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J R Lieberman

Publications and source records attributed to J R Lieberman.

At least 37 records · Page 2Linked to original sources
PubMed1999

Ultra-high-molecular weight polyethylene wear: an in vitro comparison of acetabular metal types and polished surfaces.

The generation of debris from the wear of ultra-high-molecular weight polyethylene (UHMWPE) is a well-recognized factor in the development of osteolysis and the long-term failure of total joint arthroplasties. Wear between the articulation of the femoral head and the polyethylene has been recognized for many years, but more recently, both retrieval and in vitro studies have demonstrated that convex surface wear or backside wear also occurs and may be of significance. Currently, modular acetabular components are being designed with polished surfaces, fewer screw holes, various polyethylene locking mechanisms, and stiffer metal alloys in an attempt to reduce backside wear. The purpose of this study was to determine if differences existed in UHMWPE wear based on the metal alloy used and the surface finish in modular acetabular components. Sixteen components in 4 groups were subjected to 10 million gait cycles using an in vitro joint simulator. All components used 28-mm cobalt chrome femoral heads on cobalt chrome tapered stems. The 4 groups differed only in the type of metal backing and type of interior finished surface: polished cobalt chrome, unpolished cobalt chrome, polished titanium, and unpolished titanium. UHMWPE changes were examined in terms of articular (concave) surface wear, backside (convex) surface wear, and frictional torque. The overall linear and volumetric wear rates were 1.05 mm/10 million cycles and 325 mm3/10 million cycles. No significant differences in linear and volumetric wear rates were detected between the cobalt chrome and titanium acetabular components. Surface finish did not influence wear rates. In terms of backside wear, all specimens in the 4 groups demonstrated total loss of all sputtered gold with the exception of those areas extruded through the screw holes. Extrusion through the screw holes was on the order of 0.0004 inch for all groups, and no significant difference was seen among the groups for this parameter. The measurements of articular frictional torque demonstrated a significant difference among the polished and unpolished cobalt chrome components (17.3 N x m vs 11.5 N x m; P = .0039, 2-way analysis of variance, Student's Newman Keuls method). Some designs in modular acetabular components have favored stiffer alloys, such as cobalt chrome, with polished concave surfaces to decrease wear on both the concave and the convex surfaces. In this study, there was no significant difference in wear rates noted between cobalt chrome and titanium acetabular components, and polishing of the components had no appreciable affect in reducing backside wear.

Acetabulum↗
PubMed1999

The effect of regional gene therapy with bone morphogenetic protein-2-producing bone-marrow cells on the repair of segmental femoral defects in rats.

BACKGROUND: Recombinant human bone morphogenetic proteins (rhBMPs) can induce bone formation, but the inability to identify an ideal delivery system limits their clinical application. We used ex vivo adenoviral gene transfer to create BMP-2-producing bone-marrow cells, which allow delivery of the BMP-2 to a specific anatomical site. The autologous BMP-2-producing bone-marrow cells then were used to heal a critical-sized femoral segmental defect in syngeneic rats. METHODS: Femoral defects in five groups of rats were filled with 5 x 10(6) BMP-2-producing bone-marrow cells, created through adenoviral gene transfer (twenty-four femora, Group I); twenty micrograms of rhBMP-2 (sixteen femora, Group II); 5 x 10(6) beta-galactosidase-producing rat-bone-marrow cells, created through adenoviral gene transfer of the lacZ gene (twelve femora, Group III); 5 x 10(6) uninfected rat-bone-marrow cells (ten femora, Group IV); or guanidine hydrochloride-extracted demineralized bone matrix only (ten femora, Group V). Guanidine hydrochloride-extracted demineralized bone matrix served as a substrate in all experimental groups. Specimens that were removed two months postoperatively underwent histological and histomorphometric analysis as well as biomechanical testing. RESULTS: Twenty-two of the twenty-four defects in Group I (BMP-2-producing bone-marrow cells) and all sixteen defects in Group II (rhBMP-2) had healed radiographically at two months postoperatively compared with only one of the thirty-two defects in the three control groups (beta-galactosidase-producing rat-bone-marrow cells, uninfected rat-bone-marrow cells, and guanidine hydrochloride-extracted demineralized bone matrix alone). Histological analysis of the specimens revealed that defects that had received BMP-2-producing bone-marrow cells (Group I) were filled with coarse trabecular bone at two months postoperatively, whereas in those that had received rhBMP-2 (Group II) the bone was thin and lace-like. Defects that had been treated with bone-marrow cells producing beta-galactosidase (Group III), uninfected bone-marrow cells (Group IV), or guanidine hydrochloride-extracted demineralized bone matrix only (Group V) demonstrated little or no bone formation. Histomorphometric analysis revealed a significantly greater total area of bone formation in the defects treated with the BMP-2-producing bone-marrow cells than in those treated with the rhBMP-2 (p = 0.036). Biomechanical testing demonstrated no significant differences, with the numbers available, between the healed femora that had received BMP-2-producing bone-marrow cells and the untreated (control) femora with respect to ultimate torque to failure or energy to failure. CONCLUSIONS: This study demonstrated that BMP-2-producing bone-marrow cells created by means of adenoviral gene transfer produce sufficient protein to heal a segmental femoral defect. We also established the feasibility of ex vivo gene transfer with the use of biologically acute autologous short-term cultures of bone-marrow cells.

