A Biomechanical Comparison of Periprosthetic Femoral Fracture Fixation in Normal and Osteoporotic Cadaveric Bone

Abstract Although cerclage wiring is a very useful implant, it has many problems. We manufactured an alphabet C-shaped clip with nitinol (C-clip) that has superelastic property to replace the cerclage wiring.This study aimed to compare the biomechanical stability of cerclage cable and the C-clip. Eighteen synthetic femora were tested. An unstable VB1 fractures model was constructed that oblique fracture line was 8cm below the lesser trochanter with fracture gab. The distal fixation was repaired with a locking plate and four bi-cortical screws. The proximal fixation was repaired two different methods: (1) four-threaded cerclage cables and (2) four new C-clip. In axial compression test, the C-clip was stiffer than the cerclage cable (median stiffness of C-clip = 39.28 N/mm [IQR; 38.84-41.19], cerclage cable = 34.90 N/mm [34.84-35.08], p<0.05). In the torsion test, the C-clip was 0.44 Nm/° [IQR; 0.44-0.45] and cerclage cable = 0.30 Nm/° [0.30-0.33], p<0.05). In the four-point bending test, the C-clip = 39.35 N/mm [IQR; 38.91-40.97] and cerclage cable = 28.38 N/mm, [28.33-30.79], p<0.05) The C-clip may be biomechanically superior to cerclage wiring in terms of stiffness, axial compression, torsion, and four-point bending tests and is a valuable alternative in Vancouver type B1 periprosthetic femoral fracture.

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Biomechanical characteristics of allogeneic cortical bone pins designed for fracture fixation

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.3415/vcot-07-03-0026 ◽

2008 ◽

Vol 21 (02) ◽

pp. 140-146

Author(s):

M. R. Edwards ◽

S. P. James ◽

W. S. Dernell ◽

R. J. Scott ◽

A. M. Bachand ◽

...

Keyword(s):

Stainless Steel ◽

Cortical Bone ◽

Fracture Fixation ◽

Impact Testing ◽

Left Tibia ◽

Four Point Bending ◽

And Gender ◽

The Right ◽

Biomechanical Comparison ◽

Better Than

SummaryThe biomechanical characteristics of 1.2 mm diameter allogeneic cortical bone pins harvested from the canine tibia were evaluated and compared to 1.1 mm diameter stainless steel pins and 1.3 mm diameter polydioxanone (PDS) pins using impact testing and four-point bending. The biomechanical performance of allogeneic cortical bone pins using impact testing was uniform with no significant differences between sites, side, and gender. In four-point bending, cortical bone pins harvested from the left tibia (204.8 ± 77.4 N/mm) were significantly stiffer than the right tibia (123.7 ± 54.4 N/mm, P=0.0001). The site of bone pin harvest also had a significant effect on stiffness, but this was dependent on interactions with gender and side. Site C in male dogs had the highest mean stiffness in the left tibia (224.4 ± 40.4 N/mm), but lowest stiffness in the right tibia (84.9 ± 24.2 N/mm). Site A in female dogs had the highest mean stiffness in the left tibia (344.9 ± 117.4 N/mm), but lowest stiffness in the right tibia (60.8 ± 3.7 N/mm). The raw and adjusted bending properties of 1.2 mm cortical bone pins were significantly better than 1.3 mm PDS pins, but significantly worse than 1.1 mm stainless steel pins (P<0.0001). In conclusion, cortical bone pins may be suitable as an implant for fracture fixation based on initial biomechanical comparison to stainless steel and PDS pins used in clinical practice.

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