[Experimental patello-femoral contactprint measurements. 2. Report: sagittal osteotomy of the patella according to Morscher (author's transl)].

The recommended treatment method for chondropathy from Morscher 1978 using a sagittal patellaosteotomy was tested experimentally with contact area measurements with the erasing method on 11 corpse knees of the types II, II/III and III. Measurements were made in the bending region up to 90 degrees, and in isolated positions up to 140 degrees. The measurements showed a clear decrease in the contact area of the medial side of the lateral facet, and occassional displacement of contact whereby loses on the paramedial segment were compensated for by early loading on the border segment. Thus unphysiological loading of the medial facet occurred, from which chondromalasys could develop. Only three patellas had an increased contact area during inflexions up to 90 degrees, and then only because the central cartilage area, which usually undergoes the greatest loses, was already incongruent. Since during a complete knee bending the retropatella cartilage has almost 100% contact and that due to the medial cartilage ridge a considerably smaller incongruence is present as can be expected from the bone crosssection of the patella, we cannot expect any contact increase through an osteotomy.