Animals↗
PubMed1999

Warfarin prophylaxis after total knee arthroplasty.

Low-dose warfarin prophylaxis has been found to provide safe and effective prophylaxis after TKA. The major advantage of warfarin prophylaxis is that it can be administered orally. However, monitoring of the INR level is required, and there are concerns that TKA patients may be relatively unprotected during the early perioperative period. In addition, further analysis of the impact of asymptomatic clot formation on venous stasis disease is required. Our protocol is to administer 2 weeks of DVT prophylaxis after TKA. Routine screening with ultrasonography is not recommended at this time.

Anticoagulants↗
PubMed1998

Regional gene therapy with a BMP-2-producing murine stromal cell line induces heterotopic and orthotopic bone formation in rodents.

The ability to continuously deliver osteoinductive proteins to a specific anatomic site would facilitate the treatment of fracture nonunions and other clinical problems associated with bone loss. We have developed a murine model of regional gene therapy. A bone-marrow stromal cell line infected with an adenovirus expressing recombinant bone morphogenetic protein-2 cDNA secreted biologically active bone morphogenetic protein-2. These bone morphogenetic protein-2-producing cells were able to induce abundant heterotopic bone formation when implanted into the quadriceps muscle of severe combined immune deficient mice and also successfully healed large segmental femoral defects in nude rats. These studies demonstrate that regional gene therapy with continuous delivery of osteoinductive factors to a specific anatomic site can enhance the formation and repair of bone.

Animals↗
PubMed1998

Publication rate of abstracts presented at the annual meeting of the Orthopaedic Research Society.

Although the timely conveyance of information at national meetings like those of the Orthopaedic Research Society is critical to the dissemination of new scientific research, the ultimate goal of most researchers is to publish work in peer-reviewed journals referenced in Medline. All of the abstracts that were presented at the podium at the 1991, 1992, and 1993 annual meetings of the Orthopaedic Research Society and printed in the appropriate yearly transactions were included in this study (n=888,296 per year). A detailed computerized Medline search of each author on the abstract and the appropriate keywords from the title was performed until a publication was found; otherwise, the abstract was excluded. The database was searched through June 30, 1997. A total of 463 (52%) of the abstracts were published by July 1, 1997. The percentages for each individual year were similar: 148 (50%) were published in 1991, 162 (55%) in 1992, and 153 (52%) in 1993. Publication of the majority of these papers (93.1%, 431 of 463) occurred within 4 years of the respective meeting. The Journal of Orthopaedic Research published the majority of these papers (17.5%), followed by The Journal of Bone and Joint Surgery (American), the Journal of Biomechanics, Clinical Orthopaedics and Related Research, and Spine (each 5.2%). No significant differences in the rate of publication were observed between papers of 10 broad subject categories (p=0.103). These results are similar to those from other basic science meetings and to the recently reported results for the annual meeting of the American Academy of Orthopaedic Surgeons.

