Objective: To test the mechanical strength and observe the in vivo degradation of self-made human hair keratin-polylactic acid (HHK-PLA) composite rods designed for use in internal fixation.
Methods: Twenty such HHK-PLA composite rods were tested for shear strength, bending strength and bending modulus using the material testing system MTS-858 Mini Bionix. A total of 36 samples of HHK-PLA composite rods designed for internal fixation of bone fracture were randomly implanted in dorsal subcutaneous tissue of 18 SD rats, and weight losses of these rods were measured 1, 2, 4, 8, 12, 16, 20, 24 and 28 weeks after the implantation to evaluate the in vivo degradation of the material.
Results: The initial shear strength of HHK-PLA rod was 241 MPa, bending strength 358 MPa, and bending modulus 13 GPa. The test demonstrated a slower rate of degradation in SD rats in earlier period following implantation than in later period.
Conclusion: HHK-PLA composite rods have good initial mechanical strength and tolerable degradation in vivo, and may be used potentially for internal fixation of the weigh-bearing bones of the limbs.