颈椎后纵韧带骨化手术治疗预后相关因素分析

钟卓霖 胡建华

（1.浙江大学医学院附属第四医院骨科，浙江 义乌322000；2.中国医学科学院北京协和医学院北京协和医院骨科，北京 100730）

颈椎后纵韧带骨化（ossification of the posterior longitudinal ligament,OPLL）于1838年被首次介绍[1],直至19世纪60年代由Tsukimoto[2]研究报道后才被广泛认可。OPLL是骨在后纵韧带中异化形成的一种病理状态，其可以逐步导致脊髓受压，是导致患者发生颈椎脊髓病变的常见原因，文献报道颈椎OPLL的发病率为1.9%～4.3%[3,4]。日本学者根据颈椎平片上OPLL形态学特点将其分成4种类型：节段型、连续型、混合型以及局灶型[5]。治疗上，颈椎OPLL的治疗包括保守治疗及手术治疗，前者包括密切随访、物理治疗及口服止痛药物等；后者包括前路减压融合术、后路单开门成形术以及后路椎板切除术等。

临床上，对于无症状的颈椎OPLL患者，并不提倡手术治疗，手术只适用于已经发生脊髓病变的患者，其方式通常包括前路手术及后路手术。颈椎OPLL患者术后疗效及并发症发生率不尽相同，本文即对颈椎OPLL手术治疗的预后相关因素做简要阐述。

1 K线

K线，于2008年被首次提出，是指颈椎侧位平片上C2至C7椎管中点的连线，它同时反映出颈椎曲度与后纵韧带骨化厚度两个参数；OPLL未越过K线时称为K线（+），反之为K线（-）[6]。Fujiyoshi等[6]报道，在接受颈后路减压术后，K线（-）组患者的治愈率为13.9%，而K线（+）组的为66.1%，后者的预后明显优于前者，其原因是K线（-）组患者术后脊髓不能完全漂移以获得充分减压。Koda等[7]研究报道，对于K线（-）OPLL患者而言，相对于颈后路，颈前路减压融合术更适合。Takeuchi等[8]对K线的临床意义进行进一步研究，发现术后K线（-）组患者的治愈率明显低于K线（+）组（前者为23.8%，后者为46.3%）。

2 OPLL的椎管占有率

OPLL的椎管占有率是指后纵韧带骨化的最大厚度与相应水平椎管直径的比值。Kato等[9]报道了一项关于545例颈椎OPLL患者行椎板成形术的多中心研究结果，发现OPLL患者椎板成形术后发生严重并发症的一个重要因素是术中失血量，而对于椎管占有率＞60%的患者其术中失血量明显升高，可能由骨化组织压迫硬膜外椎静脉丛，使静脉压力增加，从而导致术中静脉出血增加引起。多数学者[10-12]认为，当椎管占有率＞50%，尤其是＞60%时，接受颈后路椎板成形术的患者预后较差。

3 颈椎曲度

Ogawa等[13]报道，术前颈椎曲度后凸OPLL患者在接受颈后路椎板成形术治疗后预后较差，原因是颈后路椎板成形术对于此类患者不能实现充分减压。Yoshii等[14]报道，对于椎管占有率＞50%的颈椎OPLL患者，前路减压融合术与后路减压融合术在术后治愈率上无显著差异，但对于合并颈椎后凸的此类患者，在神经功能改善程度上，前者会比后者更胜一筹。

4 硬膜骨化

硬膜骨化于1997年首次被提出[15]，其被认为是颈椎OPLL的一种重要影像学征象，对手术方式的选择及术后患者的预后具有重大影响。当硬膜骨化时，颈前路术中分离后纵韧带和硬膜时将会变得非常困难，术中更容易发生硬膜外出血及脑脊液漏[16,17]。对于合并硬膜骨化的OPLL患者，选择前路减压融合术术后发生脑脊液漏的概率高，虽然大多数发生脑脊液漏的患者经过保守治疗后能痊愈，但这仍会显著延长患者住院时间且会增加感染的风险[16,18]。此外，脑脊液漏也可能继发脑膜炎、伤口延迟愈合、气管堵塞以及假性脑膜膨出等并发症[19]。

5 后纵韧带骨化形态

依据颈椎侧位片上后纵韧带骨化的形态，可以把OPLL分为平坦型和山丘型，对于平坦型的OPLL患者而言，颈后路椎板成形术是一种有效而又安全的手术方式；而对于山丘型的OPLL患者而言，椎板成形术的治疗效果较差，其原因是山丘型的后纵韧带骨化在局部锐性挤压脊髓，影响脊髓功能，在日本骨科协会（Japanese Orthopedic Association,JOA）评分上，山丘型明显低于平坦型[19,20]。

