Since joining the Texas Back Institute in 1996, Zigler has been an international guest lecturer on topics in spinal reconstruction, as well as a Principal Investigator for the ProDisc artificial disc replacement system's U.S. Food and Drug Administration (FDA) clinical studies.
As a condition of approval, Synthes Spine is required to conduct a five-year study assessing the long-term safety and effectiveness of the disc.
The company is also required to complete an annual analysis and report any major adverse events (such as implant breakage, subsidence or expulsion from the disc space).
More recently, questions about ethics of surgeon investigators in the Pro Disc study have been raised, specifically in a New York Times article about conflicts of interest related to his Zigler's financial ties, in which it is reported that he invested $25,000 in the company.
He has been consulted numerous times regarding the spinal injuries of such high-profile celebrities as Christopher Reeve and Jason Priestley.