Spinal cage retrieval and assessment of biologic response

Implant retrieval programs have been effective in understanding implant failure and biomaterial compatibility in joint arthroplasty; however, its application has not been extended extensively to the assessment of spinal constructs and implants. The objective of this study is to determine the efficacy of implant retrieval analysis as a standard for the assessment of explanted spinal implants. The limitations of clinical radiographic assessment of fusion through metal interbody devices are also identified. The implant analysis protocol is shown through a case report of a titanium mesh spinal fusion cage retrieved from a 54-year-old woman who had a pseudoarthrosis at the T12 cage interface. The implant analysis techniques include backscattered electron imaging, high-resolution contact radiography, histology, and fluorochrome analysis. An implant retrieval analysis program similar to the one discussed in the presented case study will enable an accurate assessment of outcomes of these commonly used implants and will guide future development.