Effect of Preoperative Vitamin D Levels on Functional Performance after Total Knee Arthroplasty

BACKGROUND: Low vitamin D levels affects muscle function. Vitamin D and calcium deficiency cause osteomalacic myopathy and poor functional recovery after hip fractures. The relationship of vitamin D and functional performance after total knee arthroplasty (TKA) is not previously reported. METHODS: Influence of vitamin D on functional performance before and after TKA was reviewed retrospectively in 120 patients. Of these, 64 had vitamin D deficiency (25-hydroxy vitamin D < 30 ng/mL) preoperatively. All 120 patients received vitamin D oral supplementation postoperatively. Functional parameters including Western Ontario and McMaster Osteoarthritis Index (WOMAC), Short-Form Health Survey questionnaire, and Knee Society Score were assessed pre- and postoperatively at 3 months. RESULTS: Preoperative function was significantly lower in osteoarthritic patients with vitamin D deficiency (WOMAC score; p = 0.040), but at 3 months all functional scores were similar. CONCLUSIONS: We concluded that vitamin D deficiency has a negative effect on function in knee osteoarthritic patients. However, postoperative vitamin D supplementation can lead to functional recovery in these patients. Thus, TKA should not be delayed in vitamin D deficient patients; rather supplementation in the postoperative period is preferable to achieve comparable functional outcome at 3 months to patients with vitamin D sufficiency.