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Biomedical subjects

R J Friedman

Publications and source records attributed to R J Friedman.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cine magnetic resonance imaging of the subcoracoid region.

Cine magnetic resonance imaging (MRI) was used to define the normal space between the humeral head and coracoid process, known as the subcoracoid space, to quantify the subcoracoid space in symptomatic patients and identify the anatomic structures responsible for narrowing of this space. The study population was comprised of 50 normal volunteers and 75 patients with shoulder pain. All subjects underwent cine MRI of the shoulder using a shoulder-rotating device that allows progressive rotation of the glenohumeral joint in 10 degrees increments from internal to external rotation while scanning the shoulder in the axial plane. In asymptomatic patients, the normal interval between the lesser tuberosity and coracoid process (coracohumeral distance) averaged 11 mm in maximum internal rotation. In symptomatic patients, impingement or entrapment of the subscapularis tendon and other soft-tissue structures between the lesser tuberosity and the coracoid process in internal rotation was identified, and the mean distance between the lesser tuberosity and coracoid process measured 5.5 mm in maximum internal rotation. This new MRI technique for shoulder imaging is safe, easy to perform, noninvasive, and well-tolerated by patients. Cine MRI provides valuable information on the subcoracoid region not obtainable with other methods.

Humans↗
PubMed1997

Is duplex venous surveillance worthwhile after arthroplasty?

Deep venous thrombosis (DVT) complicates 60% of knee and 80% of hip arthroplasties performed without prophylactic therapy. Routine postoperative duplex ultrasound surveillance has been proposed for the detection of venous thrombosis following arthroplasty. In order to determine whether surveillance represents an effective strategy to detect postoperative DVT when prophylaxis is used, surveillance duplex exams obtained after primary or revision hip or knee arthroplasty were analyzed using decision analysis techniques. DVT was suspected clinically after 95 of 738 (13%) arthroplasties, with no symptoms suggestive of DVT after the remaining 643 procedures. Surveillance duplex scans were performed within 2 weeks of 371 procedures, while no surveillance studies were performed after the remaining 272 procedures. In these asymptomatic patients only 2 (0.5%) surveillance duplex studies were positive for DVT. In contrast, 4 of 37 (11%) duplex exams and 5 of 62 (8%) contrast phlebograms performed among symptomatic patients were positive for DVT. The overall incidence of DVT after arthroplasty in the entire population was 1.4% (10/738) with no pulmonary emboli. Patient follow-up averaged 162 +/- 285 days. Using the 1995 Medicare reimbursement of $163 for venous duplex, the incremental cost was $35,000 to detect 1 additional unsuspected DVT and $110,000 per additional quality-adjusted life-year gained. The low incidence of clinically significant DVT and pulmonary emboli with current prophylaxis does not justify an aggressive screening program. Decision analysis suggests that a greater incidence of DVT is required for screening to be worthwhile.

Adolescent↗
PubMed1997

Translational injuries in posterior elbow dislocation.

We describe a new plain radiographic finding in posterior elbow dislocation: a defect in the nonarticular posterior surface of the capitellum caused by impaction of the radial head during dislocation. The defect was visible on a lateral view unobscured by overlying bony structures in the unreduced state and confirmed on both an axial view after reduction and by magnetic resonance imaging. We propose that this lesion is analogous to the Hill-Sachs/Bankart lesion complex seen in translational glenohumeral injury.

Accidents, Traffic↗
PubMed1997

Mechanical properties of rat epiphyseal cancellous bones studied by indentation testing.

Twenty-six pairs of rat femoral heads, distal femurs, proximal tibiae, and humeral heads were tested using an indentation test with a flat-ended cylindrical indentor. A useful mechanical data set including ultimate load, stiffness, and ultimate strength has been generated. Differences were found between the cancellous bones at different locations. Good correlations have been obtained between indentation depth (at 50 N load) and ultimate strength (R=-0.937, p<0.05), which means that with an increase of ultimate strength the indentation depth or deformation decreased proportionally. Based on the experimental results and the comparison with other methods in the literature, the simplicity and usefulness of this indentation test to evaluate compressive mechanical properties of rat epiphyseal cancellous bone are apparent.

