胸椎黄韧带骨化症合并脊髓型颈椎病手术方案选择

目的 探讨胸椎黄韧带骨化(ossification of ligamentum flavum,OLF)合并脊髓型颈椎病(cervical spondylotic myelopathy,CSM)手术方案的选择.方法 1991年1月至2003年1月,手术治疗胸椎OLF合并CMS患者56例,其中40例获得2年以上随访,男22例,女18例;确诊时年龄27～70岁,平均58岁;病程1～120个月,平均16.5个月.其中OLF 25例,OLF合并后纵韧带骨化(ossification of posterior longitudjnal ligament,OPLL)12例,OLF合并胸椎间盘突出3例;同时合并颈椎OPLL 23例,退变性颈椎管狭窄17例.18例一期行颈后路"单开门"椎板成形术+上胸椎椎管后壁切除术,9例一期行胸椎管后壁切除术,13例分期行颈后路和胸椎管后壁切除术.结果 40例患者的随访时间为24～227个月,平均67.5个月.根据改良Epstein手术疗效评定标准评价优良率,18例一期行颈后路"单开门"椎板成形术+上胸椎椎管后壁切除术者为88.9%(16/18),9例行胸椎管后壁切除术者为66.7%(6/9);13例分期行颈后路和胸椎管后壁切除术者为53.8%(7/13).结果 显示分期手术者术后优良率低于一期手术者,手术间隔时间在1年以内者的优良率高于间隔1年以上者.结论 上胸椎OLF合并CSM者应一期行颈椎和上胸椎脊髓减压术;下肢症状严重而上肢症状轻微者应先行胸脊髓减压术;上、下肢症状均重者应一期或分期行颈脊髓减压术和胸脊髓减压术,而分期手术者的手术间隔时间不宜过长.     

分期治疗颈椎黄韧带骨化合并后纵韧带骨化症

目的回顾性分析分期后前路手术治疗颈椎黄韧带骨化(ossification of ligamentum flavum,OLF)合并后纵韧带骨化(ossification of the posterior longitudinal ligament,OPLL)的临床疗效。方法完整随访手术治疗的颈椎OLF合并OPLL患者18例,一期行后路椎板成形术,术后严密观察6~9个月,一期术后症状改善有限,影像学检查发现前方骨化的韧带压迫脊髓,二期行前路椎体次全切除并切除骨化的韧带+植骨内固定术。术前、一期和二期术后行JOA评分并计算恢复率,测量颈椎前凸值,比较术前、术后颈椎前凸值、JOA评分和恢复率。结果椎板成形术后出现不全瘫痪症状加重者1例,C5神经根麻痹症状1例,脑脊液漏3例;二期前路手术后出现脑脊液漏2例,神经根麻痹2例,保守治疗后痊愈。平均随访时间26.3个月,术前JOA评分(7.2±1.3)分,颈椎前凸值(5.7±4.1)°;一期术后JOA评分(12.6±3.8)分,改善率为(51.6±19.3)%,颈椎前凸值(9.3±3.8)°;二期术后JOA评分(14.8±1.6)分,改善率为(72.7±13.4)%,颈椎前凸值(15.5±3.2)°。JOA评分、改善率以及颈椎前凸值在一期、二期术后与术前相比差异均有统计学意义,P0.05。结论分期后前路手术治疗可明显改善OLF合并OPLL患者术后JOA评分、恢复率和颈椎前凸值,是治疗OLF合并OPLL的一种良好方式。     

颈椎后纵韧带骨化症合并黄韧带骨化的诊断和治疗

目的　深化对颈椎后纵韧带骨化 (OPLL)合并黄韧带骨化 (OLF)的认识。方法　复习并分析 1987年 10月至 1997年10月证实为颈椎OPLL合并OLF ,并经过治疗的 9例影像学及病理学资料。结果　 9例OPLL合并OLF均采用后路椎板成形术治疗并获得显著神经功能恢复。结论　颈椎OPLL合并OLF主要依靠影像学检查进行诊断 ,后路椎板成形手术为治疗此种病症的有效方法。     

