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Biomedical subjects

R H Fitzgerald

Publications and source records attributed to R H Fitzgerald.

At least 19 recordsLinked to original sources
PubMed1996

The immune response to implant materials in humans.

The etiology of aseptic loosening of prosthetic joint replacement components is unclear. Implant materials have been considered biologically inert, but recently studies indicate that inflammatory reactions directed against the implanted materials may contribute to aseptic loosening. Data suggesting a progression from a simple inflammatory reaction to complex immune responses against the biomaterials are reviewed. The cellular responses to particles of polymethylmethacrylate, ultrahigh molecular weight polyethylene, and alloys of cobalt-chromium and titanium were assayed in vitro to determine cell proliferation in patients with underlying diagnoses of osteoarthrosis, rheumatoid arthritis, and avascular necrosis who had joint replacement. Control populations were provided by patients with similar diagnoses who were preoperative surgical candidates. The underlying diagnoses did not seem to influence responses to particle stimulation. Elevated responses to both acrylic and cobalt-chromium were observed in patients with aseptically loosened prostheses. These findings suggest that the development of a cellular response to particulate debris may be significant in the pathogenesis of aseptic loosening.

Biocompatible Materials↗
PubMed1995

Cellular proliferation and cytokine responses to polymethylmethacrylate particles in patients with a cemented total joint arthroplasty.

The in vitro response of peripheral blood mononuclear cells (MNC) from patients with cemented total hip or knee arthroplasties, and control individuals, to polymethylmethacrylate (PMMA) was assessed by cell proliferation, cytokine production, and molecular techniques. After seven days in culture, a dose-dependent proliferative response to PMMA stimulation was observed in MNC from fifteen normal individuals. A concomitant dose-dependent production of both IL-1 beta and IL-2 in response to PMMA stimulation was detected. Reverse transcription-polymerase chain reactions (RT-PCR) indicated that both IL-1 beta and IL-2 mRNA was present after 48 hours in culture with PMMA. Cellular proliferation and cytokine production (both IL-1 beta and IL-2) in 10 patients with stable, painless, well-functioning, cemented arthroplasties was significantly lower (p < 0.025) than normal controls and patients with aseptically loosened, painful, arthroplasties. The findings suggest that patients with stable cemented total joint arthroplasties are either inherently or adaptively less responsive to PMMA at a cellular level.

Base Sequence↗
PubMed1995

Preventing DVT following total knee replacement: a review of recent clinical trials.

Deep vein thrombosis (DVT) following total hip or knee arthroplasty is a frequent complication which can cause fatal pulmonary embolism (PE). Although many different approaches to its prevention have been attempted, low-dose warfarin has become the standard treatment for the prevention of thromboembolic disease following total hip and knee arthroplasty. Although subcutaneous heparin can reduce the incidence of thromboembolic disease, it has been associated with excessive bleeding complications. The introduction of low molecular weight heparins promises fewer bleeding complications with efficacy equal to that of warfarin. We wish to report the results of a randomized, prospective study comparing a low molecular weight heparin with low dose warfarin in the prevention of thromboembolic disease following total knee arthroplasty (TKA).

Adult↗
PubMed1995

The Frank Stinchfield Award. Pulmonary fat embolism in revision hip arthroplasty.

Unilateral cemented hip hemiarthroplasty was done on 16 dogs who subsequently had revision arthroplasty and who were divided into 1 control and 3 experimental groups: The first group had cement extraction using osteotomes; the second, using a high speed burr; the third, an ultrasonic tool. Hemodynamic and transesophageal echocardiographic monitoring were done. Postmortem pulmonary specimens were examined for differences in the quantity of fat emboli. There was a significant increase in emboli with the ultrasonic tool as compared with osteotomes and high speed burr. There was no significant difference in emboli between the osteotomes and high speed burr. Fat emboli syndrome is related to mechanical compression of the femoral canal. The ultrasonic instrument was unique in its tendency to cause large embolic showers, especially during extraction of the distal cement plug. In these young dogs, minimal hemodynamic changes and no cardiac dysrhythmias occurred, which in part may be attributed to their good health. These changes may remain subclinical for patients with good cardiorespiratory reserve, or may become life threatening for those with poor reserve. By outlining the mechanisms of fat embolism in revision total hip arthroplasty, it may be possible to decrease future morbidity, especially in patients who frequently have cardiopulmonary disease.

Animals↗
PubMed1995

Acetabular labrum tears. Diagnosis and treatment.

