Directed Injection of Vertebroplastic Cement at the Site of a Lytic Metastatic Lesion Restores Strength With Minimum Injection Volume

Metastatic disease in the thoracolumbar spine represents a large and growing problem. These metastases can lead to pain, pathologic fracture, and neurologic compromise. Over the last two decades, the utilization of polymethylmethacrylate (PMMA) for percutaneous vertebral stabilization has increased. Most of the biomechanical and outcomes data addresses the use of vertebroplasty and kyphoplasty procedures for osteoporotic fractures [1,2]. Use of these procedures for metastatic disease enjoys a long clinical history, but the outcomes and complications are notably higher than in osteoporosis [3,4]. Newer formulations of PMMA used in advanced systems such as the Perimeter System (DePuy, Raynham, MA) may allow carefully controlled, anatomically directed PMMA application with far greater control. However, The relative benefits of these newer, proprietary systems have not been demonstrated. Proposed benefits of direct void reconstruction, as opposed to anterior vertebral body fill include: tumor lysis, decreased risk of later tumor growth with canal compromise, the ability to use less total PMMA, decreased impact on adjacent segment mechanics, and therefore, a decreased adjacent segment fracture risk. This study was conducted to examine and compare the biomechanical effectiveness of the cement augmentation (vertebroplasty) and directed PMMA injection using the Perimeter system.