"涵洞塌陷法"360°脊髓环形减压术治疗胸椎管狭窄症

目的 探讨"涵洞塌陷法"360°脊髓环形减压术治疗胸椎管狭窄症(thoracic spinal stenosis,TSS)的手术方法和疗效.方法 2005年10月至2009年10月,手术治疗26例TSS患者,男17例,女9例;年龄43～67岁,平均56岁.19例为上胸椎(T1-4)椎管狭窄,其中5例为单纯前方后纵韧带骨化(ossification of posterior longitudinal ligament,OPLL)压迫脊髓,14例为前方OPLL合并脊髓后方黄韧带骨化(ossification of ligamentum flavum,OLF)压迫脊髓;7例为中下胸椎(T5～12)椎管狭窄,均为胸脊髓前、后方同时受压,其中5例为胸椎OLF合并OPLL,2例为胸椎OLF合并胸椎间盘突出.术前Frankel分级:B级6例,C级13例,D级7例.采用"涵洞塌陷法"360°脊髓环形减压术:首先从后路应用椎管后壁切除法,去除脊髓后方压迫;然后切除残留的关节突,沿椎弓根斜向内60°至椎体后壁两侧去除椎体后1/3的松质骨,形成一个"涵洞",分离脊髓硬膜前方与椎体后壁和OPLL的粘连后,压塌"涵洞"壁,取出OPLL块,完成脊髓前方的减压.采用椎弓根钉内固定.结果 除2例患者在术后13～27 d有短暂脊髓功能障碍加重外,余24例均恢复.术后随访时间6～30个月,平均14个月.末次随访时26例患者症状均明显改善,Frankel分级:C级2例,D级15例,E级9例.无一例发生双下肢瘫痪.结论 "涵洞塌陷法"360°脊髓环形减压术从后方一次去除胸脊髓前后方压迫,属于直接减压,术后疗效肯定.     

手术治疗颈椎后纵韧带骨化症的效果及影响因素

目的:探讨手术治疗颈椎后纵韧带骨化症(OPLL)的疗效及其影响因素.方法:2000年4月～2006年4月在我院接受手术治疗并得到随访的颈椎OPLL患者共53例,男性36例,女性17例.术前JOA评分3-12分,平均8.5±3.1分.神经症状出现时间2～81周,平均27.4±15.6周.选择术前压迫最重节段CT层面测量发育椎管面积、骨化韧带面积,计算出脊髓受压比率(骨化韧带面积/发育椎管面积),随访时测量同节段椎管扩大比率.30例采用单纯后路手术,13例行一期前后路手术,4例先行后路再行前路手术,6例单纯行前路减压.利用统计学分析软件SPSS 12.0将脊髓受压比率、术前JOA评分、手术后椎管扩大比率、手术方式选择、患者年龄、神经症状出现时间等因素与手术后JOA评分改善率进行多元相关分析.结果:随访29～101个月,平均46±16个月,术后1年JOA评分改善率为30%～72%,平均53.1%±11.4%,末次随访时JOA评分改善率为28%～68%,平均52.8%±10.5%;脊髓受压比率、术前JOA评分、手术时患者年龄与手术后JOA评分改善率之间存在相关关系,手术入路、症状持续时间、手术后椎管扩大比率与疗效无显著相关关系.结论:选择恰当的术式手术治疗颈椎后纵韧带骨化症可取得较满意的临床效果,脊髓受压严重程度、患者年龄和术前神经功能状态与疗效有相关关系.     

全椎板薄化层揭法治疗胸椎管狭窄症

目的 探讨采用全椎板薄化层揭法治疗由胸椎黄韧带骨化(ossification of ligamentum flavum,OLF)和胸椎后纵韧带骨化(ossification of posterior longimental ligament,OPLL)引起的胸椎管狭窄症的特点及疗效.方法 回顾121例胸椎管狭窄症患者的临床资料,男51例,女70例;年龄45～71岁,平均54.8岁;单纯胸椎OLF 72例,单纯胸椎OPLL 21例,合并胸椎OLF和OPLL 28例.对胸椎OLF和胸椎OPLL均采用全椎板薄化层揭法进行治疗.统计病变的节段与平面,测量椎体矢状位夹角,计算椎管面积残余率.采用日本骨科协会(Japanese Orthopaedic Association,JOA)评分系统对术前、术后脊髓功能进行评分并比较.结果 胸椎OLF的发病,下胸椎占77.0%(137/178);胸椎OPLL,上胸椎占81.1%(43/53).121例患者平均上胸椎后凸角31.5°±6.8°,下胸椎后凸角9.4°±3.5°.椎管面积残余率＞80%时,JOA评分从术前的(7.7±1.4)分提高到术后的(9.5±1.6)分;椎管面积残余率在80%～50%时,JOA评分从(5.2±1.8)分改善到(8.6±2.1)分;椎管面积残余率＜50%时,JOA评分从(4.8±1.4)分改善到(5.6±1.3)分.结论 胸椎OLF好发于下胸椎,胸椎OPLL好发于上胸椎.术前椎管面积残余率对预后有重要意义.只要临床症状和影像学表现相对应,应尽早手术,手术应尽量切除骨化物.胸椎管狭窄症术后易复发,再次手术更应注意减压范围和减压技巧.     

