Implantation zementfreier Hüftpfannen
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Technische Universität Hamburg (2023)
The most common reason for revision of a cementless hip arthroplasty in Germany is implant loosening, especially on the acteabular side. The primary stability of the press-fit cup is achieved by a force locking mechanism between the implant and the bone. For this purpose, the cavity is underreamed in relation to the cup diameter and the pressfit is gradually increased by manual implantation with mallet blows. Thus, primary stability is multifactorially influenced by the implant, the patients bone and the surgeon. Therefore, the implantation process is of great importance to achieve a sufficiently high primary stability. The aim of the study was to develop clinical recommendations for the successful implantation of cementless acetabular cups. Special attention was given to the influence of the viscoelastic behavior of bone. Within the first 600 s, the cups showed a reduction in deformation in the range of 10 – 30 % of the initial deformation achieved after implantation. In-silico, thin-walled, less rigid cup designs benefited from low relaxations, resulting in high primary stability relative to the implantation force. In-vitro, the thin-walled cup design showed the highest primary stability. The low implantation forces promoted fast and complete seating of the cup. In addition to cups with constant thin wall thickness, cups with wall thickness reduced at the pole and anatomically shaped cups can be recommended based on the numerical model. When reducing acetabular stiffness, a compromise with the allowable deformation must be made. In addition, care must be taken to use a bone-preserving technique during surgical implantation. To minimize bone damage, unnecessary blows are to be avoided. Here the surgeon can also benefit from the improved haptic and visual feedback of thin-walled designs. Automated impactor systems also offer the possibility of constant and objective energy input as well as high-frequency implantation. The latter showed an altered viscoelastic behavior of the bone between the blows compared to manually applicable frequencies and required significantly less implantation force with higher primary stability.
Primärstabilität; Pfannendeformation; Knochenschäden; Implantationsmethode; Viskoelastizität; Implantatdesign
610: Medicine, Health