3D patient-matched template guides are able to increase mean diameter and length and to improve accuracy of cortical bone trajectory screws: a 5-year international experience

The aim of this study was to analyse whether significant differences exist between free-hand 3D planning-guided screw placement and 3D printed template guided CBT screw positioning in terms of accuracy, size of screws and potential complications.Data were extracted from a prospectively collected database and resumed in a retrospective study. Adult patients fixed with CBT screws for lumbar degenerative pathologies were considered for this analysis. A group of patients in which screws were placed by using 3D planning guided free-hand technique (PG) were compared to a second group of patients that underwent screw positioning by using customised 3D printed guides (TG). Analysed parameters were size of the screws, accuracy, clinical outcomes and complications.A total number of 1004 screws and 251 patients was evaluated for this study. The PG included 158 patients (632 screws) while the TG evaluated 93 patients (372 screws). The TG group involved screws of larger size from L3 to S1. Differences between the two groups in terms of accuracy parameters reached statistical significance (p ≤ 0.05).The use of 3D patient-matched template guides was able to safely increase mean diameter and length of cortical bone trajectory screws, and also improved the accuracy of screw placement. Following previous evidence about CBT biomechanical properties, these advantages could allow to increase fixation strength over traditional convergent pedicle screw trajectories. Further biomechanics studies would be needed.