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Biomedical subjects

D J Downey

Publications and source records attributed to D J Downey.

15 recordsLinked to original sources
PubMed1991

New Mexico rattlesnake bites: demographic review and guidelines for treatment.

The demographic features, treatment, and outcome of 36 rattlesnake envenomation cases are reviewed. Two populations at special risk are identified: (1) young children (12/36) who sustain lower extremity bites, and (2) adults who consume alcohol and handle snakes (10/36) who sustain upper extremity bites. Antivenin was used in 22 cases with only one serious case of serum sickness. Three definite diagnoses of compartment syndrome were made on the basis of elevated compartment pressures. Hand bites accounted for 20 of the 36 cases. The greatest functional disability followed digit bites in that 11 patients developed decreased motion and sensation. The indications for fasciotomy and debridement are discussed, both for digit and non-digit envenomations. General treatment recommendations are given.

Adolescent↗
PubMed1991

Subchondral architecture in bones of the canine shoulder.

The distal scapula and proximal humerus from each shoulder of nine adult dogs were slab-sectioned, cleaned of soft tissues, embedded in white plastic and stained black with a silver stain. These preparations were then photographed for automated, digital, morphometric analysis of subchondral bone structure. Comparison of transverse and coronal sections through the left and right shoulders demonstrated essential isometry of trabecular patterns within each bone. Comparison of the scapula and humerus revealed significant differences in bony architecture. The subchondral plate was an average of 5.6 times thicker under the glenoid fossa than in the opposing humeral head. Deeper trabecular structure also differed with the trabecular bone volume (density) in the humerus being greater than that in the scapula. This difference reflects a greater trabecular density in the humerus with comparable trabecular thickness in both bones. These structural differences are consistent with previous functional studies of the same two bones that revealed greater mechanical stiffness beneath the glenoid fossa and greater hydraulic resistance within the humeral head.

Animals↗
PubMed1990

Optimizing bone screw pullout force.

Stability of internal fixation by plate and screw depends on the interface of bone and screw threads. Bone-screw thread design was tested in a synthetic bone model to determine maximum bone-screw pullout force. The model was confirmed to provide reproducible results in a clinically relevant range. Consistent material properties were reflected in the relatively small standard deviations in pullout force, which were less than 10% of mean values. As expected, major diameter was an important determinant of pullout force in a roughly linear manner. Pitch was important with a finer thread giving greater purchase. Minor diameter and the ratio of major to minor diameter had a small but significant effect on pullout force. This study was significant for establishing a good bone-screw testing model and suggesting important thread parameters in selecting or manufacturing a bone screw to optimize its holding power.

Biomechanical Phenomena↗
PubMed1990

A computerized approach to injury description.

The study of trauma has been handicapped from its inception by the absence of a single coherent method of cataloging injuries. The AIS and ICD-9 systems have failed to fill this void because they lack the precision necessary to describe surgically treated injuries. We conceived a simple system of injury description in which injuries are rapidly encoded using a microcomputer in sufficient detail to distinguish among millions of different injuries. This system is easily searched by a microcomputer and allows for the automatic assignment of AIS, ISS, and CPT codes. In this system a patient is described by a 'paragraph' consisting of any number of identically patterned 'sentences,' each describing one of the patient's injuries. Each 'sentence' is composed of a string of six 'words' from controlled vocabularies and has the following structure: "Body region, Organ, Anatomic region, Injury, Physiology, Treatment." Defining the vocabulary allowed for each 'word' in a 'sentence' is complex because the allowed vocabulary is dependent upon the preceding 'words' in a 'sentence,' but in practice a microcomputer simply provides short lists of acceptable choices at each step of injury description, and records the user's selections. Additionally, the microcomputer assigns AIS, ISS, and CPT codes appropriate to the injury description sentence. The ease of data entry, the fineness of detail captured, the automation of code assignment, and the accuracy of database searching for specific injuries, classes of injuries, or combinations of injuries, we believe will give this approach widespread application in academic trauma centers where an accurate and accessible trauma database is important.

Humans↗
PubMed1988

Tibialis posterior tendon rupture: a cause of rheumatoid flat foot.

Flat foot, a major cause of foot pain and disability, may result from rupture of the tibialis posterior tendon. We describe 2 patients with rheumatoid arthritis who developed flat feet secondary to surgically confirmed tendon rupture, and we discuss the anatomy and diagnosis of this condition. In the second patient, we also present the results of tendon imaging with both magnetic resonance and ultrasound.

Aged↗
PubMed1988

Apophyseal arthritis limits lumbar motion in patients with ankylosing spondylitis.

