Vitamin D deficiency and non-union in foot and ankle surgery

T.A. Ball, H.F. Readman, A. Kendal, M.J. Rogers, R. Sharp, G. Lavis, P.H. Cooke

Introduction: Vitamin D plays an important role in bone turnover. Deficiency (including borderline deficiency, or insufficiency) has a known association with fractures and has been linked to delayed or non-union of fractures. We therefore routinely test vitamin D in cases of non-union. Noting a high rate of vitamin D deficiency in this group, we instituted a policy to routinely screen for and treat vitamin D deficiency in both post-operative and pre-operative patients. We hypothesised that, in the post-operative patients, levels would correlate with rates of union.

Methods: We sent serum vitamin D levels on consecutive post-operative patients seen in clinics between January and May 2014. They included those with an arthrodesis of the ankle, triple joint or first MTPJ. Union was deemed to have occurred when the patient was comfortable full weight bearing and radiographs showed trabeculae crossing the fusion site. Non-unions were all confirmed with computed tomography.

Results: Ten patients were treated for non-union, and had a mean serum vitamin D of 58nmol/L. Fourteen patients (collected over a shorter time period) had confirmed union, with a mean vitamin D of 90nmol/L. This was statistically significant on a one tailed Student's t test (p=0.038). Vitamin D was deficient in five (50%) of non-unions and in three (21%) of unions, giving an odds ratio of 3.67.

Conclusions: Our early results show a significant association of serum vitamin D levels with likelihood of non-union, and we continue to collect data. There is a high prevalence of vitamin D deficiency in our patient population. This is of concern both for the outcome of their surgery and for their lifetime fracture risk. We recommend either screening for or presumptively treating vitamin D deficiency.