Institute of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi Province, PR China.
J Surg Res. 2012 Mar;173(1):91-8. doi: 10.1016/j.jss.2010.09.009. Epub 2010 Oct 19.
The incidence of screw loosening increases significantly in elderly patients with severe osteoporosis. Open vertebral cement augmentation of expandable pedicle screw fixation may improve fixation strength in the osteoporotic vertebrae.
Twenty cadaveric vertebrae (L1-L5) were harvested from six osteoporotic lumbar spines. Axial pullout tests were performed to compare the maximum pullout strength (Fmax) of four methods: 1. Conventional pedicle screws (CPS), 2. Expandable pedicle screws (EPS), 3. Cement augmentation of CPS (cemented-CPS), 4. Cement augmentation of EPS (cemented-EPS). Thirty-six consecutive patients with single-vertebral osteoporotic compressive fractures received posterior decompression and spinal fusion with cemented-CPS (16 cases) or cemented-EPS (20 cases). Plain film and/or CT scan were conducted to evaluate the spinal fusion and fixation effectiveness.
The Fmax and energy absorption of cemented-EPS were significantly greater than three control groups. The mean BMD in the severe osteoporosis group was significantly lower than that in the osteoporosis group (t = 2.04, P = 0.036). In the osteoporosis group, cemented-EPS improved the Fmax by 43% and 21% over CPS and cemented-CPS group. In the severe osteoporosis group, cemented-EPS increased the Fmax by 59%, 22%, and 26% over CPS, EPS, and cemented-CPS, respectively. The clinical results showed that all patients suffered from severe osteoporosis. Six months after operation, the JOA and VAS scores in cemented-EPS group improved from 11.4 ± 2.6 and 7.0 ± 1.4 mm to 24.9 ± 1.6 and 2.1 ± 1.3 mm, respectively. No screw loosening occurred in the cemented-EPS group and spinal fusion was achieved. In the cemented-CPS group, four screws loosened (4.2%) according to the radiolucency. Six months after operation, the JOA and VAS scores improved from 13.1 ± 1.9 and 7.6 ± 1.5 mm to 22.8 ± 2.2 and 2.5 ± 1.6 mm, respectively. No cement leaked into the spinal canal in both groups.
Cemented-EPS could increase fixation strength biomechanically. It could reduce the risks of screw loosening in patients with severe osteoporosis, requiring instrumented arthrodesis.
在严重骨质疏松的老年患者中，螺钉松动的发生率显著增加。经皮可扩张椎弓根螺钉固定后行椎体骨水泥强化可能会提高骨质疏松椎体的固定强度。
从 6 个骨质疏松性腰椎中取出 20 个节段（L1-L5）的尸体椎体。进行轴向拔出试验，比较 4 种方法的最大拔出强度（Fmax）：1. 常规椎弓根螺钉（CPS），2. 可扩张椎弓根螺钉（EPS），3. CPS 骨水泥强化（骨水泥强化-CPS），4. EPS 骨水泥强化（骨水泥强化-EPS）。36 例连续的单椎体骨质疏松性压缩性骨折患者接受后路减压和骨水泥强化-CPS（16 例）或骨水泥强化-EPS（20 例）融合术。对 36 例患者行 X 线平片和/或 CT 扫描，评估脊柱融合和固定效果。
骨水泥强化-EPS 的 Fmax 和能量吸收明显大于 3 个对照组。严重骨质疏松组的平均骨密度明显低于骨质疏松组（t=2.04，P=0.036）。在骨质疏松组中，骨水泥强化-EPS 使 Fmax 分别比 CPS 和骨水泥强化-CPS 组提高了 43%和 21%。在严重骨质疏松组中，骨水泥强化-EPS 分别使 Fmax 比 CPS、EPS 和骨水泥强化-CPS 组提高了 59%、22%和 26%。临床结果显示，所有患者均患有严重骨质疏松症。术后 6 个月，骨水泥强化-EPS 组的 JOA 和 VAS 评分从 11.4±2.6 和 7.0±1.4mm 分别改善至 24.9±1.6 和 2.1±1.3mm。骨水泥强化-EPS 组无螺钉松动，脊柱融合成功。骨水泥强化-CPS 组有 4 枚螺钉松动（4.2%），根据透亮线。术后 6 个月，骨水泥强化-CPS 组的 JOA 和 VAS 评分分别从 13.1±1.9 和 7.6±1.5mm 改善至 22.8±2.2 和 2.5±1.6mm。两组均无骨水泥漏入椎管。
骨水泥强化-EPS 可在生物力学上增加固定强度。对于需要器械融合的严重骨质疏松症患者，它可以降低螺钉松动的风险。
