Leatt-Brace

With neck brace and Without neck brace
Typical ROM in Posterolateral Hyperextension

Test 3

Posterolateral Hyperextension Test
(rectangular impact block set high at 45⁰)

TEST DESCRIPTION

This test determines the ability of a neck brace to reduce forces and bending moments on the neck during an injury causation mode known as Posterolateral Hyperextension. This variation of the hyperextension test seeks to create what is believed to be the most prevalent hyperextension impact scenario, one where significant Upper Neck Bending Moments My and Mx and Upper Neck Anterior/Posterior Shear Force, Fx are developed as a result of a combination of extension and simultaneous lateral movement of the neck.

To achieve this, the rectangular block used as the impact surface is set up to strike the helmet in the area from about mid face (mid visor) to the helmet top while simultaneously angled at 45 degrees to induce lateral movement.

The performance of each device is measured and compared to the results of a baseline test without a brace. A visual comparison of typical Range of Movement (ROM) of the head during hyperextension with and without a neck brace is shown in the accompanying figure.

TEST OBJECTIVE

To be successful a test device should significantly reduce the magnitude of the following parameters experienced by the neck when compared to baseline results obtained without a brace.

• Peak Upper Neck Bending Moment. My
• Integrated Absolute Moment ∫My over time (energy)
• Peak Upper Neck Bending Moment. Mx
• Integrated Absolute Moment ∫Mx over time (energy)
• Peak Resultant Nij in extension
• Peak Upper Neck Anterior/Posterior Shear Force Fx
• Integrated Absolute Shear Force ∫Fx over time (impulse)

Without neck brace and With neck brace
Typical ROM in Primary Hyperflexion

Test 4

Primary Hyperflexion Test
(with rectangular impact block set high)

TEST DESCRIPTION

This test determines the ability of a neck brace to reduce forces and bending moments on the neck during an injury causation mode known as Primary Hyperflexion. This variation of the Hyperflexion test seeks to create a scenario of almost pure Hyperflexion, one where significant Upper Neck Bending Moment in Flexion, My is developed. To achieve this, the rectangular impact block is set up to strike the rear of the helmet in the area that corresponds from the helmet top to mid face (mid visor).

The performance of each device is measured and compared to the results of a baseline test without a brace. A visual comparison of typical Range of Movement (ROM) of the head during hyperextension with and without a neck brace is shown in the accompanying figure.

TEST OBJECTIVE

To be successful a test device should significantly reduce the magnitude of the following parameters experienced by the neck when compared to baseline results obtained without a brace.

• Peak Upper Neck Bending Moment in flexion. UN My
• Integrated Upper Neck Absolute Moment ∫ UN My over time (energy)
• Peak Lower Neck Bending Moment in flexion. LN My
• Integrated Lower Neck Absolute Moment ∫ LN My over time (energy)
• Peak Resultant Nij

Without and With neck brace
Typical ROM in Anterolateral Hyperflexion

Test 5

Anterolateral Hyperflexion Test 
(with rectangular impact block set high at 45 ⁰)

TEST DESCRIPTION

This test determines the ability of a neck brace to reduce forces and bending moments on the neck during an injury causation mode known as Anterolateral Hyperflexion. This variation of the Hyperflexion test seeks to create a scenario of where both Lateral and Flexion Bending Moments My are developed in the Upper Neck.

To achieve this, the rectangular impact block is set up to strike the rear of the helmet in the area that corresponds with mid face (mid visor) to the helmet top while simultaneously angled at 45 degrees to induce lateral movement.

The performance of each device is measured and compared to the results of a baseline test without a brace. A visual comparison of typical Range of Movement (ROM) of the head during hyperextension with and without a neck brace is shown the accompanying figure.

TEST OBJECTIVE

To be successful a test device should significantly reduce the magnitude of the following parameters experienced by the neck when compared to the baseline results obtained without a brace.

• Peak Upper Neck Bending Moment. My
• Integrated Absolute Moment ∫My over time (energy)
• Peak Upper Neck Bending Moment. Mx
• Integrated Absolute Moment ∫Mx over time (energy)

Test 6

Secondary Hyperflexion and ALPT Test
(with rounded impact block)

TEST DESCRIPTION

This test evaluates the ability of a device to transfer axial force away from the cervical spine and into the upper torso, after the head has moved out of the way of the initial line of the impact force vector. In addition, the secondary phase of bending moment reduction after impact is also evaluated.

This test evaluates whether devices with allowance for more “tuck and roll” will improve neck force parameters upon impact or conversely negatively affect them.

The ability of a device to effectively distribute load transferred to it from the helmet (and hence the cervical spine) to the structures of the upper torso will subsequently be evaluated (compliance with Alternative Load Path Technology). This means that the device’s material properties will in effect be evaluated for its ability to transfer load and not be too rigid or too pliable in the process of performing this function.

If two devices are equally able to reduce the negative effects of neck injury parameters, the resultant impact on upper torso parameters (which may pose a risk if excessive) will determine which device is most effective. Transferring forces away from the cervical spine is of prime importance but this must be achieved without transferring the forces onto the vulnerable structures of the upper torso or at rates that are unsustainable.

A device must thus demonstrate that it can both transfer forces away from the upper torso but in a controlled manner (through distribution of the applied load over all the upper torso structures but excluding the clavicles) without increasing point loading levels in areas of the upper torso where injury is likely.

The performance of each device is measured and compared to the results of a baseline test without a brace.

TEST OBJECTIVE

To be successful a test device should significantly reduce the magnitude of the following parameters experienced by the neck when compared to baseline results obtained without a brace.

• Peak Upper and Lower Neck Bending Moment (My_upper/My_lower)
• Integrated Upper and Lower Neck Bending Moment (∫ My_upper/∫ My_lower)
• Peak Upper and Lower Neck Axial Force (Fz_upper/Fz_lower)
• Integrated Peak Upper and Lower Neck Axial Force (Fz_upper/Fz_lower)
• Chest Deflection
• Integrated Chest Deflection
• Resultant Neck Injury Criteria Nij