Trajectories of functional decline in knee osteoarthritis: the Osteoarthritis Initiative

Rheumatology (Oxford). 2016 May;55(5):801-8. doi: 10.1093/rheumatology/kev419. Epub 2015 Dec 24.


Objective: To describe trajectories of functional decline over 84 months and study associated risk factors among adults initially without limitation who had or were at risk of knee OA.

Methods: We used annual measures of WOMAC physical function over 84 months from the OA Initiative. We included knees with no functional limitation (i.e. WOMAC = 0) at baseline. Knee-based trajectories of functional decline from WOMAC were identified from a group-based trajectory model (PROC TRAJ).

Results: We identified five trajectories from 2110 knees (1055 participants, age 61.0 ± 9.3, BMI 27.1 ± 4.4, 52% women). Half of the knees (54%) remained free of limitation over 84 months, 26% slowly declined to a WOMAC of 1.5, 9% were limitation free for the first 36 months and declined to a WOMAC of 11.3, 6% rapidly declined over the first 12 months and gradually recovered to a WOMAC of 3.3 and 5% steadily declined to a WOMAC of 13.2. Baseline radiographic disease, knee pain, obesity and depressive symptoms at baseline were associated with trajectories of worse functional decline.

Conclusion: Five per cent of our sample initially without limitation was on a trajectory of progressive functional decline over 84 months later. We found worse disease and health status at baseline to be associated with faster decline over time.

Keywords: knee osteoarthritis; physical function; trajectory.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Depression / complications
  • Disease Progression
  • Female
  • Humans
  • Knee Joint / physiopathology
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / diagnostic imaging
  • Osteoarthritis, Knee / etiology
  • Osteoarthritis, Knee / physiopathology*
  • Overweight / complications
  • Pain / etiology
  • Pain Measurement / methods
  • Radiography
  • Risk Factors
  • Severity of Illness Index