University of Calgary BioMechanical Research
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BioMechanical Hexapod Research

Nigel Shrive Killam Research Chair FICE, P.Eng, C.Eng, Shon Darcy & Josh Rosvold PhD(Candidates)

BioMechanical Rotopod
Shon Darcy with a Hexapod

Shon Darcy PhD (Candidate), Craig Sutherland (Surgeon) image courtesy of Chris Bolin


Rotopod with Knee segment

Shon Darcy with University of Calgary Rotopod

U of Calgary Rotopod and Dr Shrive

The University of Calgary

The University of Calgary has long been committed to cutting edge research in a variety of areas. To this end, the Calgary Centre for Innovative Technology (CCIT) was built to provide a world class interdisciplinary research facility committed to producing significant advances in knowledge and finding novel solutions to strategic challenges.

One area of focus for CCIT is Biomedical Engineering. Researchers are trying to understand the factors that contribute to the development of osteoarthritis following ligament reconstructive surgery.

In order to collect the required data, researchers needed to be able to reproduce the loading and range of motion seen in living tissue in a laboratory setting.

To this end, the University of Calgary found that the Mikrolar Rotopod was able to provide all the required motion while maintaining the high degree of precision necessary to obtain accurate data.

A Robotic Testing System Which Reproduces Real Motion

The knee joint is a sophisticated biological mechanism involved in locomotion at the lower extremity. Its function is often sustained for a lifetime, at a rate of over 1 million cycles per year[1, 2], without signs of damage. Despite its apparently simple motion during gait, the knee actually features complex 3D motion that stems from the biomechanical interdependence and balance of its component tissues. Following joint injury, such balance is upset and is difficult to restore with existing clinical treatments. The knee joint is also the most commonly injured joint in the body.[3, 4] In order to successfully treat injuries to the knee the biomechanical responses of ligaments is necessary; from the clinical perspective in order to gain insight into injury mechanisms, develop prevention strategies and evaluate treatment options that optimize healing; from a basic science perspective, in order to understand the load environment of the tissues for the advancement of tissue engineering; and from an engineering perspective to develop feedback control mechanisms for assistive technology (e.g. functional electrical stimulation) to assist and mobilize patients with spinal cord injuries.

Making accurate estimations of forces that occur in a living system's locomotive apparatus remains one of the most significant challenges in orthopedic biomechanics, and the knee joint is no exception.[5-9] In fact, direct measurement of in vivo forces in the knee has not been determined experimentally until last year at the University of Calgary. [10, 11] Existing strain transducers require some form of contact with the subject tissue in order to convert the mechanical energy stored in its deformation into a measurable signal, rendering them impractical.[12-15] Thus, part of the challenge lies on identifying a non-invasive and non-destructive methodology to obtain the data of interest. Robotics has been used for many industrial applications such as automobile manufacturing, flight simulation, and spot welding. A newly developed experimental robotic manipulator, a parallel robot, boasts higher accuracy and rigidity due to its parallel design, small work volume and the proximity of the robot's global and end effector coordinate systems. These design optimizations have led to the use of this robot in one of the most advanced biomechanical applications to date, reproducing in vivo motion which is recorded in response to muscle actions. This is a powerful new methodology to understand the mechanical environment of the normal and injured knee, it will soon be able to assess the effect of multiple injuries to joint structures immediately following injury.


1. Seedhom, B. and N. Wallbridge, Walking activities and wear of prostheses. Annals of Rheumatic Diseases, 1985. 44(12): p. 838-843.
2. Schmalzried, T., Quantitative assessment of walking activity after total hip or knee replacement. Journal of Bone & Joint Surgery - American Volume, 1998. 80(1): p. 54-59.
3. Baylis, W.J. and E.C. Rzonca, Common sports injuries to the knee. Clin Podiatr Med Surg, 1988. 5(3): p. 571-89.
4. Ege, G., et al., [Knee injuries: MRI findings]. Ulus Travma Derg, 2001. 7(1): p. 60-5.
5. Debski, R.E., et al., Effect of capsular injury on acromioclavicular joint mechanics. Journal of Bone & Joint Surgery - American Volume, 2001. 83(9): p. 1344-1351.
6. Gilbertson, L., T. Doehring, and J. Kang, New methods to study lumbar spine biomechanics: delineation of in-vitro load-displacement characteristics using a robotics/UFS testing system with hybrid control. Operative Techniques in Orthopaedics, 2000. 10(4): p. 246-53.
7. Carlin, G.J., et al., In-situ forces in the human posterior cruciate ligament in response to posterior tibial loading. Journal of Biomedical Engineering, 1996. 24: p. 193-197.
8. Takai, S., et al., Determination of the in situ loads on the human anterior cruciate ligament. Journal of Orthopaedic Research, 1993. 11: p. 686-695.
9. Woo, S.L.-Y., et al., Biomechanics of the ACL: Measurements of the in situ force in the ACL and the knee kinematics. Knee, 1998. 5: p. 267-288.
10. Frank, C., et al. In Vitro Robotic Reproduction Of In Vivo Sheep Knee Kinematics - A Pilot Study Of A New Method Of Quantifying In Vivo Tissue Loads. in IOC. 2003. Greece.
11. Howard, R., JM, et al. Measurement of Loads in the Ovine Stifle Joint during In-Vitro Robotic Reproduction of In-Vivo Kinematics. in International Symposium on Ligaments and Tendons IV (4) 45. 2004.
12. Rupert, M., et al., Influence on sensor size on the accuracy of in-vivo ligament and tendon force measurements. Journal of Biomechanical Engineering, 1998. 120(12): p. 764-769.
13. Beynnon, B.D., et al. Measurement of anterior cruciate ligament strain during non-weight and weight bearing conditions. in XVII ISB Congress. 1999. Calgary.
14. Fleming, B.C., et al., The strain behavior of the anterior cruciate ligament during stair climbing: an in vivo study. Arthroscopy, 1999. 15(2): p. 185-91.
15. Fleming, B.C., et al., The strain behavior of the anterior cruciate ligament during bicycling. An in vivo study. American Journal of Sports Medicine, 1998. 26(1): p. 109-18.

To see some of the published research accomplished with the use of the University of Calgary Rotopod visit the published work page.