Abstracting and Indexing↗
PubMed1998

An assessment of orthopaedic surgeons' knowledge of medical ethics.

We developed a survey instrument to evaluate knowledge of ethical issues among orthopaedic surgeons and to assess their ability to handle ethical dilemmas. The twenty-six-item survey evaluates seven areas of medical practice: confidentiality, informed consent, truth-telling, the physician-patient relationship, economic aspects of care, end-of-life decision-making, and the approach to an incompetent colleague. It was administered to 117 attending orthopaedic surgeons and residents in two orthopaedic surgery training programs. One hundred and two orthopaedic surgeons (87 per cent) completed the survey. Overall, they correctly answered a mean of nineteen (73 per cent) of the twenty-six questions. The respondents appropriately handled questions involving economic aspects, truth-telling, confidentiality, and an incompetent colleague. However, there was poorer understanding of proper ethical conduct with regard to informed consent (58 per cent of the responses were correct), the physician-patient relationship (72 per cent of the responses were correct), and end-of-life decision-making (78 per cent of the responses were correct). No significant differences were found, with the numbers available, in overall performance according to site, attending compared with resident status, age, gender, or whether the physician had had training in ethics. Economic, social, and professional forces have increased the medical ethical issues facing orthopaedic surgeons. Medical ethics now must be taught in training programs in orthopaedic surgery. Our survey of two orthopaedic surgery training programs demonstrated that orthopaedic surgeons approach most medical ethical problems appropriately. However, improvement is needed in selected areas.

Adult↗
PubMed1998

Teaching medical ethics to orthopaedic surgery residents.

Orthopaedic surgery residents will be faced with a variety of ethical issues when they enter clinical practice. A previous survey suggested that they lack knowledge about how to approach several types of medical ethics dilemmas. We developed a medical ethics curriculum for orthopaedic surgery residents and presented it over a one-year period to the residents in one training program. The effect of the educational intervention on the residents' knowledge of medical ethics and their ability to handle hypothetical situations was measured by comparing their responses to a questionnaire, administered before and after the intervention, with those of residents in a training program in which the intervention was not provided. The twenty-five residents at the site of the educational intervention had a mean improvement of 0.10 in the overall score, from a mean score of 0.71 on the baseline survey to a mean score of 0.81 on the follow-up survey. This improvement was significantly greater than the mean improvement of 0.02 for the thirty residents at the control site, who had a mean score of 0.72 on the baseline survey and a mean score of 0.74 on the follow-up survey (p = 0.002). Six residents who participated in the medical ethics curriculum rated it as very useful; seventeen, as somewhat useful; one, as slightly useful; and one, as not at all useful. A medical ethics curriculum can increase orthopaedic residents' knowledge of medical ethics. Whether this curriculum also will lead to behavioral changes requires additional evaluation.

California↗
PubMed1997

Low-dose warfarin prophylaxis to prevent symptomatic pulmonary embolism after total knee arthroplasty.

Pulmonary embolism poses a risk to patients undergoing total knee arthroplasty. The selection of an appropriate prophylaxis agent and its implementation have been influenced by decreased duration of hospital stay and the pressures of cost containment. The purpose of this study was to determine the inpatient and outpatient pulmonary embolism rates, the number of days required to attain the target level of anticoagulation, and complications associated with the use of a low-dose warfarin prophylaxis protocol after primary and revision total knee arthroplasty. Between 1984 and 1993, there were 815 primary and revision total knee arthroplasties that received low-dose warfarin prophylaxis at our institution. The average time to attainment of the target level of anticoagulation was 3 days. The average duration of warfarin prophylaxis was 12 days. Overall, there were a total of three symptomatic pulmonary embolisms (0.3%; 95% confidence interval, 0.08%-1.1%). There were eight (1%) symptomatic deep vein thromboses (all distal). There were two deaths (0.3%), but neither one was secondary to a pulmonary embolism. Seventeen knees (2.5%) developed a hematoma after surgery, and two of these patients required drainage of the knee. Low-dose warfarin prophylaxis is safe and effective in preventing symptomatic pulmonary embolism after total knee arthroplasty.

