Inconsistent knee varus moment reduction caused by a lateral wedge in knee osteoarthritis.
OBJECTIVE
To determine--with the assistance of a larger sample size--whether the inconsistency of reducing the knee-joint varus moment with a lateral wedge in patients with medial compartment knee osteoarthritis (OA) persists and if so, what underlying mechanisms may explain it.


METHODS
Crossover design whereby 51 patients with bilateral isolated medial compartment knee OA and 19 age-matched healthy controls walked with two different wedge conditions: a 0-degree control wedge and a 6-degree lateral wedge. We conducted three-dimensional motion analysis, hip-knee-ankle (HKA) angle measurement, and radiologic assessment with Kellgren-Lawrence grade. We investigated frontal plane angles and moments at the knee and subtalar joints, ground reaction forces, and center of pressure (CoP). Moments were derived using a three-dimensional inverse dynamics model of the lower extremity.


RESULTS
Nine patients (17.6%) had an increased knee-joint varus moment with the 6-degree lateral wedge via the medially shifted location of the CoP. These patients did not differ from the remaining patients in HKA angle and radiologic assessment.


CONCLUSIONS
In approximately 18% of patients with bilateral medial compartment knee OA, the 6-degree lateral wedge seems to fail to reduce the knee-joint varus moment. The indication and limitations of lateral wedge should be confirmed by a randomized controlled study.
Kakihana
Wataru
W
Department of Rehabilitation for Movement Functions, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan.
Akai
Masami
M
Nakazawa
Kimitaka
K
Naito
Kenji
K
Torii
Suguru
S
D000368:Aged; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D009989:Orthotic Devices; D020370:Osteoarthritis, Knee / Q000534:rehabilitation*; D012775:Shoes