Stability of L-shaped and inverted triangle fixation assemblies in treating Pauwels type II femoral neck fracture: a comparative mechanical study.

PURPOSE: The aim of our study is to compare the mechanical resistance of two screw configurations in fixating type II Pauwels femoral neck fractures. METHODS: Fifteen synthetic models of femur bones in young adults were divided into three equal groups: intact (G1), models with fixation of a 5.0-mm failure zone created in the posterior cortex of the femoral neck using an L-shaped screw arrangement (G2, n = 5), and models with an identical failure zone fixated using an inverted triangle assembly (G3, n = 5). Model strength (axial loading) and rotational deviation of the fragments were load-tested until a 5.0-mm displacement was reached (step 1) and then until failure, here considered as 10.0 mm displacement in G2 and G3 or femoral neck fracture in G1 (step 2). RESULTS: In step 1, the mean resistance in G1 was 1593 N (standard deviation [SD] of 62 N); this value in G2 was 1261 N (SD 49 N) and in G3 was 1074 N (SD 153 N). During step 2, the value for G1 was 2247 N (SD 84 N), for G2 was 1895 N (SD 69 N), and for G3 was 1523 N (SD 280 N). G3 (the inverted triangle assembly) showed a significantly lower maximum load than the group using the L-shaped assembly (G2) and the control group (G1), which was significant using Kruskal-Wallis analysis of variance (p = 0.002). CONCLUSION: Under test conditions in synthetic bone, fixation using a L-shaped screw assembly provides greater mechanical resistance than an inverted triangle assembly.

The role of the medial plate for Pauwels type III femoral neck fracture: a comparative mechanical study using two fixations with cannulated screws.

BACKGROUND: The biomechanical behavior of Pauwels type III fractures should be taken into consideration when performing internal fixation, since this repair should resist the shear force inherent in the vertical fracture line to the greatest extent possible. Recently, the use of a small fragment plate on the medial face of the femoral neck has been proposed by some authors, with satisfactory initial results. In the current study we analyze the mechanical role a medial plate used as a buttress plate for Pauwels type III femoral neck fractures, comparing the resistance of two fixation configurations using three cannulated screws. METHODS: Pauwels type III fractures were simulated in synthetic bones models and two groups were created, one of those using two parallel screws at the bottom of the femoral neck and the third screw crossing the fracture horizontally (G1), and the other fixed in the same arrangement as G1, but with the addition of a medial side plate at the apex of the fracture (G2). The constructs were subjected to axial loading until catastrophic failure. RESULTS: The addition of a medial plate buttressing the femoral neck increased significantly the resistance to maximum loading (p = 0.003). CONCLUSION: Use of a medial buttress plate results in a mechanically superior construction for Pauwels type III fractures fixed with multiple cannulated screws. LEBEL OF EVIDENCE: Level IV. Biomechanical comparative study.

What is the ideal working length for bridge plating osteosynthesis of a femoral shaft fracture? A multinational online survey evaluation. / Qual é a área de trabalho ideal na fixação de uma fratura da diáfise do fêmur com placa em ponte? Estudo multinacional transversal.

OBJECTIVE: to evaluate how orthopedic surgeons in Latin America define the working length for distinct patterns of femoral shaft fracture. METHODS: a survey was developed presenting different options of working length in four femoral fracture patterns. The survey was submitted to the participants using Google Forms tool. The association between professional characteristics and medical management options according to each type of fracture was analyzed by Chi-square test, with 5% significance level. RESULTS: seven hundred and seven professionals from all Latin America answered the survey. The majority prefered a smaller working length for all situations presented in the study. There was a significant association between the main interest area and the medical preference for the management in fracture types AO 32-B3 and 32-C2 (p<0.05). Other professional characteristics had no significant association at the level of 5%. CONCLUSION: most of the study participants preferred constructions with smaller working length, representing approximately one-third of the total length of the plate, regardless of fracture pattern. There was a significant association between the main interest area (orthopedic trauma) and medical management options for fracture type AO 32-B3 and 32-C2. This can be attributed in part to the fact that these two types of fractures are considered, in the view of the authors, intermediate patterns in terms of strain. This study reinforces the importance of understanding the concept of working length, showing that its calculation remains more based on the surgeons' experience than grounded by strong biomechanical concepts governing the fracture healing process.

