A comparative biomechanical study for complex tibial plateau fractures: Nailing and compression bolts versus modern and traditional plating

Aim

To compare the biomechanical properties of a newly proposed technique, utilizing intramedullary nailing and compression bolts, for the osteosynthesis of intra-articular proximal tibial fractures with meta–diaphyseal comminution, with modern and conventional plating techniques.

Methods

Fifteen left tibia 4th generation composite Sawbones models (in 3 groups of 5 for each technique) with identically reproduced type VI Schatzker tibial plateau fractures, including meta–diaphyseal dissociation, were used. Three different techniques of osteosynthesis were tested: (a) a new technique that combines intramedullary nailing and compression bolts, (b) internal fixation with a single lateral locking plate and (c) internal fixation with dual buttress plating technique. The model-device constructs were successively subjected to 500 N, 1000 N and 1500 N load levels with five cycles applied at each level on both articular compartments and a final load cycle to failure. Four parameters were recorded for each technique: the average reversible or irreversible displacement in vertical subsidence, the horizontal diastasis of the intra-articular fracture, the average passive construct stiffness and the load to failure.

Results

The new intramedullary nailing technique provided rigid intra-articular osteosynthesis being statistically similar to dual buttress plating for subsidence at medium and higher load levels. At the same time the proposed technique provided statistically equivalent stiffness values to the single lateral locking plate incarnating the rational of biologic fixation. Average load to failure was 1611 N for single lateral locking plates, 2197 N for intramedullary nailing and 4579 N for dual buttress plating. The single lateral locking plate technique had the worse results in interfragmentary displacement while dual buttress plating was superior in stiffness from the other 2 techniques. The mode of failure differed between techniques, with collapse of medial plateau occurring exclusively in the single lateral locking plates group.

Conclusion

The proposed new technique of intramedullary nailing and compression bolts demonstrates a flexural behaviour similar to single lateral locking plates, which complies with the terms and benefits of biological fixation, while at the same time maintains a rigid intra-articular stability similar to the stiff dual buttressing plating technique.     

A comparison of the pharmacodynamic behavior of branded and biosimilar enoxaparin in primates

Pharmacodynamic behavior of branded and biosimilar enoxaparin was compared in a crossover study in primates. Blood samples collected at baseline and at 1, 4, 6, and 28 hours post-subcutaneous administration of Lovenox or Fibrinox were evaluated using clot-based and amidolytic assays. Anti-Xa levels following Fibrinox and Lovenox administration were not different. Anti-IIa levels were significantly higher in Lovenox-treated animals 1 to 6 hours post-administration. Higher drug levels were measured by Heptest in Fibrinox-treated animals from 4 to 6 hours. Pharmacokinetic differences were not observed using anti-Xa or Heptest assays. The area under the curve (anti-IIa) following Lovenox treatment was significantly larger than following Fibrinox treatment. When drug levels (anti-IIa) were plotted against anti-Xa or Heptest drug levels, a hysteretic relationship which was distinct for Fibrinox- and Lovenox-treated primates was observed suggesting a lack of bioequivalence for the low-molecular-weight heparin tested. In vivo behavior is an important consideration for defining pharmacoequivalence of complex biologic drugs.