Journal Article↗
PubMed1997

The prevention of prosthetic infection using a cross-linked albumin coating in a rabbit model.

We evaluated the effects of a serum protein coating on prosthetic infection in 29 adult male rabbits divided into three groups: control, albumin-coated and uncoated. We used 34 grit-blasted, commercially pure titanium implants. Eleven were coated with cross-linked albumin. All the implants were exposed to a suspension of Staphylococcus epidermidis before implantation. Our findings showed that albumin-coated implants had a much lower infection rate (27%) than the uncoated implants (62%). This may be a useful method of reducing the infection of prostheses.

Abscess↗
PubMed1997

Prospective analysis of total shoulder arthroplasty biomechanics.

A prospective clinical trial was undertaken to evaluate preoperative and postoperative shoulder motion clinically and roentgenographically in 9 patients with severe arthritis who underwent a total shoulder arthroplasty. The relative contributions of glenohumeral and scapulothoracic motion to scapular plane abduction were determined by obtaining roentgenograms of the shoulder region with the arm in five positions before surgery and at follow-up. Before surgery, the ratio of glenohumeral to scapulothoracic motion was 0.32:0.68, or 1:2, compared with a normal ratio of 2:1, meaning that for every degree of glenohumeral movement there were 2 degrees of scapulothoracic motion. At follow-up, statistically significant improvements in pain, motion, and function were found. However, regression analysis determined the ratio of glenohumeral to scapulothoracic motion to be 1:1.3. An abnormal ratio before surgery was associated with significant pain and decreased motion in the shoulder and represented the patients' attempt to immobilize the glenohumeral joint for pain relief and maximize shoulder movement with scapulothoracic motion. The abnormal glenohumeral-to-scapulothoracic ratio after total shoulder arthroplasty indicates that for a given amount of arm abduction, less motion occurs between the prosthetic components than in a normal glenohumeral joint. Abnormal shoulder biomechanics appear to be a function of the underlying disease process and were not restored after total shoulder arthroplasty.

Adult↗
PubMed1997

Effects of multiple freezing-thawing cycles on ultimate indentation load and stiffness of bovine cancellous bone.

OBJECTIVE: To assess the effects of multiple freezing-thawing cycles on ultimate indentation load and stiffness of bovine tibial cancellous bone with regard to freezing conditions (saline solution or air) or methods of thawing (saline solution or air). SAMPLES: 4 tibias from 4 adult cows. PROCEDURE: The proximal portions of the tibias were sectioned to produce 20-mm-thick bone slices. Slices were subjected to 5 freezing-thawing cycles under 4 conditions: freezing with and without saline solution, then thawing in saline solution or exposed to the air. The mechanical properties of the bone slices before and after the treatments were measured, using an indentation test for comparison. Indentation testing was performed before and after freezing-thawing cycles to measure differences in mechanical parameters. RESULTS: Significant differences in mechanical parameters were not found for bone specimens frozen in saline solution and thawed in saline solution; frozen without saline solution and thawed in air; frozen in saline solution and thawed in air; or frozen without saline solution and thawed in saline solution. CONCLUSIONS: Multiple thawing-freezing cycles do not significantly affect the ultimate indentation load and stiffness of bovine tibial cancellous bone.

Animals↗
PubMed1996

Influence of biomaterial surface texture on bone ingrowth in the rabbit femur.

The purpose of this study was to examine both the histologic and the mechanical characteristics of bone apposition to an experimental surface, arc-deposited titanium, in a rabbit model and to compare them with those of four previously studied surfaces: one layer of cobalt-chromium beads, three layers of cobalt-chromium beads, plasma-sprayed cobalt-chromium, and uncoated titanium alloy. Bilateral cylindrical implants were press-fit into the lateral femoral condyles of 70 adult New Zealand White rabbits, which were allowed unrestricted activity and then killed at 6 or 12 weeks. The distal femora were harvested, radiographed, and prepared for either mechanical or histologic evaluation. All of the implants with coated surfaces had significantly greater shear strength than the implants of grit-blasted titanium alloy after both 6 and 12 weeks. After 6 weeks, maximum bone apposition occurred in the beaded surfaces. After 12 weeks, the shear strengths and bone apposition of implants of arc-deposited titanium and of one and three layers of cobalt-chromium beads were significantly greater than those of implants of plasma-sprayed cobalt-chromium and grit-blasted titanium alloy. The histologic studies correlated with the mechanical results. After 12 weeks, the bone apposition and mechanical stability of arc-deposited titanium were similar to those of a single layer of beads. There appeared to be no advantage to multiple layers of beads, and the plasma-sprayed cobalt-chromium and grit-blasted titanium surfaces showed lower shear strength and bone apposition than the other groups.