An acetabular labrum tear was diagnosed and treated in 56 hips in 55 patients. Mechanical hip pain after a relatively minor injury with an associated click characterized the history. The tear of the labrum was shown with arthrography in 88% of the patients. Overall, 89% of the patients were improved by the diagnosis and treatment of an acetabular labrum tear: all 7 patients treated nonsurgically and 42 of 46 patients treated surgically. In recent years, it has been possible to arthroscopically confirm the diagnosis and treat some of these patients.

Acetabulum↗
PubMed1994

Prophylaxis against infection in total joint arthroplasty. One day of cefuroxime compared with three days of cefazolin.

The efficacy of cefuroxime was compared with the efficacy of cefazolin for prophylaxis against postoperative wound infection in a prospective, double-blind, multicenter study of 1354 patients who had had elective primary or revision total hip or knee arthroplasty. The patients were randomly assigned to receive either 1.5 grams of cefuroxime followed by 750 milligrams eight and sixteen hours later (for a total of one day of antibiotic treatment), or one gram of cefazolin every eight hours for nine doses (for a total of three days of antibiotic treatment). The first dose of each drug was administered fifteen to sixty minutes before the operative incision was made (for a primary operation) or after tissue samples had been obtained for culture (for a revision procedure). After the operation, the patients were assessed daily while hospitalized and then at two to three months and one year after the operation. Demographic characteristics and risk factors were similar in the two groups. For the patients who had had a primary hip arthroplasty, the rate of deep wound infection was 0.5 per cent (one of 187) for those who had received cefuroxime and 1.2 per cent (two of 168) for those who had received cefazolin. For the patients who had had a primary knee arthroplasty, the rate of deep wound infection was 0.6 per cent (one of 178) for those who had received cefuroxime and 1.4 per cent (three of 207) for those who had received cefazolin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

The use of porous prostheses in delayed reconstruction of total hip replacements that have failed because of infection.

Between March 1984 and March 1989, thirty-four patients who had an infection at the site of a cemented total hip prosthesis were managed with resection arthroplasty and delayed implantation of a porous total hip prosthesis without cement. The interval from the time of the resection arthroplasty to the implantation of another prosthesis averaged eight months (range, three to nineteen months). At an average of forty-seven months (range, twenty-four to seventy-two months) after the reimplantation, six patients (18 per cent) had recurrence of the infection. Patients who had rheumatoid arthritis were at significantly higher risk for the development of a recurrent infection (p < 0.01). Of the twenty-eight patients who did not have a recurrent infection, six had definite radiographic evidence of loosening of the femoral component at the latest follow-up evaluation. For twenty-five of the twenty-eight patients, sufficient data were available for calculation of the Mayo Clinic hip score; only fourteen (56 per cent) of these patients had a satisfactory functional outcome. The high (68 per cent) rate of complications and the long-term durability of the prosthesis in these patients remain a concern. The fact that 18 per cent of the patients had a recurrent infection suggests that avoidance of the use of bone cement does not improve the rate of resolution of infection after a delayed revision operation in patients who have an infection following a total hip arthroplasty.

Adult↗
PubMed1994

Controversies in the prevention of deep vein thrombosis with total hip arthroplasty.

Thromboembolic disease is a serious problem that is growing because both total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients are now being discharged from the hospital as early as the fourth postoperative day. The current estimate is that 50,000 deaths a year in the United States can be attributed to this disease process, and it is an equally large problem in other countries such as Great Britain (Table 1). Thromboembolic disease is asymptomatic in the vast majority of patients undergoing joint replacement. Approximately one in six patients develops the condition following THA or TKA.

Anticoagulants↗
PubMed1993

A prospective randomized study of a collar versus a collarless femoral prosthesis.

A prospective, randomized study of 44 collared versus 40 collarless cemented HD-2 total hip arthroplasties (THAs) was performed in 84 patients. Seventy patients were examined at an average of 4.6 years after surgery. Five hips have required, or are scheduled to have, revision arthroplasty: two with collared prostheses and three with collarless prostheses. Good collar contact with the proximal medial femur was achieved in 47% of the collared prostheses. No patient with good contact has required or is scheduled to have revision hip surgery. Radiolucent lines were greater in both frequency and width in Gruen Zones 2 and 7 in patients with a collarless prosthesis. Loss of endosteal height of the femoral neck was 3.5 mm in patients with collarless prostheses and 1.7 mm in patients with collared prostheses. Loss in height of the femoral neck was 2.6 mm in patients with collared prostheses with poor bone contact and 0.7 mm in patients with collared prostheses with good bone contact. The mean preoperative and postoperative Harris hip scores for the collarless group and for the collared group were not statistically different. There were no statistically significant differences in acetabular position, the incidence of acetabular radiolucent lines, or femoral subsidence between patients treated with collared or collarless prostheses. This study demonstrates that it is possible to stress the proximal medial portion of the femur with a collared prosthesis. Furthermore, a significant increase is identified in both the frequency and width of radiolucent lines in patients with collarless prostheses in Zones 2 and 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1992

Total hip arthroplasty sepsis. Prevention and diagnosis.

