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Biomedical subjects

J R Chapman

Publications and source records attributed to J R Chapman.

At least 91 records · Page 5Linked to original sources
PubMed1994

Iatrogenic fractures of the femoral neck during closed nailing of the femoral shaft.

We have reviewed our experience of four iatrogenic femoral neck fractures in 315 consecutive closed intramedullary nailings with the AO/ASIF universal femoral nail. The average neck-shaft angle in the bones that fractured was 139.3 degrees +/- 1.2 degrees SD (136 to 141); in the whole series the average neck-shaft angle was 125.3 degrees +/- 8.6 degrees and only 11 had angles of more than 135 degrees. The upper ends of the nails in the four which fractured were 17 mm, 5 mm, 3 mm, and 1 mm below the tip of the greater trochanter. In the seven patients with neck-shaft angles greater than 135 degrees but with no fracture, none of the nails had been inserted beyond the tip of the greater trochanter. We nailed six cadaver femora to simulate the forces produced by intramedullary nailing. Despite deep insertion, only one of the six sustained a neck fracture. This specimen had a radiographic neck-shaft angle of 140 degrees against an average of 127.3 degrees +/- 4.0 degrees for the other five. We believe that the medial prong of the AO insertion jig, with its medial overhang of 2 to 3 mm, may impinge on the superior aspect of a valgus femoral neck during final impaction, causing a neck fracture. This may be avoided by leaving the end of the nail above the tip of the trochanter in such cases.

Adolescent↗
PubMed1994

Effect of sterilization and storage treatments on screw pullout strength in human allograft bone.

Many conflicting studies have been performed evaluating the effects of sterilization and storage treatments on the mechanical properties of allograft bone. In the current study, four right and left matched, sterile, deep-frozen, tibial pairs from human donors with an average age of 32 years were tested. One tibia from each pair served as a matched control for the opposite side. Each tibia was cut into four equal segments. One segment of each tibia underwent no treatment; the other three underwent one of the following treatments: irradiation, freeze drying, or ethylene oxide (ETO). Screw pullout tests were performed using four 3.5-mm cortical screws per segment. Sixteen screw pullout tests were performed for each allograft treatment. The freeze-dried specimens required significantly less force for screw pullout. The screw pullout force for the irradiated specimens and the ETO specimens did not significantly differ from their controls. These results indicate that freeze drying affected screw pullout strength. This method of processing should be questioned for structural allografts in which screw fixation is mandatory. The use of irradiation or ETO for sterilization may not have an adverse effect on screw pullout strength.

Biomechanical Phenomena↗
PubMed1993

Inhibition of PHA induced mononuclear cell proliferation by FK506 in combination with cyclosporine, methylprednisolone, 6-mercaptopurine and mycophenolic acid.

In vitro inhibition of human peripheral blood mononuclear cell (PBMC) proliferation by immunosuppressive drugs has been shown to correlate with clinical outcomes in kidney transplant patients. The aim of our study was to analyse the degree of variability of in vitro interactions of FK506 (FK) with combinations of cyclosporin A (CyA), methylprednisolone (MP), 6-mercaptopurine (6ME), and mycophenolic acid (MPA) using phytohaemagglutinin (PHA) stimulated PBMCs. Our hypotheses were: that a wide range of interindividual variation would be detected; and that certain combinations of drugs would have a synergistic inhibitory effect on PHA stimulated PBMCs. Cells were cultured in supplemented RPMI 1640 for 65 hours at 37 degrees C in humidified 5% CO2 - 95% air and proliferative responses measured by 3H-thymidine incorporation over a further 24 hours. Inhibition of PBMC proliferation was assessed over 10 FK concentrations ranging from 1 x 10(-8) to 10 micrograms/ml using both volunteer controls (n = 51) and dialysis patients (n = 23). A wide range of interindividual variability of FK inhibition occurred throughout the range of FK concentrations tested, becoming less variable at the higher concentrations. The interactions of FK with CyA, MP, 6ME and MPA were assessed using PBMCs from 12 volunteer controls. For FK at 1 x 10(-8) micrograms/ml; CyA, MP, 6ME and MPA were used at 0.01 microgram/ml. For FK at 1 x 10(-7) micrograms/ml; CyA, MP, 6ME and MPA were used at 0.1 microgram/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclosporine↗
PubMed1993

Closed interlocking nailing of femoral shaft fractures: assessment of technical complications and functional outcomes by comparison of a prospective database with retrospective review.

