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Soft robotic apparel to avert freezing of gait in Parkinson’s disease

Nature Medicine volume 30, pages 177–185 (2024)Cite this article

Subjects

Abstract

Freezing of gait (FoG) is a profoundly disruptive gait disturbance in Parkinson’s disease, causing unintended stops while walking. Therapies for FoG reveal modest and transient effects, resulting in a lack of effective treatments. Here we show proof of concept that FoG can be averted using soft robotic apparel that augments hip flexion. The wearable garment uses cable-driven actuators and sensors, generating assistive moments in concert with biological muscles. In this n-of-1 trial with five repeated measurements spanning 6 months, a 73-year-old male with Parkinson’s disease and substantial FoG demonstrated a robust response to robotic apparel. With assistance, FoG was instantaneously eliminated during indoor walking (0% versus 39 ± 16% time spent freezing when unassisted), accompanied by 49 ± 11 m (+55%) farther walking compared to unassisted walking, faster speeds (+0.18 m s−1) and improved gait quality (−25% in gait variability). FoG-targeting effects were repeatable across multiple days, provoking conditions and environment contexts, demonstrating potential for community use. This study demonstrated that FoG was averted using soft robotic apparel in an individual with Parkinson’s disease, serving as an impetus for technological advancements in response to this serious yet unmet need.

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Fig. 1: Soft robotic apparel.
Fig. 2: Effects of the robotic apparel based on repeated measurements.
Fig. 3: Intermittent assistance test as direct validation on the immediate effects of the robotic apparel.
Fig. 4: Utility of robotic apparel in outdoor, community-based environments.
Fig. 5: Effects of hip flexion robotic apparel on gait biomechanics.

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Data availability

All study data necessary to interpret, verify and extend this work are available in the Source Data section. This includes data for Figs. 1–5 and Extended Data Figs. 2–5. Source data are provided with this paper.

Code availability

The controls for robotic apparel were adapted from Kim et al.40,70, and the IMU-based real-time gait metric estimation algorithm was adapted from Arens et al.55.

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Acknowledgements

We thank T. Akbas, S. Park, A. Eckert-Erdheim, D. Orzel, A. Huang and S. Sullivan for their contributions to this work. This material is based on work supported by the National Science Foundation (CMMI-1925085; C.J.W.), the National Institutes of Health (U01 TR002775; C.J.W. and T.D.E.) and the Massachusetts Technology Collaborative, Collaborative Research and Development Matching Grant (C.J.W.). This work is also partially funded by the John A. Paulson School of Engineering and Applied Sciences at Harvard University (C.J.W.). J.K. appreciates financial support from the Samsung Scholarship.

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Author notes

  1. These authors contributed equally: Jinsoo Kim, Franchino Porciuncula.

Authors and Affiliations

  1. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, MA, USA

    Jinsoo Kim, Franchino Porciuncula, Hee Doo Yang, Andrew Chin & Conor J. Walsh

  2. Department of Physical Therapy, Boston University, Boston, MA, USA

    Franchino Porciuncula, Nicholas Wendel, Teresa Baker & Terry D. Ellis

  3. Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA

    Conor J. Walsh

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Contributions

J.K., F.P., T.D.E. and C.J.W. conceived of the study concept and designed the research. J.K. implemented the control and hardware of the robotic apparel. J.K., H.D.Y., N.W., T.B. and A.C. conducted the experiments. J.K. processed and analyzed the experimental data. J.K., F.P., T.D.E. and C.J.W. prepared and revised the paper. All authors reviewed and approved the final manuscript.

Corresponding authors

Correspondence to Terry D. Ellis or Conor J. Walsh.

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Competing interests

Patents describing the robotic apparel components documented in this article have been filed with the US Patent Office by Harvard University. C.J.W. is an inventor on the following patents and patent applications: US 9,351,900, US 10,278,883, US 14/660,704, US 15/097,744 and US 14/893,934. Harvard University has entered into a licensing agreement with ReWalk Robotics. C.J.W. was previously a paid consultant for ReWalk Robotics. The other authors declare no competing interests.

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Nature Medicine thanks Alice Nieuwboer, Gregory Sawicki and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Jerome Staal, in collaboration with the Nature Medicine team.

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Extended data

Extended Data Fig. 1 Study flow and protocol overview.

Summary schematic of five study visits. For each study visit, timed walking trials under single-task conditions during medication on-phase were performed (middle column in Study Visits 1-5). Additionally, conditions that further provoked FoG were administered based on medication timing (Study Visit 2), cognitive loading using dual-task challenge (Study Visit 3), and outdoor walking (Study Visit 5). The study also included conditions examining the immediacy of device effects through intermittent assistance (Study Visits 2 and 4), the underlying biomechanical mechanisms (Study Visit 1), and the effects of force levels when providing low assistance (Study Visit 3).

Extended Data Fig. 2 Effects of force levels.

a, Occurrence of freezing during timed 2-minute walking trials. b, Walking distance during timed 2-minute walking trials. All trials were conducted in the laboratory during the medication on-phase and under single-task conditions (Study Visit 3). A peak force of 80 N was applied during ASSIST ON, while a peak force of 20 N was applied during Low ASSIST. Data for ASSIST OFF and ASSIST ON were previously included in Fig. 2.

