Evaluation of Bisphosphonate Coated Pins for Extern Fixation in Tibia Osteotomy

The pin fixation and the risk for pin loosening and pintract infection is intimately connected Moroni et al., Magyar et al. Toksvig-Larsen and W-Dahl) The pin performance ratio for insertion to extraction torque (PPI) varies significantly between screw types.

The extraction torque force is the most important value and it is estimated that a removal torque around 300 Nm probably will be the best bon-pin fixation in clinical practice.

In animal studies and even in clinical studies the hydroxyapatite (HA) coated screw retained the highest level of osseointegration. However, the fixation for HAscrews is, especially in diaphyseal bone, the risk for too tight fixation, with extreme difficulties to remove the screws in few cases as a result ( high pain and seldom it is impossible to remove the screw) Coating by biphosphonate is a new novel technique with preclinical appealing performance, which theoretically should make this coating very appealing in clinical practice. The theory behind this technique is that it create a good pinfixation reasonable easy to remove.

The current most used cortical screw designs performed poorest in terms of fixation (PPI)

Method