Biomechanical evaluation of a new concept for screw-in-screw fixation of fragility sacrum fractures (SacrumFix)
AO Trauma
Background
Surgical treatment of fragility sacrum fractures with percutaneous sacroiliac (SI) screw fixation is associated with high failure rates of screw loosening, cut-through and turn-out. The latter is a common cause for complications, being detected in up to 14% of the patients.
Goal
To develop a new screw-in-screw concept and prototype implant for fragility sacrum fracture fixation and test it biomechanically versus transsacral and SI screw fixations.
Results
Twenty-seven artificial pelves with discontinued symphysis and a vertical osteotomy in zone 1 after Denis were assigned to 3 study groups, fixed with either a transsacral screw, a SI screw, or the new screw-in-screw implant, and biomechanically tested using validated setup and test protocol for application of complex axial and torsional loading to failure. Interfragmentary movements and implant motions in terms of pull-out, cut-through, tilt, and turn-out were significantly higher for SI screw fixation compared to both transsacral screw and screw-in-screw fixations. In addition, transacral screw and screw-in-screw fixations revealed similar construct stability. Moreover, screw-in-screw fixation successfully prevented turning-out of the implant, that remained at 0° rotation around the nominal screw axis during testing for all specimens.
Kamer L, Noser H, Arand C, Handrich K, Rommens PM, Wagner D. Artificial Intelligence and CT-based 3D statistical modeling to assess trans-sacral corridors and plan implant positioning. J Orthop Res. 2021;epub Feb 15. https://doi.org/10.1002/jor.25010
Acklin Y (MD), University Hospital Basel, Basel, Switzerland
Rommens P (Prof), University Medical Center Mainz, Mainz, Germany
Wagner D (MD), University Medical Center Mainz, Mainz, Germany