Vincenzo Giordano1,2, Roger Pletsch Paes3, Danilo Diniz Alves3, Arthur Bonfim Amaral3, William D Belangero4, Marcos Giordano5, Anderson Freitas6, Hilton A Koch7. 1. Serviço de Ortopedia E Traumatologia Prof. Nova Monteiro, Hospital Municipal Miguel Couto, Clínica São Vicente, Rua João Borges 204, Gávea, Rio de Janeiro, RJ, 22451-100, Brazil. v_giordano@me.com. 2. Núcleo Especializado de Ortopedia e Traumatologia, Clínica São Vicente, Rio de Janeiro, Brazil. v_giordano@me.com. 3. Serviço de Ortopedia E Traumatologia Prof. Nova Monteiro, Hospital Municipal Miguel Couto, Clínica São Vicente, Rua João Borges 204, Gávea, Rio de Janeiro, RJ, 22451-100, Brazil. 4. Departamento de Ortopedia e Traumatologia, Universidade Estadual de Campinas, Campinas, Brazil. 5. Serviço de Traumato-Ortopedia, Hospital de Força Aérea do Galeão, Rio de Janeiro, Brazil. 6. Serviço de Quadril - Hospital Ortopédico e Medicina Especializada - HOME, Brasília, Brazil. 7. Departamento de Radiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Abstract
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.
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.
Entities:
Keywords:
Analysis of equipment failure; Bone screws; Femoral neck; Hip fractures; Internal fracture fixation; L shaped; L-shaped assembly; Mechanical torsion
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