming the articulations between adjacent MCs and/or adjacent distal carpal bones. The joint surfaces between the 4th MC and the capitate and/or the hamate were also variable and had 5 different types of articulation. The area of the 2nd and 3rd CMC joints was found to have the highest incidence (18%) of carpal coalition, and when present there was a dorsal bone prominence and an absence of the normal dorsal ligament anatomy.

Aged↗
PubMed2001

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.

Aged↗
PubMed2001

Variations in the skeletal morphologic features of the wrist.

Increased attention to and interest in the wrist and the field of hand surgery has brought about the discovery, rediscovery, and better description of variations in the skeletal morphologic features of the hand and wrist. In the second through fifth carpometacarpal joints, the fourth carpometacarpal articulation is the area of greatest variability. In the midcarpal joint, the scaphotrapeziotrapezoid and the capitolunate (hamate) articulations are areas of considerable variability in their skeletal morphologic features. New knowledge and awareness of variations in skeletal morphologic features in the carpus offer a better understanding and the opportunity to revisit various injury patterns and/or orthopaedic problems, and normal kinetics and kinematics to assess the effect and any differences that may be related to these different skeletal morphologic features.

Hand↗
PubMed2001

Kinematics of the wrist with a new dynamic external fixation device.

The kinematic properties of a new dynamic external fixator device for treatment of distal radial fractures are described. Using a combination of data obtained from computed tomography scans and high-speed video images, a three-dimensional reconstruction of carpal motion was made. To describe carpal motion, the radiolunate, capitolunate, and scapholunate angles were measured during flexion and extension and during radioulnar deviation. During these types of motion, the device changed normal carpal kinematics to a limited extent although the differences in kinematic pattern with and without the device were small. The results for flexion and extension correspond with data from previously published studies with other dynamic external fixators. However, because the new device (Flexafix) allows flexion and extension and radioulnar deviation, in contrast to other dynamic external fixation devices, with its use normal carpal kinematics can be approached more closely.

Adult↗
PubMed2001

Advances in the skeletal anatomy of the wrist.

Over the past decade there has been an increased interest in and study of the skeletal anatomy of the wrist. Different morphologic patterns of carpal anatomy have been identified and classified in the wrist. Certain morphologic types of carpal bones have been shown to have a correlation with the development of arthritis in joints of the wrist. Different shapes of carpal bones have also been shown to determine and affect the type of kinematics that they demonstrate.

Arthroscopy↗
PubMed2001

The dorsal ligaments of the wrist.

The anatomy and function of the dorsal ligaments of the wrist have received increased attention over the past decade. The anatomy, variability, osseous attachments, and function of the dorsal radiocarpal (DRC) and the dorsal intercarpal (DIC) ligaments have been studied. More detailed anatomic and mechanical studies of the subregions of the intercarpal ligaments have also been recently reported. The DRC and the DIC form a lateral V configuration that allows normal carpal kinematics while maintaining an indirect dorsal stabilizing effect on the scaphoid throughout the range of motion of the wrist. The DRC and the DIC together, in their lateral V configuration, act effectively as a dorsal radioscaphoid ligament that has the ability to vary its length three-fold by changing the angle between two arms of the V.

Biomechanical Phenomena↗
PubMed2000

The scaphotrapezio-trapezoidal joint. Part 1: An anatomic and radiographic study.

To evaluate anatomic variations and distribution of degenerative changes in the scaphotrapezio-trapezoidal (STT) joint, 165 embalmed cadaver wrists were examined. An interfacet ridge on the distal scaphoid was found in 81% of the wrists and the shape of the distal joint surface of the scaphoid was classified into 3 types. Underdevelopment of the capitate-trapezium ligament was found in 15% of the wrists. A new skeletal measurement for the inclination of the joint surface of the trapezium-trapezoid in the STT joint (TT inclination) was investigated anatomically and radiographically. Degenerative changes were found in 39% of the wrists. The most common location of degenerative changes was on its ulnar aspect on the distal scaphoid and on the radial and central aspect of the trapezoid on the TT side. The presence of degenerative changes had a significant correlation with a higher anatomic and/or radiographic TT inclination and/or underdevelopment of the capitate-trapezium ligament.

Adult↗
PubMed2000

Scaphoid nonunions: a 3-dimensional analysis of patterns of deformity.

