Takeoka Yoshiki, Yurube Takashi, Maeno Koichiro, Kanda Yutaro, Tsujimoto Ryu, Miyazaki Kunihiko, Kakiuchi Yuji, Miyazaki Shingo, Zhang Zhongying, Takada Toru, Nishida Kotaro, Doita Minoru, Kuroda Ryosuke, Kakutani Kenichiro
Department of Orthopaedic Surgery Kobe University Graduate School of Medicine Kobe Japan.
Maeno Orthopaedic Clinic Himeji Japan.
JOR Spine. 2020 Feb 3;3(1):e1080. doi: 10.1002/jsp2.1080. eCollection 2020 Mar.
Laminoplasty using hydroxyapatite (HA) spacers is widely performed in patients with cervical myelopathy. However, spacer dislocation is a critical complication caused by bone absorption and inadequate bone conductivity, and can result in dural damage and restenosis. We thus designed a prospective cohort study to clarify the feasibility of increased porosity HA spacers for double-door laminoplasty by analyzing computed tomography (CT) images. Forty-seven patients underwent cervical laminoplasty. Two different types of CERATITE HA spacer were used, either high porosity (50%) or low porosity (35%). These HA spacers were placed in an alternating manner into the laminae in each patient. In total, 85 high-porosity (50%) HA spacers and 84 low-porosity (35%) HA spacers were implanted. At postoperative 2 weeks, 3 months, 6 months, and 1 year, CT images were obtained. In both groups, the percentage of bone-bonding boundary area of the HA spacer in contact with laminae and bone volume of the spinous process relative to the 2-week value were calculated by a 3D and 2D CT-image pixel analysis. The bone-bonding ratio was significantly higher in high-porosity (50%) than low-porosity (35%) HA spacers at 3 months and thereafter (1 year, 69.3 ± 27.8% and 49.7 ± 32.9% respectively, < .01). The bone volume in both groups significantly decreased with time (1 year, 73.2 ± 29.8% and 69.0 ± 30.4% respectively, < .01), indicating bone absorption. This showed no significant difference between the HA spacers ( = .15) but was higher in high-porosity (50%) than low-porosity (35%) HA spacers throughout the study period. Meanwhile, spacer breakage was found in 4.7% of high-porosity (50%) HA spacers and 1.2% of low-porosity (35%) HA spacers ( = .37). In summary, high-porosity (50%) HA spacers have the advantages of accelerated bone bonding and relatively decelerated bone absorption compared to low-porosity (35%) HA spacers; however, possibly more frequent breakage of HA spacers with a high porosity (50%) requires careful, extended postoperative follow-up.
使用羟基磷灰石（HA）间隔器进行的椎板成形术在脊髓型颈椎病患者中广泛应用。然而，间隔器移位是一种由骨吸收和骨传导性不足引起的严重并发症，可导致硬脊膜损伤和再狭窄。因此，我们设计了一项前瞻性队列研究，通过分析计算机断层扫描（CT）图像来阐明增加孔隙率的HA间隔器用于双开门椎板成形术的可行性。47例患者接受了颈椎椎板成形术。使用了两种不同类型的CERATITE HA间隔器，即高孔隙率（50%）或低孔隙率（35%）。这些HA间隔器在每位患者的椎板中交替放置。总共植入了85个高孔隙率（50%）的HA间隔器和84个低孔隙率（35%）的HA间隔器。在术后2周、3个月、6个月和1年时获取CT图像。在两组中，通过三维和二维CT图像像素分析计算HA间隔器与椎板接触的骨结合边界面积百分比以及棘突的骨体积相对于2周时的值。在3个月及之后（1年时，分别为69.3±27.8%和49.7±32.9%，P<0.01），高孔隙率（50%）HA间隔器的骨结合率显著高于低孔隙率（35%）HA间隔器。两组的骨体积均随时间显著减少（1年时，分别为73.2±29.8%和69.0±30.4%，P<0.01），表明存在骨吸收。这在HA间隔器之间无显著差异（P = 0.15），但在整个研究期间，高孔隙率（50%）HA间隔器的骨体积高于低孔隙率（35%）HA间隔器。同时，在4.7%的高孔隙率（50%）HA间隔器和1.2%的低孔隙率（35%）HA间隔器中发现间隔器断裂（P = 0.37）。总之，与低孔隙率（35%）HA间隔器相比，高孔隙率（50%）HA间隔器具有加速骨结合和相对减缓骨吸收的优点；然而，高孔隙率（50%）HA间隔器可能更频繁的断裂需要仔细、延长的术后随访。
