# Characterizing and Restoring Joint Motion in Patients with Hallux Rigidus: Human Subject Testing

> **NIH VA I01** · VA PUGET SOUND HEALTHCARE SYSTEM · 2020 · —

## Abstract

PROJECT SUMMARY/ABSTRACT
The first metatarsophalangeal joint (MTPJ1) is one of the sites most often affected by osteoarthritis (OA), leading
to a condition called hallux rigidus (HR). This is very common, estimated to affect 25% of the adult population
and increasing in prevalence with age. The number of patients seen by the Veterans Health Administration (VHA)
for HR has more than doubled over the last decade. In contrast to degenerative OA at the hip and knee, which
is commonly treated with joint replacement arthroplasties, the most common surgical treatment for severe HR is
arthrodesis, which eliminates joint function. This approach does not allow modification of footwear, interferes
with some activities (e.g., yoga, Pilates) and may lead to secondary complications such as metatarsalgia and
mobility restrictions. To date, various designs for MTPJ1 arthroplasties have been proposed, but none have been
particularly successful, with high failure rates due to loosening and regular reports of implant migration. This may
be in part because of the relatively small amount of cortical bone in the metatarsal head and proximal phalangeal
regions, making it difficult to achieve adequate fixation of the prosthetic components. Development of new
implants aimed at addressing these problems has been limited by the quantitative data regarding the mechanical
environment of the MTPJ1. Similarly, due to technological limitations, there is no precise 3D kinematic data
available to describe the envelope of normal MTPJ1 function required during activities of daily living. Our recent
work has established the groundwork for a computational modeling workflow to optimize MTPJ1 implant design,
and we have had initial success generating novel, evidence-based implant concepts that emphasize strong initial
component fixation. In this project, we intend to advance this work, increasing our ability to improve MTPJ1
implant technology through computational modeling and robotic gait simulation of human cadavers. These
better-performing implants will ultimately lead to improved patient outcomes. We intend to achieve these aims
by: 1) characterizing pathological and healthy MTPJ1 function during different activities of daily living; 2) using a
cadaveric robotic gait simulator to measure the effectiveness of existing implants and our novel implants at
restoring MTPJ1 function; and 3) further refining our musculoskeletal and finite element computational models
of the MTPJ1, improving their accuracy and validating their ability to generate clinically-informative results. It is
our working hypothesis that a successful MTPJ1 implant will exhibit both strong initial component fixation and
physiologically normative joint biomechanics; presently, our preliminary design work has emphasized the former,
while [the literature on knee joint replacements supports] the latter. We believe this research has the potential to
reinvigorate the advancement of MTPJ1 arthroplasty, which at present is p...

## Key facts

- **NIH application ID:** 10070546
- **Project number:** 1I01RX003259-01A2
- **Recipient organization:** VA PUGET SOUND HEALTHCARE SYSTEM
- **Principal Investigator:** William R. Ledoux
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2020
- **Award amount:** —
- **Award type:** 1
- **Project period:** 2020-10-01 → 2024-09-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10070546

## Citation

> US National Institutes of Health, RePORTER application 10070546, Characterizing and Restoring Joint Motion in Patients with Hallux Rigidus: Human Subject Testing (1I01RX003259-01A2). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10070546. Licensed CC0.

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