Primary Hyperparathyroidism and Lumbar Spinal Fusion Outcomes: A Propensity-Matched Cohort Study

Hyperparathyroidism (HPT) is associated with deterioration of bone microarchitecture, but its impact on lumbar fusion outcomes is poorly characterized, and existing spine data largely reflect dialysis-driven secondary HPT. We evaluated whether preoperative primary HPT is associated with complications after lumbar fusion, and whether preoperative parathyroidectomy modifies these outcomes.

Using the TriNetX Research Network, we identified adults undergoing lumbar fusion with and without preoperative primary HPT; propensity score matching (1:1) yielded 775 patients per group. A prespecified subgroup compared primary HPT patients with and without preoperative parathyroidectomy (208 per group). Outcomes were pseudoarthrosis, instrumentation failure, revision at 2 and 5 y, and 90-d medical complications, including emergency department (ED) utilization.

No mechanical outcome differed significantly between groups. At 5 y, instrumentation failure was 3.29% versus 2.48% (risk ratio [RR] 1.33, 95% confidence interval 0.74-2.39; P = 0.34), revision 2.51% versus 2.92% (RR 0.86, 0.47-1.58; P = 0.63), and pseudoarthrosis 7.79% versus 6.73% (RR 1.16, 0.80-1.67; P = 0.43). Ninety-d ED utilization was higher with primary HPT (15.7% versus 11.1%; RR 1.42, 1.10-1.84; P = 0.007); other complications did not differ. The parathyroidectomy subgroup was underpowered, with mechanical events below reporting thresholds.

Preoperative primary HPT was not associated with increased instrumentation failure, revision, or pseudoarthrosis through 5 y, though confidence intervals do not exclude smaller effects. The principal difference was higher early ED utilization. The underpowered subgroup permitted no conclusion regarding the effect of preoperative parathyroidectomy.