Vitamin D levels in patients undergoing knee arthroplasty: Does vitamin D status effect postoperative outcomes?

SummaryBackground & aimsWe investigated the prevalence of vitamin D deficiency in 92 patients undergoing knee arthroplasty and examined whether vitamin D status was related to postoperative outcomes.MethodsVitamin D levels were measured in 92 patients undergoing knee arthroplasty. Subjects completed the Activities-specific Balance Confidence Scale-UK (ABC-UK) and the WOMAC Osteoarthritis Index preoperatively and 6 months postoperatively.ResultsNine subjects were taking vitamin D supplements. Mean vitamin D in this group was 74.2 ± 16.9 nmol/L (range 48–95) compared with 56.0 ± 22.5 nmol/L (range 16–122) in those not taking supplements (p = 0.02). Thirteen subjects (14%) had vitamin D <30 nmol/L (deficiency) and 20 (22%) had levels 30–49 nmol/L (insufficiency). Six months postoperatively subjects showed significant improvements in ABC-UK and WOMAC Osteoarthritis Index scores, however, those with vitamin D <30 nmol/L showed less improvement in the stiffness and physical function subsets of the WOMAC Osteoarthritis Index. Change in stiffness in vitamin D deficient subjects was 0 ± 3.3 vs. −1.6 ± 2.0 (p = 0.03). A similar (non-significant) trend was seen for the physical function subset (−6.0 ± 23.6 vs. −14.2 ± 13.5, p = 0.1).ConclusionsThese findings suggest that undiagnosed vitamin D deficiency is common in patients undergoing knee replacement surgery and may have a negative impact on postoperative outcomes.