Monostotic manifestation of fibrous dysplasia in the spine is exceedingly rare. We report the case of a 30 year-old woman suffering from slowly increasing low back pain. Radiologically a polycyclic, slightly gadolinium-enhancing, solitary lesion within the first lumbar vertebral body was detected. The lesion was removed and stabilized with bone marrow transplant. We describe the radiological and histopathological findings.

The activity of knee-related muscles was registered via exercising on a bicycle ergometer by 17 patients with clinically diagnosed chondropathia patellae. M. quadriceps activity was shorter and the hamstring activity longer in the chondropathy group compared with a matched healthy control group. The changes in m. quadriceps occurred to an almost equal extent in lateral and medial sections. In five patients with unilateral complaints, the electromyographic changes were nevertheless noted on both sides. The study shows that chondropathia patellae involves a change in muscle control affecting not only the knee extensors but also the hamstrings. Through the changed innervation pattern the coactivation phase, i.e. the phase of simultaneous activation of knee flexors and extensors at the end of the extension phase, takes place at a higher angle of flexion. Physiotherapy should involve all knee-related muscles and should include not only isometric but also dynamic exercises.

The object of this study was to find out whether an arthrotomy of the knee would damage joint proprioception. Twenty patients who underwent arthrotomy, and 20 patients after arthroscopy, were tested on a modified ergometer and the electromyographic action of their quadriceps and hamstrings recorded. The quadriceps action started later and had a shorter duration (20 ms) after arthrotomy. The differences are statistically significant in intra-individual comparison both for vastus lateralis and medialis, in comparison with the normal group for only the vastus medialis. There were no significant differences in muscle control after arthroscopy. These results are in favor of preferring arthroscopy to arthrotomy whenever possible.

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Apart from the advantages of plate osteosynthesis, like primary bone healing and immediate post-operative mobilisation treatment, the disadvantages of this method must be mentioned. First of all these are the high pressure on the surface of the bone by the plate and the high tension stress on the bone by the thread of the screws, which can lead to bone atrophy. Besides the splinting by the plate is accompanied by a functional lack of the bone. The bone reacts on this "stress protection" by reduction of material, especially under the plate. These disadvantages shall be avoided by a new osteosynthesis system, called ZESPOL, which has been developed in Poland. Here the plate does not contact directly the bone, but is fixed above the periost by special screw bolts. Although this method is used in Poland clinically with success, until now no experimental examinations concerning the stability of this osteosynthesis have been published. In the following biomechanical tests we examined, whether the new method achieves a comparable interfragmental compression like common selfcompressing plate systems. We measured the maximal interfragmental compression with an interposed piezo-electric element on human cadaver tibiae. Because the original ZESPOL plates have greater dimensions than common plates, we did not use these original plates. In order to get a comparability between the two systems, we modified small Autocompression plates (ACP) by milling a slot in the underside, so that they could be used with the original ZESPOL screw bolts. These modified ZESPOL plates we compared with common 6-hole Autocompression plates and cortical screws.(ABSTRACT TRUNCATED AT 250 WORDS)