Steward Sara K T, Brodin Erik, Gadomski Ben, Nelson Bradley, Easley Jeremiah
Colorado State University College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA.
Ann Transl Med. 2023 Mar 15;11(5):191. doi: 10.21037/atm-22-2746. Epub 2023 Feb 20.
The metatarsal bone is commonly utilized in preclinical fracture models in sheep. A majority of studies achieve fracture stabilization with bone plating, but more recently intramedullary interlocking nails (IMN) have been utilized. The mechanical properties of this unique surgical technique utilizing an IMN has not yet been fully elucidated or compared to the traditional locking compression plating (LCP) technique. We hypothesize that a mid-diaphysis metatarsal critical-sized osteotomy stabilized with an IMN will provide equivalent mechanical stability to LCP with less variance of mechanical properties across specimens.
Sixteen ovine hind limbs were transected at the mid tibia with soft tissue intact and utilized for implantation. A 3-cm osteotomy was created in the mid-diaphysis of all metatarsi. For the IMN group, a 147 mm × 8 mm IMN was implanted from distal to proximal through the sagittal septum of the distal metatarsus and the bolts locked in place using an IMN guide system. For the LCP group, a 3.5-mm 9-hole LCP was secured to the lateral aspect of the metatarsus with three locking screws in the proximal and distal holes leaving the central three holes empty. All metatarsal constructs were fitted with three strain gages on proximal and distal metaphyses and the lateral aspect of the IMN or LCP at the osteotomy site. Non-destructive mechanical testing was performed in compression, torsion, and four-point bending.
The IMN constructs showed overall greater construct stiffness with less variance in strain between constructs than the LCP constructs in 4-point bending, compression, and torsion.
IMN constructs may provide superior mechanical properties for a critical-sized osteotomy model of the ovine metatarsus when compared to lateral LCP constructs. Further investigation comparing characteristics of fracture healing between IMN and LCP is warranted.
跖骨常用于绵羊的临床前骨折模型。大多数研究通过接骨板实现骨折固定，但最近也开始使用髓内交锁钉（IMN）。这种使用IMN的独特手术技术的力学性能尚未得到充分阐明，也未与传统的锁定加压接骨板（LCP）技术进行比较。我们假设，用IMN固定的骨干中段跖骨临界尺寸截骨术将提供与LCP相当的力学稳定性，且各标本间力学性能的差异较小。
16只羊的后肢在胫骨中段横断，保留软组织完整，用于植入。在所有跖骨的骨干中段制造一个3厘米的截骨术。对于IMN组，通过远端跖骨的矢状中隔从远端向近端植入一根147毫米×8毫米的IMN，并使用IMN导向系统将螺栓锁定到位。对于LCP组，将一个3.5毫米的9孔LCP用近端和远端孔中的三个锁定螺钉固定在跖骨外侧，中间三个孔为空。所有跖骨结构在近端和远端干骺端以及截骨部位的IMN或LCP外侧均安装了三个应变片。进行压缩、扭转和四点弯曲的无损力学测试。
在四点弯曲、压缩和扭转中，IMN结构总体上显示出比LCP结构更高的结构刚度，且结构间应变差异更小。
与外侧LCP结构相比，IMN结构在绵羊跖骨临界尺寸截骨术模型中可能提供更好的力学性能。有必要进一步研究比较IMN和LCP之间骨折愈合的特征。
