Bio-integrative vs Metallic Screws in Calcaneus Osteotomies: A Non-Inferiority Randomized Clinical Trial
Authors: Mansur Nacime Salomao Barbachan , Carvalho Kepler A.M. , Chinelati Rogerio Marcio Kajimura , Fayed Aly M. , Schmidt Eli , Lalevee Matthieu , Rojas Edward O. , Ehret Amanda , Chrea Bopha , de Cesar Netto Cesar 
Published: December 2023

Category: Hindfoot; Other Introduction/Purpose: The use of bio-integrative implants in orthopedic surgery is growing exponentially. Advantages, such as reduced implant-related artifact production, lower removal rates, and superior bone interaction, have been advocated. However, while many biomechanical and histological reports could sustain its structural and biological properties, only some clinical studies were produced that could support its use. Therefore, this trial intended to determine the bio-integrative screws' capacity to reach the same clinical and radiographical outcomes of current metallic screws in calcaneus osteotomies. Our main hypothesis was that metallic and bio-integrative screws would not present differences when comparing bone healing and complications. Methods: This was a single center, in parallel groups, randomized non-inferiority clinical trial (NCT05018130) that included patients undergoing a calcaneal sliding osteotomy from November 2021 to January 2023. Patients were randomized in a 1 to 1 ratio by software in the metallic or bio-integrative groups, and allocation occurred after anesthesia was carried out. Surgeries were performed by a single surgeon respecting the same technique, using two canulated 4mm screws, either titanium or fiber, according to the treatment group. The primary outcome was determined by bone using weight-bearing computed tomography (WBCT) in the 6th postoperative week. At least 50% of bone trabeculae crossing the osteotomy site needed to be observed to be considered positive. Secondary outcomes included minor and major complications and bone healing, assessed in the 2nd, 4th, 6th, 12th, 24th, and 48th weeks of follow-up. Two assessors performed readings. Between-group differences were measured with ANOVA and chi-square tests. Results: After twenty-nine patients were assessed initially, 22 subjects were found eligible and included in the study. Groups were similar demographically (ps>0.37), with ten patients allocated to the bio-integrative and 12 to the metallic group. The mean follow- up was 31.64 weeks (min 6; max 48) with no losses through the endpoints. Considering WBCT bone healing at six weeks, the bio (80%) and the metallic (75%) groups had similar rates (p=0.58). At 12 weeks, bone healing was slightly higher in the bio-integrative group (100% vs. 92%; p=0.004). No major complications were observed. Minor complications were similar between groups (10% in bio; 16% in metallic; p=0.56) and composed of superficial infections (one bio, one metallic) and delayed wound healing (one metallic), all resolved by six weeks. Conclusion: Bio-integrative screws presented similar results to metallic screws when used in calcaneus osteotomies, considering bone healing and complications. No differences were found in a medium to long-term follow-up, and no major complications were reported. This non-inferiority clinical trial could contribute to the body of literature supporting the use of bio-integrative screws in clinical practice. Larger and longer trials are necessary to determine the superiority of any implant and its impact on orthopedic surgery.