中线腰椎融合技术在老年退行性腰椎疾病应用的早期临床疗效及置钉注意事项

Early clinical outcome of midline lumbar fusion in the treatment of senile lumbar degeneration and precautions for screw placements

中文关键词:  皮质骨轨迹螺钉  中线腰椎融合术  腰椎融合术

英文关键词:Cortical bone trajectory  Midline lumbar fusion  Lumbar spine  Fusion

中文摘要:

  【摘要】 目的：探讨中线腰椎融合技术（midline lumbar fusion，MIDLF）治疗老年退行性腰椎疾病的效果、安全性及皮质骨轨迹（cortical bone trajectory，CBT）螺钉固定技术置钉注意事项。方法：回顾性分析我院2018年4月~9月收治的采用MIDLF治疗老年退行性腰椎疾病患者16例，男性8例，女性8例。年龄 58～81岁，平均68.7±7.7岁。手术节段均为L4/5。术中均应用CBT螺钉固定技术。入钉点的选择参考上位节段的下关节突最尖端下移约5mm（a值）与峡部最窄处内移约4mm（b值）的交点，记录手术时间、术中出血量、手术并发症等。应用视觉模拟评分法（visual analogue scale，VAS）记录术前和末次随访时腰腿痛情况，应用腰椎JOA评估患者手术后功能改善情况，所有患者出院前及术后12个月均行腰椎CT扫描。通过Rao分级标准评价置钉准确性，置钉优良率=置钉优良数/总置钉数×100%。在术后出院前CT测量螺钉的外倾角、尾倾角、a值和b值。对未突破皮质组与突破皮质组上述4个参数进行比较。结果：手术时间平均174.3±27.9min（133~232min），术中出血量平均69.3±36.7ml（30~150ml），术后总引流量平均147.5±95.2ml（20~315ml），术后住院天数平均2.5±0.8d（2~4d）。术后随访时间平均15.1±2.0个月（12~20个月）。术后1例患者出现足下垂和血肿，有5枚CBT改为椎弓根螺钉固定。其他患者无术中和术后并发症。术前VAS腰痛评分4.5±1.7分，末次随访时为1.1±0.5分，差异有统计学意义（t=7.013，P<0.001）；术前VAS腿痛评分5.6±1.0分，末次随访时为1.1±0.9分，差异有统计学意义（t=13.006，P<0.001）；术前腰椎JOA评分15.7±2.4分，末次随访时为23.9±2.1分，差异有统计学意义（t=-16.364，P=0.000）。参考术后出院前CT进行Rao分级：0级46枚，1级4枚，2级3枚，3级6枚。置钉的优良率为84.7%（50/59），突破皮质骨的螺钉有13枚（13/59，22%），其中突破椎弓根内壁的3枚，突破椎体的10枚。未突破皮质骨组与突破皮质骨组比较分析显示螺钉外倾角有显著性差异（11.0°±3.7° vs 14.9°±3.8°，P=0.002），而尾倾角（15.0°±8.4° vs 16.9°±9.2°，P=0.502）、a值（5.6°±1.2° vs 5.7°±1.4°，P=0.687）、b值（4.1°±1.0° vs 4.4°±1.6°，P=0.459）未见显著性差异。结论：MIDLF技术应用于老年退行性腰椎疾病患者时，创伤小，可获得良好的手术效果，入钉点的选择参考上位节段的下关节突最尖端下移5.6~5.7mm（a值）与峡部最窄处内移4.1~4.4mm（b值）的交点，但是CBT螺钉置钉的容错率低，置钉技术要求高，置钉时螺钉外倾不要过大，角度11°为宜。

英文摘要:

  【Abstract】 Objectives: To explore the potential advantages of midline lumbar fusion(MIDLF) in the patients with lumbar disc herniation and discuss the safety and precautions of cortical bone trajectory(CBT) screw fixation technique. Methods: A retrospective analysis was made of 16 patients with senile lumbar degeneration treated with MIDLF from April to September 2018, including 8 males and 8 females. The age ranged from 58 to 81 years, with an average of 68.7±7.7 years. All patients were operated L4/5. CBT screw fixation technique was used in all operations. The selection of the insertion point refers to the intersection of about 5mm (a value) below the lowest tip of the inferior articular process of the upper vertebra and about 4mm (b value) inward from the narrowest point of the isthmus. The operation time, intraoperative blood loss and complications were recorded. Visual analog scale(VAS) was used to evaluate the low back pain and leg pain. JOA was used to assess the functional outcome of patients before and after operation. All patients were scanned using CT before and 12 months after discharge. The accuracy of screw placement was evaluated by Rao classification criteria. Excellent rate of screw placement = number of excellent screws/total number of screws × 100%. The lateral angle, caudal angle, a value and b value of the screws were measured by CT before discharge. The four parameters mentioned above were compared between the no perforation group and the perforation group. Results: The average operation time was 174.3±27.9min (133-232min), the average intraoperative blood loss was 69.3±36.7ml(30-150ml), the average postoperative total drainage volume was 147.5±95.2ml (20-315ml), and the average postoperative hospital days were 2.5±0.8 days(2-4 days). The average follow-up time was 15.1±2.0months(12-20 months). One patient developed foot drop and hematoma, and 5 CBTs were fixed with pedicle screws. No complications occurred in other patients. The VAS score of low back pain before surgery was 4.5±1.7 and at the final follow-up was 1.1±0.5, with significant lystatistical difference(t=7.013, P<0.001); the VAS scoreof leg pain before surgery was 5.6±1.0 and at the final follow-up was 1.1±0.9, the difference was statistically significant(t=13.006, P<0.001). The JOA score was 15.7±2.4 preoperative and 23.9±2.1 at the final follow-up, the difference was statistically significant (t=-16.364, P=0.000). According to the postoperative CT before discharge, the Rao classification was performed: 46 screws in grade 0, 4 screws in grade 1, 3 screws in grade 2, 6 screws in grade 3. The excellent rate of screw placement was 84.7%(50/59). Thirteen screws(13/59, 22%) perforatedthe cortical bone, including 3 cases perforated the inner wall of pedicle and 10 cases perforated the vertebrate. There were significant differences in lateral angle(11.0°±3.7° vs 14.9°±3.8°, P=0.002) between the no perforation group and the perforation group, and no significant differences were found in caudal angle (15.0°±8.4° vs 16.9°±9.2°, P=0.502), a value(5.6°±1.2° vs 5.7°±1.4°, P=0.687) and b value (4.1°±1.0° vs 4.4°±1.6°, P=0.459). Conclusions: MIDLF is an effective technique for lumbar spine surgery. The selection of the insertion point should refer to the intersection point of 5.6-5.7mm (a value) below the most tip of the inferior articular process of the upper segment and 4.1-4.4mm (b value) moving inward from the narrowest point of the isthmus. CBT screw insertion has low error tolerance and therefore it′s highly technical demanding. During screws placement, the inclination of the screws should not be too largeandthe lateral angle of 11° is suggested.