PURPOSE OF THE STUDY: We present an in vitro biomechanical study performed to evaluate and compare, for an experimentally produced fracture of the calcaneum (Duparc grade IV), the reaction of 3 standard models of internal fixation commonly used in these fractures and which occupy different volumes. MATERIALS AND METHODS: We compared different methods of fixation using fresh human calcanei. In two experimental series, we compared triangular internal fixation (3 1/4 tube AO plates Saragaglia), Y internal fixation (2 1/3 tube AO plates Bezes), isolated screw technique (three 3.5 diameter screws, two 4.5 diameter screws). The plates and screws were made of identical material (316L). Both series used 8 pairs of bone (talo-calcaneum system) with the same fracture submitted to a 200N to 1000N load. Stiffness and movement were analyzed using 8 references on the calcaneum. RESULTS: The stiffness and movement analysis with 8 references points demonstrated the superior resistance to bending with the triangular internal fixation. Fixation stability was significantly better than with the Y or screw technique. DISCUSSION: This study underlined the importance of triangular trabecular organization of cancellous bone on calcaneum biomechanics. We showed that the 3 (anterior, posterior and inferior) trabeculae must be repaired in calcaneum fractures to achieve horizontal and vertical stability of the talar joint. CONCLUSION: In our hands, restoration of the triangular architecture of calcaneum fractures, to resemble a roof truss, where the talus is fixed to the triangle vertex, is fundamental to obtain a rigid and stable internal fixation.
PURPOSE OF THE STUDY: We present an in vitro biomechanical study performed to evaluate and compare, for an experimentally produced fracture of the calcaneum (Duparc grade IV), the reaction of 3 standard models of internal fixation commonly used in these fractures and which occupy different volumes. MATERIALS AND METHODS: We compared different methods of fixation using fresh human calcanei. In two experimental series, we compared triangular internal fixation (3 1/4 tube AO plates Saragaglia), Y internal fixation (2 1/3 tube AO plates Bezes), isolated screw technique (three 3.5 diameter screws, two 4.5 diameter screws). The plates and screws were made of identical material (316L). Both series used 8 pairs of bone (talo-calcaneum system) with the same fracture submitted to a 200N to 1000N load. Stiffness and movement were analyzed using 8 references on the calcaneum. RESULTS: The stiffness and movement analysis with 8 references points demonstrated the superior resistance to bending with the triangular internal fixation. Fixation stability was significantly better than with the Y or screw technique. DISCUSSION: This study underlined the importance of triangular trabecular organization of cancellous bone on calcaneum biomechanics. We showed that the 3 (anterior, posterior and inferior) trabeculae must be repaired in calcaneum fractures to achieve horizontal and vertical stability of the talar joint. CONCLUSION: In our hands, restoration of the triangular architecture of calcaneum fractures, to resemble a roof truss, where the talus is fixed to the triangle vertex, is fundamental to obtain a rigid and stable internal fixation.