Ellen Tsaprailis, Tyrone Burke, February 3, 2022

Carleton’s Latest Partnership with the Ottawa Hospital Research Institute is a New Lab to Design Better Orthopedic Implants and Surgical Techniques

The latest health technology partnership between Carleton University, the Ottawa Hospital Research Institute and the hospital’s Division of Orthopedic Surgery is the creation of a new lab, named the Ottawa Orthopaedic Biomechanical Laboratory, with the goal of improving orthopedic implants and surgical repairs.

Everyday movements can put a surprising amount of force on joints. While walking at a moderate pace, a person’s knee absorbs as much as two and a half times their body weight with each step. Climbing the stairs can put as much as six times a person’s body weight on a hip joint.

This is only the first challenge of designing effective orthopedic implants. After patients recover from surgery, they want to regain full mobility. Athletes often seek a return to peak performance. To meet patients’ needs, implants or surgical repairs to joints must be able to endure adverse conditions.

With Carleton investing $140,000 into the $560,000 Biomechanical Lab, this three-way partnership will use a new robotic arm to evaluate the materials and techniques used in implants, and to more accurately model their performance.

“There are a lot of mechanics to consider in surgical repairs of anatomy. In terms of how we move, and how the joints are loaded—ultimately how a reconstruction technique performs,” says Andrew Speirs, Associate Professor in the Department of Mechanical and Aerospace Engineering and part of the Biomechanical Lab as one of the Carleton researchers.

Made by KUKA, a German industrial robotics and factory automation company, the new arm will be housed at The Ottawa Hospital’s Civic Campus. Carleton researchers will use it to better understand the biomechanics of orthopedic implants, while researchers from the Ottawa Hospital Research Institute will use digital imaging equipment to examine how ligaments stretch under different knee alignments and how that contributes to premature implant wear.

Chief of Orthopaedic Surgery and lead Ottawa Hospital researcher of the Biomechanical Lab Dr. Paul Beaulé says they are using the KUKA arm for model purposes.

“The actual purpose of the KUKA robot is to precisely reproduce real-life joint motions and forces so that we can better understand how injuries happen and to test innovative orthopedic procedures/implants to address these injuries,” says Beaulé.

The KUKA robotic arm is similar to the factory robots that are commonly used on automotive assembly lines and can move in three dimensions. By mimicking the complex range of motion of the joints themselves, it will enable more accurate simulation of how force is actually exerted on hips and knees.

“In a reconstruction of an anterior cruciate ligament (ACL) in the knee, stability is very important,” Speirs says. “When a knee moves about, you want the ACL to constrain motion at certain times, so it does not hyperextend, but you also don’t want the knee to resist during normal motion. How a knee moves post-operatively depends on the material used, and exactly how and where it is placed in the knee. That would be the type of scenario we will be able to test. This robot can apply rotations and see how forces affect the reconstruction.”

Speirs’ primary research focus is on osteoarthritis and mechanical loading in the hip joint. There is a common deformity at the top of the femur (thigh bone) that can rub on the acetabulum—the socket in the pelvis where the femur fits to create a hip. This deformity occurs in about 15 per cent of all people, and can cause degeneration in the labrum, a fibrous structure on the rim of that socket. It is strongly associated with osteoarthritis, but it’s not currently possible to identify which people with the deformity will develop the condition, and which ones will not.

“With this robot, you can load the joint with the same forces it would experience in daily life. Anything that involves flexing the hip—climbing stairs, sitting down, leaning down, or tying your shoe,” says Speirs. “More precise data about the load that is applied will help make our mathematical models more accurate.”

Dr. Braden Gammon is the Clinical Director of the new Biomechanical Lab and says they will be investing in a digital image correlation system.

“This will allow us to non-invasively assess the properties of materials such as stress and strain through non-contact analysis. It will further our understanding of the biomechanical underpinnings of musculoskeletal pathology and allow for testing of medical devices, biological and bioengineered material,” says Gammon.

The new equipment also presents an opportunity to test 3D printed materials that could make better implants. Mechanical and Aerospace Engineering Professor Hanspeter Frei will be using the robotic arm to explore the potential of novel materials, and innovative manufacturing techniques could make implants stronger and more durable.

“There are a lot of things you can do with 3D printing that can’t be done with traditional manufacturing methods,” says Speirs. “There are trade-offs with implants. A really stiff implant will support the load on the joint, but take too much pressure off the bone. That can cause a loss of bone mass—not unlike what an astronaut experiences when they spend time in space. When a patient loses bone around the implant, it can come loose and can break. 3D printing could help design implants that are not as stiff. And they could be potentially more porous, which could allow the bone to grow into those pores and make the implant more secure.

“3D printing enables you to design shapes that would be very difficult in traditional manufacturing.”

Beaulé has collaborated for more than a decade with Speirs and Frei and plans to continue their long-standing partnership.

“We greatly cherish these collaborations as it brings the best expertise from both sides of the equation—i.e., bench side to clinical translation,” says Beaule. “These collaborations resulted in all of us receiving the Kappa Delta Award in 2018 which is the most prestigious musculoskeletal research award in North America.”

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