Varus thrust and knee frontal plane dynamic motion in persons with knee osteoarthritis.
OBJECTIVE
Varus thrust visualized during walking is associated with a greater medial knee load and an increased risk of medial knee osteoarthritis (OA) progression. Little is known about how varus thrust presence determined by visual observation relates to quantitative gait kinematic data. We hypothesized that varus thrust presence is associated with greater knee frontal plane dynamic movement during the stance phase of gait.


METHODS
Participants had knee OA in at least one knee. Trained examiners assessed participants for varus thrust presence during ambulation. Frontal plane knee motion during ambulation was captured using external passive reflective markers and an 8-camera motion analysis system. To examine the cross-sectional relationship between varus thrust and frontal plane knee motion, we used multivariable regression models with the quantitative motion measures as dependent variables and varus thrust (present/absent) as predictor; models were adjusted for age, gender, body mass index (BMI), gait speed, and knee static alignment.


RESULTS
236 persons [mean BMI: 28.5 kg/m(2) (standard deviation (SD) 5.5), mean age: 64.9 years (SD 10.4), 75.8% women] contributing 440 knees comprised the study sample. 82 knees (18.6%) had definite varus thrust. Knees with varus thrust had greater peak varus angle and greater peak varus angular velocity during stance than knees without varus thrust (mean differences 0.90° and 6.65°/s, respectively). These patterns remained significant after adjusting for age, gender, BMI, gait speed, and knee static alignment.


CONCLUSIONS
Visualized varus thrust during walking was associated with a greater peak knee varus angular velocity and a greater peak knee varus angle during stance phase of gait.
Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. Electronic address: hsini@northwestern.edu.
A H
AH
Chang
J S
JS
Chmiel
K C
KC
Moisio
O
O
Almagor
Y
Y
Zhang
S
S
Cahue
L
L
Sharma
D000368:Aged; D015992:Body Mass Index; D017760:Bone Malalignment / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D005684:Gait / Q000502:physiology*; D056305:Genu Varum / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D011859:Radiography; D016138:Walking / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology
Gait analysis; Instability; Knee osteoarthritis; Varus thrust