Medical Design Technology

Testing MDTmag.com 36 / March 2014

By Dipl.-Ing. Andrej Mahr, Applications Engineer, MTS Systems Corp.

There are 1.4 million trauma-related spinal injuries every year around the world1, of which 15% require surgical intervention2. Many of these cases involve teenagers who have their entire lives ahead of them, making pain elimination and mobility restoration especially critical. Improving healing time is also essential. According to a recent study out of Ireland, traumatic spinal injury patients require an average of 46 days of inpatient care.

The Institute of Technology, Tallaght (ITT Dublin) is a university-level institution located in South Dublin, Ireland. The

Research Applied –

Enhancing Healthcare with Test Equipment

Spinal trauma has significant impacts on quality of life for patients requiring surgical treatment. Therefore, ensuring the best technology and techniques are utilized for an improved level of care is paramount. This article shows how MTS Systems helps biomechanical engineering students optimize two common spinal trauma surgery procedures.

Bioengineering Technology Centre (BTC) provides applied research within the ITT School of Engineering, offering intensive instruction to a handful of students pursuing advanced degrees in biomechanical engineering. BTC strives to apply engineering principles to medical problems, with the goal of yielding new innovations that can be used in clinical practice to enhance patient quality of life.

Most recently, the BTC has focused its applied research on optimizing two widely used spinal surgery procedures — spinal fracture stabilization and balloon kyphoplasty — to help surgeons produce the best outcomes and minimize common post-surgery complications, both of which reduce hospital time.

The spinal fracture stabilization procedure uses screws and rods to mechanically stabilize the injured portion of the spine.

Balloon kyphoplasty uses an in-
flatable balloon to restore height
for a collapsed vertebrae, fol-
lowed by bone cement injection
to stabilize the structure. Many
kyphoplasty patients fracture
adjacent areas of their spine after healing
from surgery.

Optimizing both procedures involves the
same challenges for the BTC. The research-
ers must find a way to gather meaningful
test data in a test lab environment through
the accurate replication of in-vivo loads and
moments of the human spine.

“The spine is a fascinating area of study, because it is such a complex mechanical system with so many unknowns,” said Colin Bright, the postgraduate student leading the fracture stabilization study. “Our goal was to capture data from real-life simulations and adapt it to a test environment in order to reduce the unknowns with fracture stabilization and balloon kyphoplasty.”

The MTS Solution

The BTC employs an MTS Model 858 Bionix Test System with MTS Flex Test controls and MTS MultiPurpose Test Ware software ( www.mts.com) to support its applied research initiatives. This servohydraulic system can precisely simulate a full range of motions to spine specimens in six degrees of freedom, including flexion, extension, lateral bending, torsion, X-axis shear, and Z-axis shear. Test load data from a six degrees of freedom load cell and test displacement data from angular displacement transducers are acquired during the kinematic simulations on the test system.

Both the fracture stabilization and balloon kyphoplasty studies utilize porcine vertebral specimens, which are similar in size and structure to the human spine. The MTS Bionix test system is first used to induce spinal injuries that both procedures typically treat. Next, each procedure is performed on the specimen and then subjected to a series of static and fatigue mechanical tests.