gms | German Medical Science

Objectives: This study assesses the biomechanical efficacy of cost-effective world wide available materials as alternatives to costum external fixators, with a focus on application in Low- and Middle-Income Countries (LMICs).

Does the use and application of such materials guarantee stiffness equivalent to commercially available fixation systems?

Methods: Experimental tests utilized M10 A2 stainless steel threaded rods (10.0 mm) with nuts and washers in combination with medically approved Schanz screws (5.0 mm) or Kirschner wires (3.0 mm) to fabricate various fixator constructs. To standardize the hole spacing and length of the pins/Kirschner wires, the constructs were applied using a template. Four study groups were formed. The constructs underwent biomechanical axial load testing on calf ulna comminuted fracture models, benchmarked against a commercial external fixator. Dynamic testing of the stiffness of the four groups was conducted over 20 cycles, each with a load of 450 Newton (N).

Results and conclusion: The results of the biomechanical investigation show that the threaded rod with nuts and washers, in combination with 5.0 mm Schanz screws, achieves similar stiffness to a commercially available external fixator. The combination of threaded rod and 3.0 mm Kirschner wires demonstrated significantly lower stiffness.

Stiffness of the four test groups in the 5^th and 20^th cycle sowed, that the threaded rod with Schanz screws achieves 80.96% of the stiffness of the commercially available fixation system. The Kirschner wires achieve 44.0% and the threated Kirschner wires 41.44%, respectively.

The cost of an off-label system for the threaded rod, nuts, and washers was 1.85 EUR, excluding the Schanz screws and Kirschner wires.

The study concludes that developing a biomechanically adequate, cost-efficient external fixator is feasible. This implies significant implications for improving the accessibility and quality of fracture care in LMICs.

Figure 1 [Abb. 1]

Table 1 [Tab. 1]