Influence of implant length and bone defect situation on primary stability after distal femoral replacement in vitro

• Verfasst von: Nadorf, Jan [VerfasserIn]
• Verfasst von: Klein, Simon Benjamin [VerfasserIn]
• Verfasst von: Gantz, Simone [VerfasserIn]
• Verfasst von: Kretzer, Jan Philippe [VerfasserIn]
• Verfasst von: Bischel, Oliver E. [VerfasserIn]
• Titel: Influence of implant length and bone defect situation on primary stability after distal femoral replacement in vitro
• Verf.angabe: Jan Nadorf, Simon B. Klein, Simone Gantz, Eike Jakubowitz, Jan Philippe Kretzer, Oliver E. Bischel
• E-Jahr: 2017
• Jahr: 6 August 2017
• Umfang: 9 S.
• Fussnoten: Gesehen am 30.08.2018
• Titel Quelle: Enthalten in: The knee
• Ort Quelle: Amsterdam [u.a.] : Elsevier Science, 1994
• Jahr Quelle: 2017
• Band/Heft Quelle: 24(2017), 5, Seite 1016-1024
• ISSN Quelle: 1873-5800
• DOI: doi:10.1016/j.knee.2017.07.010
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Distal femur
• Sach-SW: Implant fixation
• Sach-SW: Megaprosthesis
• Sach-SW: Megasystem-C
• Sach-SW: Primary stability
• Sach-SW: Tumor prosthesis
• K10plus-PPN: 1580542468

Abstract

Background: Aseptic loosening is the major reason for failure of distal femoral replacement using current modular megaprostheses. Although the same stems are used for proximal and distal replacement, survival rates in clinical studies with distal reconstruction were lower within the same system compared to proximal reconstruction. We analyzed whether primary stability as presupposition for long-term fixation can be achieved with a current tapered stem design. Additionally, we hypothesized that stem length affects primary stability depending on bone defect situations. Methods: A modular tumor system (Megasystem-C®, Link GmbH, Hamburg, Germany) with two different tapered stems (100 and 160mm) was implanted in eight Sawbones® in two consecutively created defect situations (10 and 20cm proximal to knee joint level). Primary rotational stability was investigated by measuring relative micromotions between implant and bone to identify the main fixation areas and to characterize the fixation pattern. Results: The fixation differed between the two stem lengths and with respect to both defect situations; however in each case the main fixation area was located at or close to the femoral isthmus. Highest relative micromotions were measured with the 160-mm stem at the distal end within small bone defects and at the proximal end when defects were increased. Conclusions: The analyzed design seemed to create sufficient primary stability along the main fixation areas of the implant. Based on these results and with respect to oncologic or potential revision situations, we suggest the use of the shorter stem to be more favorable in case of primary implant fixation.