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Biomedical subjects

J N Argenson

Publications and source records attributed to J N Argenson.

23 records · Page 2Linked to original sources

Oral rifampin plus ofloxacin for treatment of Staphylococcus-infected orthopedic implants.

We examined the effectiveness and safety of the combination of rifampin plus ofloxacin given orally for treating prosthetic orthopedic implants infected with staphylococci. The prospective cohort study was conducted in a referral public hospital with ambulatory care services between 1985 and 1991. Consecutive patients from whom Staphylococcus organisms susceptible to the study drugs were isolated from their orthopedic implants and who had no contraindication to the treatment were eligible for the study. All patients were treated orally with rifampin, 900 mg/day, plus ofloxacin, 600 mg/day. Patients with hip prosthesis infection were treated for 6 months, with removal of any unstable prostheses after 5 months of treatment; patients with knee prosthesis infection were treated for 9 months, with removal of the prosthesis after 6 months of treatment; and patients with infected bone plates were treated for 6 months, with removal of the plate after 3 months of treatment, if necessary. Monthly clinical evaluations were conducted until the completion of the treatment and follow-up or telephone interviews were conducted at 6, 12, 24, 36, 48, and 60 months thereafter. Treatment failures were documented by clinical evaluation, sampling of the infected site for culture and antibiotic activity measurement, and fistulography, if possible. Cure was defined as the absence of clinical, biological, and radiological evidence of infection 6 months after the completion of treatment, treatment failure was defined as the absence of cure, and relapse was defined as the reappearance of infection caused by the same Staphylococcus isolate that caused the original infection, regardless of the timing of this secondary infection. Among 51 patients included in the study and evaluable for safety, 4 patients had side effects and were not evaluable for treatment effectiveness; the overall success rate was 74% among 47 patients, with a success rate of 81% for the hip prosthesis group, 69% for the knee prosthesis group, and 69% for the osteosynthesis device group. Eight treatment failures were relaxed to the isolation of a resistant bacterium. The combination of rifampin administered orally plus ofloxacin is a suitable alternative to the conventional long-term intravenous therapy for treatment of orthopedic implants infected with staphylococci.

Administration, Oral↗

The morphology of the proximal femur. A three-dimensional radiographic analysis.

Biological fixation of cementless femoral implants requires primary stability by optimal fit in the proximal femur. The anatomy of the bone must then be known precisely. We analysed in vitro the accuracy of bone measurements of 32 femurs and compared the dimensions obtained from radiographs and CT scans with the true anatomical dimensions. Standard radiographs gave only a rough approximation of femoral geometry (mean difference: 2.4 +/- 1.4 mm) insufficiently accurate to allow selection of the best fitting prosthesis from a range of sizes and altogether inadequate to design a custom-made prosthesis. CT scans give greater accuracy (mean difference: 0.8 +/- 0.7 mm) in our experimental conditions, but in clinical practice additional sources of error exist.

Aged↗

Polyethylene wear in meniscal knee replacement. A one to nine-year retrieval analysis of the Oxford knee.

We recovered 23 meniscal bearings from 18 failed bicompartmental Oxford knee prostheses. They had been implanted for one to nine years. The minimum thickness of the retrieved bearings was measured and compared with the thickness of 25 unused bearings. The mean penetration rate, calculated by two methods, was either 0.043 or 0.026 mm per annum. This compares with 0.19 mm per annum reported for the Charnley hip. The use of a fully congruous meniscal bearing prosthesis can reduce wear in knee arthroplasty to a very low rate.

Humans↗

[Bilateral genu flessum in a patient with Cooley's disease].

An original case of bilateral knee flexion of sixty degrees is reported in a twenty-four year old mean, with a beta-thalassemia diagnosed at three years old. The defect of straightening is the result of premature epiphysis fusion, only posterior in this case, and affecting preferentially the tibia. That is the reason why the flexion has been corrected by a bilateral tibial soustraction osteotomy, under the tibial tuberosity. The consolidation of the osteotomies has been obtained without any complications, with a complete extension and normal walk in a man moving only with a wheelchair before surgery. No similar case seems to be described in this kind of pathology.

Adult↗

[Biomechanical study of the Oxford knee prosthesis with mobile meniscus].

Polyethylene meniscal bearing of the Oxford knee produce conforming surfaces and are free to move with knee movements. We studied polyethylene wear of 23 meniscal bearings implanted after a mean time of 38 months. The mean penetration rate of the polyethylene was 0.026 mm per year, statistically correlated with implanted time. The large areas of contact provided by such design are able to reduce polyethylene wear in knee prosthesis at levels smaller to those reported for hip. We also studied bearing movement on six cadaveric specimens fixed in a six degrees of freedom rig. The movements take place in both compartments of the knee in the same direction as for normal menisci during flexion-extension and rotation. Unicompartmental arthroplasty using meniscal bearing knee can restore such movements when the anterior cruciate ligament is present.

Aged↗