We tested the hypothesis that the fracture location of scaphoid nonunions relates to the fracture displacement, development of dorsal intercalated segment instability (DISI) deformity, and changes in the contact area of the bones in the radiocarpal joint. Eleven patients with scaphoid nonunions were examined with 3-dimensional computed tomography and a new method of proximity mapping. Two different patterns of displacement of scaphoid nonunions were demonstrated, 1 volar and 1 dorsal. All patients with a volar pattern scaphoid nonunion had a DISI deformity. Only a few of the patients with a dorsal pattern scaphoid nonunion, mostly in longstanding nonunions, had a DISI deformity. The fracture line was generally distal to the dorsal apex of the ridge of the scaphoid in the volar-type fractures and proximal in the dorsal displaced fractures. The proximity map of the distal fragment of the scaphoid on the radius in the volar type shifts radial compared with normal; in the distal type it shifts dorsal. Neither of the patterns showed any significant changes of the proximity map in the radiocarpal joint at the proximal scaphoid fragment and the lunate. Whether the fracture line passes distal or proximal to the dorsal apex of the ridge of the scaphoid appears to determine the likelihood of subsequent fracture displacement, DISI deformity, and contact area of the bones in the radiocarpal joint.

Adult↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Adult↗
PubMed1999

The dorsal ligaments of the wrist: anatomy, mechanical properties, and function.

The purpose of this study was to examine the anatomy and mechanical properties of the dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments of the wrist and to better understand the functional design of the dorsal ligaments. The DRC ligament was consistently found to originate from the dorsal margin of the distal radius and extended ulnar obliquely and distally. Its radial fibers attached to the lunate and lunotriquetral interosseous ligament. The DRC ligament then inserted onto the dorsal tubercle of the triquetrum. The DIC ligament originated from the triquetrum and extended radially and attached onto the lunate, inserted into the dorsal groove of the scaphoid, and then extended to the trapezium. The DRC and DIC ligaments together, in their lateral V configuration, act effectively as a dorsal radioscaphoid ligament that has the ability to vary its length by changing the angle between the 2 arms of the V. The DRC-DIC ligaments' lateral V configuration allows normal carpal kinematics while maintaining its indirect dorsal stabilizing effect on the scaphoid throughout the range of motion of the wrist.

Adult↗
PubMed1999

Radiographic-anatomic correlation at different wrist articulations.

The radiographs of 52 fresh cadaveric wrists were reviewed to assess their reliability in predicting the presence or absence of degenerative changes at the radiocarpal, midcarpal, and carpometacarpal joints. Direct comparison with anatomic dissection showed that except for the radioscaphoid articulation, there were no other sites with significant correlation between the radiographic and anatomic findings. We conclude that plain radiographs are not totally reliable for assessing changes of degenerative joint disease in the wrist.

Cadaver↗
PubMed1999

Acrometastasis in renal cell carcinoma.

Acrometastasis is rare and may occur as the primary manifestation of an occult malignant tumor. Clinically, it may mimic benign osteoarthritic diseases, thus resulting in misdiagnosis and improper treatment. We describe a patient with renal cell carcinoma that presented itself as a case of chronic osteomyelitis after trauma to a finger. Such a lesion presents diagnostic challenges to both clinicians and histopathologists.

Bone Neoplasms↗
PubMed1998

High-speed, three-dimensional kinematic analysis of the normal wrist.

Carpal kinematics during a wrist flexion/extension motion using high-speed videodata acquisition was investigated. A cadaver forearm was stabilized, allowing unconstrained excursion of the wrist for passive range of motion (ROM). The extensor and flexor pairs of the wrist were looped together and a 1-lb weight was attached to each pair, simulating synergistic muscle tension. Capitate/radius and third metacarpal/radius angles were calculated to determine which measurement would be best for determining global wrist angle. The average difference in capitate/radius and third metacarpal/radius angles at each respective flexion/extension wrist angle for all wrists was 1.1 degrees +/- 1.6 degrees (the maximum difference was 4 degrees). Hence, the capitate-third metacarpal joint can be considered rigid. Capitate/lunate motion as described by capitate-radius Euler angles ranged from -16.9 to 23.5 with total capitate/lunate motion of 40.5 (35%) in the 114 degrees total global wrist ROM measured. Radius/lunate motion as described by lunate-radius angle ranged from -8.2 to 48.4 with total radius/lunate motion of 56.5 (49%) in the 114 degrees total global wrist ROM measured. During global wrist motion, the radiolunate joint contributes more motion in flexion than the capitolunate joint and the capitolunate joint contributes more motion in extension than the radiolunate joint. The instantaneous screw axes (ISAs) were calculated for each third metacarpal position with respect to the radius. The average distance difference between ISAs for the 4 wrists tested was -1.23 +/- 14.97 pixels. The maximum distance was 56.51 pixels and the minimum was -24.09 pixels. This new combination of motion analysis and 3-dimensional reconstructions of computed tomography images affords a high-speed, dynamic analysis of kinematics. It shows that during wrist flexion/extension, normal carpal kinematics does not have an ISA fixed in or limited to the capitate. In addition, the ISA data provide evidence that translational motion is a real and measurable component of normal carpal motion. These findings alter the understanding of carpal kinematics obtained from the results of previous studies which suggested that the center of rotation was fixed in the capitate.

Adult↗