Pivazyan Gnel, Winters Carlynn G, Brooks Daina M, Sandhu Faheem A, Cunningham Bryan W
Department of Neurosurgery, MedStar Georgetown University Hospital, Washington , District of Columbia , USA.
Department of Orthopaedic Surgery, Musculoskeletal Research Center, MedStar Union Memorial Hospital, Baltimore , Maryland , USA.
Neurosurgery. 2024 Jan 1;94(1):217-225. doi: 10.1227/neu.0000000000002686. Epub 2023 Sep 14.
Posterior reconstruction of the cervicothoracic junction poses significant biomechanical challenges secondary to transition from the mobile cervical to rigid thoracic spines and change in alignment from lordosis to kyphosis. After destabilization, the objectives of the current investigation were to compare the rod strain and multidirectional flexibility properties of the cervicothoracic junction using a 4-rod vs traditional 2-rod reconstructions.
Ten human cadaveric cervicothoracic specimens underwent multidirectional flexibility testing including flexion-extension, lateral bending, and axial rotation. After intact analysis, specimens were destabilized from C4 to T3 and instrumented from C3 to T4. The following reconstructions were tested: (1) 3.5-mm titanium (Ti) 2-rod, (2) 3.5-mm Ti 4-rod, (3) 4.0-mm cobalt chrome (CoCr) 2-rod, (4) 4.0-mm CoCr 4-rod, and (5) Ti 3.5- to 5.5-mm tapered rod reconstructions. The operative level range of motion and rod strain of the primary and accessory rods were quantified.
The addition of accessory rods to a traditional 2-rod construct improved the biomechanical stability of the reconstructions in all three loading modalities for Ti ( P < .05). The accessory CoCr rods improved stability in flexion-extension and axial rotation ( P < .05). The addition of accessory rods in Ti or CoCr reconstructions did not significantly reduce rod strain ( P < .05). CoCr 2 and 4 rods exhibited less strain than both Ti 2 and 4 rods.
Supplemental accessory rods affixed to traditional 2-rod constructs significantly improved stability of Ti alloys and CoCr alloy materials. The 4.0-mm CoCr rods provided greater stability than 3.5-mm Ti rods in flexion-extension, lateral bending, and axial rotation. While rod strain was not significantly reduced by the addition of accessory rods, it was reduced in CoCr rod treatment groups compared with the Ti rods.
由于从活动的颈椎向僵硬的胸椎过渡，以及从脊柱前凸到后凸的排列变化，颈胸交界区的后路重建面临重大的生物力学挑战。在进行去稳定化处理后，本研究的目的是比较使用4棒与传统2棒重建方式时颈胸交界区的棒材应变和多向柔韧性特性。
对10个人类尸体颈胸标本进行多向柔韧性测试，包括屈伸、侧屈和轴向旋转。在完整分析后，将标本从C4至T3进行去稳定化处理，并从C3至T4进行器械固定。测试了以下几种重建方式：(1) 3.5毫米钛（Ti）2棒；(2) 3.5毫米Ti 4棒；(3) 4.0毫米钴铬（CoCr）2棒；(4) 4.0毫米CoCr 4棒；以及(5) Ti 3.5至5.5毫米渐变棒重建。对主棒和副棒的手术节段活动范围和棒材应变进行了量化。
在传统2棒结构上增加副棒，在所有三种加载方式下，对于Ti材料都提高了重建的生物力学稳定性（P < 0.05）。副CoCr棒在屈伸和轴向旋转时提高了稳定性（P < 0.05）。在Ti或CoCr重建中增加副棒并没有显著降低棒材应变（P < 0.05）。CoCr 2棒和4棒比Ti 2棒和4棒表现出的应变更小。
附于传统2棒结构上的补充副棒显著提高了钛合金和CoCr合金材料的稳定性。在屈伸、侧屈和轴向旋转方面，4.0毫米CoCr棒比3.5毫米Ti棒提供了更高的稳定性。虽然增加副棒并没有显著降低棒材应变，但与Ti棒相比，CoCr棒治疗组的棒材应变有所降低。
