ABSTRACT
Introduction Sacroiliac joint dislocations are caused by high energy trauma and commonly treated with the iliosacral screw fixation or the anterior plating of the sacroiliac joint (SIJ). However, there is a lack of consensus regarding which procedure is the most successful in treating sacroiliac joint dislocations. This aims to compare stiffness and maximum load of pelvises with sacroiliac joint dislocations treated with both procedures in a synthetic bone model. Methods Synthetic pelvises were mounted and divided into 2 treatment groups ( n = 5): a model with two orthogonal plates placed anteriorly to the SIJ (PPS group) and another with two iliosacral screws fixating the SIJ (SPS group), both with pubic symphysis fixation. The maximum load supported by each sample was observed and the stiffness was calculated from the curve load vs displacement. The mean values of load to failure and stiffness for each group were compared with the Mann-Whitney U test ( p < 0.05 was considered significant for all analysis). Results The mean load to failure supported by the PPS group was 940 ± 75 N and the SPS was 902 ± 56 N, with no statistical difference. The SPS group showed higher values of stiffness (68.6 ± 11.1 N/mm) with statistical significant difference in comparison to the PPS sample (50 ± 4.0 N/mm). The mode of failure was different in each group tested. Conclusion Despite lower stiffness, the anterior plating fixation of the sacroiliac joint can be very useful when the iliosacral screw fixation cannot be performed. Further studies are necessary to observe any differences between these two procedures on the clinical and surgical setting.
ABSTRACT
Abstract Introduction Sacroiliac joint dislocations are caused by high energy trauma and commonly treated with the iliosacral screw fixation or the anterior plating of the sacroiliac joint (SIJ). However, there is a lack of consensus regarding which procedure is the most successful in treating sacroiliac joint dislocations. This aims to compare stiffness and maximum load of pelvises with sacroiliac joint dislocations treated with both procedures in a synthetic bone model. Methods Synthetic pelvises were mounted and divided into 2 treatment groups (n= 5): a model with two orthogonal plates placed anteriorly to the SIJ (PPS group) and another with two iliosacral screws fixating the SIJ (SPS group), both with pubic symphysis fixation. The maximum load supported by each sample was observed and the stiffness was calculated from the curve load vs displacement. The mean values of load to failure and stiffness for each group were compared with the Mann-Whitney U test (p< 0.05 was considered significant for all analysis). Results The mean load to failure supported by the PPS group was 940 ± 75 N and the SPS was 902 ± 56 N, with no statistical difference. The SPS group showed higher values of stiffness (68.6 ± 11.1 N/mm) with statistical significant difference in comparison to the PPS sample (50 ± 4.0 N/mm). The mode of failure was different in each group tested. Conclusion Despite lower stiffness, the anterior plating fixation of the sacroiliac joint can be very useful when the iliosacral screw fixation cannot be performed. Further studies are necessary to observe any differences between these two procedures on the clinical and surgical setting.
Resumo Introdução Usualmente, as luxações sacroilíacas são tratadas com parafusos iliossacrais ou com placas anteriores à articulação sacroilíaca (ASI). Este estudo compara a rigidez e carga máxima suportada pelos dois tipos de fixações acima citados, utilizando pelves sintéticas. Método Dez pelves sintéticas foram divididas em dois grupos (n= 5). No grupo denominado PlaCF, a ASI foi fixada com duas placas anteriores. No grupo ParCF, a ASI foi fixada com dois parafusos iliossacrais no corpo da primeira vertebra sacral (S1). A rigidez e carga máxima suportada por cada montagem realizada, foi mensurada. A análise estatística foi realizada através do teste U de Mann-Whitney (p< 0.05 foi considerado estatisticamente significativo para todas as análises). Resultados A carga máxima suportada até a falha da fixação pelos grupos PlaCF e ParCF foram respectivamente 940 ± 75 N e 902 ± 56 N, não havendo diferença estatística entre eles. A rigidez obtida pelo grupo ParCF foi maior e com diferença estatística em relação ao grupo PlaCF (68.6 ± 11.1 N/mm e 50 ± 4.0 N/mm respectivamente). Conclusão Apesar da menor rigidez obtida no grupo PlaCF, as placas anteriores à ASI podem ser uma ótima opção no tratamento da luxação sacroilíaca quando os parafusos iliossacrais não puderem ser utilizados. Outros estudos são necessários para detectar possíveis diferenças entre os dois procedimentos do ponto vista cirúrgico e clínico.
Subject(s)
Sacroiliac Joint , Wounds and Injuries , Biomechanical Phenomena , Bone and Bones , Bone Plates , Joint Dislocations , Joint InstabilityABSTRACT
BACKGROUND: The purpose of this study was to evaluate the role of a non-locking plate applied to the anteromedial surface of the proximal humerus on loads at the implant-bone interface of non-locking and locking lateral plate fixation of proximal humeral fractures with a medial gap. METHODS: Twenty synthetic humeri models were used. In fifteen, the proximal portion of the humerus was osteotomized to create a two-part surgical neck fracture, with a 10-mm medial gap and a 5-mm lateral gap; five models were controls. In the osteotomized humeri, five models were stabilized with a locking lateral plate (group L), five with a locking lateral plate and an anteromedial non-locking plate (group L+T), and five with a non-locking lateral plate and a non-locking anteromedial plate (group T+T). All humeri were tested under axial loading until catastrophic failure, which was characterized as complete closure of the medial gap. Stiffness was calculated using force vs. displacement curves. The data were analyzed via descriptive and inferential studies, at a 5% significance level. RESULTS: Statistically significant differences were seen among all the constructions. The combination of a lateral locking plate with an anteromedial non-locking plate (group L+T) was the stiffest construction, while the combination of a non-locking lateral plate with a non-locking anteromedial plate (group T+T) was the least stiff, even in comparison with a single locking lateral plate (p = 0.01). When the two groups which utilized a lateral locking plate (groups L+T and L) were compared, the group with additional anteromedial support demonstrated greater stiffness (p = 0.03), and stiffness values for the control group comprised of intact humeri models were even higher (p = 0.01). CONCLUSION: Combining a lateral locking plate with a non-locking anteromedial plate provides a stiffer construction for fixation of unstable two-part proximal humerus fractures with a medial gap. Mechanical benefits of medial support with a second non-locking antero-medial plate seems to be related with better construct stability in terms of strength and fatigue, potentially reducing the risk of varus collapse of the humerus head and fracture healing disturbances.
