Rate and Predictors of Adjacent-Level Fracture after Kyphoplasty with Vertebral Radiofrequency Ablation

A controversy in the osteoporosis domain is whether the stiff modulus of conventional polymethyl methacrylate (PMMA) cement is associated with adjacent-level fracture after kyphoplasty. This remains similarly understudied in the cancer population for patients undergoing kyphoplasty following same-session radiofrequency (RF) ablation within the vertebral body.

Materials and Methods:

IRB-approved retrospective review of all patients undergoing RF ablation + kyphoplasty from 2019 through 2022 at one academic institution, including imaging (pre-procedure and latest available post-procedure) and clinical notes. Patients without imaging follow-up were excluded. In total, 68 procedures for 53 patients were included; mean age 62.4 (range 34-85), 66% female, 30% known osteoporosis, 46% thoracic, 48% lumbar, 6% thoracic + lumbar, 15% myeloma cancer type, 19% received same-level radiotherapy, 38% had endplate discontinuity pre-procedure. Mean imaging follow-up was 258 days post-kyphoplasty (range 7-840 days). Statistical analysis via Microsoft Excel.

Results:

Adjacent level fractures were observed following 7/68 (10.3%) procedures in 6/53 patients at a mean of 220 days post-kyphoplasty (range 7-832 days). Osteoporosis was observed at a higher rate in the adjacent level fracture population compared to the others (5/7 (71%) versus 11/61 (15.4%) p < 0.01). Where imaged/charted, index fracture at the thoracolumbar junction (T11-L2), cement leak into adjacent disc, same-level radiotherapy, and myeloma cancer type were observed for 5/7 (71%), 3/7 (43%), 0/7 (0%), and 0/7 (0%) of procedures that developed fractures, versus 29/61 (48%), 21/61 (34%), 13/61 (20%), and 10/61 (16%) of others (p = 0.23, 0.66, 0.17, 0.27 respectively). Kyphoplasty cement volume (available for 44/68 procedures) was a mean of 4.5 mL per level (range 1.2 – 15.6 mL). Mean cement volume was 5.4 ± 1.1 mL (95% CI) (n=5) in the adjacent-level fracture procedures versus mean of 4.4 ± 0.7 mL (95% CI) (n=39) in others; overlapping confidence intervals indicate lack of significant difference.

Conclusion:

Adjacent-level fractures were observed after 10% (7/68) of RF ablation + kyphoplasty procedures. Osteoporosis history was significantly associated with adjacent fracture risk. Thoracolumbar index fracture, kyphoplasty cement volume, adjoining discal cement extrusion, same-level radiotherapy, or myeloma cancer type were not significantly associated with adjacent fracture risk in this series.