Numerical Evaluation of the Knee Arthrodesis Using a Modified External Fixator

This work presents the numerical results of arthrodesis using a modified bilateral-monoplanar external fixator for the treatment of septic sequelae of the knee joint. The knee arthrodesis serves as an option of salvage treatment for failed total knee arthroplasty procedures [1]. The arthrodesis technique used in this work was promoted with external fixation consisting on the union of two or more femoral pins with two or more tibial pins through bended lateral bars. Biplanar fixation has higher sagittal stability and higher fusion rates than the monoplanar fixation, but the level of compression on the fusion area as well as the extension of contact area can have a great impact on the bone union. Hence, the main purpose of this work is to give the surgeons additional information on how to influence positively the knee arthrodesis, namely relatively to the fixation level, the homogeneity of contact and to the compression level, but also about some possible complications. The arthrodesis technique was implemented using the CAD Solidworks (R) software and the numerical analysis was carried out on ADINA (R) software. With this methodology it was possible to recreate the mechanical procedure of the knee arthrodesis and the results indicate that the arthrodesis technique is not only influenced by the parameters associated with the kind of externatal fixator used, but also with the type of supported used to perform the external fixation assembly.