From general physical laws simple formulae have been deduced from which the rigidity of an external fixation unit mounted in different ways becomes mathematically calculable. Furthermore, the stability of various mounting systems under bending forces was investigated experimentally. Particular attention was paid to details of operating technique which are of special importance to the stability of the whole construction. The calculated data are consistent with the mechanical test results. The best arrangement of the Steinmann pins and Schanz screws is discussed, and how to mount the frame optimally, depending on the specific type and location of the fracture. Special instructions concerning the mounting of the external fixation unit are given which, depending on the specific circumstances, guarantee optimum stability of the unit.
Shortening of the distal fibula after malleolar fracture is accompanied with important alterations of the biomechanics and the compressive forces of the ankle joint. The relationship between the extent of shortening, the degree of valgus position of the talus and the reduction of the joint surfaces is described on the basis of experimental investigations. The importance of these circumstances for treatment of malleolar fractures is discussed.
At 89 Patients with painfull wrist and clinical symptoms like a lesion of the triangular disc, arthrography of the radiocarpal joint was performed. In 18 cases with corresponding arthrographical findings removal of the disc results in clear recovery respectively painlessness. That simple operation seems to be an alternative to the resection of the ulna and a replaceable method if symptomatology and arthrography are accordingly. The described proceeding becomes important because no recovery was seen by conservative treatment.
To obtain valid information on stress tolerance of pertrochanteric fractures, we exposed three different methods of osteosyntheses to dynamical stress and the results were compared. The methods of osteosyntheses were application of a 130 degrees angle plate, performing an adjoining osteosynthesis with bone cement or using cephalocondylar nails. The measurements in connection with photographical and roentgenological examinations of osteosyntheses under stress gave the following results: Compared with the other methods treatment with condylar nails gave equal results in static behaviour yet was clearly superior in its dynamic reaction.
Roentgenological signs, which seems typically for a posttraumatic lesion of the articular disc of the wrist in case they appeared together with a corresponding clinical manifestation, were found in arthrographies of wrist by 89 patients with posttraumatic troubles. Four different types of roentgenolo-ic alterations and the difficulties by examinating them were described. In our opinion arthrography of the wrist is a successfull method to apprehend a lesion of the triangular disc.
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