0
Research Papers

Effect of Surgery to Implant Motion and Force Sensors on Vertical Ground Reaction Forces in the Ovine Model

[+] Author and Article Information
Safa T. Herfat

Department of Biomedical Engineering, Tissue Engineering and Biomechanics Laboratories, University of Cincinnati, Mail Location 0048, Cincinnati, OH 45221-0048herfatmt@mail.uc.edu

Jason T. Shearn1

Department of Biomedical Engineering, Tissue Engineering and Biomechanics Laboratories, University of Cincinnati, Mail Location 0048, Cincinnati, OH 45221-0048jason.shearn@uc.edu

Denis L. Bailey

 University of Cincinnati, 2901 Woodside Drive, Cincinnati, OH 45221-0048baileyds@mail.uc.edu

R. Michael Greiwe

 Commonwealth Orthopaedics Centers, 560 Loop Road, Edgewood, KY 41017; Department of Orthopaedic Surgery, University of Cincinnati, 231 Albert Sabin Way, Mail Location 0212, Cincinnati, OH 45267-0212mike.greiwe@gmail.com

Marc T. Galloway

 Cincinnati Sportsmedicine and Orthopaedic Center, 10663 Montgomery Road, Cincinnati, OH 45242mtgalloway@aol.com

Cindi Gooch

Department of Biomedical Engineering, Tissue Engineering and Biomechanics Laboratories, University of Cincinnati, Mail Location 0048, Cincinnati, OH 45221-0048goochc@uc.edu

David L. Butler

Department of Biomedical Engineering, Tissue Engineering and Biomechanics Laboratories, University of Cincinnati, Mail Location 0048, Cincinnati, OH 45221-0048david.butler@uc.edu

1

Corresponding author.

J Biomech Eng 133(2), 021010 (Jan 31, 2011) (9 pages) doi:10.1115/1.4003322 History: Received July 20, 2010; Revised November 29, 2010; Posted December 22, 2010; Published January 31, 2011; Online January 31, 2011

Activities of daily living (ADLs) generate complex, multidirectional forces in the anterior cruciate ligament (ACL). While calibration problems preclude direct measurement in patients, ACL forces can conceivably be measured in animals after technical challenges are overcome. For example, motion and force sensors can be implanted in the animal but investigators must determine the extent to which these sensors and surgery affect normal gait. Our objectives in this study were to determine (1) if surgically implanting knee motion sensors and an ACL force sensor significantly alter normal ovine gait and (2) how increasing gait speed and grade on a treadmill affect ovine gait before and after surgery. Ten skeletally mature, female sheep were used to test four hypotheses: (1) surgical implantation of sensors would significantly decrease average and peak vertical ground reaction forces (VGRFs) in the operated limb, (2) surgical implantation would significantly decrease single limb stance duration for the operated limb, (3) increasing treadmill speed would increase VGRFs pre- and post operatively, and (4) increasing treadmill grade would increase the hind limb VGRFs pre- and post operatively. An instrumented treadmill with two force plates was used to record fore and hind limb VGRFs during four combinations of two speeds (1.0 m/s and 1.3 m/s) and two grades (0 deg and 6 deg). Sensor implantation decreased average and peak VGRFs less than 10% and 20%, respectively, across all combinations of speed and grade. Sensor implantation significantly decreased the single limb stance duration in the operated hind limb during inclined walking at 1.3 m/s but had no effect on single limb stance duration in the operated limb during other activities. Increasing treadmill speed increased hind limb peak (but not average) VGRFs before surgery and peak VGRF only in the unoperated hind limb during level walking after surgery. Increasing treadmill grade (at 1 m/s) significantly increased hind limb average and peak VGRFs before surgery but increasing treadmill grade post op did not significantly affect any response measure. Since VGRF values exceeded 80% of presurgery levels, we conclude that animal gait post op is near normal. Thus, we can assume normal gait when conducting experiments following sensor implantation. Ultimately, we seek to measure ACL forces for ADLs to provide design criteria and evaluation benchmarks for traditional and tissue engineered ACL repairs and reconstructions.

FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Fore and hind limb VGRFs normalized to bodyweight plotted against normalized gait cycle. 0 and 1 on the x-axis correspond to consecutive hoof strikes. The gray shaded regions correspond to the segment of the gait cycle when all limbs are in contact with the force plates. The letters at the top of the nonshaded regions correspond to left and right fore limb(s) (F) and hind limb(s) (H) that are in contact with the force plates.

Grahic Jump Location
Figure 2

Top: AIFP implanted into a sagittal slit in the distal portion of the ACL, oriented with the open end of the sensor pointed distal, and secured into the slit by placing a suture proximal and distal (arrows) to the leadwire (L). Bottom: electromagnetic sensors (circled) implanted on the medial distal femur and medial proximal tibia.

Grahic Jump Location
Figure 3

Speed did not significantly affect average VGRF (N=10) but did significantly alter hind limb peak VGRFs and hind limb peak timing. Average VGRF at 1.0 m/s and 1.3 m/s on a level surface. 0 and 1 on the x-axis correspond to consecutive hoof strikes.

Grahic Jump Location
Figure 4

Grade did significantly affect average and hind limb peak VGRF at the slower speed (N=10). Average VGRF at 1.0 m/s on a level and inclined (6 deg) surface. Grade shifted VGRFs from the fore to hind limbs. 0 and 1 on the x-axis correspond to consecutive hoof strikes.

Grahic Jump Location
Figure 5

Fore and hind limb VGRFs were consistent across subjects (N=10) with small interanimal variability. Average VGRF at 1.0 m/s on a level surface. 0 and 1 on the x-axis correspond to consecutive hoof strikes. The dashed lines correspond to VGRF maximums and minimums.

Grahic Jump Location
Figure 6

Implantation surgery did not significantly affect average VGRFs and only significantly increased the peak VGRF for the unoperated hind limb (N=6). The difference between average VGRFs before and after surgery 1.0 m/s on a level surface.

Grahic Jump Location
Figure 7

Implantation surgery did not significantly affect average VGRFs and only significantly increased the peak VGRF for the unoperated hind limb (N=5). The difference between average VGRFs before and after surgery at 1.3 m/s on a level surface.

Grahic Jump Location
Figure 8

Implantation surgery did not significantly affect average VGRFs or hind limb peak VGRFs (N=5). The difference between average VGRFs before and after surgery at 1.0 m/s on an inclined (6 deg) surface.

Grahic Jump Location
Figure 9

Implantation surgery did not significantly affect average VGRFs and only significantly decreased the peak VGRF for the operated hind limb (N=5). The difference between average VGRFs before and after surgery at 1.3 m/s on an inclined (6 deg) surface.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In