Volume 73, Issue 6 p. 781-787
Original Article

Effects of Vitamin D Supplementation on Disabling Foot Pain in Patients With Symptomatic Knee Osteoarthritis

Liudan Tu

Liudan Tu

The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China, and University of Tasmania, Hobart, Tasmania, Australia

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Shuang Zheng

Shuang Zheng

University of Tasmania, Hobart, Tasmania, Australia

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Flavia Cicuttini

Flavia Cicuttini

Monash University, Melbourne, Victoria, Australia

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Xingzhong Jin

Xingzhong Jin

University of Tasmania, Hobart, Tasmania, and the University of Sydney, New South Wales, Australia

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Weiyu Han

Weiyu Han

University of Tasmania, Hobart, Tasmania, Australia, and Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China

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Zhaohua Zhu

Zhaohua Zhu

University of Tasmania, Hobart, Tasmania, Australia, and Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China

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Benny Antony

Benny Antony

University of Tasmania, Hobart, Tasmania, Australia

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Tania Winzenberg

Tania Winzenberg

University of Tasmania, Hobart, Tasmania, Australia

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Graeme Jones

Graeme Jones

University of Tasmania, Hobart, Tasmania, Australia

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Jieruo Gu

Jieruo Gu

The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China

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Anita E. Wluka

Anita E. Wluka

Monash University, Melbourne, Victoria, Australia

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Changhai Ding

Corresponding Author

Changhai Ding

The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China, University of Tasmania, Hobart, Tasmania, Australia, Monash University, Melbourne, Victoria, Australia, and Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China

Address correspondence to Changhai Ding, MD, Clinical Research Centre, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China. Email: [email protected].

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First published: 05 July 2020
Citations: 13
ClinicalTrials.gov identifier: NCT01176344.
Supported by the Australian National Health and Medical Research Council (project code 605501). Drs. Winzenberg and Wluka are recipients of a National Health and Medical Research Council Career Development Fellowship. Dr. Jones is recipient of a National Health and Medical Research Council Practitioner Fellowship. Dr. Ding is recipient of an Australian Research Council Future Fellowship.
Drs. Tu and Zheng contributed equally to this work.
No potential conflicts of interest relevant to this article were reported.

Abstract

Objective

The present study was undertaken to determine whether vitamin D supplementation or maintaining sufficient vitamin D level reduces foot pain over 2 years in patients with symptomatic knee osteoarthritis (OA).

Methods

A post hoc study was conducted from a randomized, double-blind, placebo-controlled trial named the Vitamin D Effect on Osteoarthritis (VIDEO) study. Symptomatic knee OA patients with serum 25-hydroxyvitamin D levels between 12.5 nmoles/liter and 60 nmoles/liter were included and randomly allocated to either monthly vitamin D3 or placebo treatment (1:1) for 2 years. Manchester Foot Pain and Disability Index (MFPDI) was used to evaluate foot pain and disabling foot pain was defined as at least 1 of the 10 functional limitation items (items 1–9 and 11) being documented as on “most/every day(s)” in the last month. A repeated-measures, mixed-effects model was used to analyze the change of MFPDI scores between groups adjusting for potential confounders.

Results

A total of 413 patients with a mean age of 63.2 years (49.7% males) were enrolled and 340 completed the study. The mean MFPDI score was 22.8 ± 7.3, with 23.7% of participants having disabling foot pain at baseline. There were significant differences in MFPDI scores change between groups over 2 years, with more improvements in the vitamin D group than in the placebo group (–0.03 versus 1.30; P = 0.013) and more improvement in those maintaining sufficient vitamin D levels (n = 226) than those who did not (n = 114) (–0.09 versus 2.19; P = 0.001).

Conclusion

Vitamin D supplementation and maintenance of sufficient vitamin D levels may improve foot pain in those with knee OA.