Department of Physical Therapy, Asia University, Taichung, Taiwan.
Department of Orthopedics, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Orthopedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Comput Biol Med. 2021 Dec;139:105036. doi: 10.1016/j.compbiomed.2021.105036. Epub 2021 Nov 14.
Porous interbody cages, manufactured using additive laser melting technology, have recently been used in lumbar fusion surgery. The major advantage of a porous cage is the presence of space inside the cage for bone ingrowth. However, the biomechanical effects of different porosities on the lumbar segment with and without bone fusion (ingrowth) are still unclear. Hence, the present study aimed to compare the biomechanical responses, including the stress and range of motion (ROM) of the lumbar L3-L4 segments with three different types of porous cages along with a posterior instrument (PI) with and without bone fusion using computer simulation. A lumbar L3-L4 segment model with a PI and porous cages was used in this study. Three different porosities, namely 12.5, 41.2, and 80.84% were used. The diameter of the pores of the porous cage was uniformly set to 0.5 mm. In addition, a traditional PEEK cage was used in this study. Two different bone statuses, with and without bone fusion (ingrowth into the pores of the porous cage and the inner space of the PEEK cage), were considered. The results indicated that although the contact pressure on the bone surface reduced, the cage stress increased with increasing cage porosity. Furthermore, cage stress and contact pressure also increased in cases with bone fusion compared with those without bone fusion. The contact pressure on the bone surface with a cage porosity of 80.8% decreased by 40% (from 943.1 to 575.5 MPa), 37.7% (from 133 to 82.9 MPa), 40.4% (from 690.8 to 412 MPa), and 34.2% (from 533 to 351.1 MPa), respectively, for flexion, extension, lateral bending, and rotation, respectively, compared with that with a cage porosity of 12.5%. The rotational ROM of the PEEK cage with bone fusion was clearly larger than those of the porous cages. Porous cages have recently become popular owing to improved manufacturing technology. This study provides scientific data on the strength and weakness of porous cages with different porosities for clinical use.
采用增材激光熔融技术制造的多孔椎间融合器最近已应用于腰椎融合手术中。多孔融合器的主要优点是融合器内部存在允许骨长入的空间。然而，不同孔隙率对有骨融合（长入）和无骨融合的腰椎节段的生物力学影响仍不清楚。因此，本研究旨在通过计算机模拟比较三种不同孔隙率的多孔融合器和后路内固定器（PI）在有和无骨融合时的生物力学响应，包括腰椎 L3-L4 节段的应力和活动范围（ROM）。本研究使用了带 PI 和多孔融合器的腰椎 L3-L4 节段模型。使用了三种不同的孔隙率，分别为 12.5%、41.2%和 80.84%。多孔融合器的孔直径均匀设置为 0.5mm。此外，本研究还使用了传统的 PEEK 融合器。考虑了两种不同的骨状态，有和无骨融合（骨长入多孔融合器的孔隙和 PEEK 融合器的内部空间）。结果表明，尽管骨表面的接触压力降低，但随着融合器孔隙率的增加，融合器的应力增加。此外，与无骨融合相比，有骨融合时融合器的应力和接触压力也增加。孔隙率为 80.8%的融合器的骨表面接触压力分别降低了 40%（从 943.1 降至 575.5 MPa）、37.7%（从 133 降至 82.9 MPa）、40.4%（从 690.8 降至 412 MPa）和 34.2%（从 533 降至 351.1 MPa），分别在屈伸、侧屈和旋转时。与孔隙率为 12.5%的融合器相比，PEEK 融合器的骨融合旋转 ROM 明显更大。由于制造技术的改进，多孔融合器最近变得流行。本研究为临床应用中不同孔隙率多孔融合器的强度和弱点提供了科学数据。
