Lower preoperative serum calcium is associated with increased risk of postoperative complications in patients undergoing orthopedic surgery

1. Lower preoperative serum calcium levels were associated with a higher risk of postoperative complications in older orthopedic patients.

Evidence Rating Level: 2 (Good)

As the incidence of orthopedic diseases and demand for surgery among older adults are increasing, reducing the occurrence of orthopedic surgical complications is becoming increasingly important. Serum calcium plays a crucial role in maintaining physiological functions such as muscle contraction, nerve conduction, blood coagulation, and cell signalling. Hypocalcemia has been linked with postoperative morbidity and mortality. However, research on the use of serum calcium as a prognostic indicator in orthopedic surgery is lacking. This study thus assessed the ability of preoperative serum calcium levels to predict the occurrence of postoperative complications in geriatric orthopedic surgery. This prospective cohort study from December 20th, 2023, to April 24th, 2025, included orthopedic surgery patients aged >60 years in China, who were followed up for three months postoperatively. Serum calcium levels were classified into three groups: low (1.82–2.19 mmol/L), medium (2.19–2.32 mmol/L), and high (2.32–2.75 mmol/L). The primary outcome was postoperative complications. In total, 690 patients were included, with 230 in the low serum calcium group (mean [SD] age, 70.7 [7.3]; 116 female [50.4%]), 221 in the middle group (mean [SD] age, 70.7 [7.3]; 79 female [35.7%]), and 239 in the high group (mean [SD] age, 68.1 [6.3]; 85 female [35.6%]). Postoperative complications occurred in 101 patients (43.9%) in the low group, 74 (33.5%) in the medium group, and 64 (26.8%) in the high group. For every 1 mmol/L increase in blood preoperative serum calcium level, the odds of postoperative complications decreased by 76% (OR: 0.24, CI: 0.07–0.76). Compared to the high calcium group, patients in the low serum calcium group had a 79% higher risk of complications (OR = 1.79, 95% CI: 1.12–2.78). A nonlinear association was found between serum calcium levels and postoperative complications, with the inflection point at 2.4 mmol/L, below which lower serum calcium levels were associated with increased risk of complications. Overall, this study found that lower preoperative serum calcium levels were associated with a higher risk of postoperative complications, with levels below 2.4 mmol/L potentially indicating a poorer prognosis. These findings highlight the importance of preoperative calcium screening and correction to mitigate postoperative complications.

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