Ankylosing spondylitis patients who develop progressive spinal flexion may assume this posture to alleviate the pain of apophyseal arthritis. To examine this relationship, we scored injury to L4-L5 and L5-S1 apophyseal joints, as assessed by computed tomography, in 10 men with early ankylosing spondylitis. Both by the modified Schober test and by radiography of the lateral spine, impaired spinal motion correlated highly with evidence of apophyseal injury.

Adolescent↗
PubMed1988

Hydraulic resistance: a measure of vascular outflow obstruction in osteonecrosis.

This study introduces hydraulic resistance (HR) as a new method to measure intraosseous vascular outflow resistance in the human proximal femur. HR is the standard measure of resistance to fluid flow in porous matrices and is derived from serial pressure/flow determinations. Eighteen hips were studied in 11 patients taken to surgery for core decompression therapy of presumable atraumatic osteonecrosis of the femoral head. HR was much higher in osteonecrotic (174 +/- 29 mm Hg min/ml, SE) than in normal human cadaveric femora (14 +/- 6) and was also higher in subcapital (253 +/- 39) than intertrochanteric sites (78 +/- 17). HR correlated highly with baseline intraosseous pressure (r = 0.74, p less than 0.001). HR testing is a simple, practical method which quantifies outflow obstruction of the intraosseous circulation. We believe this test will be helpful in the diagnosis of atraumatic osteonecrosis and in the understanding of its underlying pathophysiology.

Adult↗
PubMed1988

Ligament length relationships in the moving knee.

This article presents an investigation of potential ligament attachment sites for surgical reconstruction of the anterior and posterior cruciate ligaments as well as for the lateral extraarticular iliotibial band tenodesis. Our methodology was based on quantitative measurements of knee anatomy and motion in fresh cadavers, not on biomechanical modeling. Using computer search techniques, we located all the ligament insertion sites that were nearly isometric for motion of the intact knee.

Biomechanical Phenomena↗
PubMed1988

The effect of compressive loading on intraosseous pressure in the femoral head in vitro.

We measured intraosseous pressures in twenty human hips from cadavera during progressive serial applications of load using a materials-testing machine. Pressure rose in strict proportion to load at each of four different testing sites. In the femoral head, the mean response to loads applied over 0.1 second was 55 +/- 66 millimeters of mercury per 980 newtons. This value was 3.6 times higher than the mean response in a region cephalad to the acetabulum and 2.6 and 2.8 times higher than the mean response in the femoral neck and intertrochanteric regions. In further studies within the femoral head, pressures were accentuated and reduced by factors of 1.7 and 0.4, respectively, at faster (0.03 second) and slower (1.0 second) loading times.

Biomechanical Phenomena↗
PubMed1987

Cutaneous and ocular side-effects of oral photochemotherapy: results of an 8-year follow-up study.

To determine the long-term cutaneous side-effects of oral photochemotherapy (PUVA), we examined 95 patients, 59 with psoriasis and 36 with mycosis fungoides (MF). These comprised 80% and 69% respectively of the patients with these disorders treated with PUVA in our department from 1977 to 1985. Two psoriatic patients had squamous carcinomas, both of whom had received high cumulative UVA doses and also methotrexate concurrently with PUVA. Six patients with MF had actinic keratoses. The mean age of these patients (69 years) was significantly greater than the mean age of the patients without actinic keratoses (54 years), but there was no significant difference in their cumulative UVA doses. No patients developed basal cell carcinomas or malignant melanoma. 'PUVA lentigines' were found in 46% of the patients. They were most frequent in patients currently being treated and in those who had received high cumulative UVA doses, but persisted for up to 7 years after discontinuing therapy. Seventy-one patients had yearly ophthalmological examinations, or a single examination at least 3 months after commencing PUVA. This examination included retinal function tests to detect any subclinical visual impairment. Five of these patients had cataract prior to PUVA therapy, and were significantly older (mean age 71 years) than those without cataract (mean age 53 years). Three patients (mean age 61 years) developed new lens opacities whilst receiving PUVA. However, none of these patients was considered to have cataract as none had impairment of visual acuity due to lens opacity. No patients without lens opacity developed evidence of subclinical visual impairment.

Actins↗
PubMedDate not supplied

Magnetic resonance image findings in congenital talipes equinovarus.

Magnetic resonance imaging (MRI) was used to image the feet of 10 infants with congenital talipes equinovarus. Images in an intermediate density and T2 sequence are most useful. In the transverse plane, the primary deformity appears to be localized to a medical deviation of the talar neck and head, with an accompanying internal rotation of the calcaneus relative to the talar body. The posterior calcaneus is laterally deviated by this rotation. In the sagittal plane, the deformity appears to lie in a parallelism in the subtalar relationship.

Clubfoot↗