Syndesmosis dislocation and ankle ligament stress in the posterior malleolus fracture fixated - "in vitro analysis".

PURPOSE: The objectives of this study were to compare syndesmosis dislocation and ankle ligament stress after the fixation of the posterior malleolus fracture (PMF) with four different techniques by Finite Element Analysis (FEM). METHODS: Four internal fixation techniques used for fixation of PMF were assessed by FEM: posterior one-third tubular 3.5 mm buttress plate (PP) with one screw (PP 1 screw), PP with two screws (PP 2 screws), two cannulated 3.5 mm lag screws in the anteroposterior (AP) direction (AP lag screws), and two posteroanterior (PA) cannulated 3.5 mm lag screws (PA lag screws). PMF with 30% fragment size was simulated through computational processing reconstructed from computed tomography (CT). The simulated loads of 700 N and 1200 N were applied to the proximal tibial end. The FEM evaluated the syndesmosis dislocation (mm) and stress values of the posterior tibiofibular ligament (PTFL) (in Kpa) and deltoid ligament (in Kpa) in the four mentioned subgroups. RESULTS: We found that with a load of 700 N, syndesmosis dislocation varied from 6.5 to 7.9 mm, being the lowest and greatest for PA lag screw and PP 1 screw, respectively. In all groups was observed a greater dislocation in the syndesmosis at 1200 N of load. We observed that the stress values on the PTFL were lower for AP lag screws and PP 2 screws with 700 N and 1200 N, respectively. For both loads, PP 1 screw presented the greatest stress. Regarding the stress in the deltoid ligament, the AP lag screws presented the lowest stress for 700 N and PP 1 screw for 1200 N. For all fixation techniques, the syndesmosis displacement and ligament stresses were higher when 1200 N were imposed. CONCLUSION: This study demonstrated that PMF fixed with lag screws presents greater stability in the distal tibiofibular syndesmosis and higher joint loadings promoted greater displacement and ligaments stress, regardless of the fixation technique. Besides, lower stress in the syndesmosis is accompanied by a greater load on the deltoid ligament.

Evaluation of the Reproducibility of the Schatzker Classification Reviewed by Kfuri for Tibial Plateau Fractures.

Objective The Schatzker classification is the most used for tibial plateau fractures. Kfuri et al. 12 reviewed Schatzker's initial classification describing in more detail the involvement of the tibial plateau in the coronal plane, allowing a better understanding of the fracture pattern and a more accurate surgical planning. The objectives of the present study are to evaluate the interobserver agreement of these classifications and to evaluate the influence of the experience of the observer on the reproducibility of the instruments. Methods An observational and retrospective study was conducted by evaluating the radiological study of 20 adult individuals with tibial plateau fractures, including radiographs and computed tomography (CT). The fractures were classified once by 34 examiners with varied experience (24 specialists and 10 residents in Orthopedics and Traumatology), according to the Schatzker classification and to the modification proposed by Kfuri. The Fleiss Kappa index was used to verify interobserver agreement. Results The interobserver agreement index was considered moderate for the Schatzker classification (κ = 0.46) and mild for the Kfuri modification (κ = 0.30). The Schatzker classification showed moderate agreement, with κ = 0.52 for residents and κ = 0.45 among specialists. The Kfuri classification showed mild agreement, with Kappa values for residents and specialists of 0.39 and 0.28, respectively. Conclusion The Schatzker classification and the classification modified by Kfuri presented moderate and mild interobserver agreement, respectively. In addition, the residents presented higher agreement than the specialists for the two systems studied.

Evaluation of the Reproducibility of the Schatzker Classification Reviewed by Kfuri for Tibial Plateau Fractures / Avaliação da reprodutibilidade da classificação de Schatzker revisada por Kfuri para as fraturas do planalto tibial

Abstract Objective The Schatzker classification is the most used for tibial plateau fractures. Kfuri et al.12 reviewed Schatzker's initial classification describing in more detail the involvement of the tibial plateau in the coronal plane, allowing a better understanding of the fracture pattern and a more accurate surgical planning. The objectives of the present study are to evaluate the interobserver agreement of these classifications and to evaluate the influence of the experience of the observer on the reproducibility of the instruments. Methods An observational and retrospective study was conducted by evaluating the radiological study of 20 adult individuals with tibial plateau fractures, including radiographs and computed tomography (CT). The fractures were classified once by 34 examiners with varied experience (24 specialists and 10 residents in Orthopedics and Traumatology), according to the Schatzker classification and to the modification proposed by Kfuri. The Fleiss Kappa index was used to verify interobserver agreement. Results The interobserver agreement index was considered moderate for the Schatzker classification (κ = 0.46) and mild for the Kfuri modification (κ = 0.30). The Schatzker classification showed moderate agreement, with κ = 0.52 for residents and κ = 0.45 among specialists. The Kfuri classification showed mild agreement, with Kappa values for residents and specialists of 0.39 and 0.28, respectively. Conclusion The Schatzker classification and the classification modified by Kfuri presented moderate and mild interobserver agreement, respectively. In addition, the residents presented higher agreement than the specialists for the two systems studied.

