Affect of implant size and bone defect state of affairs on main stability after distal femoral alternative in vitro.
Knee. 2017 Oct;24(5):1016-1024
Authors: Nadorf J, Klein SB, Gantz S, Jakubowitz E, Kretzer JP, Bischel OE
BACKGROUND: Aseptic loosening is the main motive for failure of distal femoral alternative utilizing present modular megaprostheses. Though the identical stems are used for proximal and distal alternative, survival charges in scientific research with distal reconstruction had been decrease inside the similar system in comparison with proximal reconstruction. We analyzed whether or not main stability as presupposition for long-term fixation will be achieved with a present tapered stem design. Moreover, we hypothesized that stem size impacts main stability relying on bone defect conditions.
METHODS: A modular tumor system (Megasystem-C®, Hyperlink GmbH, Hamburg, Germany) with two totally different tapered stems (100 and 160mm) was implanted in eight Sawbones® in two consecutively created defect conditions (10 and 20cm proximal to knee joint stage). Main rotational stability was investigated by measuring relative micromotions between implant and bone to establish the primary fixation areas and to characterize the fixation sample.
RESULTS: The fixation differed between the 2 stem lengths and with respect to each defect conditions; nevertheless in every case the primary fixation space was situated at or near the femoral isthmus. Highest relative micromotions had been measured with the 160-mm stem on the distal finish inside small bone defects and on the proximal finish when defects had been elevated.
CONCLUSIONS: The analyzed design appeared to create adequate main stability alongside the primary fixation areas of the implant. Based mostly on these outcomes and with respect to oncologic or potential revision conditions, we recommend using the shorter stem to be extra favorable in case of main implant fixation.
PMID: 28793976 [PubMed – indexed for MEDLINE]