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Biomedical subjects

S F Viegas

Publications and source records attributed to S F Viegas.

At least 73 records · Page 4Linked to original sources
PubMed1990

The lunatohamate articulation of the midcarpal joint.

Sixty-one cadaveric wrists were dissected to assess the frequency of a medial lunate facet as well as any associated pathologic changes in the midcarpal joint. Two types of lunate were identified: Type I (39.3%), in which no medial facet was present, and Type II (60.7%), in which there was a medial facet. The medial facets in the Type II lunates ranged from a shallow 2 mm facet to a deep 6 mm facet. Significant cartilage erosion with exposed subchondral bone at the proximal pole of the hamate, which was not identifiable by radiograph, was evident at dissection in 57% of the Type II lunates, whereas none (0%) of the Type I lunates had such associated hamate pathology. Midcarpal joint arthroscopy appears to be the diagnostic procedure of choice to assess the presence of hamate proximal pole arthrosis.

Cadaver↗
PubMed1990

Medial (hamate) facet of the lunate.

One hundred sixty-five cadaveric wrists were dissected to assess the incidence of a medial (hamate) facet on the lunate and any associated pathologic conditions. Forty-seven of these specimens and 137 clinical patients' radiographs were reviewed to attempt to recognize and further assess the incidence of a medial (hamate) facet on the lunate. Two types of lunate were identified. Type I, in which there was no medial facet, was evident in 34.5% of the dissected specimens and type II, in which there was a medial facet, was evident in 65.5% of the dissected specimens. The medial facets in the type II lunates ranged from a shallow 1 mm facet to a deep 6 mm facet. Significant cartilage erosion with exposed subchondral bone at the proximal pole of the hamate, which was not identifiable by radiograph, was evident at dissection in 44.4% of the type II lunates, while none (0%) of the type I lunates had such associated hamate pathologic conditions. This type II lunate, with the high incidence of associated hamate pathology, may be an unidentified cause of wrist pain on the ulnar side.

Adolescent↗
PubMed1990

Evaluation of the biomechanical efficacy of limited intercarpal fusions for the treatment of scapho-lunate dissociation.

An experimental model that uses a static positioning frame, pressure-sensitive film, and a microcomputer-based videodigitizing system was used to measure the contact areas and pressures in a group of wrists in their "normal" state, after ligament sectioning, which resulted in stage III perilunate instability and then following different types of simulated carpal fusions. Compared with a normal wrist, there is an overall decrease in load in the lunate fossa and a significant increase in load in the scaphoid fossa in the wrist with stage III perilunate instability. Scaphoid-trapezium-trapezoid and scaphoid-capitate fusions transmitted almost all load through the scaphoid fossa. Scaphoid-lunate, scaphoid-lunate-capitate, and capitate-lunate fusions all distributed load more proportionately through both scaphoid and lunate fossae. The positioning of the carpal bones within a limited carpal fusion was also found to affect the load distribution in the wrist. The scaphoid-lunate, scaphoid-lunate-capitate, or capitate-lunate fusions, with attention to the relative carpal alignment within the limited fusion seem to offer more promise for treatment of perilunate instability biomechanically than the scaphoid-trapezium-trapezoid or scaphoid-capitate fusions.

Adult↗
PubMed1990

Avulsion of the triceps tendon.

Avulsion of the triceps tendon is a rare injury. The clinical examination, including a test for complete rupture of the tendon, radiographic findings, characteristics of the normal maturation of the olecranon, and the surgical treatment of this injury are reviewed.

Adolescent↗
PubMed1989

Modified technique of intramedullary fixation for wrist arthrodesis.

Twenty-five normal subjects were studied to assess the possible relation of various wrist postures on grip strengths. Most subjects were found to have the strongest grip strengths in a position of neutral deviation and one half of their maximum extension. A small subpopulation normally postured their clenched fists in slight ulnar deviation rather than in neutral deviation. These patients were strongest in ulnar deviation and one half of their maximum extension. A modification of the wrist arthrodesis technique was developed using intramedullary pin fixation in a series of 10 patients. Fusion was successful in all 10 wrists. This technique retains the advantages of speed and simplicity of previous intramedullary fixation methods and also affords the additional advantage of permitting the wrist to be placed in varying degrees of extension and ulnar deviation.

