Degradable poly-lactic-co-glycolic acid and non-degradable polymer implants result in similar fracture healing at early timepoints

IF 1.4 3区医学 Q4 ENGINEERING, BIOMEDICAL

Clinical Biomechanics Pub Date : 2025-05-09 DOI:10.1016/j.clinbiomech.2025.106545

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.

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可降解聚乳酸-羟基乙酸和不可降解聚合物植入物在早期骨折愈合的效果相似

背景：虽然骨折修复需要刚性的骨折块间固定，但已知过硬的植入物会造成应力屏蔽，最终抑制愈合。虽然骨折部位的逐渐动力化可以加速和改善成骨，但这种方法需要外固定物或二次手术。本研究利用可生物降解植入物作为骨折愈合过程中逐渐被动动力化的机制。方法采用大鼠股骨截骨模型，将增材制造的聚乳酸-羟基乙酸植入物与几何匹配的不可降解生物相容性树脂植入物进行比较。3周和6周时通过显微计算机断层扫描、组织学和力学测试评估骨愈合情况。通过对大鼠模型和未加载的体外降解模型中使用的板的测试来评估植入物降解动力学。通过显微计算机断层扫描、组织学和愈合股骨的力学测试进行的定量骨测量显示，在3周或6周时，可降解和不可降解植入物之间没有差异。可降解种植体显著增加骨体积与总体积平均密度之比(p <；0.0001)和愈伤组织与皮质体积(p <；0.05)，比值为3 ~ 6周。聚乳酸-羟基乙酸装置在第0周明显比树脂坚硬，但由于体内降解，两组在第6周时相当。体内动态载荷在3 (p <；0.05)和6 (p <；0.01)周，但在体外模型中没有观察到这一点。这项早期时间点研究的结果证明了由种植体材料力学驱动的被动内部断裂动力化的可行性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Clinical Biomechanics 医学-工程：生物医学

CiteScore

3.30

自引率

5.60%

发文量

189

审稿时长

12.3 weeks

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.