During normal patient activity, spinal constructs can be subjected to high in vivo loading that can result in catastrophic failure. Spinal injuries often occur due to rotation, dislocation, bending, and axial loading. Simple static testing is able to evaluate the load required to result in spinal fracture. Cyclic testing is also performed in order to evaluate the amount of cycles it takes for fatigue failure to occur.
Service life testing of spinal constructs is critical as fatigue failure is more common than catastrophic failure. Loading is typically applied with a constant-amplitude, load-controlled sinusoidal waveform, running in excess of five million cycles.
ASTM F1717, Standard Test Methods for Spinal Implant Constructs in a Vertebrectomy Model, specifies methods for both the static and fatigue testing of spinal implant assemblies.
For the majority of spinal construct testing, ultra high molecular weight polyethylene (UHMWPE) blocks are used rather than vertebrae to eliminate the variances that bone properties and geometry may introduce.
Our universal testing systems are ideal for static tensile and compressive tests. We suggest using static software test packages, such as Bluehill®, to record load-displacement curves and to perform calculations required by the ASTM standard.
For application of torsional strain, we recommend any of our torsion tabletop testing systems. The 55MT MicroTorsion system can be used when multiple revolutions are required. The ElectroPuls E3000 Linear-Torsion test instrument is a versatile system capable of ±135° rotation, and also offers the flexibility to handle both axial and torsional fatigue testing.
If you need to achieve exceptional response and accuracy across the frequency range, or if you are looking to test the durability of spinal constructs, we suggest using the ElectroPuls™ All-Electric Dynamic Test Instrument combined with WaveMatrix™. Control features, such as auto tuning and inertial compensation using Dynacell™, optimize system response, waveform fidelity, and resolution.