Effective combination of bone substitute and screws in the jail technique: a biomechanical study of tibial depression fractures

Bone substitute first or screws first? A biomechanical comparison of two operative techniques for tibial-head depression fractures

“…For the maximum load, it was not important at which time of the operation the bone substitute was applied. This is well in agreement with the results of our previous study demonstrating, when applying a combination of bone substitute and screws, the screws to be the main component of the osteosynthesis for the maximum load [10].…”

“…As bone substitute, drillable calcium phosphate cement, Norian drillable (Synthes), was used. The study demonstrated the importance of bone substitute for the displacement of the articular fracture fragment, whereas for the maximum load the screws were crucial [10]. However, a direct comparison of the two possible operative techniques now available by the drillable option is still lacking.…”

“…Thus, in the main testing series, axial forces were applied 3,000 times with 25 mm/min. First, ten settling cycles were performed with a load from 20 to 125 N. Then, the 3,000 measuring cycles followed with 20 to 250 N and in the end a load-to-failure test completed the test setup [6,10,11]. The force used under cyclic loading represents a typical load under partial weight bearing postoperatively after stabilization of tibial head fractures.…”

“…To simulate a tibial depression fracture of the lateral tibial plateau (AO:41-B2.2), an axial force was induced with an indentor at 500 mm/min on the lateral tibial plateau after setting five predetermined breaking points in a 12-mm-diameter circle [10,11]. The depth of the depressed fracture fragment was set at 15 mm, measured from the articular surface of the tibial plateau [10]. Subsequently, the fractures were reduced indirectly by a K-wire guided cannulated ram until the articular surface of the lateral tibial plateau was restored anatomically (Fig.…”

“…This drilling option allows to first fill up the defect and then to position the screws later. In a pilot biomechanical study, we have demonstrated, in principle, the suitability of the new calcium phosphate cement as a bone substitute in tibial head depression fractures [10]. However, so far, studies comparing the two operative techniques that have become possible with the new material and its drillable option have not been performed.…”