Uei Hiroshi, Tokuhashi Yasuaki, Maseda Masafumi, Nakahashi Masahiro, Sawada Hirokatsu, Matsumoto Koji, Miyakata Hiroyuki
Department of Orthopaedic Surgery, Nihon University School of Medicine, 30-1 Oyaguchi Kami-cho, Itabashi-ku, Tokyo, 173-8610, Japan.
J Orthop Surg Res. 2018 Oct 12;13(1):252. doi: 10.1186/s13018-018-0960-5.
Proximal junctional kyphosis (PJK) following adult spinal deformity (ASD) surgery in elderly patients is markedly influenced by osteoporosis causing additional vertebral fracture and loosening of pedicle screws (PS). This study aimed to investigate the association between mean bone density represented in Hounsfield units (HU) on spinal computed tomography (CT) and revision surgery for PJK or postoperative additional vertebral fracture following ASD surgery in elderly patients.
The subjects were 54 ASD patients aged 65 years or older who were treated with correction and fusion surgery of four or more levels and could be followed for 2 years or longer. Bone density was measured before surgery using lumbar dual-energy X-ray absorptiometry (DXA) and spinal CT in all patients. The patients were divided into group A (n = 14) in which revision surgery was required for PJK or additional vertebral fracture and group B (n = 40) in which revision surgery was not required. We retrospectively investigated incidences of PJK, additional vertebral fracture, and PS loosening, perioperative parameters, radiographic parameters before and after surgery, and osteoporosis treatment administration rate.
No significant difference was noted in young adult mean (YAM) on DXA between groups A and B, respectively (P = 0.62), but the mean bone densities represented in HU of the T8 (P = 0.002) and T9 (P = 0.01) vertebral bodies on spinal CT were significantly lower in group A, whereas those of the L4 (P = 0.002) and L5 (P = 0.01) vertebral bodies were significantly higher in group A. The incidence of PJK was not significantly different (P = 0.07), but the incidence of additional vertebral fracture was significantly higher in group A (P < 0.001). The incidences of uppermost PS loosening within 3 months after surgery were 71% and 40% in groups A and B, respectively (P = 0.04).
In elderly patients who required revision surgery, the mean bone densities of vertebral bodies at T8 and T9 were significantly lower. The mean bone density represented in HU on spinal CT may be useful for risk assessment of and countermeasures against revision surgery after ASD surgery in elderly patients.
老年患者成人脊柱畸形（ASD）手术后的近端交界性后凸（PJK）受骨质疏松的影响显著，可导致额外的椎体骨折和椎弓根螺钉（PS）松动。本研究旨在调查老年患者ASD手术后，脊柱计算机断层扫描（CT）上以亨氏单位（HU）表示的平均骨密度与PJK翻修手术或术后额外椎体骨折之间的关联。
研究对象为54例65岁及以上接受四级或以上矫正融合手术且随访时间达2年或更长时间的ASD患者。所有患者术前均采用腰椎双能X线吸收法（DXA）和脊柱CT测量骨密度。患者分为因PJK或额外椎体骨折需要翻修手术的A组（n = 14）和不需要翻修手术的B组（n = 40）。我们回顾性调查了PJK、额外椎体骨折和PS松动的发生率、围手术期参数、手术前后的影像学参数以及骨质疏松治疗给药率。
A组和B组的DXA测量的青年成人平均值（YAM）分别无显著差异（P = 0.62），但A组脊柱CT上T8椎体（P = 0.002）和T9椎体（P = 0.01）的平均骨密度（以HU表示）显著较低，而A组L4椎体（P = 0.002）和L5椎体（P = 0.01）的平均骨密度显著较高。PJK的发生率无显著差异（P = 0.07），但A组额外椎体骨折的发生率显著更高（P < 0.001）。术后3个月内最上方PS松动的发生率在A组和B组分别为71% 和40%（P = 0.04）。
在需要翻修手术的老年患者中，T8和T9椎体的平均骨密度显著较低。脊柱CT上以HU表示的平均骨密度可能有助于评估老年患者ASD手术后翻修手术的风险并采取相应对策。
