Two-year results of spinal fracture treatment using carbon implants (Multicenter study)

Introduction A good alternative to bone autograft fusion is the utilization of implants produced from non-biological materials. Such implants can reduce the duration of surgery as well as tissue morbidity, while meeting the mechanical strength and osteoconductivity requirements. According to the study results, carbon is a promising material for interbody fusion because of its biocompatibility and osseointegration, as well as an elastic modulus that is close to bone tissue. Methods From 2015 to 2017 a randomized multicenter study was conducted. Three centers took part in the study: the National Medical Research Center of Traumatology and Orthopedics named after N.N. Priorov; Novosibirsk Research Institute for Traumatology and Orthopedics named after Ya.L. Tsivyan; Saint-Petersburg National Phtisiopulmonology Research Institute. One hundred thirteen patients with vertebral body fractures were included in the study and underwent surgical treatment using posterior interbody fusion. In 75 patients (66.37 %, group I) carbon-carbon implants were used, and in 38 patients (group II) – titanium cages. Patient examination was conducted using one protocol, preoperative examination methods and at 6, 12, and 24 month follow-ups, and included VAS score, SF-36 questionnaire, and ASIA scale, as well as CT examination and fusion progress assessment according to G. Tan’s classification. Results The 2-year study showed statistically significant differences between index (carbon implants) and control (titanium cages) groups. Although bone fusion progressed very slowly in the study group (in 86 % of cases no bone fusion was observed at first follow-up 6 months after surgery), the VAS and SF-36 scores were comparable in study and control groups. Discussion Carbon implants are characterized not only by high mechanical strength but also by a significant ability to osteoconductivity that allow for effective bone-carbon fusion due to their porous structure and an elastic modulus of 20–30 GPa, that is comparable to that of bone tissue. These characteristics were confirmed by radiological data (absence of implant subsidence in 38 out of 58 patients (65.51 %) at 24 month follow-up. Titanium implants with an elastic modulus of 80 GPa had a subsidence rate of 100 %.