Background: Calcium sulphate bio-absorbable antibiotic beads are increasingly used for the management and prevention of prosthetic joint infections. Their benefits include the concentrated delivery of local antibiotics, while avoiding systemic toxicity. The development of post-operative hypercalcemia following use of these beads is an under-recognised complication.
Case: An 85-year-old female, with a normal pre-operative calcium and history of osteoporosis managed with denosumab injections, presented with symptomatic hypercalcemia 1 week following revision of a right total knee replacement. Antibiotic-loaded calcium sulphate beads were inserted to the joint intra-operatively. Day 7 post-operatively, she became acutely delirious, and was found to be hypercalcemic (corrected calcium 3.3mmol/L, parathyroid hormone level <0.3). Her multiple myeloma screening, ACE level and morning cortisol level were unremarkable, with 25-hydroxy vitamin D 62, and 1,25-dihydroxy vitamin D 13. She was treated with intravenous fluids for 5 days. Her confusion and corrected calcium improved to 2.51 by day 11 post-operation, allowing her to resume rehabilitation.
Conclusion: The use of intra-operative calcium sulphate antibiotic beads can cause severe symptomatic hypercalcemia and prolong hospital admissions. Risk of hypercalcaemia can be compounded by patient factors including post-operative immobility and surgical factors including the dose of calcium-beads used and joint-vascularity. This case raises awareness of the potential for unintended systemic absorption of antibiotic-eluting calcium beads.