Significant improvement in axial load stability with the pre-tensioned pelvic external fixator: A biomechanical analysis in a model with type C Tile lesion. / Mejora significativa de la estabilidad a carga axial con el fijador externo pélvico pretensado: análisis biomecánico en un modelo con lesión Tile tipo C.

OBJECTIVE: The aim of our work is to check if the use of a pre-tensed bar connected to 2supra-acetabular Schanz pins is more stable in a pelvic with a tile C1 injury. MATERIAL AND METHODS: We used synthetic pelvis (N=5) with a unstable vertical injury, stabilized with both the standard and the pre-tensed system. They both were submitted to axial loading. We measured applied forces and the position of markers that were positioned in the sacroiliac and symphysis joints. We determined the relative movements between injured surfaces, rigidity, resistance and when each system failed. RESULTS: When using the pre-tensed fixator, the rigidity was much higher in the sacro-iliac joint (P=.043) being 3.45 times higher, being also 2.06 times higher in pubic symphysis (P=.043). The resistance against failure was 2 times higher too (P=.043). DISCUSSION: The increased axial stability with the pre-tensed external fixator accords with its ability to make active compression in both posterior and anterior elements of the pelvic ring, which was previously demonstrated. This result supports the preliminary clinic outcomes that were obtained. CONCLUSIONS: The pre-tensed external fixator increases the axial stability of the pelvic ring's posterior elements in a synthethic pelvis with a Tile C1 injury, without decreasing it's capacity to achieve an anterior stability.

[Translated article] Significant improvement in axial load stability with the pre-tensioned pelvic external fixator: A biomechanical analysis in a model with type C Tile lesion.

OBJECTIVE: The aim of our work is to check if the use of a pre-tensed bar connected to 2 supra-acetabular Schanz pins is more stable in a pelvic with a tile C1 injury. MATERIAL AND METHODS: We used synthetic pelvis (N = 5) with a unstable vertical injury, stabilized with both the standard and the pre-tensed system. They both were submitted to axial loading. We measured applied forces and the position of markers that were positioned in the sacroiliac and symphysis joints. We determined the relative movements between injured surfaces, rigidity, resistance and when each system failed. RESULTS: When using the pre-tensed fixator, the rigidity was much higher in the sacro-iliac joint(P=.043) being 3.45 times higher, being also 2.06 times higher in pubic symphysis (P=.043). The resistance against failure was 2 times higher too (P=.043). DISCUSSION: The increased axial stability with the pre-tensed external fixator accords with its ability to make active compression in both posterior and anterior elements of the pelvic ring, which was previously demonstrated. This result supports the preliminary clinic outcomes that were obtained. CONCLUSIONS: The pre-tensed external fixator increases the axial stability of the pelvic ring's posterior elements in a synthethic pelvis with a Tile C1 injury, without decreasing it's capacity to achieve an anterior stability.