Vitamin D deficiency impairs quadriceps strength without modulating inflammatory cytokines in patients with knee osteoarthritis (1041.2)

Abstract

The objective of this study was to test the hypothesis that vitamin D deficiency exacerbates quadriceps weakness and increases serum cytokines in patients with knee osteoarthritis (OA). Patients (<60 y) with unilateral knee pain, radiographic evidence of knee OA, and quadriceps weakness participated in this study. Patients were excluded if they presented other co‐morbidities or the use of supplements. Serum 25(OH)D concentrations categorized patients as vitamin D deficient (n=17; 蠄20 ng/mL), insufficient (n=21; 20‐29 ng/mL), or sufficient (n=18; 蠅30 ng/mL) after completing all data collection and measurements. Single‐leg strength (1 set x 6 repetitions of concentric knee extension and flexion contractions at 60°/s on each leg) and blood cytokine, carotene (α and β), lutein, zeaxanthin, ascorbic acid, uric acid, and tocopherol (α and γ) concentrations were measured. Knee extension (quadriceps) torque, power, work, and deceleration were impaired (all p<0.05) with vitamin D deficiency. Deficiency did not increase circulating cytokines but associated with an increase in blood uric acid and γ‐tocopherol concentrations (both p<0.05). In conclusion, vitamin D deficiency is detrimental to quadriceps function in patients with knee OA. Future studies are encouraged to examine other anti‐inflammatory agents, such as γ‐tocopherol, when investigating the role of vitamin D status on inflammatory cytokines.