Adult↗
PubMed1989

The effects of various load paths and different loads on the load transfer characteristics of the wrist.

An experimental model that incorporated a static positioning frame, pressure-sensitive film, and a microcomputer-based videodigitizing system was used to analyze the effects of different loading pathways and various loads on the contact area and pressures within the wrist joint. There was no statistically significant difference in loading the wrist with comparable weights through the second and third metacarpals, through all five metacarpals, or through weights suspended from the wrist flexor and extensor tendons. A nonlinear relation was discovered between increasing loads and greater overall contact areas. The general distribution of the contact between the scaphoid and the lunate contact areas was consistent at all of the loads tested with 60% of the total contact area involving the scaphoid contact area and 40% involving the lunate contact area. Loads greater than 46 pounds were not found to significantly increase the overall contact areas implying that the cartilage of the wrist joint was maximally compressed at loads of this magnitude. At loads higher than 46 pounds it appears that average high pressures increase in a more direct correlation with the increase in weight. The overall contact area even at the highest loads tested were not more than 40% of the available joint surface. The contact areas were not concentric or symmetric as is characteristic of the incongruance of the radio/triangularfibrocartilage (ulna)/carpal joint.

Adult↗
PubMed1989

Complex fracture-dislocation of a fifth metacarpophalangeal joint: case report and literature review.

An uncommon complex fracture-dislocation of the fifth metacarpophalangeal joint with an unusually important fracture component is presented. The injury was successfully treated by a combination of open reduction exposing the entrapping structures and percutaneous pin fixation. The case demonstrated the classic pathomechanics as described by Kaplan in 1957. The widened joint space and interposed sesamoid as described by Nutter in 1940 were seen on radiographs.

Adult↗
PubMed1989

Treatment of high-pressure water gun injection injury of the foot with adjunctive hyperbaric oxygen: a case report.

High-pressure injection injuries are reported often in the hand and occasionally in the foot. Injection with water and air causes minimal tissue damage but nevertheless requires irrigation, minimal debridement, administration of antibiotics, and concern for development of compartment syndrome. The outcome for patients injected with water and air should be excellent. Adjunctive hyperbaric oxygen causes immediate resolution of subcutaneous emphysema, edema, and pain for more rapid rehabilitation.

Adult↗
PubMed1989

Magnetic resonance imaging in the assessment of revascularization in Kienbock's disease. A preliminary report.

A 25-year-old man with stage II Kienbock's disease of his left lunate underwent an initial period of immobilization. He was subsequently treated by ulnar lengthening, with a good outcome. Magnetic resonance imaging (MRI) was utilized to demonstrate the lack of improvement with cast immobilization and the revascularization that followed surgical treatment. This new application of MRI in cases of avascular necrosis of the lunate may be helpful in the early identification of revascularization.

Adult↗
PubMed1989

Cherry pitter's thumb. Case report and review of the literature.

Perineural fibrosis and scarring of the digital nerves in the hand can result from chronic compression and repetitive trauma. The digital nerves in the thumb have been reported to undergo these changes as a result of such trauma from bowling and the use of fine instruments by a jeweler. This article describes a case of digital neuropathy of the thumb resulting from a cherry-pitting instrument. A protective neoprene thumb sleeve and avoidance of further trauma to the nerves relieved the patient's symptoms.

Adult↗
PubMed1989

Floating dislocated elbow: case report and review of the literature.

A 59-year-old shrimper sustained ipsilateral fractures of the midshafts of the humerus, ulna, and radius, as well as an ipsilateral posterior dislocation of the elbow. The mechanism of this unusual injury involved the winch system of a shrimpboat. Closed reduction of the dislocation along with open reduction and internal fixation of the fractures allowed early elbow motion. The resulting final range of motion and function were good.

