The treatment of calcaneus fractures is even to the most experienced of orthopaedic trauma surgeons. Open reduction and internal plate fixation is the treatment of choice in most fractures in young patients. Similar to other body regions, plates with locked screws have recently been introduced. The goal for designing plates with locked screws is to improve overall stability for the fixation of the fracture. Increased stability may provide a window for more aggressive postoperative treatment including early, unprotected weight bearing. The application of this modality of treatment will invariably improve patients´ clinical course and outcome. The success or potential complications when using calcaneal fixations with locked screws has not been reported so far. Problems know from other body regions may also occur at the calcaneus. Problematic is for example the fixed possible angle between plate and locked screw that is 90° for most implants. This fixed angle may complicate the correct placement of plate screws. Another problem may be caused by the locking process itself that prevents the technique of pulling the plate to the bone by tightening a plate screw. The plate fixation of calcaneal fractures with plates without locked screws is characterized by a compression of the plate to the lateral wall of the calcaneus which results in the force-connection-principle. This is difficult with a plate with standard locked screws because the screws lock with the plate before the plate is pressed to the bone. Consequently, a force-connection is not achieved.
To avoid the weaknesses of the previous systems (uniaxially lockes screws, no force-connection), the new Polyaxial Calcaneus Locking Plate System was developed.