6 脊髓信号改变

颈椎OPLL患者手术预后与术前颈椎核磁（magnetic resonance,MR）图像上脊髓信号的改变也有密切关系，这与既往脊髓型颈椎病合并脊髓信号改变与手术预后关系的研究结果相似[21,22]。Ito等[22]根据MR T2序列上脊髓信号的特点将脊髓变性分为3级：1级，轻度，信号没有任何改变；2级，中度，信号模糊改变；3级，重度，信号明显改变。随访119例患者后发现，术前脊髓信号改变与手术的预后密切相关，脊髓信号级别越高，预后越差[22]。也有研究[23]报道，术前颈椎MR T1序列图像上信号降低也是术后预后较差的因素之一。

7 合并外伤

OPLL合并脊髓损伤（spinal cord injury,SCI）在临床中也常见，文献[24,25]报道在SCI患者中，合并OPLL的发生率达38%。Soon等[26]报道，OPLL合并SCI的患者手术预后与术前MR T2图像上脊髓信号改变、脊髓受压的严重程度及患者神经功能状态密切相关；术前MR T2像上脊髓信号改变越明显，脊髓受压越严重，或术前神经功能越差，患者的预后越差。

8 手术方式

手术是有症状的颈椎OPLL患者的主要治疗方式，主要包括颈前路手术、颈后路手术以及后前路联合手术。前路减压手术能获得更好的减压效果，尤其对于脊髓明显受压的患者，但是对于某些此类患者而言，脊髓受压越严重也就意味着在行前路手术时脊髓受损害的风险越高，术后预后反而较差[19]。前路手术主要包括椎体次全切除合并融合术、椎间盘切除合并融合术，以及漂浮减压术；后路手术是间接减压，手术技术上比较容易达到，该术式主要包含椎板成形术、椎板切除术及椎板切除合并融合术；也有学者建议对于少数颈椎OPLL患者可以选择后前路联合手术[14,27-29]。选择不同的手术方式，患者的预后会有不同。技术上，因前路手术是直接减压神经，术中容易发生脊髓损伤和脑脊液漏，尤其对于合并硬膜骨化的患者，且相比较而言，颈前路通常需要更长的手术时间；而后路手术是间接减压，相对而言发生脊髓神经损伤的风险较小，但是术中容易出血，尤其是当椎管占有率＞60%时，术中出血明显增加，术后并发症风险显著上升[9,10,14,19]。Kim等[11]报道，对于OPLL椎管占有率≥60%或MR提示脊髓信号改变的颈椎OPLL患者，颈椎前路减压融合术的手术治疗效果要优于颈后路椎板成形术。Liu等[30]比较颈后路椎板扩大成形术与椎板切除内固定融合术治疗颈椎曲度偏直（C2-7的Cobb角介于0°～10°）的OPLL患者的治疗效果，结果表明，相对于颈后路椎板切除内固定融合术，颈后路椎板扩大成形术在术后神经功能恢复及颈部功能改善方面更具优势，疼痛评分及术后轴性疼痛也较低。鉴于前后路手术各自的优缺点，有学者提出后前路联合治疗复杂的颈椎OPLL患者。Lee等[27]提出540°颈椎组合术式治疗颈椎广泛OPLL伴颈椎后突患者，该术式一期行后路椎板切除及小关节松解+螺钉固定术，二期行前路椎间盘切除融合+后路内固定融合术，术后JOA评分由术前8.2分提高到14.8分，OPLL椎管占有率从73.5%降到38.4%。此外，荟萃分析[4]报道，行颈后路单开门减压的颈椎OPLL患者，OPLL影像学上进展率明显高于颈椎减压融合术组（前者为62.5%，后者为7.6%）。

9 其他

此外，颈椎OPLL手术治疗的预后与患者年龄也密切相关，年龄越大，预后差的可能性越大，其原因是滋养脊髓的血管在老年患者中易发生动脉粥样硬化，这使脊髓在应激条件下容易发生缺血，不利于术后脊髓神经功能的恢复[26]；术前患者症状持续时间长、合并糖尿病史、JOA评分低都是患者术后恢复较差的预测因素[23,31,32]。

尽管颈椎OPLL已被临床医师所熟知，但目前仍有较多问题需要进一步研究。手术是颈椎OPLL患者的主要治疗方式，如何根据患者不同的临床特点及不同的影像学特征选择合适的手术方式需要每一位脊柱外科医师思考，在以后的临床治疗中，需要更多的长期随访研究为临床决策提供参考依据。

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