ISRCTN94818153.

Trial name or title	A Randomised, Double‐Blind, Placebo‐Controlled Trial of Vitamin D Supplementation in the Management of Symptomatic Knee Osteoarthritis (the VIDEO study)
Methods	Randomised, double‐blind, placebo‐controlled study. Duration: 36 months
Participants	Men and women with primary knee osteoarthritis Estimated enrolment: N = 800
Interventions	Cholecalciferol 800 IU/day Placebo
Outcomes	Pain, quality of life
Starting date	1 February 2004
Contact information	Richard Keen, Metabolic Unit, Royal National Orthopaedic Hospital Stanmore, Brockley Hill, Stanmore, HA7 4LP, UK
Notes	Trial status: completed (end date: 31 August 2011)