Analysis of Variance↗
PubMed1996

Prevention of bacterial adherence to implant surfaces with a crosslinked albumin coating in vitro.

Titanium surfaces were coated with bovine serum albumin using carbodiimide, a crosslinking agent. The durability of the coated surfaces and the inhibitory effect of the albumin coating on bacterial adherence were tested in vitro for 20 consecutive days at 37 degrees C in phosphate buffered saline, with intermittent agitation. The results showed that only 10% of the coated bovine serum albumin decayed off the surface during the 20-day incubation period. The inhibition rate of the albumin coating on bacterial adherence remained high (greater than 8.5%) throughout the experiment. The results suggested potential use of this crosslinked albumin coating to reduce bacterial adherence and thus the subsequent possibility of prosthetic or implant infection in vivo.

Bacterial Adhesion↗
PubMed1996

Family, peer, and neighborhood influences on academic achievement among African-American adolescents: one-year prospective effects.

Using a 1-year prospective design, this study examined the influence of family status variables (family income, parental education, family structure), parenting variables (maternal support and restrictive control), peer support, and neighborhood risk on the school performance of 120 African American junior high school students. In addition to main effects of these variables, neighborhood risk was examined as a moderator of the effects of parenting and peer support. Family status variables were not predictive of adolescent school performance as indexed by self-reported grade point average. Maternal support at Time 1 was prospectively related to adolescent grades at Time 2. Neighborhood risk was related to lower grades, while peer support predicted better grades in the prospective analyses. Neighborhood risk also moderated the effects of maternal restrictive control and peer support on adolescent grades in prospective analyses. These findings highlight the importance of an ecological approach to the problem of academic underachievement within the African American Community.

Achievement↗
PubMed1996

Long-term compressive property durability of carbon fibre-reinforced polyetheretherketone composite in physiological saline.

In total hip arthroplasty, concerns such as corrosion and stress shielding associated with stiff metallic femoral components have led to the development of low stiffness advanced fibre-reinforced polymer (FRP) composite femoral components. Carbon fibre-reinforced polyetheretherketone (CF/PEEK) composite material is now one of the primary material systems being considered for composite hip stem development. As a hip stem, a composite material must be able to support a complex state of stress in the in vivo environment without failure. Considering the loading conditions of a hip stem (superimposed compression and bending), and the fact that FRP composites typically possess lower compressive than tensile strength, the compressive behaviour of FRP composites becomes very important for femoral component design. This paper presents an investigation of the long-term durability of 0 degree and 90 degrees compressive strengths of CF/PEEK composite following physiological saline saturation. 0 degree and 90 degrees compressive moduli and Poisson ratio (v12) properties are also reported. Samples were tested following conditioning in physiological saline at 37, 65 and 95 degrees C for time periods from 0 to 5000 h. Dry samples were tested as controls. Results show no significant loss in compressive property values of the saline-saturated or the dry control samples as a function of conditioning time or temperature.

Benzophenones↗
PubMed1996

The incidence of malignant melanoma in the United States: issues as we approach the 21st century.

The risk of malignant melanoma developing in an American in the United States has now reached 1 in 87 (up more than 1800% since the 1930s). This rising incidence of malignant melanoma is, in fact, real because (1) it is not due to increased surveillance; (2) it is not due to better cancer-counting methods in general; (3) it is not due to changes in histologic diagnostic criteria; (4) it is being noted worldwide; and (5) most importantly, despite rising survival percentages, the mortality rate from malignant melanoma also continues to rise. On the basis of these trends, incidence rates for malignant melanoma will continue to rise for at least the next 10 to 20 years, although the demographics of those affected may change. Effective programs to improve public and professional education must be developed to enhance early clinical detection and behavioral changes. An establishment of a National Melanoma Registry is needed to more effectively assess the magnitude and impact of future incidence and the success of prevention program efforts into the next century.

