TY - JOUR T1 - Dr. Koeckhoven, <em>et al</em> reply JF - The Journal of Rheumatology JO - J Rheumatol SP - 2079 LP - 2079 DO - 10.3899/jrheum.160835 VL - 43 IS - 11 AU - ESMEE KOECKHOVEN AU - MARIKE VAN DER LEEDEN AU - LEO D. ROORDA AU - NATASJA M. VAN SCHOOR AU - PAUL LIPS AU - ARJAN DE ZWART AU - JOOST DEKKER AU - MARTIN VAN DER ESCH AU - WILLEM F. LEMS Y1 - 2016/11/01 UR - http://www.jrheum.org/content/43/11/2079.1.abstract N2 - To the Editor:We highly appreciate the letter of Tufan, et al1, in which they showed their interest in our manuscript “The Association between Serum 25-hydroxy Vitamin D Level and Upper Leg Strength in Patients with Knee Osteoarthritis: Results of the Amsterdam Osteoarthritis Cohort”2. Tufan, et al suggested that the assessment of 25-hydroxy Vitamin D [25(OH)D] should be … Address correspondence to M. van der Leeden, Amsterdam Rehabilitation Research Center | Reade, P.O. Box 58271, 1040 HG Amsterdam, the Netherlands. E-mail: M.vd.Leeden{at}reade.nl ER -