A metal, currently used primarily in electronics, is getting attention as a new biomaterial for spinal implants. While rarer and about 30 times the price of titanium, tantalum is being recognized for biocompatibility and excellent fusion promotion.
Porous tantalum has been used clinically as a coating for acetabular cups in hip arthroplasty for over 20 years and recently has been considered for spine surgery. An article published in the March 2020 issue of the Journal of Spine Surgery analyzed recent spine fusion studies comparing the material to autograft. In the article, “Tantalum: the next biomaterial in spine surgery?” Patel, et al., reviewed over a dozen studies investigating the metal in cervical or lumbar fusions.
The authors found that cervical fusion rates were slightly lower, though statistically significant when comparing a porous tantalum cage alone to autograft (89.0% vs. 92.8%), and even lower for tantalum with autograft. However, patients with tantalum cages experienced far fewer complications or revisions, partially due to very low infection rates.
Interestingly, porous tantalum alone resulted in higher fusion rates in the lumbar spine compared with autograft (93.4% vs. 80%). The studies included in the analysis varied quite a bit in reported fusion rates for tantalum. One study mentioned a reason being difficulty in assessing fusion radiographically because of the radiopacity of the tantalum.
It is hard to draw broad conclusions from this analysis comparing several studies with different surgical techniques or comparison devices.
Currently, Zimmer Biomet is the only orthopedic device manufacturer offering tantalum implants, which they brand as “Trabecular Metal”. They produce dental, hip, knee, shoulder, ankle, and spine implants using porous tantalum as a coating for cups and stems, or the entire implant, in the case of spine implants.
Zimmer Biomet currently offers tantalum devices for cervical and both posterior and anterior lumbar fusion as well as vertebral body replacements for corpectomy. Zimmer’s porous tantalum implants are produced through a proprietary chemical deposition process. Whether tantalum will become tantalizing enough as a biomaterial to induce additional manufacturers to offer implants made of the stuff is yet to be seen.
