Poster CC2 - Using an instrumented insole to estimate Achilles tendon loading in pregnant women during walking

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Afua Nkansah-Andoh

Graduate Student
University of Pennsylvania
Philadelphia, Pennsylvania, United States

Co-Author(s)

Michelle Meyers

Graduate Student
University of Pennsylvania, United States
Devyn Russo, BS (she/her/hers)

Clinical Research Coordinator
University of Pennsylvania
Conshohocken , Pennsylvania, United States

Primary Investigator(s)

Casey Humbyrd, MD, MBE

Chief, Foot and Ankle Division
University of Pennsylvania, United States

Last Author(s)

JB

Josh Baxter

Assistant Professor of Orthopaedic Surgery
University of Pennsylvania, United States

Introduction: Over 3 million women per year in the United States alone get pregnant [1], and nearly 70% of these women experience some type of musculoskeletal pain such as lower back pain, leg pain, or pelvic girdle pain [2]. Despite the large number of pregnant women with musculoskeletal pain and symptoms, biomechanical research has largely avoided studying the effects of pregnancy on musculoskeletal function and symptoms. While most pregnant women experience musculoskeletal pain and symptoms, it is unclear how tendon loading - which is the primary driver of joint loading - changes during pregnancy. The purpose of this study was to quantify Achilles tendon loading in pregnant women while walking and compare it to females who are not pregnant. We hypothesized that pregnant women in their third trimester of pregnancy walk with different Achilles tendon loading profiles compared to women who are not pregnant and have never been pregnant.

Materials and

Methods: 8 third trimester patients (age: 34.25 ±3.45 y/o, BMI: 28.83 ± 3.54 kg/m^2) and 7 control patients (age: 27.00 ± 1.41 y/o, BMI: 22.34 ± 2.14 kg/m^2 ) performed diagonal walks on flat ground at a medium walking speed after providing informed consent in this IRB-approved study. The BMI for the control and third trimester patients was calculated using their weight at the time of the visit. Patients were provided sneakers (Air Pegasus: Nike, Beaverton, OR) containing an instrumented insole (Loadsol, Novel) to wear during their visit. We used the instrumented insoles to estimate Achilles tendon loading because these sensors increase our ability to collect data faster compared to using embedded force plates that only capture valid data when a patient steps directly on the force plate. Patients were instructed to perform 6 trials at their self-selected medium walking speed for ~6 meters. We estimated the moment about the ankle using our validated algorithm that used foot-ground interaction forces measured by the instrumented insoles [4]. We then divided this ankle moment by 5 cm, which is the Achilles tendon moment arm, to estimate the load experienced by the Achilles tendon. We normalized Achilles tendon loading by body weight to compare between patients. The data for the third trimester and control patients was then averaged using a bootstrap with a confidence interval of 95%.

Results, Conclusions, and Discussions: Results and

Discussion: Comparing both the third trimester patients and the control patients, the third trimester patients had an average peak load of 3.06 times body weight while the control patients had a peak load of 3.36 times body weight (Figure 1). Additionally, the third trimester patients had a higher initial load experienced by the Achilles tendon in the first 25% of their step compared to the control patients. We hypothesize that the higher initial load experienced by the Achilles tendon in the first 25% of the stance is because of the change in center of mass that pregnant women experience due to the additional weight that they are carrying in the front of their body. Because of this additional weight, their feet must support more weight as they enter heel-strike so they do not fall forward as they walk, causing an increase in the initial load experienced by the Achilles tendon during walking.

Conclusion: Our preliminary findings suggest that pregnant women in their third trimester of pregnancy walk with altered Achilles tendon loading compared to non-pregnant females. Establishing biomechanical differences between pregnant women and non-pregnant women could serve as a predictor for musculoskeletal pain experienced during walking for pregnant women.

Acknowledgements (Optional):

References:
[1] M. J.K., B. Hamilton E., J. A., A. Driscoll, and C. Valenzuela, Births: Final data for 2021, Jan. 2023. doi:10.15620/cdc:122047
[2] F. M. Kovacs, E. Garcia, A. Royuela, L. González, and V. Abraira, “Prevalence and factors associated with low back pain and pelvic girdle pain during pregnancy,” Spine, vol. 37, no. 17, pp. 1516–1533, Aug. 2012. doi:10.1097/brs.0b013e31824dcb74
[3] F. Dehghan et al., “The effect of relaxin on the musculoskeletal system,” Scandinavian Journal of Medicine & Science in Sports, vol. 24, no. 4, Nov. 2013. doi:10.1111/sms.12149
[4] T. J. Hullfish and J. R. Baxter, “A simple instrumented insole algorithm to estimate plantar flexion moments,” Gait & Posture, vol. 79, pp. 92–95, Jun. 2020. doi:10.1016/j.gaitpost.2020.04.016