Histopathologic Findings of Retrieved Specimens of Vertebroplasty with Polymethylmethacrylate Cement

In Brief Study Design. Case control study. Objective. To investigate the histopathologic findings of 2 retrieved specimens from failed vertebroplasty with polymethylmethacrylate (PMMA) cement. Summary of Background Data. Vertebroplasty using PMMA cement has been commonly used to treat debilitating back pain from compression fracture, angiomas, and metastatic cancer. However, there was concern about the unpredictable future results with PMMA cement. The histopathologic changes were rarely reported. Methods. There were 2 PMMA augmented and 3 nonaugmented fractured vertebral bodies retrieved for histopathologic study. Between the 2 groups, we compared the findings of bone necrosis, foreign body reaction, fibrotic wall formation, and neovascularization. Results. Bone necrosis was noted in the periphery of PMMA cement, which was surrounded by fibrotic tissues. In contrast, no fibrotic wall formation could be found in the nonaugmented control group. Foreign body reaction was only noted in PMMA augmented cases, and neovascularization was only noted in the control cases. Conclusion. PMMA cement might not be as bioinert as we considered. Therefore, the long-term safety of vertebroplasty should be further evaluated. Polymethylmethacrylate (PMMA) cement is nonabsorbable and not osteoconductive. There was concern about the unpredictable future results with vertebroplasty using PMMA cement. The histopathologic changes at the interface between PMMA and cancellous bone may provide an important clue to the etiology of the failed PMMA vertebroplasty. The exothermic reaction during polymerization may cause thermal necrosis of surrounding tissues. Foreign body reaction and the fibrotic wall formation were also noted at the cement-bone interface. “The repairing process” and neovascularization could not be found in PMMA augmented vertebral bodies. Therefore, PMMA cement is not so bioinert and biocompatible. The long-term durability of PMMA vertebroplasty may be questioned.