Resumo Objetivo A classificação de Schatzker é a mais utilizada para as fraturas do planalto tibial. Kfuri et al.12 revisaram a classificação inicial de Schatzker descrevendo com mais detalhes o envolvimento do planalto tibial no plano coronal, permitindo uma melhor compreensão do padrão de fratura e um planejamento cirúrgico mais acurado. Os objetivos do presente estudo são avaliar a concordância inter-observador dessas classificações e avaliar a influência da experiência dos observadores na reprodutibilidade dos instrumentos. Métodos Foi realizado um estudo observacional e retrospectivo, por meio da avaliação do estudo radiológico de 20 indivíduos adultos com fraturas do planalto tibial, incluindo radiografias e tomografia computadorizada (TC). As fraturas foram classificadas 1 vez por 34 examinadores com experiência variada (24 especialistas e 10 residentes em Ortopedia e Traumatologia), de acordo com a classificação de Schatzker e com a modificação proposta por Kfuri. O índice Kappa de Fleiss foi usado para verificar a concordância interobservadores. Resultados O índice de concordância inter-observador foi considerado moderado paraa classificação de Schatzker (κ = 0,46) e leve para a modificação de Kfuri (κ = 0,30). A classificação de Schatzker apresentou concordância moderada, com κ = 0,52 para residentes e κ = 0,45 entre os especialistas. A classificação de Kfuri apresentou concordância leve com valores de Kappa para residentes e especialistas de 0,39 e 0,28, respectivamente. Conclusão A classificação de Schatzker e a classificação modificada por Kfuri apresentaram concordância interobservadores moderada e leve, respectivamente. Além disso, os residentes apresentaram concordâncias superiores aos especialistas para os dois sistemas estudados.

Biomechanical comparison of four different posterior malleolus fixation techniques: A finite element analysis.

PURPOSE: The objective of this study was to compare the biomechanical behavior of four fixation methods for posterior malleolar fracture (PMF) by finite element analysis (FEM). METHODS: Four internal fixation techniques used for fixation of PMF were assessed by FEM - a computational study: posterior one-third tubular 3.5 mm buttress plate (PP) with one screw (PP 1 screw), PP with two screws (PP 2 screws), two cannulated 3.5 mm lag screws in the antero-posterior (AP) direction (AP lag screws), and two postero-anterior (PA) cannulated 3.5 mm lag screws (PA lag screws). PMF with 30% and 50% fragment sizes were simulated through computational processing reconstructed from computed tomography (CT). The simulated loads of 700 N and 1500 N were applied to the proximal tibial end. The FEM evaluated the total and localized displacements of the PMF. For the analysis of stresses, the variables maximum principal (traction) and minimum principal (compression) were used. For the metallic implants, the equivalent von Mises stress (VMS) was used. RESULTS: PA lag screw showed the lowest values for total and localized displacement, minimum and maximum total stress, and VMS in both physiological conditions and sizes of posterior malleolus involvement. The localized displacement was statistically lower for lag screws compared to PP techniques at 700 N (p < 0.05) and 1200 N (p < 0.05). The maximum total stress was statistically lower for PA lag screws compared to PP 1 fixation with 700 N (p = 0.03) and 1200 N (p = 0.039). CONCLUSION: PA lag screws yield better results in terms of total and localized displacement, minimum and maximum total stress, and VMS in both physiological conditions and sizes of posterior malleolus involvement. These results demonstrate that PA lag screws are biomechanically the most efficient technique for the fixation of PMF.

Evaluation of the Reproducibility of Lauge-Hansen, Danis-Weber, and AO Classifications for Ankle Fractures.

Objective The present study aims to analyze the intra- and interobserver reproducibility of the Lauge-Hansen, Danis-Weber, and Arbeitsgemeinschaft für Osteosynthesefragen (AO) classifications for ankle fractures, and the influence of evaluators training stage in these assessments. Methods Anteroposterior (AP), lateral and true AP radiographs from 30 patients with ankle fractures were selected. All images were evaluated by 11 evaluators at different stages of professional training (5 residents and 6 orthopedic surgeons), at 2 different times. Intra- and interobserver agreement was analyzed using the weighted Kappa coefficient. Student t-tests for paired samples were applied to detect significant differences in the degree of interobserver agreement between instruments. Results Intraobserver analysis alone had a significant agreement in all classifications. Moderate to excellent interobserver agreement was highly significant ( p ≤ 0.0001) for the Danis-Weber classification. The Danis-Weber classification showed, on average, a significantly higher degree of agreement than the remaining classification systems ( p ≤ 0.0001). Conclusion The Danis-Weber classification presented the highest reproducibility among instruments and the evaluator's little experience had no negative influence on the reproducibility of ankle fracture classifications. Level of Evidence II, Diagnostic Studies - Investigating a Diagnostic Test .