Adult↗
PubMed1997

Outcome after total hip arthroplasty. Comparison of a traditional disease-specific and a quality-of-life measurement of outcome.

The purpose of this study was to examine the relationship between the Harris Hip Score (HHS), a traditional method of patient assessment of a total hip arthroplasty (THA), and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), a commonly used health-related quality-of-life survey. One hundred forty patients returning for routine clinical follow-up evaluation of a primary THA were asked to fill out the SF-36 quality-of-life survey, as well as questions concerning their perceptions of their THA. The patient's surgeon assessed the THA with the traditional HHS. The correlations between the HHS and the SF-36 domains were highest in the physical component summary scores for male patients of all ages and female patients 65 years of age or older. The correlations were lower for the mental component summary scores of all patients, but particularly in female patients younger than 65. When the SF-36 scores were compared with age and sex-matched population norms, both age and sex were found to be important. Men younger than 65 had scores lower than norms in the physical function domains, but were comparable in the mental health domains. The older men had scores comparable to the norms in all domains. Female patients of all ages, however, had lower scores in the physical function domains. The greatest differences were noted in the female patients younger than 65. The HHS is commonly used to assess disease-specific pain and function in THA patients; however, the results of this study suggest that the SF-36 health survey can capture additional important quality-of-life domains that are influenced by a THA and that these domains are influenced by the age and sex of the patient. The combination of a disease-specific scoring system and a quality-of-life survey would allow a more global assessment of a THA in all patients. Studies evaluating the results of THAs should either assess the results of male and female patients separately when sample size is sufficiently large or use sex as a possible covariate in a multivariate analysis.

Adolescent↗
PubMed1997

Impact of declining reimbursement and rising hospital costs on the feasibility of total hip arthroplasty.

Total hip arthroplasty, although a very successful clinical treatment, remains an expensive procedure in an era of constrained health care resources. Hospitalization cost, charge, and reimbursement data were compared between all patients who underwent elective, primary, unilateral total hip arthroplasty in 1988 and 1993 at the UCLA Medical Center. Although length of hospitalization decreased by 36%, increases both in unit supply costs and in the intensity of hospital services prevented a statistically significant reduction in total hospitalization cost. Reimbursement declined by 27% after calculating inflation with the Consumer Price Index for Medical Care. Further, the margin by which reimbursement exceeded cost decreased from 66% in 1988 to 8% in 1993. These trends constitute a serious threat to the financial feasibility of total hip arthroplasty.

Aged↗
PubMed1997

The efficacy of prophylaxis with low-dose warfarin for prevention of pulmonary embolism following total hip arthroplasty.

The selection of a prophylaxis regimen and its implementation have been influenced considerably by the decreased duration of hospital stays and the pressures of cost containment. The purpose of the present study was to determine the rate of symptomatic pulmonary embolism both before and after discharge, the number of days required to achieve an adequate level of anticoagulation, and the complications associated with the use of low-dose warfarin after total hip arthroplasty. Between 1987 and 1993, 1099 primary and revision total hip arthroplasties were performed in 940 patients who received low-dose warfarin for prophylaxis against thromboembolic disease. The average duration of prophylaxis was fifteen days (range, one to twenty-nine days). The target level of anticoagulation (as indicated by a prothrombin time of fourteen to seventeen seconds) was achieved an average of three days (range, one to sixteen days) after the operation. The level of anticoagulation was lower than the target range at the time of discharge after 257 total hip arthroplasties (23.4 per cent), and the target level was never achieved during the period of hospitalization after fifty-four such procedures (4.9 per cent). Twelve total hip arthroplasties were associated with a symptomatic pulmonary embolism; the over-all prevalence of this complication therefore was 1.1 per cent (95 per cent confidence interval, 0.4 to 1.9 per cent). Four pulmonary emboli were diagnosed before discharge and eight, after discharge. A fatal pulmonary embolism occurred after one procedure (0.1 per cent). Patients who had a history of symptomatic venous thromboembolic disease had a significantly increased risk of symptomatic pulmonary embolism after total hip arthroplasty (p = 0.001, Fisher exact test). A major bleeding episode occurred after thirty-two total hip arthroplasties (2.9 per cent). Patients who had a prothrombin time of more than seventeen seconds had a significantly increased risk of hematoma formation (p = 0.003, chi-square analysis). Prophylaxis with low-dose warfarin is safe and effective for the prevention of pulmonary embolism after total hip arthroplasty.

