RESUMO
OBJECTIVE: To using finite element analysis to investigate the effects of the traditional titanium alloy Gamma nail and a biodegradable magnesium alloy bionic Gamma nail for treating intertrochanteric fractures. METHODS: Computed tomography images of an adult male volunteer of appropriate age and in good physical condition were used to establish a three-dimensional model of the proximal femur. Then, a model of a type 31A1 intertrochanteric fracture of the proximal femur was established, and the traditional titanium alloy Gamma nails and biodegradable magnesium alloy bionic Gamma nails were used for fixation, respectively. The von Mises stress, the maximum principal stress, and the minimum principal stress were calculated to evaluate the effect of bone ingrowth on stress distribution of the proximal femur after fixation. RESULTS: In the intact model, the maximum stress was 5.8 MPa, the minimum stress was -11.7 MPa, and the von Mises stress was 11.4 MPa. The maximum principal stress distribution of the cancellous bone in the intact model appears in a position consistent with the growth direction of the principal and secondary tensile zones. After traditional Gamma nail healing, the maximum stress was 32 MPa, the minimum stress was -23.5 MPa, and the von Mises stress was 31.3 MPa. The stress concentration was quite obvious compared with the intact model. It was assumed that the nail would biodegrade completely within 12 months postoperatively. The maximum stress was 18.7 MPa, the minimum stress was -12.6 MPa, and the von Mises stress was 14.0 MPa. For the minimum principal stress, the region of minimum stress value less than -10 MPa was significantly improved compared with the traditional titanium alloy Gamma nail models. Meanwhile, the stress distribution of the bionic Gamma nail model in the proximal femur was closer to that of the intact bone, which significantly reduced the stress concentration of the implant. CONCLUSION: The biodegradable magnesium alloy bionic Gamma nail implant can improve the stress distribution of fractured bone close to that of intact bone while reducing the risk of postoperative complications associated with traditional internal fixation techniques, and it has promising clinical value in the future.
Assuntos
Pinos Ortopédicos , Fixação Intramedular de Fraturas/instrumentação , Fraturas do Quadril/cirurgia , Desenho de Prótese , Adulto , Ligas , Cadáver , Análise de Elementos Finitos , Humanos , Magnésio , Masculino , TitânioRESUMO
In this work, a tandem reversible addition fragmentation chain transfer (RAFT)/click chemistry method was developed to prepare amide-polystyrene-silica (NHCO-Psty-silica) stationary phase. Styrene was immobilized on amino-silica surface via an azide functionalized RAFT agent in a one-pot procedure. The resultant NHCO-Psty-silica column demonstrates better performance for shielding of residue silanols than traditional ODS column, which was ascertained by Engelhardt test (E test), Tanaka test (T test), Galushko test (G test), and Walters test (W test). Our results showed lower values of silanol activity calculated according to the formula in these standard tests for NHCO-Psty-silica column compared to the ODS column we tested. As a result, the NHCO-Psty-silica is suitable for the separation of basic compounds. The hydrophobic, anion exchanging and π-π interaction of the column toward analytes were also evaluated. Moreover, the NHCO-Psty-silica column also showed excellent stability with pure water as mobile phase.