Biomechanical evaluation of proximally placed femoral less-invasive stabilization system plates.

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Abstract

[Indexed for MEDLINE] 6. Int Orthop. 2015 Sep;39(9):1737-42. doi: 10.1007/s00264-015-2764-0. Epub 2015 Apr 16. Periprosthetic supracondylar femoral fractures following knee arthroplasty: a biomechanical comparison of four methods of fixation. Mäkinen TJ(1), Dhotar HS, Fichman SG, Gunton MJ, Woodside M, Safir O, Backstein D, Willett TL, Kuzyk PR. Author information: (1)Mount Sinai Hospital, Division of Orthopaedic Surgery, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada, tatu.makinen@hus.fi. PURPOSE: The aim of this study was to determine the biomechanical properties of four fixation options for periprosthetic supracondylar femoral fractures. METHODS: Fourth-generation composite femurs were implanted with a posterior-stabilizing femoral component of total knee arthroplasty. All femurs were osteotomized to produce a AO/OTA 33-A3 fracture pattern and four different constructs were tested: (1) non-locking plate; (2) polyaxial locking plate; (3) intramedullary fibular strut allograft with polyaxial locking plate; (4) retrograde intramedullary nail. The composite femurs underwent non-destructive tests to determine construct stiffness in axial and torsional cyclic loading. The final testing consisted of quasi-static axial loading until failure. RESULTS: Under cyclic torsional loading, the retrograde intramedullary nail was less stiff than non-locking plate, polyaxial locking plate and intramedullary fibular strut allograft with polyaxial locking plate (p = 0.046). No differences were detected in cyclic axial loading between the different constructs. During quasi-static axial loading to failure, the intramedullary nail achieved the highest axial stiffness while the non-locking plate showed the lowest (p = 0.036). CONCLUSIONS: The intramedullary fibular strut allograft with polyaxial locking plate did not prove to be significantly better to the polyaxial locking plate only in a periprosthetic distal femur fracture model. DOI: 10.1007/s00264-015-2764-0