Source data

Extended Data Fig. 3 Intermittent assistance without verbal prompts.

a, Time series data of applied hip flexion force (top) and participant’s stride length (bottom). Sequential intervals of 30-s bouts with and without assistance were implemented across three intervals amounting to a total of 3 min of walking. Different from Fig. 3, the operator did not give any verbal notice of the assistance mode change to the participant. Data during ASSIST ON and ASSIST OFF are plotted in red and gray, respectively, and the gray shaded regions indicate FoG episodes during ASSIST OFF. There was no FoG episode during ASSIST ON. b, Stride length per interval. Stride lengths in all intervals are presented in box plots (center line: median; box limits: upper and lower quartiles; whiskers: 1.5 × interquartile range; points: outliers), and asterisks indicate statistically significant differences (two-sided randomization test with a stride-level median as a test statistic; ***P < 0.001). Interval 1 (n=26 independent strides for ASSIST ON and n=32 independent strides for ASSIST OFF; P < 0.001), interval 2 (n=29 independent strides for ASSIST ON and n=31 independent strides for ASSIST OFF; P < 0.001), and interval 3 (n=26 independent strides for ASSIST ON and n=19 independent strides for ASSIST OFF; P < 0.001). c, Occurrence of freezing per interval based on duration (left y axis) and percent time spent freezing (right y axis).

Source data

Extended Data Fig. 4 Preserved regulation of stride length: A potential reason for the effects of the robotic apparel.

Stride length over time during timed 2-minute walking trials. The linear regression slope of stride length leading to the onset of FoG was examined. a, ASSIST OFF vs. ASSIST ON (Study Visit 1). Markers in light gray and red are for ASSIST OFF and ASSIST ON, respectively. The shaded regions in light gray indicate FoG episodes during ASSIST OFF (Linear regression: y = −4.65⋅10−3 × time + 1.15, n = 48 independent strides; a two-sided, one-sample t-test for the slope, P = 3.08⋅10−12, t = −9.37, df = 46). There was no FoG episode during ASSIST ON. b, NO SUIT vs. ASSIST ON (Study Visit 4). Markers in dark gray and red are for NO SUIT and ASSIST ON, respectively. The shaded regions in dark gray indicate FoG episodes during NO SUIT (Linear regression: y = −3.42⋅10−3 × time + 1.09, n = 66 independent strides; a two-sided, one-sample t-test for the slope, P = 2.45⋅10−16, t = −10.97, df = 64). There was no FoG episode during ASSIST ON.

Source data

Extended Data Fig. 5 Variability of stride length: A potential reason for the effects of the robotic apparel.

Stride length arrhythmicity during timed 2-minute walking trials (n = 6 independent walking bouts for BASELINE and n = 6 independent walking bouts for ASSIST ON; P = 0.031). Each study visit was conducted on a separate day. A summary bar plot is presented as mean ± s.d., with an asterisk indicating a statistically significant difference (two-sided Wilcoxon signed-rank test; *P < 0.05). Baseline includes both NO SUIT and ASSIST OFF conditions. The coefficient of variance (in stride length) was measured as the ratio of the standard deviation to the mean.

Source data

Extended Data Table 1 Duration of turns and excluded strides in the timed walking trials
Full size table

Supplementary information

Reporting Summary

Supplementary Video 1

The effects of robotic apparel during medication on-phase. Video excerpt during a 2MWT provides a side-by-side comparison of walking with (right; ASSIST ON) and without (left; ASSIST OFF) the robotic apparel, tested during medication on-phase under single-task conditions. A physical therapist provided close supervision for general participant safety during the walking test. Other researchers managed video recording, measured distance with a handheld measuring wheel and ensured having a wheelchair on standby, if needed. Distance counters on the top right and left corners provide walking distance in real time.

Supplementary Video 2

The effects of robotic apparel during medication relative off-phase. Video excerpt during a 2MWT provides a side-by-side comparison of the effects of robotic apparel, tested during suboptimal timing of dopaminergic medication (relative off-phase) under single-task conditions. Experimental setup is identical to Supplementary Video 1.

Supplementary Video 3

Intermittent assistance of the robotic apparel. Video excerpt during a 4-min walking trial demonstrates the immediate effects of the robotic apparel on averting FoG tested during medication on-phase and under single-task conditions. The immediate effects of the robotic apparel were demonstrated by intermittent assistance of the robotic apparel (that is, serial on and off at 30-s intervals). The inset figures on the top-right corner show the applied hip flexion force and the participant’s thigh angle in real time.

Supplementary Video 4

The effects of robotic apparel when walking outdoors. The video excerpt during a 6MWT provides a side-by-side comparison of walking with (right; ASSIST ON) and without (left; NO SUIT) the robotic apparel in real-world, outdoor community settings. The testing took place during the medication on-phase under single-task conditions.

Supplementary Video 5

Effects of the robotic apparel during short-distance walking. Video samples during short-distance walking based on the 10-m walk test (comfortable speed) provide side-by-side comparison of gait quality related to the assistance of robotic apparel. Procedures were performed during medication on-phase and under single-task conditions. Kinematic measurements of walking were obtained using a three-dimensional motion capture system and wearable sensors.

Source data

Source Data Figs. 1–5

Statistical source data for Figs. 1–5.

Source Data Extended Data Figs. 2–5

Statistical source data for Extended Data Figs. 2–5.

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Kim, J., Porciuncula, F., Yang, H.D. et al. Soft robotic apparel to avert freezing of gait in Parkinson’s disease. Nat Med 30, 177–185 (2024). https://doi.org/10.1038/s41591-023-02731-8

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