In the treatment of spinal diseases, the spinal nail rod system is widely used as an important surgical treatment modality to restore the stability and function of the spine. However, with the increase in surgical patients and the extension of the number of years of surgery, the long-term stability and durability of the spinal nail rod system have become the focus of attention. Spinal injuries usually occur as a result of dislocations or fractures due to rotational, curved, or axial loading conditions. Static tests are used to assess the loads that will result in spinal fractures, while fatigue tests are performed to assess the number of cycles required for failure to occur when a component is subjected to repetitive loads at lower forces.

Lifetime testing of fatigue or spinal structures is crucial because fatigue failure is more common than catastrophic failure. Loads are typically applied in a constant-amplitude, load-controlled sinusoidal waveform that runs more than 5 million times.

The test for Spinal Implant Constructs nail screw, rod stipulated in the standard ASTM F1717, ASTM F2706, ISO 12189.

1, ASTM F1717 : Standard Test Methods for Spinal Implant Constructs in a Vertebrectomy Model.

Four test incldue in ASTM F1711

1.1, Static compression bending test
1.2, Static tensile bending test
1.3, Static torsion test
1.4, Dynamic compression bending fatigue test

2, ASTM F2706, “Standard Test Methods for Occipital-Cervical and Occipital-Cervical-Thoracic Spinal Implant Constructs in a Vertebrectomy Model” describes static test methods for fatigue tests on occipital-cervical and occipital-cervical-thoracic spinal implants in a vertebrectomy model.

Five test incldue in ASTM F2706

2.1, Static compression bending test

2.2, Static tensile bending test

2.3, Static torsion test

2.4, Dynamic compression bending fatigue test

2.5, Dynamic torsion fatigue test

3, ISO 12189:2008

Implants for surgery — Mechanical testing of implantable spinal devices — Fatigue test method for spinal implant assemblies using an anterior support

The spinal implant to be tested is securely mounted on a test block made of ultra-high molecular weight polyethylene (UHMWPE). The number of test blocks used simulates the vertebrae. The type and number of test blocks depends on the position of the vertebrae to be simulated. Between the test blocks, springs with specified stiffness values simulate the intervertebral disc and provide additional anterior support as specified in ASTM F1717.

ISO 12189 Dynamic Pedicle System Test Model. Light gray: PE (polyethylene) block simulates vertebral body, blue: connecting rod implant with dynamic section (black spring), dark gray: pedicle screw, red spring: calibration spring simulates intervertebral disc.

The test is performed under sinusoidal load with a maximum test frequency of 5 Hz. This force, in turn, depends on the position of the spine to be modeled. (lumbar spine: 0.6-2.0 kN / neck: 0.05-0.15 kN). The test ends when 5 million duty cycles are reached or when the structure has a mechanical failure. The results of the fatigue test must be summarized with an S-N curve. These tests are performed at ambient temperature, but can also be repeated in a Ringer's solution at 37 °C if necessary to simulate physiological environmental conditions and determine possible corrosion effects.

Main Parameter of the UnitedTest Fatigue and static testing system:

Max. dynamic load:±10KN  Accuracy ±1%

Max. static load: ±10kN

Dynamic fluctuation: Less than ±1%FS

Actuator max. stroke: ±50mm, accuracy ±0.5%FS

Amplitude at Max. frequency: ±1mm

Max. Frequency: 0.1HZ~15Hz

Max. line velocity: 150mm/s

For more information or details, please contact us:

Email: export@unitedtest.com 

whatsapp: +8613911165373

ASTM F1717-21: Standard Test Methods for Spinal Implant Constructs in a Vertebrectomy Model

ASTM F2706-18 : Standard Test Methods for Occipital-Cervical and Occipital-Cervical-Thoracic Spinal Implant Constructs in a Vertebrectomy Model

ISO 12189: 2008 Implants for surgery — Mechanical testing of implantable spinal devices — Fatigue test method for spinal implant assemblies using an anterior support