[Osteosynthesis of thalamic fractures of the calcaneus using triangulation-fixed 1/4-tube plates. Preliminary results of 32 osteosyntheses]. / L'ostéosynthèse des fractures thalamiques du calcanéum par plaques "1/4 de tube" montées en triangulation. Résultats préliminaires de 32 ostéosynthèses.

The authors present a new type of osteosynthesis fixture used in calcaneal thalamus fracture repair. This consists in triangulation fixation, the upper- and retromost part of the thalamus being the apex of the triangle. This is performed using 2 or 3 1/4-tube A.O. instrumentation plates, with adaptable positioning according to the type of fracture. This system presents two advantages compared to currently used fixation components: it is less bulky and is associated with a reduced risk of skin-related complications. Calcaneal reconstruction is much more stable because the plates are in alignment with talocalcaneal stress lines, on the one hand, and because they form a truss that counteracts secondary displacement of the reconstructed thalamus. 32 calcaneal syntheses were thus performed during the period between July 1983 and July 1988. These included 8 stage III DUPARC fracture cases (25%), 21 stage IV cases (65.6%), and 3 stage V cases (9.4%). Nine 2-plate fixtures were assembled in an circumflex-like manner and 23 operations involved setting up the fixation components in a "closed triangle". Cuboid anchorage was necessary in 11 cases. Uncomplicated cutaneous necrosis occurred only once in this series (i.e., 3.2%). The stability of this operative procedure was assessed by measurements of Boehler's angle in the immediate postoperative period and after consolidation. The fixation was perfectly stable in 94% of cases (angle loss less than or equal to 5 degrees). Secondary angle loss occurred in 6% of cases (i.e., 2 cases, 8 degrees and 12 degrees respectively), one of which was caused by untimely weight-bearing. Moreover, no case of plate disruption was reported in this series.