Correlation of Serum Vitamin D Levels with Functional Outcome in Patients with Osteoarthritis of the Knee

Abstract

Background: Knee osteoarthritis (OA) is the most common degenerative joint disease characterized by pain, stiffness, and functional disability. Recent evidence suggests that Vitamin D deficiency could be involved in cartilage degeneration, muscle weakness and clinical symptom deterioration in OA patients.

Objectives

1. To estimate serum Vitamin D levels in patients with knee osteoarthritis.
2. To assess the correlation between serum Vitamin D levels and functional outcome using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).
3. To evaluate the association of Vitamin D deficiency with disease severity.

Materials and Methods: A prospective observational study was conducted among 100 patients diagnosed with primary knee osteoarthritis attending the Orthopedics outpatient department of a tertiary care hospital. Serum 25-hydroxy Vitamin D [25(OH)D] levels were measured using chemiluminescent immunoassay. Functional outcome was assessed using the WOMAC score. Patients were categorized into Vitamin D deficient (<20 ng/mL), insufficient (20–30 ng/mL), and sufficient (>30 ng/mL) groups. Statistical analysis included Pearson correlation and ANOVA.

Results: The mean serum Vitamin D level among OA patients was 22.8 ± 8.6 ng/mL. Vitamin D deficiency was observed in 52% of patients. Mean WOMAC scores were significantly higher among Vitamin D-deficient patients (58.6 ± 11.4) compared to insufficient (48.7 ± 9.3) and sufficient groups (39.5 ± 8.7) (p<0.001). Serum Vitamin D levels demonstrated a significant negative correlation with WOMAC scores (r = –0.61, p<0.001).

Conclusion: Vitamin D deficiency is highly prevalent among patients with knee osteoarthritis and is significantly associated with poorer functional outcomes. Monitoring and correction of Vitamin D deficiency may contribute to improved clinical management of knee OA.

Keywords: Osteoarthritis, Vitamin D, WOMAC score, Functional outcome, Knee osteoarthritis