2024, Vol. 28 ›› Issue (24): 3807-3813

Biomechanical analysis on Vancouver BI periprosthetic femoral fractures fixed by a customized anatomical plate system

Wang Jiaqi1, 2, Luo Xiaozhong1, 2, Tong Yi1, Lu Xiaobo2, Shi Weixiang1, Zhou Xin1, Wu Gang1, Ding Yong1, Zhang Caidong1   

Abstract: BACKGROUND: At present, the use of a locking bone plate combined with steel wire or steel cable for the treatment of periprosthetic femoral fracture often adopts monocortical fixation, which is not stable and the proximal end of the bone cannot be achieved anatomically fitted by plate. The customized anatomical plate system can effectively solve this problem.
OBJECTIVE: To explore the biomechanical strength of a customized anatomical plate system in fixation of Vancouver BI periprosthetic femoral fracture.
METHODS: CT thin layer scanning data of normal femurs of 1 006 cases were selected and input into the MIMICS 21.0 software to establish the three-dimensional reconstruction model of the femur, which was set as the three-dimensional reconstruction group. 56 complete human femoral specimens were selected as the femoral specimen group. The measured results of the two groups for femoral anatomical appearance were compared. If there was no significant difference between the two groups, the approximate appearance of a customized anatomical plate system was designed based on the measurement results in MIMICS 21.0 software and NX11.0 software. The customized anatomical plate system was designed and prepared according to the above measurement results. Eight pairs of frozen human femurs were selected to make Vancouver BI periprosthetic femoral fracture, which of the left were thin layer scanned by dual-source CT to obtain data. The data were transferred to determine the customized anatomical plate system model by the above design software. Eight sets of customized anatomical plate systems were ultimately produced, relying on the instrument company. The eight pairs of models were numbered 1-8. The left side was fixed with the customized anatomical plate system (customized anatomical plate system group); the right side was fixed with a metal locking plate system-large locking plate (claw plate group). L1-L4 and R1-R4 were subjected to vertical short-cycle loading test and vertical loading test. L5-L8 and R5-R8 were subjected to horizontal short-cycle loading test and four-point bending test. The vertical loading test and four-point bending test were used to collect bending load, bending displacement, and bending strain. Two short cycle loading tests were used to collect strain displacement to compare the maximum load, maximum displacement, bending stiffness, and short-period displacement resistance of the two kinds of bone plates.
RESULTS AND CONCLUSION: (1) There were no significant differences in all indexes between the three-dimensional reconstruction group and the femoral specimen group (P > 0.05). Individual customized anatomical plate system was designed based on the measurement results combined with digital software. (2) In the vertical loading test, the maximum load was higher (P=0.015), the maximum bending displacement was smaller (P=0.014), and the bending stiffness was higher (P=0.005) in the customized anatomical plate system group compared with the claw plate group. (3) In the four-point bending test, the maximum load was higher (P=0.023), the bending stiffness was higher (P=0.005), and the maximum bending displacement was not significant (P=0.216 > 0.05) in the customized anatomical plate system group compared with the claw plate group. (4) In the vertical short-cycle loading test, the average level of bending displacement in the customized anatomical plate system group (0.23±0.10 mm) was significantly lower than that in the claw plate group (0.44±0.02 mm)
(P < 0.05). (5) There was no significant difference in the average level of bending displacement between the two groups in the horizontal short cycle loading test (P > 0.05). (6) It is concluded that the customized anatomical plate system has personalized anatomical characteristics, and the fixation of Vancouver BI periprosthetic femoral fracture is more stable, which has certain significance for clinical treatment.

Key words: periprosthetic femoral fracture, customized anatomical plate system, biomechanics, anatomical morphology of femur, Vancouver classification