Quantifying varus thrust in knee osteoarthritis using wearable inertial sensors: A proof of concept

Abstract

Background: Varus thrust during walking, visualized as excessive frontal plane knee motion during weight acceptance, is a modifiable risk factor for progression of knee osteoarthritis. However, visual assessment does not capture thrust severity and quantification with optical motion capture is often not feasible. Inertial sensors may provide a convenient alternative to optical motion capture. This proof-ofconcept study sought to compare wearable inertial sensors to optical motion capture for the quantification of varus thrust.Methods: Twenty-six participants with medial knee osteoarthritis underwent gait analysis at selfselected and fast speeds. Linear regression with generalized estimating equations assessed associations between peak knee adduction velocity or knee adduction excursion from optical motion capture and peak thigh or shank adduction velocity from two inertial sensors on the lower limb. Relationships between inertial measures and peak external knee adduction moment were assessed as a secondary aim.Findings: Both thigh and shank inertial sensor measures were associated with the optical motion capture measures for both speeds (P < 0.001 to P = 0.020), with the thigh measures having less variability than the shank. After accounting for age, sex, body mass index, radiographic severity, and limb alignment, thigh adduction velocity was also associated with knee adduction moment at both speeds (both P < 0.001).Interpretation: An inertial sensor placed on the mid-thigh can quantify varus thrust in people with medial knee osteoarthritis without the need for optical motion capture. This single sensor may be useful for risk screening or evaluating the effects of interventions in large samples.

Discovering Knee Osteoarthritis Imaging Features for Diagnosis and Prognosis: Review of Manual Imaging Grading and Machine Learning Approaches

“…By analysing those data, the potential OA-related changes could be recognized. Besides, the quantification of varus thrust in patients with medial knee OA could be done with the placement of inertial sensor at mid-thigh [17].…”

Osteoarthritis year in review 2021: mechanics

“…Several studies used different subsets of a full IMU sensor setup to demonstrate the presence of joint kinematic differences in knee OA and hip OA 70e74 . Besides overall joint kinematics, specific kinematic targets like trunk lean/center of mass position 68 or knee varus thrust 75 can be feasibly tracked with IMUs, making IMUs useful for targeted biomechanics studies in OA.…”

Inertial Measurement Units and Application for Remote Health Care in Hip and Knee Osteoarthritis: Narrative Review

“…Single-leg sensor metrics were associated with surrogate measures of varus thrust, and midthigh adduction velocity was significantly associated with peak external knee adduction moment 3 IMU b (Trigno IM Sensors, Delsys Inc) on thigh, midshank, and distal shank Knee OA a (n=26) Costello et al, 2020 [33] Positive correlation between lateral thrust and change in medial meniscus extrusion 2 IMU c (WAA-010, ATR-Promotions) placed on tibia and foot Knee OA (n=44) Ishii et al, 2020 [34] Moderate correlation found between acceleration peak in IMU frame and KAM, values from shank IMU had strongest correlation 6 IMU c (TSND151, ATR-Promotions) on pelvis, sternum, shanks, and thighs Knee OA (n=22) Iwama et al, 2021 [35] High accuracy and repeatability of foot progression angle measures, and feedback effectiveness was similar between wearable and laboratory feedback setups 7 IMU b (MTw, Xsens Technologies BV) on pelvis, thighs, shanks, and feet Healthy (n=11) Karatsidis et al, 2018 [38] Two machine learning algorithms were highly accurate (R 2 approximately 0.95) in predicting KAM using IMU input 2 IMU c (DA14583, Dialog Semiconductor) on malleoli Healthy (n=12), knee OA (n=78) Wang et al, 2020 [36] Good correlation coefficients to discriminate between different foot progression angle walking conditions 2 IMU b (MTw Awinda, Xsens Technologies BV) on feet Healthy (n=5) Wouda et al, 2021 [37] Participants were able to respond to feedback during walking and adopt target foot progression angle conditions Single IMU b (custom-made) embedded in shoe sole Healthy (n=10) Xia et al, 2020 [39] a OA: osteoarthritis.…”

“…Different sensor configurations during walking have been used to quantify varus thrust in gait; and one study using sensors on the thigh, midshank, and distal shank showed that midthigh sensor metrics were associated with optical motion capture thrust measurements while having less variability than midshank sensors [33]. Another study using sensors on the tibial tubercles and dorsal surface of the foot found greater peak varus thrust in the severe OA group when compared with their early-stage OA group [34].…”