Abstract #1182064: Recurrent Hypercalcemia Following Calcium Sulfate Bead Placement

Abstract

Stimulan® (Smith & Nephew) beads are antibiotic-loaded calcium sulfate beads (CSB) that are used to prevent and treat joint infections intraoperatively. They are used to prevent systemic toxicity of oral and intravenous (IV) antibiotics and can also be used as bone void fillers. We present a case of recurrent transient hypercalcemia due to calcium sulfate beads leading to prolonged hospitalization and IV bisphosphonate treatment. A 65-year-old female with chronic kidney disease (stage 3b) and no prior calcium disorder presented to her orthopedic surgeon with severe osteoarthritis in her left hip after having failed multiple non-surgical interventions. She subsequently underwent left total hip arthroplasty (THA) that was complicated by a prosthetic joint infection requiring THA revision for which she received 10 cc of CSB in the hip joint during the 1st stage revision surgery. On post-operative day 3, her calcium level rapidly increased from 8.3 to 12.6 mg/dL. She was treated with intravenous fluids for dehydration with resolution of hypercalcemia and discharged home. One month later, she was admitted for revision of left THA with insertion of CSB. On post-operative day 3, her calcium increased from 9.3 to 13.8 mg/dL requiring fluids and calcitonin with suspicion that CSB may be the etiology. Two months later, she was admitted with polymicrobial drug resistant infection of the left hip. She underwent another left THA revision with insertion of 20 cc of CSB beads instead of the 10 cc kits previously used. Once again, on post-operative day 3, her calcium levels increased from 8.2 to 14.5 mg/dL. At this time, she was treated with intravenous fluids, calcitonin and 60mg IV pamidronate. Hypercalcemia workup did not show another etiology for hypercalcemia with a suppressed PTH level and normal PTH-related peptide, 25-hydroxy and 1,25-dihydroxy vitamin D levels. Kidney function was at baseline during each admission. The patient endorsed fatigue and constipation. As highlighted above, each episode of hypercalcemia peaked on post-operative day three and resolved within one week. When 20 cc of CSB were used, the peak calcium was more severe necessitating IV bisphosphonate therapy. CSB were not used in subsequent surgical revisions resulting in normal calcium levels. While CSB-induced hypercalcemia has been reported, this case highlights the importance of recognizing this entity and being aware that susceptible patients may be more likely to have recurrence with re-use. Pre- and post-CSB calcium levels should be measured in patients who receive CSB and they should be used at the minimum effective dose. Treatment of CSB-induced hypercalcemia may be considered when hypercalcemia is severe.