Biomechanical analysis of elastic nail combined with end caps and wire fixation for long oblique femoral shaft fractures

doi:10.3969/j.issn.2095-4344.2965

Abstract

Abstract: BACKGROUND: The use of elastic nails to treat children with unstable fractures or heavier children often results in shortening, angular or rotational deformities.
OBJECTIVE: To provide a theoretical basis for internal fixation choice for femoral long oblique fracture by elastic nails combined with end caps or wire using biomechanical test.
METHODS: An identical length oblique midshaft fracture was created in eight small adult cadaveric femurs harvested from four donors. Two 3.5-mm titanium elastic nails were introduced intramedullary into all femur models. According to the different fracture fixations, all models were divided into four groups (group A: titanium elastic nail, group B: titanium elastic nail+wire, group C: titanium elastic nail+caps, group D: titanium elastic nail+wire+caps). Nondestructive axial compression, four-point bending and torsion tests were conducted. Stiffness, displacement and torque were analyzed.
RESULTS AND CONCLUSION: (1) In the axial compression tests, stiffness was increased by 509% and displacement was decreased by 74% using the titanium elastic nail+cap combination compared with titanium elastic nail alone (group A) (P < 0.01). (2) The titanium elastic nail+wire combination (group B) showed larger stiffness (P < 0.01) and smaller displacement (P < 0.01) in the sagittal plane bending test; and as well as larger stiffness (P < 0.01) and smaller displacement (P < 0.01) in coronal plane bending test; and larger stiffness in torsion test (P < 0.01). The end caps with wire in group D improved the stiffness significantly in all directions. (3) The results have demonstrated that end caps fixation helps to increase the axial stability of the long oblique fracture model, and combined wire fixation increases the structural stability under torsional and bending loads, which provides a good reference for clinical treatment of children with unstable femoral shaft fractures.

Key words: bone, femoral shaft, fracture, long oblique, children, displacement, biomechanics, load, elastic nail, tail cap

CLC Number:

Tan Jiachang, Yuan Zhenchao, Wu Zhenjie, Liu Bin, Zhao Jinmin. Biomechanical analysis of elastic nail combined with end caps and wire fixation for long oblique femoral shaft fractures[J]. Chinese Journal of Tissue Engineering Research, 2021, 25(3): 334-338.

Figures/Tables 5

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