Mechanical factors relate to pain in knee osteoarthritis

Clin Biomech (Bristol, Avon). 2008 Jul;23(6):796-805. doi: 10.1016/j.clinbiomech.2008.01.014. Epub 2008 Mar 17.


Background: Pain experienced by people with knee osteoarthritis is related to psychosocial factors and damage to articular tissues and/or the pain pathway itself. Mechanical factors have been speculated to trigger this pain experience; yet mechanics have not been identified as a source of pain in this population. The purpose of this study was to identify whether mechanics could explain variance in pain intensity in people with knee osteoarthritis.

Methods: Data from 53 participants with physician-diagnosed knee osteoarthritis (mean age=68.5 years; standard deviation=8.6 years) were analyzed. Pain intensity was reported on the Western Ontario and McMaster Universities Osteoarthritis Index. Mechanical measures included weight-bearing varus-valgus alignment, body mass index and isokinetic quadriceps torque. Gait analysis captured the range of adduction-abduction angle, range of flexion-extension angle and external knee adduction moment during level walking.

Findings: Pain intensity was significantly related to the dynamic range of flexion-extension during gait and body mass index. A total of 29% of the variance in pain intensity was explained by mechanical variables. The range of flexion-extension explained 18% of variance in pain intensity. Body mass index added 11% to the model. The knee adduction moment was unrelated to pain intensity.

Interpretation: The findings support that mechanical factors are related to knee osteoarthritis pain. Because limitations in flexion-extension range of motion and body size are modifiable factors, future research could examine whether interventions targeting these mechanics would facilitate pain management.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arthralgia / physiopathology*
  • Biomechanical Phenomena / methods
  • Female
  • Gait*
  • Humans
  • Knee Joint / physiopathology*
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / physiopathology*
  • Pain Measurement
  • Range of Motion, Articular*
  • Statistics as Topic