Ion Carrera1, Pablo Eduardo Gelber2,3, Gaetan Chary4,5, Miguel A González-Ballester4,6, Juan Carlos Monllau3,7, Jerome Noailly4,5. 1. Orthopaedic Surgery Department, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, C/Sant Quintí 89, 08041, Barcelona, Spain. dr.carrera@orthopaedic-trauma.eu. 2. Orthopaedic Surgery Department, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, C/Sant Quintí 89, 08041, Barcelona, Spain. 3. ICATME-Hospital Universitari Quirón-Dexeus, Universitat Autònoma de Barcelona, Sabino de Arana 5-19, 08028, Barcelona, Spain. 4. Department of Communication and information Technologies (DTIC), Universitat Pompeu Fabra, Barcelona, Spain. 5. Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain. 6. ICREA, Pg. Lluis Companys 23, 08010, Barcelona, Spain. 7. Orthopaedic Surgery Department, Parc de Salut Mar, Universitat Autònoma de Barcelona, Barcelona, Spain.
Abstract
PURPOSE: To assess, with finite element (FE) calculations, whether immediate weight bearing would be possible after surgical stabilization either with cannulated screws or with a locking plate in a split fracture of the lateral tibial plateau (LTP). METHODS: A split fracture of the LTP was recreated in a FE model of a human tibia. A three-dimensional FE model geometry of a human femur-tibia system was obtained from the VAKHUM project database, and was built from CT images from a subject with normal bone morphologies and normal alignment. The mesh of the tibia was reconverted into a geometry of NURBS surfaces. A split fracture of the lateral tibial plateau was reproduced by using geometrical data from patient radiographs. A locking screw plate (LP) and a cannulated screw (CS) systems were modelled to virtually reduce the fracture and 80 kg static body-weight was simulated. RESULTS: While the simulated body-weight led to clinically acceptable interfragmentary motion, possible traumatic bone shear stresses were predicted nearby the cannulated screws. With a maximum estimation of about 1.7 MPa maximum bone shear stresses, the Polyax system might ensure more reasonable safety margins. CONCLUSIONS: Split fractures of the LTP fixed either with locking screw plate or cannulated screws showed no clinically relevant IFM in a FE model. The locking screw plate showed higher mechanical stability than cannulated screw fixation. The locking screw plate might also allow full or at least partial weight bearing under static posture at time zero.
PURPOSE: To assess, with finite element (FE) calculations, whether immediate weight bearing would be possible after surgical stabilization either with cannulated screws or with a locking plate in a split fracture of the lateral tibial plateau (LTP). METHODS: A split fracture of the LTP was recreated in a FE model of a human tibia. A three-dimensional FE model geometry of a human femur-tibia system was obtained from the VAKHUM project database, and was built from CT images from a subject with normal bone morphologies and normal alignment. The mesh of the tibia was reconverted into a geometry of NURBS surfaces. A split fracture of the lateral tibial plateau was reproduced by using geometrical data from patient radiographs. A locking screw plate (LP) and a cannulated screw (CS) systems were modelled to virtually reduce the fracture and 80 kg static body-weight was simulated. RESULTS: While the simulated body-weight led to clinically acceptable interfragmentary motion, possible traumatic bone shear stresses were predicted nearby the cannulated screws. With a maximum estimation of about 1.7 MPa maximum bone shear stresses, the Polyax system might ensure more reasonable safety margins. CONCLUSIONS: Split fractures of the LTP fixed either with locking screw plate or cannulated screws showed no clinically relevant IFM in a FE model. The locking screw plate showed higher mechanical stability than cannulated screw fixation. The locking screw plate might also allow full or at least partial weight bearing under static posture at time zero.
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