Adult↗
PubMed1997

Tourniquet pressures on pediatric patients: a clinical study.

A clinical study was undertaken to evaluate pneumatic tourniquet pressures required for hemostasis in extremity surgery of pediatric patients. Occlusion pressures were measured by Doppler, and tourniquet pressures were set 50 mm above this value. Of 29 cases, 86% were determined to provide adequate hemostasis throughout the procedure. Maximum mean pressures used in the upper and lower extremity groups were 173.4 +/- 11.6 mm Hg (range: 155 to 190 mm Hg) and 176.7 +/- 28.7 mm Hg (range: 140 to 250 mm Hg), respectively, accounting for adjustments made to inadequate initial settings. This study suggests that lower tourniquet pressures than previously used may be needed to maintain adequate hemostasis in pediatric patients.

Adolescent↗
PubMed1997

Influence of health status and the timing of surgery on mortality in hip fracture patients.

The purpose of the study was to determine the relationship of preoperative health status and time to surgery to mortality and late functional outcome in hip fracture patients. The records of 168 consecutive patients who had operations for 171 intertrochanteric or femoral neck fractures were reviewed retrospectively. Preoperative health status was assessed by the American Society of Anesthetists (ASA) classification. Postoperative outcome was determined by mortality and ambulatory status. The follow-up period for survivors averaged 33 months. The overall mortality was 14% at 1 year, which rose to 26% at 2 years, and 33% at 3 years. The 3-year mortality was significantly less for ASA I and II patients (23%) than for ASA III, IV, and V patients (39%). There was also a significant difference in mortality between patients having surgery within 24 hours of admission (20%) and those having surgery beyond 24 hours of admission (50%). Even when only the healthy subgroup of ASA I and II patients were considered, the relative risk of death was 4.5 times greater if surgery occurred after 24 hours from admission. These data support the concept that hip fracture patients are not a homogeneous group with respect to mortality and that the ASA classification is a good predictor of mortality. Patients who had surgery within 24 hours of admission had a significantly lower mortality rate than did patients having surgery beyond 24 hours of admission, regardless of their preoperative ASA classification.

Adult↗
PubMed1996

Wear of the polyethylene liner-metallic shell interface in modular acetabular components. An in vitro analysis.

The purpose of this study was to determine the effect of compression cycles and wear patterns on the polyethylene liner-metallic shell interface in modular acetabular components. Articular frictional torque was also measured. Modular acetabular components from five manufacturers were tested. The polyethylene liners were sputter coated with gold on the convex surface to enhance the visualization of wear and deformation patterns. Each component was cycled for 10 million cycles in a hydraulic fatigue testing machine. Frictional torque was measured prior to the start of the cyclic loading and in increments of 2 million cycles. Frictional torque was significantly lower in the design with an enhanced polyethylene liner. Abrasion of the gold from the convex surface of polyethylene liners varied from 2 to 23% between designs. Extrusion of the polyethylene into the screw holes in the metallic shells was universal. Three modes of damage (burnishing, punch-out, and gouging) were identified on the convex surface of the polyethylene liner. Abrasion of the gold from the convex surface of the polyethylene varied greatly between designs. This is indicative of relative motion between the polyethylene liner and the metallic shell. This motion must be minimized to limit the generation of wear debris from the convex surface of the polyethylene. Several aspects of modular acetabular component design could be implemented to potentially reduce wear, including limiting the number of holes available for screw placement, smoothing out the edges of the screw holes to avoid punch-out, and avoiding supplemental fixation of the liner unless it is essential to prevent motion between the liner and the metallic shell.

Analysis of Variance↗
PubMed1996

Differences between patients' and physicians' evaluations of outcome after total hip arthroplasty.

