Flanagan B P, LeCronier D, Kubacki M R, Telehowski P, Atkinson P
McLaren-Flint 401 S. Ballenger Hwy, Flint, MI 48532.
Kettering University 1700 University Ave, Flint, MI 48504.
Iowa Orthop J. 2014;34:68-73.
Traditional interlocked intramedullary (IM) nails have recently been modified to provide enhanced angular stability. These so-called 'angle-stable' IM nails are designed to eliminate construct toggle and also provide increased axial, bending, and torsional stiffness. While this added stability is needed for small fracture gaps to heal, angle-stable nails may be too stiff for large fracture gaps to unite. Even though relative stability is recommended for large fracture gaps, recent in vivo data indicates that traditional nails may allow for too much motion for healing to occur. The current study evaluated a modified technique for implanting an angle-stable nail which allows for an intermediate amount of stability. The compliance of the nail construct was adjusted by over-drilling the near cortex interlocking hole. This led to increased construct motion in torsion, but less so in axial compression and bending. This modification creates stability which is partway between angle-stable and traditional IM nail designs. These findings were unchanged after 50,000 fatigue loading cycles. By carefully selecting the magnitude of over-drilling, the compliance of the construct can easily be modified as it is being implanted. This design modification may lead to more reliable fracture union since the surgeon can tailor the nail compliance to the injury and bone quality.
传统的带锁髓内钉最近已进行改良，以增强角度稳定性。这些所谓的“角度稳定型”髓内钉旨在消除结构松动，并提高轴向、弯曲和扭转刚度。虽然小骨折间隙愈合需要这种额外的稳定性，但角度稳定型髓内钉对于大骨折间隙愈合可能太硬。尽管对于大骨折间隙推荐相对稳定性，但最近的体内数据表明，传统髓内钉可能会允许过多的运动而无法实现愈合。本研究评估了一种植入角度稳定型髓内钉的改良技术，该技术可实现中等程度的稳定性。通过对近侧皮质互锁孔进行过度钻孔来调整钉结构的顺应性。这导致结构在扭转时的运动增加，但在轴向压缩和弯曲时运动增加较少。这种改良创造出的稳定性介于角度稳定型和传统髓内钉设计之间。经过50000次疲劳加载循环后，这些结果没有变化。通过仔细选择过度钻孔的程度，在植入过程中可以轻松改变结构的顺应性。这种设计改良可能会导致更可靠的骨折愈合，因为外科医生可以根据损伤情况和骨质来调整钉的顺应性。
