# Prospective validation of mean metacarpophalangeal joint extension as a measure of diabetes-related fibrotic hand manifestations

## TL;DR

This study shows that measuring hand joint extension can help assess fibrotic hand conditions in diabetes patients.

## Contribution

The study introduces mean metacarpophalangeal joint extension as a unified measure for diabetes-related fibrotic hand conditions.

## Key findings

- Mean MCP extension was significantly lower in individuals with hand conditions compared to those without.
- MCP extension correlated with physician-rated severity but weakly with grip strength and the Duruöz Hand Index.
- MCP extension demonstrated strong inter-rater reliability and sensitivity to change over time.

## Abstract

Hand conditions in diabetes, namely, limited joint mobility (LJM), flexor tenosynovitis (FT), carpal tunnel syndrome (CTS), and Dupuytren disease (DD), share a common pathophysiological process involving pro-fibrotic inflammation in flexor structures. A unified, quantitative measure of disease severity across these conditions is lacking, limiting correlational research. We evaluated mean metacarpophalangeal (MCP) joint extension as a potential measure of severity.

We assessed 2,405 adults, including individuals with type 1 diabetes (n=291), type 2 diabetes (n=877), prediabetes (n=326), and non-diabetic controls (n=911). MCP extension was calculated as the average maximum passive extension of the second to fifth fingers, measured with a protractor. Validity was determined by correlating MCP extension with physician-rated severity (convergent) and hand grip strength and the Duruöz Hand Index (DHI, both divergent). Inter-rater reliability was tested in 128 individuals, and sensitivity to change was evaluated in 143 participants assessed at two time points.

Mean MCP extension was significantly lower in individuals with all hand conditions (42.4° LJM, 42.8°FT, 39.9° DD, 51.7 °CTS) than in those without (58.6°, all p<0.05). MCP extension correlated with physician-rated severity (−0.5, p<0.01) and weakly with DHI (R2 = 0.03) and grip strength (R2 = 0.07). Inter-rater reliability was strong (ICC 0.72), and MCP extension demonstrated sensitivity to change, worsening over 8 months (SRM −0.61).

Mean MCP extension is a valid, reliable, and responsive measure for assessing fibro-inflammatory hand conditions in diabetes.

https://ctri.nic.in/Clinicaltrials/login.php, identifier CTRI/2020/12/030057.