Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.
Neurosurg Focus. 2011 Oct;31(4):E9. doi: 10.3171/2011.7.FOCUS11125.
The long-term outcome of lumbar dynamic stabilization is uncertain. This study aimed to investigate the incidence, risk factors, and outcomes associated with screw loosening in a dynamic stabilization system.
The authors conducted a retrospective review of medical records, radiological studies, and clinical evaluations obtained in consecutive patients who underwent 1- or 2-level lumbar dynamic stabilization and were followed up for more than 24 months. Loosening of screws was determined on radiography and CT scanning. Radiographic and standardized clinical outcomes, including the visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, were analyzed with a focus on cases in which screw loosening occurred.
The authors analyzed 658 screws in 126 patients, including 54 women (42.9%) and 72 men (57.1%) (mean age 60.4 ± 11.8 years). During the mean clinical follow-up period of 37.0 ± 7.1 months, 31 screws (4.7%) in 25 patients (19.8%) were shown to have loosened. The mean age of patients with screw loosening was significantly higher than those without loosening (64.8 ± 8.8 vs 59.3 ± 12.2, respectively; p = 0.036). Patients with diabetes mellitus had a significantly higher rate of screw loosening compared with those without diabetes (36.0% vs 15.8%, respectively; p = 0.024). Diabetic patients with well-controlled serum glucose (HbA1c ≤ 8.0%) had a significantly lower chance of screw loosening than those without well-controlled serum glucose (28.6% vs 71.4%, respectively; p = 0.021). Of the 25 patients with screw loosening, 22 cases (88%) were identified within 6.6 months of surgery; 18 patients (72%) had the loosened screws in the inferior portion of the spinal construct, whereas 7 (28%) had screw loosening in the superior portion of the construct. The overall clinical outcomes at 3, 12, and 24 months, measured by VAS for back pain, VAS for leg pain, and ODI scores, were significantly improved after surgery compared with before surgery (all p < 0.05). There were no significant differences between the patients with and without screw loosening at all evaluation time points (all p > 0.05). All 25 patients with screw loosening were asymptomatic, and in 6 (24%) osseous integration was demonstrated on later follow-up. Also, there were 3 broken screws (2.38% in 126 patients or 0.46% in 658 screws). To date, none of these loosened or broken screws have required revision surgery.
Screw loosening in dynamic stabilization systems is not uncommon (4.7% screws in 19.8% patients). Patients of older age or those with diabetes have higher rates of screw loosening. Screw loosening can be asymptomatic and presents opportunity for osseous integration on later follow-up. Although adverse effects on clinical outcomes are rare, longer-term follow-up is required in cases in which screws become loose.
腰椎动态稳定的长期疗效尚不确定。本研究旨在探讨动态稳定系统中螺钉松动的发生率、危险因素和结果。
作者对连续接受 1 或 2 个节段腰椎动态稳定治疗并随访超过 24 个月的患者进行了病历、影像学研究和临床评估的回顾性分析。通过影像学和 CT 扫描确定螺钉松动。分析了与螺钉松动相关的影像学和标准化临床结果，包括视觉模拟评分（VAS）和 Oswestry 残疾指数（ODI）评分，并重点关注发生螺钉松动的病例。
作者共分析了 126 例患者的 658 颗螺钉，其中女性 54 例（42.9%），男性 72 例（57.1%）（平均年龄 60.4±11.8 岁）。在平均 37.0±7.1 个月的临床随访期间，25 例患者（19.8%）的 31 颗螺钉（4.7%）显示松动。螺钉松动患者的平均年龄明显高于无松动患者（64.8±8.8 岁比 59.3±12.2 岁，p=0.036）。合并糖尿病的患者螺钉松动发生率明显高于无糖尿病患者（36.0%比 15.8%，p=0.024）。血糖控制良好（HbA1c≤8.0%）的糖尿病患者螺钉松动的几率明显低于血糖控制不佳的患者（28.6%比 71.4%，p=0.021）。在 25 例螺钉松动的患者中，22 例（88%）在术后 6.6 个月内发现；18 例（72%）在脊柱结构的下部发现松动螺钉，而 7 例（28%）在结构的上部发现螺钉松动。术后 3、12 和 24 个月时，通过 VAS 评估腰痛、VAS 评估腿痛和 ODI 评分，患者的总体临床结果均明显优于术前（均 p<0.05）。在所有评估时间点，松动螺钉与无松动螺钉的患者之间均无显著差异（均 p>0.05）。所有 25 例螺钉松动的患者均无症状，6 例（24%）在后期随访时发现有骨整合。另外，有 3 颗螺钉断裂（126 例患者中有 2.38%，658 颗螺钉中有 0.46%）。迄今为止，这些松动或断裂的螺钉均无需翻修手术。
动态稳定系统中的螺钉松动并不少见（19.8%的患者中有 4.7%的螺钉）。年龄较大或合并糖尿病的患者螺钉松动发生率较高。螺钉松动可能无症状，并在后期随访中出现骨整合的机会。尽管对临床结果的不良影响罕见，但对于螺钉松动的患者需要进行长期随访。