The purpose of this study was to compare patients' and physicians' evaluations of the results of 147 total hip arthroplasties. The patients and physicians independently evaluated pain and over-all satisfaction with the outcome of the procedure using a 10.0-centimeter visual-analog scale. They also answered a questionnaire with which they assessed general health, functional ability, and pain. The mean (and standard deviation) analog rating for pain (with 0.0 centimeters indicating no pain and 10.0 centimeters, severe pain) was 1.7 +/- 2.6 centimeters as assessed by the patients and 1.1 +/- 1.8 centimeters as assessed by the physicians (p < 0.001, paired t test). The mean analog rating for over-all satisfaction (with 0.0 centimeters indicating poor and 10.0 centimeters, excellent) was 8.6 +/- 2.1 centimeters as assessed by the patients and 8.8 +/- 1.7 centimeters as assessed by the physicians (p = 0.07, paired t test). There was a marked disparity between the patients' and the physicians' scores when the patients assigned a low score to a particular area. For the thirty patients who rated the pain as more than 4.0 centimeters, the mean analog rating was 6.8 +/- 2.1 centimeters according to the patients, while it was 3.6 +/- 2.7 centimeters according to the physicians (p < 0.001, linear regression). The mean analog rating for over-all satisfaction according to the nineteen patients who rated this parameter as less than 7.0 centimeters was 3.8 +/- 2.0 centimeters, while the mean rating according to the physicians 6.5 +/- 2.8 centimeters (p < 0.001, linear regression). The patients' and physicians' evaluations were similar regarding the results of the total hip arthroplasty when the patients had little or no pain and were satisfied with the result. However, the disparity increased as the patients' ratings for pain increased and their ratings for over-all satisfaction decreased. This study highlights a discrepancy between patients' and physicians' evaluations of the results of total hip arthroplasty. This discrepancy increased when the patient was not satisfied with the outcome. The use of patients' self-administered questionnaires as well as traditional physician-generated assessments may provide a more complete evaluation of the results of total hip arthroplasty.

Activities of Daily Living↗
PubMed1996

Bone morphogenetic protein-2: biology and applications.

Bone morphogenetic protein-2 is a low molecular weight glycoprotein, classified as a morphogen. The sine qua non of bone morphogenetic protein is consistently reproducible induction of bone development in heterotopic sites. Bone morphogenetic proteins belong to the expanding transforming growth factor-beta superfamily. Bone morphogenetic protein-2 has pleiotropic functions that range from extraskeletal and skeletal organogenesis to bone generation and regeneration. Bone morphogenetic protein induced bone formation in postfetal life recapitulates the process of embryonic and endochondral ossification. Through recombinant gene technology, human bone morphogenetic protein-2 is available in almost unlimited amounts for basic research and clinical trials. Human bone morphogenetic protein-2 induces structurally sound orthotopic bone in a variety of experimental systems, including femoral defects in rats, tibial and ulnar defects in rabbits, femoral defects in sheep, mandibular defects in dogs, spinal fusion in dogs, and porous ingrowth in rats. Human bone morphogenetic protein-2 research extends to the fields of developmental biology, genetics, and evolution. Bone morphogenetic protein has been used successfully at the authors' institution to heal clinical nonunions and to achieve spinal fusion. This report reviews the current understanding of bone morphogenetic proteins in general and BMP-2 in particular and summarizes their potential applications.

Animals↗
PubMed1995

Hip arthroplasty in patients with chronic renal failure.

Patients with chronic renal failure who underwent total hip arthroplasty were retrospectively evaluated. Thirty hips in patients with renal transplants and 16 hips in patients on chronic renal dialysis were reviewed. The average follow-up period was 54 months. The renal transplant patients exhibited generally satisfactory results. Their postoperative course was comparable to that of patients with avascular necrosis undergoing hip reconstruction without underlying renal disease. However, patients undergoing hip arthroplasty while on chronic renal dialysis had poor results (81%), including a deep infection rate of 19%. It was concluded that total hip arthroplasty be reserved for patients who are expecting a renal transplant or preferably those who have already received a successful transplant.

Adult↗