Inertial Sensor Angular Velocities Reflect Dynamic Knee Loading during Single Limb Loading in Individuals Following Anterior Cruciate Ligament Reconstruction.

Kristamarie Pratt,Susan Sigward

doi:10.3390/s18103460

Abstract

Difficulty quantifying knee loading deficits clinically in individuals following anterior cruciate ligament reconstruction (ACLr) may underlie their persistence. Expense associated with quantifying knee moments (KMom) and power (KPow) with gold standard techniques precludes their use in the clinic. As segment and joint kinematics are used to calculate moments and power, it is possible that more accessible inertial sensor technology can be used to identify knee loading deficits. However, it is unknown if angular velocities measured with inertial sensors provide meaningful information regarding KMom/KPow during dynamic tasks post-ACLr. Twenty-one individuals 5.1 ± 1.5 months post-ACLr performed a single limb loading task, bilaterally. Data collected concurrently using a marker-based motion system and gyroscopes positioned lateral thighs/shanks. Intraclass correlation coefficients (ICC)(2,k) determined concurrent validity. To determine predictive ability of angular velocities for KMom/KPow, separate stepwise linear regressions performed using peak thigh, shank, and knee angular velocities extracted from gyroscopes. ICCs were greater than 0.947 (p < 0.001) for all variables. Thigh (r = 0.812 and r = 0.585; p < 0.001) and knee (r = 0.806 and r = 0.536; p < 0.001) angular velocities were strongly and moderately correlated to KPow and KMom, respectively. High ICCs indicated strong agreement between measurement systems. Thigh angular velocity (R2 = 0.66; p < 0.001) explained 66% of variance in KPow suggesting gyroscopes provide meaningful information regarding KPow. Less expensive inertial sensors may be helpful in identifying deficits clinically.

Highlights

Marker-based three-dimensional motion analysis is the current gold standard for quantification of movement deficits during dynamic tasks following knee injury or surgery
This study aims to advance the previous work relating between limb ratios in inertial sensor outputs of segment angular velocity to knee power deficits during a single limb loading task [21]
The inability to quantify common knee loading deficits in the clinic in individuals following anterior cruciate ligament reconstruction (ACLr) is concerning as post-surgery these individuals aim to return to high level dynamic tasks, where the knee plays an essential role in force attenuation [25,26,27]

Summary

Introduction

Marker-based three-dimensional motion analysis is the current gold standard for quantification of movement deficits during dynamic tasks following knee injury or surgery. This technology uses three-dimensional marker positions (recorded at 250–340 Hz), and ground reaction force data (1360–1500 Hz) to calculate knee moments, angular velocities, and power. These analyses are complex, expensive, and time-consuming; impractical in clinical settings. Differences in angles may be difficult to detect during more dynamic tasks as individuals go through nearly 30–50 degrees of flexion in less than 200 milliseconds. Recent advances in wireless capabilities and data storage in wearable technology make inertial sensors more affordable and practical for movement assessments outside a motion analysis laboratory [3,4,5,6,7]

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Conclusion