Biomedical subjects
Publications and source records attributed to J H van Rappard.
Three patients with subfascial lipoma of the forehead are presented. These deeply placed lipomas are seen in up to fifty percent of the lipomas of the scalp. A characteristic feature is the intact skin line pattern over the tumour. Surgical treatment involves incision of the aponeurosis of the M. occipitofrontalis.
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In this paper we present mathematical models of tissue expanders of several shapes. Within the restrictions of the models, relations are given between surface-area gain and volume of the expanders. It is shown that for the most frequently used expander shapes, the relevant formulas are simple and do not require computer facilities. It is discussed that the approach unavoidably leads to considerable overestimation of the area gain but may serve as a necessary starting point for further research. Furthermore, the rate of overestimation appears to follow such a regular pattern that it can quite easily be compensated for by means of a correcting factor.
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Using a relatively simple test, breaking pressures of 50 gel-filled breast implants that had to be removed have been evaluated. These pressures values were compared with forces generated in executing closed capsulotomy (nutcracker method). It is shown that there is a negative correlation between pressure resistance of breast implants and duration of implantation. After an implantation time of more than five years, our advice is to perform closed capsulotomy if done in a very gentle way, and implant rupture then certainly has to be taken into account.
In this paper, the subject of surface-area gain in tissue expansion is approached from three sides. With the help of a mathematical approach, the theoretical increase in surface area was calculated in relation to the specifications of the expanders. In an in vitro model, these mathematical data were confirmed to be reliable. To determine the real surface-area gain that takes place in vivo, measurements on pigs were performed. It appears that only about 35 percent of the mathematically expected increase in surface area takes place. Moreover, a clear difference was observed between the surface-area gain for the different shapes of tissue expanders.
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A series of 1600 patients suffering from injury to the lateral ligaments of the ankle were treated conservatively with plaster and bandages. In 35 cases the instability persisted and these patients required a Watson-Jones repair. This repair yielded a successful result in over 90% of cases.