Energy Required for Fracture in Synthetic Proximal Femoral Models After Synthesis Material Removal: a Biomechanical Study Using Cannulated Screws, Dynamic Hip Screws, and Proximal Femoral Nails.

Objective The present study aims to identify the energy required for synthetic proximal femoral fracture after removal of three implant types: cannulated screws, dynamic hip screws (DHS), and proximal femoral nail (PFN). Methods Twenty-five synthetic proximal femur bones were used: 10 were kept intact as the control group (CG), 5 were submitted to the placement and removal of 3 cannulated screws in an inverted triangle configuration (CSG), 5 were submitted to the placement and removal of a dynamic compression screw (DHSG), and 5 were submitted to the placement and removal of a proximal femur nail (PFNG). All samples were biomechanically analyzed simulating a fall on the greater trochanter using a servo-hydraulic machine to determine the energy (in Joules [J]) required for fracture. Results All samples presented basicervical fractures. The energy required for fracture was 7.1 J, 6.6 J, 6 J, and 6.7 J for the CG, CSG, DHSG and PFNG, respectively. There was no statistically significant difference (considering a 95% confidence interval) in energy among the study groups ( p = 0.34). Conclusion There was no statistically significant difference in the energy required to cause a synthetic proximal femoral fracture after removing all three implant types and simulating a fall over the greater trochanter.

Evaluation of the Reproducibility of Lauge-Hansen, Danis-Weber, and AO Classifications for Ankle Fractures / Avaliação da reprodutibilidade das classificações Lauge-Hansen, Danis-Weber e AO para fraturas do tornozelo

Abstract Objective The present study aims to analyze the intra- and interobserver reproducibility of the Lauge-Hansen, Danis-Weber, and Arbeitsgemeinschaft für Osteosynthesefragen (AO) classifications for ankle fractures, and the influence of evaluators training stage in these assessments. Methods Anteroposterior (AP), lateral and true AP radiographs from 30 patients with ankle fractures were selected. All images were evaluated by 11 evaluators at different stages of professional training (5 residents and 6 orthopedic surgeons), at 2 different times. Intra- and interobserver agreement was analyzed using the weighted Kappa coefficient. Student t-tests for paired samples were applied to detect significant differences in the degree of interobserver agreement between instruments. Results Intraobserver analysis alone had a significant agreement in all classifications. Moderate to excellent interobserver agreement was highly significant (p ≤ 0.0001) for the Danis-Weber classification. The Danis-Weber classification showed, on average, a significantly higher degree of agreement than the remaining classification systems (p ≤ 0.0001). Conclusion The Danis-Weber classification presented the highest reproducibility among instruments and the evaluator's little experience had no negative influence on the reproducibility of ankle fracture classifications. Level of Evidence II, Diagnostic Studies - Investigating a Diagnostic Test.

Resumo Objetivo Avaliar a reprodutibilidade intra- e interobservador das classificações de Lauge-Hansen, Danis-Weber e Arbeitsgemeinschaft für Osteosynthesefragen (AO) para as fraturas de tornozelo, e a influência do estágio de formação dos participantes na avaliação. Métodos Foram selecionadas radiografias de 30 pacientes com fratura de tornozelo nas incidências anteroposterior (AP), perfil e AP verdadeiro. Todas as imagens foram avaliadas por 11 participantes em diferentes estágios de formação profissional (cinco residentes e seis cirurgiões ortopédicos), em dois momentos distintos. Analisou-se a concordância inter- e intraobservador por meio do coeficiente Kappa ponderado. O teste t de Student para amostras pareadas foi aplicado para verificar se havia diferença significativa no grau de concordância interobservador entre os instrumentos. Resultado Observou-se que existe concordância significativa em todas as classificações quando da análise intraobservador isolada. Existe concordância interobservador altamente significativa de grau moderado a ótimo na classificação de Danis-Weber (p ≤ 0,0001). A classificação de Danis-Weber apresentou, em média, grau de concordância significativamente maior que as outras classificações (p ≤ 0,0001). Conclusão A classificação de Danis-Weber se mostrou a mais reprodutiva entre os instrumentos avaliados, e a pouca experiência do avaliador não influencia negativamente a reprodutibilidade das classificações das fraturas do tornozelo. Nível de Evidência II, Estudos Diagnósticos - Investigação de um Exame para Diagnóstico.

