**Author details**

*Clinical Implementation of Bone Regeneration and Maintenance*

diabetes (**Table 2**).

**6. Summary**

1 year post-operative [60]. Cages were unable to be stratified by type and may have been "PEEK, titanium, mesh, or porous." Patients were stratified by the number of levels treated, tobacco use, and diabetic conditions. Overall *nonunion rates were significantly higher in the cage group* (5.32%) than in allograft group (1.97%) (*p* < 0.0001). Notably, patients receiving intervertebral cages showed higher rates of nonunion regardless of other factors such as, levels treated, tobacco use, and

While autograft use is common for bone grafting procedures, it is associated with limitations, including donor site morbidity, limited quantities, and unsatisfactory biological activity. For ACDF, autograft use has steadily declined in favor of alternatives, primarily structural bone allografts and PEEK cages [18, 30]. Favorably, each has mechanical properties similar to autograft, with comparable elastic modulus and sufficient strength for intended applications. However, *in vivo* models demonstrate lack of osseointegration for PEEK, as well as fibrous tissue growth. Poor integration can lead to graft subsidence and pseudarthrosis, and ultimately pain, immobility and sensory loss. In contrast, structural allografts act as an osteoconductive scaffold demonstrating osseointegration in a rat model and have a long history of successful clinical use. These differences are reflected in clinical outcomes, as detailed in this chapter and summarized in **Table 3**. As shown, fusion rates when using PEEK cages were generally lower than when structural allografts were used. Moreover, the use of PEEK cages, and cages in general, in ACDF surgery presented a significantly higher rate of pseudarthrosis vs. structural allografts, lead-

Due to lack of osseointegration of PEEK reported both pre-clinically and clinically, researchers have modified its surface or sought other materials in attempt to improve clinical outcomes. There are promising advances in porous and titanium

In conclusion, although conventional PEEK cages have similar elastic modulus as structural allografts and autografts, they display poorer osseointegration characteristics compared to human bone implants. Comparative clinical analyses indicate that structural allografts yield higher fusion rates and lower incidence of pseudar-

We would like to thank Julie B. McLean, PhD, for editorial assistance.

NC, ECG, and MAM are employees of LifeNet Health, a nonprofit organization.

ing to a greater rate for the need for subsequent revision surgery.

throsis than conventional PEEK cages in ACDF procedures.

coatings and clinical efficacy is being assessed.

**Acknowledgements**

**Conflicts of interest**

**76**

Nigeste Carter, Elena C. Gianulis and Mark A. Moore\* LifeNet Health, Virginia Beach, VA, USA

\*Address all correspondence to: mark\_moore@lifenethealth.org

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