Accidents, Occupational↗
PubMed1989

Mycobacterium marinum flexor tenosynovitis.

Four culture-positive cases of flexor tenosynovitis of the hand caused by Mycobacterium marinum are reported. The organisms were cultured at 32 degrees. All patients were treated with a combination of flexor tenosynovectomy and antimycobacterial treatment with ethambutol and rifampin. The length of antimycobacterial treatment ranged from nine to 22 months. All four patients responded to treatment with cessation of signs of infection, increased range of motion, and complete wound healing.

Adult↗
PubMed1988

Pressure distribution in the wrist joint.

We performed a study to determine pressure distribution properties of the normal radio-carpal joint. A system was developed for measurement of the contact pressure within the wrist joint surfaces. The transducer was based on Fuji pressure-sensitive paper, which was inserted into the joint space through a dorsal capsular incision. The hand was then positioned using a jig that permitted free axial loading of the joint. Each of five specimens was tested in 36 positions combining flexion/extension with radio/ulnar deviation and supination/pronation. The transducers were analyzed for contact area, scapho-lunate contact area ratio, pressure, and centroid locations using a microcomputer-based video-imaging system. The scaphoid and lunate contact areas on the radius and triangular fibrocartilage were separate and distinct in all wrist positions. Together these contact areas accounted for a relatively small fraction of the total joint surface area (average contact area/total joint area = 0.206, SD = 0.0495). For an applied 103 Newton compressive load, the high pressure averaged 3.17 MPa (SD = 0.83 MPa). Overall, the scaphoid contact area was 1.47 times that of the lunate, although variations occurred with position, as in flexion, in which the scaphoid/lunate area ratio was 0.83. The high-pressure centroids of both scaphoid and lunate contact areas shifted palmarly from 20 degrees of flexion to 20 degrees of extension and then dorsally with further extension. The scaphoid-lunate intercentroid distance averaged 14.91 mm with a range of 10-20 mm.

Carpal Bones↗
PubMed1988

Palmar lunate dislocation with a dorsal scaphoid fracture variant.

A 20-year-old man had a dorsally displaced fracture of the proximal pole of the scaphoid and an ipsilateral palmar lunate dislocation--a rare combination of injuries that has not been previously reported. The most likely pathomechanics of this injury is a sheer fracture of the proximal pole of the scaphoid by the dorsal lip of the distal radius as the injury shifts from a dorsal perilunate to a palmar lunate pattern.

Adult↗
PubMed1988

Comparative mechanical properties of various Kirschner wire configurations in transverse and oblique phalangeal fractures.

A biomechanical study assessed the comparative mechanical properties of various wire configurations used in transverse and oblique phalangeal fractures. The configurations included crossed, oblique, and intramedullary wire techniques using 0.028-inch diameter (d) or 0.035-inch d Kirschner (K) wires. Six different configurations were tested in both the oblique fracture pattern and in the transverse fracture pattern. The mechanical properties were determined after either oblique or transverse osteotomy and fixation of the proximal phalanx. Each fixation technique was tested in apex palmar, apex dorsal, and lateral bending, as well as in torsion and distraction. The results showed that of the configurations tested, four crossed 0.028-inch d Kirschner wires obtained the highest rigidity in the transverse fracture pattern and three oblique 0.035-inch d Kirschner wires obtained the highest rigidity in the oblique fracture pattern.

Aged↗
PubMed1988

Arthroscopic treatment of osteochondritis dissecans of the scaphoid.

Osteochondritis dissecans of the carpal scaphoid has been reported only rarely in the literature. A 29-year-old, right-hand-dominant oil-field worker with symptomatic osteochondritis dissecans of the left carpal scaphoid was treated by arthroscopic debridement and drilling of the lesion. Preliminary follow-up at 9 months revealed a dramatic relief in his symptoms.

Adult↗