Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
Institute of Forming Technology and Machines, Leibniz University Hannover, Garbsen, Germany.
PLoS One. 2020 May 5;15(5):e0231823. doi: 10.1371/journal.pone.0231823. eCollection 2020.
Intramedullary nailing of diaphyseal femoral fractures is a commonly used treatment method in dogs because of its biological and biomechanical advantages compared to bone plating. To achieve adequate resistance of the intramedullary nail against torsional and axial compressive forces, additional application of transcortical screws is needed. As these interlocking screws represent a frequent cause of post-operative complications, a new expandable intramedullary nail (EXPN) was developed, which was designed to provide adequate fracture stabilisation without the need for transcortical fixation. The evaluation of the biomechanical properties of the new EXPN with regard to torsional, compressive and bending stability as well as direct comparison to the biomechanical properties of conventional Steinmann (STMN)- and interlocking (ILN) nails was carried out with different biomechanical test arrangements. No significant statistical differences regarding the torsional and bending resistance between the EXPN and ILN group were seen, which indicates that rotatory as well as bending stability of the innovative EXPN is similar to the conventional ILN. Nevertheless, the percentage deviation between the attempted and successfully reached physiological compressive forces was significantly higher (p = 0.045) in the EXPN group compared to the ILN group, which indicates that the compressive stability of the innovative EXPN might be weaker compared to the ILN. In summary, the new EXPN represents an interesting alternative to conventional intramedullary nails. However, in direct comparison to conventional interlocking nails, the EXPN has shown weaknesses in the neutralization of axial compressive forces, which indicates that at least biomechanically the interlocking nail seems advantageous. Further in-vitro and in-vivo investigations are required before clinical use can be recommended.
髓内钉固定股骨干骨折是犬中常用的治疗方法，因为与钢板固定相比，它具有生物力学优势。为了使髓内钉具有足够的抗扭转和轴向压缩力，需要额外应用皮质骨螺钉。由于这些锁定螺钉是术后并发症的常见原因，因此开发了一种新的可膨胀髓内钉 (EXPN)，旨在提供足够的骨折稳定性，而无需皮质固定。通过不同的生物力学测试装置，对新型 EXPN 的扭转、压缩和弯曲稳定性的生物力学特性进行了评估，并与传统斯氏 (STMN) 和锁定 (ILN) 钉的生物力学特性进行了直接比较。EXPN 和 ILN 组的扭转和弯曲阻力没有显著的统计学差异，这表明创新的 EXPN 的旋转和弯曲稳定性与传统的 ILN 相似。然而，与 ILN 组相比，EXPN 组尝试达到并成功达到生理压缩力的百分比偏差明显更高 (p = 0.045)，这表明创新的 EXPN 的压缩稳定性可能比 ILN 弱。总之，新型 EXPN 是传统髓内钉的一种有趣的替代方案。然而，与传统的锁定钉直接比较，EXPN 在中和轴向压缩力方面存在弱点，这表明在生物力学方面，锁定钉似乎具有优势。在推荐临床使用之前，需要进行进一步的体外和体内研究。