OBJETIVO: avaliar a conduta de cirurgiões ortopédicos da América Latina na definição da área de trabalho em distintos padrões de fratura da diáfise do fêmur. MÉTODOS: foi desenvolvido um questionário em que foram apresentadas opções de fixação extra-medular em quatro padrões de fratura da diáfise do fêmur com três diferentes áreas de trabalho. O questionário foi submetido aos participantes utilizando-se a ferramenta Googleforms. A associação entre as características profissionais e as opções de conduta médica de acordo com cada tipo de fratura foi analisada pelo teste de qui-quadrado, com nível de significância de 5%. RESULTADOS: setecentos e sete profissionais da América Latina responderam o questionário. A maioria dos participantes optou por uma menor área de trabalho na osteossíntese em todas as situações do estudo. Observou-se associação significativa entre a especialidade e a conduta médica nas fraturas do tipo AO 32-B3 e 32-C2 (p < 0,05). As demais características profissionais não mostraram associação significativa. CONCLUSÃO: a maioria dos participantes deste estudo prefere construções com menor área de trabalho, representando aproximadamente um terço do comprimento total da placa, independentemente do padrão de fratura. Houve associação significativa entre o tipo de especialidade (trauma ortopédico) e as opções de conduta para as fraturas do tipo AO 32-B3 e 32-C. O presente estudo reforça a importância da compreensão do conceito de área de trabalho, mostrando que sua estimativa continua sendo baseada mais na experiência do cirurgião do que em conceitos biomecânicos que regem o processo de consolidação de fraturas.

Qual é a área de trabalho ideal na fixação de uma fratura da diáfise do fêmur com placa em ponte? Estudo multinacional transversal / What is the ideal working length for bridge plating osteosynthesis of a femoral shaft fracture? A multinational online survey evaluation

RESUMO Objetivo: avaliar a conduta de cirurgiões ortopédicos da América Latina na definição da área de trabalho em distintos padrões de fratura da diáfise do fêmur. Métodos: foi desenvolvido um questionário em que foram apresentadas opções de fixação extra-medular em quatro padrões de fratura da diáfise do fêmur com três diferentes áreas de trabalho. O questionário foi submetido aos participantes utilizando-se a ferramenta Googleforms. A associação entre as características profissionais e as opções de conduta médica de acordo com cada tipo de fratura foi analisada pelo teste de qui-quadrado, com nível de significância de 5%. Resultados: setecentos e sete profissionais da América Latina responderam o questionário. A maioria dos participantes optou por uma menor área de trabalho na osteossíntese em todas as situações do estudo. Observou-se associação significativa entre a especialidade e a conduta médica nas fraturas do tipo AO 32-B3 e 32-C2 (p < 0,05). As demais características profissionais não mostraram associação significativa. Conclusão: a maioria dos participantes deste estudo prefere construções com menor área de trabalho, representando aproximadamente um terço do comprimento total da placa, independentemente do padrão de fratura. Houve associação significativa entre o tipo de especialidade (trauma ortopédico) e as opções de conduta para as fraturas do tipo AO 32-B3 e 32-C. O presente estudo reforça a importância da compreensão do conceito de área de trabalho, mostrando que sua estimativa continua sendo baseada mais na experiência do cirurgião do que em conceitos biomecânicos que regem o processo de consolidação de fraturas.

ABSTRACT Objective: to evaluate how orthopedic surgeons in Latin America define the working length for distinct patterns of femoral shaft fracture. Methods: a survey was developed presenting different options of working length in four femoral fracture patterns. The survey was submitted to the participants using Google Forms tool. The association between professional characteristics and medical management options according to each type of fracture was analyzed by Chi-square test, with 5% significance level. Results: seven hundred and seven professionals from all Latin America answered the survey. The majority prefered a smaller working length for all situations presented in the study. There was a significant association between the main interest area and the medical preference for the management in fracture types AO 32-B3 and 32-C2 (p<0.05). Other professional characteristics had no significant association at the level of 5%. Conclusion: most of the study participants preferred constructions with smaller working length, representing approximately one-third of the total length of the plate, regardless of fracture pattern. There was a significant association between the main interest area (orthopedic trauma) and medical management options for fracture type AO 32-B3 and 32-C2. This can be attributed in part to the fact that these two types of fractures are considered, in the view of the authors, intermediate patterns in terms of strain. This study reinforces the importance of understanding the concept of working length, showing that its calculation remains more based on the surgeons' experience than grounded by strong biomechanical concepts governing the fracture healing process.