gms | German Medical Science

Objectives: Multi-fragmentary fractures in orthopedic trauma surgery regularly contain fragments, that are too small for fixation with screws or k-wires. For those bony or osteochondral fragments a bone glue would be desirable to enable anatomic reduction and avoid discarding of small fragments. Besides, bone glues enable temporary fixation of fracture fragments to visualize the reduction and the fit before the definitive osteosynthesis is done. However, currently available bone glues are either cytotoxic, non resorbable and not cohesive in an aqueous environment or mechanical weak. Magnesium phosphate cements used as bone glues may have the potential to overcome those downsides.

Methods: Pure split fractures of the lateral tibial plateau were created in dissected porcine tibiae. The lateral fracture fragment was then glued on the condyle with a bone adhesive. One pure magnesium phosphate (Mg3PO4 + MgO + phytic acid), one magnesium calcium phosphate (Mg2.75Ca0.25PO4 + MgO + phytic acid), one magnesium phosphate cement that had undergone modified temperature stages during sintering (Mg3O8P2 * xH2O) and a commercial cyanoacrylate glue (Glubran^® 2) were biomechanically evaluated. Load was applied on the glued fracture fragment with the femoral component of a knee hemiarthroplasty. Cyclic loading with increasing load levels and load to failure test were conducted.

Figure 1 [Fig. 1]

Results and conclusion: Regarding the magnesium phosphate formulations, the one with additional low amounts of calcium demonstrated the highest cyclic load (162±40 N vs. 125±52 N vs. 100 ±35 N) and the highest load to failure (295±84 N vs. 287±126 N vs. 215±83 N). The commercial cyanoacrylate (Glubran^® 2) yielded the highest values of all 4 adhesives under both types of loading (cyclic: 449±136 N, load to failure: 1051±375 N).

A magnesium calcium phosphate bone adhesive provides clinical desired strength and stability and thus might be suitable for intraoperative fixation of small fragments. Additionally, this formulation avoids the downsides of glues based on formaldehyde or cyanoacrylate.