# Multiscale correlations between joint and tissue-specific biomechanics and anatomy in postmortem ovine stifles

## TL;DR

This study explores how joint and tissue biomechanics in sheep knees relate to anatomical features, offering insights into knee health assessment.

## Contribution

The paper introduces multiscale correlations between joint-level and tissue-specific biomechanics in ovine stifles.

## Key findings

- Joint laxity forces correlate positively with inter-epicondylar distance.
- Tendon and ligament viscoelasticity correlates with joint laxity, but not cartilage or menisci.
- Tissue viscoelasticity and T2* show mixed correlations depending on the tissue type.

## Abstract

Joint stability depends on various properties that include the bone anatomy, joint capsule geometry and stiffness, and soft tissues within. The multiscale biomechanical relationships between the whole joint and individual tissues are useful in estimating the physiological condition of the knee. To better understand these relationships, we evaluated multiple structural and mechanical parameters in healthy ovine stifles, specifically joint laxity, joint morphology, individual tissue T2* relaxation and mechanical properties of ligaments (ACL, PCL, MCL, LCL), patellar tendon, menisci, and cartilage. By combining mechanical testing at two length scales and magnetic resonance imaging (MRI) scans, we quantify the strength of correlation coefficients between measured metrics, among joint size, whole joint and individual tissue properties. We observe positive correlations between joint laxity forces and the inter-epicondylar distance. Further, the viscoelastic properties of the tendons and ligaments correlate positively with joint laxity forces; however, no such correlations were observed for the cartilage and menisci. We also found weak inverse correlation between tissue viscoelasticity and T2* for MCL; and positive correlations for cartilage and menisci, LCL and PCL respectively. These results provide useful insights into the role of individual tissues that are crucial in measuring whole joint responses as key indicators of knee health.

The online version contains supplementary material available at 10.1038/s41598-025-87491-w.