Departments of Neurological Surgery and.
J Neurosurg Spine. 2013 Oct;19(4):454-63. doi: 10.3171/2013.6.SPINE12282. Epub 2013 Aug 23.
The paracoccygeal approach allows for instrumentation of L5/S1 and L4/5 by using a transsacral rod (AxiaLIF; TransS1, Inc.). The authors analyzed clinical and radiographic outcomes of 1- or 2-level AxiaLIF procedures with focus on durability of the construct.
This was a retrospective study of 38 consecutive patients who underwent either 1-level (32 patients) or 2-level (6 patients) AxiaLIF procedures at the authors' institution. The Oswestry Disability Index (minimum clinically important difference [MCID] ≥ 12) and visual analog scale ([VAS]; MCID ≥ 3) scores were collected. Disc height and Cobb angles were measured on pre- and postoperative radiographs. Bony fusion was determined on CT scans or flexion/extension radiographs.
Implantation of a transsacral rod allowed for intraoperative distraction of the L5/S1 intervertebral space and resulted in increased segmental lordosis postoperatively. At a mean follow-up time of 26.2 ± 2.4 months, however, graft subsidence (1.9 mm) abolished partial correction of segmental lordosis. Moreover, subsidence of the construct reduced L5/S1 lordosis in patients with 1-level AxiaLIF by 3.2° and L4-S1 lordosis in patients with 2-level procedures by 10.1° compared with preoperative values (p < 0.01). Loss of segmental lordosis predicted failure to improve VAS scores for back pain in the patient cohort (p < 0.05). Overall, surgical intervention led to modest symptomatic improvement; only 26.3% of patients achieved an MCID of the Oswestry Disability Index and 50% of patients an MCID of the VAS score for back pain. At last follow-up, 71.9% of L5/S1 levels demonstrated bony fusion (1-level AxiaLIF 80.8%, 2-level AxiaLIF 33.3%; p < 0.05), whereas none of the L4/5 levels in 2-level AxiaLIF fused. Five constructs developed pseudarthrosis and required surgical revision.
The AxiaLIF procedure constitutes a minimally invasive technique for L5/S1 instrumentation, with low perioperative morbidity. However, the axial rod provides inadequate long-term anterior column support, which leads to subsidence and loss of segmental lordosis. Modification of the transsacral technique to allow for placement of a solid interposition graft may counteract subsidence of the construct.
经骶骨入路可通过使用经骶骨棒（AxiaLIF；TransS1，Inc.）对 L5/S1 和 L4/5 进行器械操作。作者分析了经作者所在机构进行的 1 或 2 个节段 AxiaLIF 手术的临床和影像学结果，重点关注了该结构的耐久性。
这是一项回顾性研究，纳入了在作者所在机构接受 1 个节段（32 例患者）或 2 个节段（6 例患者）AxiaLIF 手术的 38 例连续患者。收集了 Oswestry 残疾指数（最小临床重要差异 [MCID]≥12）和视觉模拟量表（[VAS]；MCID≥3）评分。在术前和术后的影像学上测量椎间盘高度和 Cobb 角。通过 CT 扫描或屈伸位 X 线片确定骨融合情况。
经骶骨棒的植入允许术中 L5/S1 椎间盘的牵开，并导致术后节段前凸增加。然而，在平均 26.2±2.4 个月的随访时，移植物沉降（1.9mm）消除了节段前凸的部分矫正。此外，在接受 1 个节段 AxiaLIF 的患者中，结构沉降使 L5/S1 前凸减少了 3.2°，在接受 2 个节段手术的患者中 L4-S1 前凸减少了 10.1°，与术前相比（p<0.01）。节段前凸的丧失预测了患者队列中 VAS 腰痛评分改善失败（p<0.05）。总体而言，手术干预导致症状适度改善；只有 26.3%的患者 Oswestry 残疾指数达到 MCID，50%的患者 VAS 腰痛评分达到 MCID。末次随访时，71.9%的 L5/S1 水平显示骨融合（1 个节段 AxiaLIF 为 80.8%，2 个节段 AxiaLIF 为 33.3%；p<0.05），而 2 个节段 AxiaLIF 中没有 L4/5 水平融合。5 个结构发生假关节形成，需要手术修正。
AxiaLIF 手术是一种用于 L5/S1 器械操作的微创技术，围手术期发病率低。然而，轴向杆提供了不足够的长期前柱支撑，导致沉降和节段前凸丧失。对经骶骨技术的修改以允许放置实心间置物可能会抵消结构的沉降。
