The ESKA femoral neck endoprosthesis (CUT) is a mini endoprosthesis anchored in the metaphysis for surgical management of young arthrosis patients with good bone quality. The necessary surgical intervention can be considered minimally invasive and adequate because only the affected femoral head is removed. The preserved femoral neck is used for fixation of the endoprosthesis to obtain proximal physiological force transmission and avoid stress shielding. Since the diaphyseal marrow cavity is not opened, the procedures entail decidedly less blood loss. Should the need arise to change the endoprosthesis, an endoprosthetic stem anchored in the diaphysis can easily be implanted after resection of the femoral neck near the base.

In endoprosthetics alumina ceramic femoral heads have been established for many years and their outstanding wear characteristics are scientifically proven. The taper connection between the hard but brittle ceramic head and the metallic stem must be performed by the operating surgeon intraoperatively. Thereby it is left to the surgeon to interpret imprecise and strongly deviating instructions given from manufacturer to manufacturer. This study clarifies the enormously large variations of interpretation in the clinical everyday life based on interviews and force measurements during handling when assembling. In comparable situations the axial cone setting forces, applied by a total of 39 operating surgeons from German hospitals, varied between 273 N and 7848 N. An additional coupling strength examination in the laboratory shows that torque loadings necessary for loosening several cone connection designs are in the range of those occurring under usual in vivo situations. This leads to the conclusion that for low-force-connected cone tapers joint friction of the artificial hip joint can cause a rotation and thus a loosening of the ceramic head of the implant neck during everyday activities. The authors proclaim the urgent necessity for clear handling references and the supply of a reproducibly safe taper lock method.

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While the principle of enlarging the surface area has been recognized and used in different ways for some time, there is often no schematic, detailed description or fundamental research. Taking a surface structure consisting of trabecular three-dimensional connecting elements, essential parameters are shown, making it clear that the flexible dynamic reaction of the effective "anchoring space" with a suitable specified shape (construction height, alignment, network) can be reproducibly shaped and used. This has led to a hip endoprosthesis with a graduated surface structure. The construction height of the trabecular structure varies, decreasing from proximal to distal.

The abductor apparatus (gluteal muscles and fascia lata) and the superior gluteal nerve remain intact. Immediate lateral positioning is allowed after surgery. The scar is unremarkable.