Effect of romosozumab administration on proximal junctional kyphosis in corrective spinal fusion surgery

The effect of romosozumab administration in patients undergoing corrective spinal fusion surgery has not yet been analyzed.

To examine the effect of romosozumab administration on reducing the incidence of proximal junctional kyphosis (PJK), particularly PJK due to fractures (PJK-Fx), in patients undergoing spinal corrective fusion surgery.

Retrospective cohort study.

A total of 111 patients aged >50 years underwent corrective fusion surgery (>2 vertebrae) for adult spinal deformity or vertebral compression fracture between June 2010 and July 2023.

The primary outcome was the incidence of PJK, whereas the secondary outcomes were changes in Hounsfield unit (HU) values, surgical complications, and clinical outcomes measured using the Japanese Orthopaedic Association (JOA) and visual analog scale scores.

The patients were divided into the romosozumab (n=32) and nonromosozumab groups (n=79). Romosozumab was typically administered 2 months before surgery in the romosozumab group. Demographic data, surgery-related factors, and radiographic parameters were analyzed. HU values at the upper instrumented vertebra+1 (UIV+1) were measured preoperatively and at 1 year postoperatively. After the univariate analysis of preoperative factors associated with PJK, multivariate logistic regression was used to identify factors associated with PJK.

Romosozumab significantly increased the HU values at UIV+1 (-1.22% vs 13.60%, p<.001) and reduced the incidence of PJK (39.24% vs 18.75%, p=.046), particularly PJK-Fx (26.58% vs 6.25%, p=.019) and osteoporosis-related complications (55.70% vs 34.38%, p=.011). The multivariate analysis showed a significantly lower incidence of PJK (adjusted odds ratio = 0.32, p=.033), particularly PJK-Fx (adjusted odds ratio = 0.15, p=.018). There was a tendency for better JOA scores at 1 year postoperatively in the romosozumab group (21.49 vs 23.62, p=.071).

Romosozumab administration effectively increased bone density and reduced the risk of PJK, particularly PJK-Fx, and osteoporosis-related complications in patients undergoing corrective spinal fusion surgery. Administration of romosozumab 2 months before surgery enhanced bone mineral density and strength, leading to better surgical outcomes and fewer complications. Further long-term studies are needed to confirm these findings and optimize treatment protocols.