Off-label Use of an External Hand Fixator for Craniomaxillofacial Fractures – an Anatomical Feasibility Study

Abstract Background The lack of resources limits the treatment of craniomaxillofacial fractures in low-income countries (LIC). Therefore, Barton bandage and/or interdental wiring are considered being gold standard in these regions. The fracture reduction is maintained by permanent occlusion for 6 weeks, which often leads to limited compliance and dissatisfying results. Furthermore, in these conditions the healing of nasopharyngeal fistula is difficult. During humanitarian missions CMF need to be treated by trauma surgeons. The aim of this cadaver-based study is to evaluate the feasibility of the use of an external face fixator (EFF) for the treatment of CMF, its biomechanical values and to define the optimal pin insertion points and angles. Material and methods A commercially available AO hand fixator was used. Craniomaxillofacial fractures type Le Fort 1-3 with split fracture of the hard palate were treated with EFF on 13 anatomical specimens. The fractures were created using a chisel. The pins were placed in specific anatomical regions. The maximal pull-out force [N] of the pins was analysed by a tensile force gauge. As a reference, Fmax of the mandibular pins was evaluated. Computer tomography (CT) scans were performed on the healthy, fractured and EFF-treated skulls. After reduction and EFF placement an adequate reposition was shown in the CT scans. Results The pull-out forces for the single pins were as follows: mandibular pins (n=15, median 488N), supraorbital pins (n=15, median 455.0N), zygomatic pins (n=14, median 269.1N), medial hard palate pins (n=12, median 208.4N) and lateral hard palate pins (n=8, median 49.6N). Conclusions The results of the presented study on the cadaver show, that the operation technique is feasible, and the stability of the EFF is sufficient for maintaining the reduction. In addition, the required pins can be safely inserted into the described areas and a good reduction result can be achieved. The technique of the EFF offers a feasible alternative to the non-surgical treatment of CMF in LIC. Thus, the gap between the open reduction and internal fixation techniques (mini-plates) used in High-income countries and the Barton bandage used in LIC can be closed. Trial registration: A vote of the local ethics committee was obtained (13.01.2022, Ethikkommission Land Salzburg, Austria). EK Nr: 1198/2021 Level of evidence: Level 2