[A contribution to the biostatic analysis of the hip joint III (author's transl)].

Following description of a model which can be applied in clinical practice for planning an operation with regard to the load and strain placed on the hip joint, as expounded in previous articles, the present article explains two more realistic possibilities of calculation of the pressure on the joint. We now have, therefore, three pressure models which can be compared with each other: 1. Assumption of equal distribution of the pressure over the hip joint with calculation of the maximal pressure. 2. Assumption of a linear drop in pressure from the acetabulum in the direction of the floor of the acetabulum. 3. Assumption that the articular cartilage displays an ideally elastic behaviour (calculation of pressure according to Hooke's Law). The last-named model No. 3 is probably the most realistic one, but in view of the fact that it requires complicated calculations, it will be employed in specific cases only, which will usually be mostly of a theoretical nature; Model No. 1 requires a reasonable amount of calculation and will suffice, as shown in the present article, for daily routine surgical planning.