Although closed interlocking femoral nailing is generally considered to be a difficult but effective procedure, the true incidence of technical complications has not been well documented. Similarly, long-term and functional patient-oriented data are limited. We reviewed our experience with an interlocking nail system that was introduced in our institution in October 1987. One hundred and twenty-three patients were retrospectively reviewed with particular attention to technical complications (Group I). A second group of 144 patients with femoral shaft fractures were reviewed prospectively as a part of our Orthopaedic Trauma Outcome Database (Group IIA). In the earlier retrospective group, the technical complications in 123 cases included one distal screw fracture, one broken drill bit left (in situ), one "missed" locking distal screw, and three cases where comminution at the fracture site was increased. In the prospective group of 144 fractures, the technical complications included two "missed" distal locking screws, two broken screws, and one bent nail due to additional secondary trauma. In a third group of 56 patients (Group IIB) selected from Group IIA, an abbreviated functional assessment was performed at a minimum of 12 months postinjury. Of this group, 37% of the patients had pain that was described as related to barometric changes and was either constant or activity related; 39% had some limitation in ability to ambulate or stand. Nine percent had to obtain new employment or seek job modifications. Based on our data we conclude that closed intramedullary nailing can be done at a Level I Trauma Center with relatively few technical complications, but the functional outcomes are not as good as had been previously believed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Transplantation in Australia--50 years of progress.

OBJECTIVE: To review the history of clinical transplantation practice in Australia. DATA SOURCES AND STUDY SELECTION: The first major source was published reports, chiefly in The Medical Journal of Australia (129 articles). The second source was personal communication with those involved in early and current transplantation programs. DATA EXTRACTION AND SYNTHESIS: The first known transplant of each organ in Australia and the results of current programs have been documented. CONCLUSIONS: Transplantation of the kidney, liver, heart, lung, pancreas, cornea, or bone marrow are available and accepted therapies for an increasing number of suitable patients, limited mainly by the number of donors.

Australia↗
PubMed1992

Potential for cadaveric organ retrieval in New South Wales.

OBJECTIVES: To measure the potential for cadaver organ retrieval in New South Wales and to determine the reasons for potential donors failing to become actual donors. DESIGN: Prospective audit of all patients dying in five hospitals in New South Wales between 1 December 1989 and 30 November 1990; quality assurance of the data by independent medical specialist and if disagreement by study committee. PATIENTS: 2879 patients (100% of all deaths) yielding 364 patients with coma and 181 potential donors. OUTCOME MEASURES: Realistic medically suitable potential donor rate, missed potential donor rate, rate of potential donors with permission refused, donor rate, reasons for realistic medically suitable potential donors failing to become actual donors. RESULTS: 2879 deaths yielded 73 medically suitable potential donors, resulting in 19 actual donors, 30 missed potential donors, 19 potential donors with permission refused, and five in whom adequate resuscitation failed. The most common reason for a potential donor failing to become an actual donor was a decision by the senior medical practitioner to withdraw or not to institute ventilatory or haemodynamic support (26/73). The second major obstacle was refusal of permission by the next of kin (17/73). Assuming that the potential donor rate was that implied by the observed donor rate (13/million population/year) the projected missed potential donor rate was 9/million population/year (95% confidence interval 4 to 15) and the projected rate of potential donors with permission refused was 13/million population/year (95% confidence interval 5 to 22). Assuming that the rate of potential donors in the study hospitals was the same as in the other New South Wales hospitals, the projected donor rate for New South Wales was 18/million population/year (10 to 26); the projected missed potential donor rate was 15/million population/year (7 to 23); and the projected rate of potential donors with permission refused was 18/million population/year (10 to 27). CONCLUSIONS: The donor rate could be increased 70%-80% by overcoming the reluctance of medical practitioners to resuscitate missed potential donors and increased further by gaining permission for organ retrieval from the next of kin.

Cadaver↗