Postoperative deep wound infection following total hip arthroplasty remains a serious and all too frequent complication. Although diagnostic capabilities have improved with the evolution of new imaging and immunologic techniques, the devastating consequences for patients with an early diagnosis cannot yet be aborted. Thus, further emphasis must be placed on prevention of this complication. Although major referral centers have managed to achieve exceptionally low incidences of postoperative sepsis with the prophylactic administration of antimicrobial agents and discipline within the operating room, these advances have not translated into a similar reduction of the national experience. Thus, further investigation and the development of additional techniques must be sought.

Hip Prosthesis↗
PubMed1991

Bypassing femoral cortical defects with cemented intramedullary stems.

The objective of this investigation was to examine the effect of cemented intramedullary stem bypass on bone torsional property in the presence of femoral cortical defect. We intended to test two hypotheses; first, intramedullary fixation without bypass will accentuate the stress concentration effect and second, there will be an optimal length of stem bypass beyond the defect. Cemented intramedullary stems were used to bypass 50% diaphyseal diameter unicortical defects in paired, fresh-frozen canine femora. One member of each pair served as an unaltered control and all specimens were tested to failure in torsion. Both single-tailed paired t-test and analysis of variance were used for data analysis. Bones subjected to the cortical defect and no bypass were substantially weakened, exhibiting only 44 +/- 8% of control side maximum torque (p less than 0.001). Positioning of the intramedullary stem with its tip at the center of the defect provided a small degree of strength improvement, achieving 60 +/- 7% of control side maximum torque. One and two diaphyseal diameter bypass, however, significantly (p less than 0.01) improved bone torsional strength, resulting in 80 +/- 6% and 84 +/- 13% of control side maximum torque, respectively. Three diameter bypass achieved only 68 +/- 8% of control side maximum torque. This significant (p less than 0.05) decline in strength when compared to two diameter bypass appears to indicate that the length of stem bypass beyond the cortical defect does have an optimum, probably due to the geometric characteristics of the canine femora.

Animals↗
PubMed1991

Metachronous infections in patients who have had more than one total joint arthroplasty.

Sixty-eight patients who had had 159 replacement arthroplasties of more than one major joint between 1975 and 1984 and who had had an infection after at least one of these procedures were identified in a retrospective review. Subsequent infection in another total joint replacement was documented in ten of these patients. The risk of development of an infection about another total joint replacement after an infection had occurred about one total joint replacement in a patient who had had more than one arthroplasty was 18 per cent, according to the survivorship-analysis method of Kaplan and Meier. Many variables that were previously thought to increase the risk of infection, such as rheumatoid arthritis, older age of the patient, previous operations, and the use of corticosteroids or immunosuppressive agents, or both, were not found to increase the risk of a subsequent infection in patients who had had more than one arthroplasty with infection of one of the arthroplasties. The recent occurrence of a major systemic infection did increase the risk of infection about the other total joint replacements. Eight of the ten subsequent joint infections were due to the same causative organism as the index infection about a total joint replacement and occurred within the first year after the index infection. The initial treatment of the index infection included specific parenteral antimicrobial therapy combined with débridement and excisional arthroplasty in forty patients, removal of the components and arthrodesis in three patients, and débridement with retention of the prosthesis in twenty-five patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Limitations of indium leukocyte imaging for the diagnosis of spine infections.

The usefulness of indium-111 white blood cell (WBC) scintigraphy in the detection of spine sepsis was studied in 22 patients who had open or percutaneous biopsies for microbiologic diagnosis. The indium images in 18 patients with vertebral infection were falsely negative in 15 (83%) and truly positive in 3 (17%). All four patients with negative cultures and histology had true-negative scans. The indium-111 WBC imaging results yielded a sensitivity of 17%, a specificity of 100%, and an accuracy rate of 31%. Prior antibiotic therapy was correlated with a high incidence of false-negative scans and photon-deficient indium-111 WBC uptake. The usefulness of indium-111 WBC scintigraphy for the diagnosis of vertebral infection may be limited to those patients who have not been treated with antibiotics previously.

Anti-Bacterial Agents↗