Energy Required for Fracture in Synthetic Proximal Femoral Models After Synthesis Material Removal: a Biomechanical Study Using Cannulated Screws, Dynamic Hip Screws, and Proximal Femoral Nails / Energia necessária para a ocorrência de fratura em modelos sintéticos de fêmur proximal após retirada de material de síntese: Um estudo biomecânico com parafuso canulado, parafuso dinâmico do quadril e haste femoral proximal

Abstract Objective The present study aims to identify the energy required for synthetic proximal femoral fracture after removal of three implant types: cannulated screws, dynamic hip screws (DHS), and proximal femoral nail (PFN). Methods Twenty-five synthetic proximal femur bones were used: 10 were kept intact as the control group (CG), 5 were submitted to the placement and removal of 3 cannulated screws in an inverted triangle configuration (CSG), 5 were submitted to the placement and removal of a dynamic compression screw (DHSG), and 5 were submitted to the placement and removal of a proximal femur nail (PFNG). All samples were biomechanically analyzed simulating a fall on the greater trochanter using a servo-hydraulic machine to determine the energy (in Joules [J]) required for fracture. Results All samples presented basicervical fractures. The energy required for fracture was 7.1 J, 6.6 J, 6 J, and 6.7 J for the CG, CSG, DHSG and PFNG, respectively. There was no statistically significant difference (considering a 95% confidence interval) in energy among the study groups (p = 0.34). Conclusion There was no statistically significant difference in the energy required to cause a synthetic proximal femoral fracture after removing all three implant types and simulating a fall over the greater trochanter.

Resumo Objetivo Identificar a energia necessária para ocorrência de fratura do fêmur proximal em osso sintético após retirada de três modelos de implantes: parafusos canulados, parafuso dinâmico do quadril (dynamic hip screw-DHS) e haste femoral proximal (proximal femoral nail-PFN). Métodos Foram utilizados 25 modelos de ossos sintéticos da extremidade proximal do fêmur: 10 unidades de grupo controle (GC), 5 unidades após colocação e retirada de 3 parafusos canulados colocados em configuração de triângulo invertido (GPC), 5 unidades após colocação e retirada do parafuso de compressão dinâmico (GDHS), e 5 unidades após colocação e retirada da haste de fêmur proximal (GPFN). Uma análise biomecânica foi realizada em todas as amostras simulando uma queda sobre o grande trocânter utilizando uma máquina servo-hidráulica com o objetivo de verificar a energia (em Joules [J]) necessária até a ocorrência de fratura nos diferentes grupos. Resultados Todos os grupos apresentaram fratura basocervical. Os grupos GC, GPC, GDHS e GPFN apresentaram, respectivamente, valores de 7.1J, 6.6J, 6J e 6.7J de energia até ocorrência da fratura. Não houve diferença estatisticamente significativa (intervalo de confiança de 95%) na energia entre os grupos de estudo (p = 0,34). Conclusão Não houve diferença estatisticamente significativa nos valores de energia necessária para ocorrência de fratura da extremidade proximal do fêmur após a retirada de três tipos de implantes utilizando modelos sintéticos simulando queda sobre o grande trocânter.

Biomechanical Test Following Removal of a Dynamic Hip Screw: In Vitro Analysis.

The objective of this study was to evaluate, by means of a static flexural test, the biomechanical parameters necessary for the occurrence of a proximal femoral fracture in a synthetic bone model after the removal of a dynamic hip screw (DHS) and comparing the results obtained with a reinforcement technique using polymethylmethacrylate (PMMA). Twenty synthetic bones made of the same material and from the same manufacturer were used: ten units as the control group (CG), five units as the test group without reinforcement (TG), and five units as the test group with reinforcement (TGR). The biomechanical analysis was performed simulating a fall over the trochanter using a servo-hydraulic machine. In the control group, the assay was performed with its integrity preserved. In the TG and TGR groups, a DHS model was introduced, and the tests were performed as follows: TG after simple removal of the synthesis material, and in the TGR group, after removal of the synthesis material and filling the orifice of the femoral neck with PMMA. All groups presented with a basicervical fracture of the femoral neck. The CG group presented a mean of 935 newtons (N) of maximum load and 7.0 joules (J) of energy for fracture occurrence. TG and TGR groups presented, respectively, a maximum load of 750 N and 1,068 N, and energy of 6.0 J and 7.3 J. According to the one-way analysis of variance (ANOVA), there was no significant difference in flow load (p = 0.16), energy to flow (p = 0.16), stiffness (p = 0.28), maximum load (p = 0.10), and energy to fracture (p = 0.54) between the studied groups. The removal of the DHS implant from the synthetic bone did not present a significant increase of the maximum load and the energy necessary for the occurrence of a fracture with the use of the PMMA reinforcement technique.