Inconsistent knee varus moment reduction caused by a lateral wedge in knee osteoarthritis

Am J Phys Med Rehabil. 2007 Jun;86(6):446-54. doi: 10.1097/PHM.0b013e31805bfff5.


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.

Design: 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.

Conclusion: 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.

MeSH terms

  • Aged
  • Biomechanical Phenomena
  • Case-Control Studies
  • Female
  • Humans
  • Orthotic Devices*
  • Osteoarthritis, Knee / rehabilitation*
  • Shoes