# Muscle-Tendon Structure and Function Following Chronic Limb-Shortening Imposed by Proximal Row Carpectomy

> **NIH NIH F31** · NORTHWESTERN UNIVERSITY · 2020 · $40,733

## Abstract

PROJECT SUMMARY/ABSTRACT.
 Most cases of wrist osteoarthritis (OA) are a form of degenerative arthritis associated with severe pain.
Because a functional, pain free wrist is essential for a functional hand, wrist OA precludes many tasks of
everyday life (i.e. opening a door, carrying groceries). One of the most common surgical treatments for severe
wrist OA, proximal row carpectomy (PRC), involves removal of the entire proximal row of carpal bones,
shortening the forearm-to-hand length. This procedure is successful in relieving pain and improving function
relative to an untreated wrist. However, compared to a healthy wrist, PRC often yields decreased range of
motion and loss of grip strength. The cause of these functional deficits following PRC is not understood.
 Following PRC, forearm-to-hand length is decreased without concomitant surgical shortening of
muscle-tendon units. As a result, surgeons have an anecdotal assumption that post-PRC deficits arise, in part,
because the muscle-tendon units are relatively long, or “slackened” due to the surgery. However, studies in
animal models and our preliminary data in humans suggest that, when maintained in a shortened position for
an extended time, muscles lose sarcomeres in series, resulting in atrophy and increased passive stiffness.
Based on these objective studies, we hypothesize that the limb shortening imposed by PRC results in
decreased serial sarcomere number and muscle volume, decreasing active muscle force-generating capacity.
We will test our hypothesis by implementing novel, in vivo imaging techniques in both limbs of individuals with
unilateral PRCs. We will quantify interlimb differences in serial sarcomere number (Aim 1) and muscle volume
(Aim 2) and determine their contributions to functional deficits. We will measure sarcomere length via second
harmonic generation microendoscopy, fascicle length using extended field-of-view-ultrasound, and both tendon
length and muscle volume using 3D ultrasound. From these data, we will identify chronic differences in muscle
structure following PRC limb shortening by calculating serial sarcomere number (optimal fascicle length) and
physiological cross-sectional area. Quantitative biomechanical measures of muscle function and clinical
impairment, including passive joint torques and maximum isometric grip force, will also be assessed.
Quantifying muscle-tendon structural adaptations to this chronic limb shortening will inform the development of
more effective rehabilitation protocols and surgical interventions for individuals with severe wrist OA.
 The proposed research will develop experimental skills necessary to link muscle structural changes to
clinical deficits. In addition, training on surgical and rehabilitation treatments, effective teaching and mentoring,
collaborating and communicating with scientific and clinical audiences, and clear, succinct scientific writing
skills are planned. This training and research will provide the necessary experi...

## Key facts

- **NIH application ID:** 9910726
- **Project number:** 1F31AR076920-01
- **Recipient organization:** NORTHWESTERN UNIVERSITY
- **Principal Investigator:** Amy Adkins
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $40,733
- **Award type:** 1
- **Project period:** 2020-03-01 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9910726

## Citation

> US National Institutes of Health, RePORTER application 9910726, Muscle-Tendon Structure and Function Following Chronic Limb-Shortening Imposed by Proximal Row Carpectomy (1F31AR076920-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9910726. Licensed CC0.

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