Standardized experimental nerve crush attempts should include the number, duration, and intensity (amount of pressure) of crushes. The authors have developed a new crushing device, a clamp with which predetermined forces can be applied to nerves. This allows the exertion of different, standardized forces to crush a nerve within a scale that produces second-degree injuries. The main advantages of the clamp are that it is small, although very robust, is purely mechanical, and is easy to handle. The jaws of the clamp are not serrated, so that pressure on the nerve is uniformly transmitted. To avoid unintended nerve damage, the edges of the jaws are smoothly rounded off. The closure of the clamp is mechanized by a spring. As the spring is exchangeable, any number of different preloads are available. The force can be varied, according to different requirements, and is applicable to variantly thick nerves in any experimental animal, thus enhancing standardization, and making cross-over comparisons of experimental study results possible.

The learning curve is a graphic representation of the relationship between the experience of a surgeon and one or more performance indicators. The operation time alone is an insufficient indicator to assess the performance of a surgeon. The procedure time has to be set in relation to the complication rate and in laparoscopic surgery to the conversion rate. Techniques to visualize the changes over time are the moving average method for the operation time and the Cusum method for dichotomous outcomes, like the conversion and the complication rates. At the time when the learning curve reaches the plateau phase this representation can be used to assess the quality of a surgeon or a team in one hospital. As far as there is no validated complexity scale for laparoscopic procedures available it is difficult to compare patient populations between different hospitals. Out of this reason the learning curve is no legitimate instrument to rank surgeons or different hospitals.

Histiocytosis X developed in five patients (one woman and four men) when aged between 15 and 44 years. The initial sign in four of them was eosinophilic granuloma of the bone, in one it was pulmonary involvement. In three patients the disease remained confined to bone, while in two it involved the lungs and central nervous system, respectively. Osteolysis regressed spontaneously in one of the men, while in the woman there has been no recurrence 8 years after resection of the focus. In another man an osteolytic focus in a rib was noted after a 9-year recurrence-free interval. The man with pulmonary and bone involvement received chemotherapy with vinblastine and prednisone: dyspnoea and cough disappeared, vital capacity improved and the interstitial lung changes regressed. The osteolytic foci were repeatedly irradiated in the man with bone and CNS involvement. This brought about considerable reduction in pain but no significant radiological changes of the foci. Two courses of chemotherapy were given over 12 years, once with vincristine and prednisone, afterwards with cyclophosphamide. This arrested the progression of the osteolytic foci, but each time they recurred when the drugs were stopped.