Adult↗
PubMed1996

Prevention of sepsis in total joint arthroplasty.

Because of the adoption of effective prophylactic measures such as improved operating room techniques and systemic antibiotics, the prosthetic infection rate for artificial joint procedures has been reduced to 1-2%. However, because of the devastating results and large number of prosthetic procedures, prosthetic infection remains a major challenge. Common pathogens and mechanisms of infection, methods of preventing bacterial adherence to biomaterial surfaces, and clinical preventive strategies for prosthetic infections are discussed.

Bacterial Adhesion↗
PubMed1996

Osteonecrosis of the humeral head in sickle cell disease.

To determine the effects of sickle cell disease on the glenohumeral joint, 28 shoulders in 14 patients with SS sickle cell hemoglobinopathy were studied clinically and roentgenographically. patients were randomly selected; their mean age was 46 years (range, 22 to 63 years). Pain, stability, and function of the shoulders were assessed, and roentgenograms were evaluated for osteonecrosis. All 28 shoulders had some degree of pain with activity, but functional range of motion was maintained despite symptoms. Seventy-one percent of the patients had had total hip arthroplasty and 21% had had total knee arthroplasty for osteonecrosis; there was a mean of 1.5 previous joint implants per patient. Our study results show that, in patients with sickle cell hemoglobinopathy, symptoms of humeral head osteonecrosis are better tolerated than those of osteonecrosis in the lower extremities, delaying the need for surgical intervention. With severe pain and functional limitations, shoulder arthroplasty is the procedure of choice in this patient population. However, the risks are greater for patients with sickle cell disease than for other patients who have humeral head osteonecrosis, and thorough preoperative medical and anesthesia evaluations are necessary. These patients require perioperative transfusion or plasmapheresis and sufficient intraoperative hydration and oxygenation to avoid precipitating a sickle cell crisis; in addition, use of methyl methacrylate should be avoided.

Adult↗
PubMed1996

A safety and efficacy comparison study of two dosing regimens of epoetin alfa in patients undergoing major orthopedic surgery.

Previous studies have demonstrated the efficacy of perioperative Epoetin alfa in decreasing allogeneic transfusion exposure in patients undergoing orthopedic surgery. A randomized, multicenter trial was conducted comparing the safety and efficacy of a weekly Epoetin alfa dosing regimen in patients with hemoglobin levels > or = 10 to < or = 13 g/dL scheduled to undergo major elective orthopedic arthroplasty, with a daily regimen previously shown to be effective. patients on the weekly regimen showed a greater baseline-to-presurgery hemoglobin increase versus the daily regimen group (1.44 +/- 1.029 g/dL versus 0.73 +/- 0.867 g/dL). Moreover, the weekly 600 IU/kg regimen was similar to the daily 300 IU/kg regimen with respect to safety and the avoidance of allogeneic transfusion. These data showed the weekly Epoetin alfa regimen to be at least as efficacious as the daily regimen and more convenient.

Aged↗
PubMed1996

Mechanical symmetry of rabbit bones studied by bending and indentation testing.

OBJECTIVE: To determine whether mechanical parameters of rabbit long bones are bilaterally symmetric. ANIMALS: Adult male New Zealand White rabbits. PROCEDURE: 17 pairs of femurs, tibias, and humeri were mechanically tested with 3-point bending (for diaphyseal bone) and indentation (for epiphyseal bone). RESULTS: Significant differences were not found between the right and left femur, tibia, or humerus for all bending parameters. Significant differences were not found between the right and left femoral, tibial, or humeral epiphyses for all indentation parameters. CONCLUSIONS: The results indicate mechanical symmetry of rabbit long bones in terms of mean value. The study also developed a normal comparable database for bending and indentation parameters of the rabbit femur, tibia, and humerus.

Animals↗