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.

No abstract

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.