Evolutionary approaches to technological complexity tend to ignore the role of invention. In this paper, we follow the theory of invention developed by Brian Arthur to trace historically the emergence of complexity in the case of the artificial disc, a surgical prosthesis used in the treatment of spinal pain. The notion of structural deepening helps us to understand the emergence of complexity ?in the form of designed and unexpected relationships between elements- during the invention process. Structural deepening describes the growth of complexity as a consequence of the ?crude? nature of the original concept of the new technology (the base principle), which needs more design sophistication to enhance basic performance. The history of the artificial intervertebral disc offers an excellent context for investigating structural deepening. We find that one factor is influential in the extent of structural deepening is the success or failure of the ?technological neighbors? of the artificial disc. This ?neighborhood effect? consists of a reduction in complexity ?borrowed? from the technological neighbors. We call this process ?architectural stabilization?.