Anna N. Smith , Kathryn S. Strand , Trent J. Levy , Joseph B. Ulsh , Stephen Ching , Edgardo J. Arroyo , Robert L. Mauck , Michael W. Hast
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引用次数: 0
Abstract
Background
Although rigid interfragmentary fixation is required for fracture repair, overly stiff implants are known to cause stress shielding which ultimately inhibits healing. While gradual dynamization of the fracture site both accelerates and improves osteogenesis, this approach requires external fixators or secondary surgeries. This study leverages biodegradable implants as mechanisms of gradual, passive dynamization during fracture healing.
Methods
Using a rat femoral osteotomy model, additively manufactured poly-lactic-co-glycolic acid implants were compared to geometrically matched non-degradable biocompatible resin devices. Bone healing was assessed at 3 and 6 weeks via micro-computed tomography, histology, and mechanical testing. Implant degradation kinetics were assessed through testing of plates that were used in the rat model and with an unloaded in vitro degradation model.
Findings
Quantitative bone measures made with micro-computed tomography, histology, and mechanical testing of the healing femora revealed no differences between degradable and non-degradable implants at 3 or 6 weeks. Degradable implants caused significant increases in bone volume to total volume mean density (p < 0.0001) and callus to cortical volume (p < 0.05) ratios between 3 and 6 weeks. Poly-lactic-co-glycolic acid devices were significantly stiffer than resin at week 0, but the two groups were equivalent by week 6 due to in vivo degradation. In vivo ambulatory loading caused significant losses of degradable implant stiffness at both 3 (p < 0.05) and 6 (p < 0.01) weeks, but this was not observed in the unloaded in vitro model.
Interpretation
The results from this early timepoint study demonstrate the feasibility of passive, internal fracture dynamization driven by implant material mechanics.
期刊介绍:
Clinical Biomechanics is an international multidisciplinary journal of biomechanics with a focus on medical and clinical applications of new knowledge in the field.
The science of biomechanics helps explain the causes of cell, tissue, organ and body system disorders, and supports clinicians in the diagnosis, prognosis and evaluation of treatment methods and technologies. Clinical Biomechanics aims to strengthen the links between laboratory and clinic by publishing cutting-edge biomechanics research which helps to explain the causes of injury and disease, and which provides evidence contributing to improved clinical management.
A rigorous peer review system is employed and every attempt is made to process and publish top-quality papers promptly.
Clinical Biomechanics explores all facets of body system, organ, tissue and cell biomechanics, with an emphasis on medical and clinical applications of the basic science aspects. The role of basic science is therefore recognized in a medical or clinical context. The readership of the journal closely reflects its multi-disciplinary contents, being a balance of scientists, engineers and clinicians.
The contents are in the form of research papers, brief reports, review papers and correspondence, whilst special interest issues and supplements are published from time to time.
Disciplines covered include biomechanics and mechanobiology at all scales, bioengineering and use of tissue engineering and biomaterials for clinical applications, biophysics, as well as biomechanical aspects of medical robotics, ergonomics, physical and occupational therapeutics and rehabilitation.