颈椎后路单开门成形扩大椎管术治疗颈椎后纵韧带骨化症

目的总结颈椎后路单开门椎管扩大成形术治疗颈椎后纵韧带骨化症（ossification of posterior longitud inal ligam ent,OPLL）的临床效果。方法对13例OPLL患者施行颈椎后路单开门椎管扩大成形术。结果本组平均手术时间150（120～180）m in,术中出血量平均为500（300～800）m l。随访3～18个月,术后15月JOA平均改善率53.35%（18.3%～85.7%）,临床症状较术前明显改善。本组2例术后有节段性神经根麻痹,无一例出现脑脊液漏、感染等其它并发症。结论颈椎后路单开门椎管扩大成形术治疗颈椎OPLL效果确切,并发症少。     

胸椎后纵韧带骨化致椎管狭窄症的临床特征和手术治疗方法

目的 探讨胸椎后纵韧带骨化致椎管狭窄症的临床特征和手术治疗方法.方法 2004年1月至2009年3月,手术治疗胸椎后纵韧带骨化致椎管狭窄症患者21例,男13例,女8例;年龄34～71岁,平均51.2岁;病程2～50个月,平均11个月.病变位于上胸段(T1～T4)4例,中胸段(T5～T8)7例,下胸段(T9～T12)10例;合并黄韧带骨化9例,合并颈椎后纵韧带骨化8例.11例行后路椎板切除术,10例行侧前方减压术.结果 后路椎板切除手术时间90～240 min,平均140 min.侧前方减压手术时间110～360min,平均240min.术后患者症状未加重,未出现神经系统并发症、无蛛网膜下腔感染和伤口感染.术后6个月日本骨科协会(Japanese Orthopaedic Association,JOA)评分为8～15分,平均(9.17±1.63)分;其中神经功能改善率8例为优,6例为良,5例为可,2例为差,优良率为66.7%.术后12个月JOA评分为8～15分,平均(10.23±1.64)分;其中神经功能改善率8例为优,7例为良,4例为可,2例为差,优良率为71.4%.结论 胸椎后纵韧带骨化致椎管狭窄临床表现多样,常合并颈椎后纵韧带骨化和黄韧带骨化,后路椎板切除术和侧前方减压术有较好疗效.     

颈椎后纵韧带骨化症术后骨化进展分析

目的 研究颈椎后纵韧带骨化(ossification of posterior longitudinal ligament,OPLL)症术后骨化进展情况.方法 对2001年1月至2007年12月手术治疗的95例颈椎OPLL患者进行回顾性研究,男72例,女23例;年龄40～73岁,平均56.3岁;随访时间1～6年,平均3.1年.颈椎前路手术36例,颈椎后路全椎板减压固定手术57例,前后路联合手术2例.根据术前、术后随访时的X线、CT及MR影像学资料对骨化进展情况进行测量,并通过统计分析性别、年龄、涉及C3OPLL、伴胸椎OPLL、骨化类型、随访时间、手术方式、日本矫形外科学会评分(Japanese orthopaedic association scores,JOA评分)及改善率与骨化术后进展的关系.结果 95例颈椎OPLL术后随访患者中,术后骨化进展39例,男28例,女11例;手术时年龄41～71岁,平均55.9岁;年龄≤49岁12例,50～59岁12例,60～69岁12例,年龄≥70岁3例.颈椎OPLL后路手术后骨化进展有35例,而前路手术后骨化进展仅4例.以骨化物长度和(或)厚度进展≥2mm为标准,单纯骨化长度进展4例;骨化长度、厚度均进展33例;单纯骨化厚度进展2例.骨化长度进展2～20 mm,平均(7.74±4.71)mm;骨化厚度进展2～6 mm,平均(2.67±1.51)mm.在术后1～3年内骨化进展速度呈下降趋势,4～6年骨化则有部分加速趋势.JOA评分及其改善率在术后3年内达到最佳值.统计结果 显示颈椎OPLL术后骨化进展与患者年龄、手术方式以及涉及C3OPLL明显相关.结论 颈椎OPLL术后骨化进展有相当的发生率,涉及C3OPLL、行颈椎后路全椎板切除手术、年轻的颈椎OPLL患者其骨化进展率相对较高.在中短期(1～6年)随访时间内,JOA评分及其改善率受骨化进展影响不大.     

颈椎后纵韧带骨化症的手术治疗

目的探讨颈椎后纵韧带骨化症手术治疗方法及其疗效。方法回顾性分析2002年1月至2008年1月我院65例颈椎后纵韧带骨化症手术治疗病例。均有程度不等的脊髓压迫症状。41例合并发育性颈椎管狭窄,平均椎管狭窄率42．1％。术前均行X线、CT平扫加矢状位重建和MRI检查。其中23例行前路手术,37例行后路手术,5例行前后路联合手术。结果65例获6～72个月随访,平均随访时间19个月。根据日本矫形外科学会评分标准,颈前路手术平均改善率70％,颈后路手术平均改善率66．3％,颈前后路联合手术平均改善率75．4％。术后并发节段性神经根麻痹5例。结论根据患者病情和影像学表现,尤其是CT矢状位重建,仔细分析后纵韧带骨化部位、范围及椎管狭窄率,选择合适手术方法,方能减少并发症,提高手术疗效。     

Circumspinal decompression for thoracic myelopathy due to combined ossification of the posterior longitudinal ligament and ligamentum flavum

Ossification of the posterior longitudinal ligament (OPLL) combined with ossification of the ligamentum flavum (OLF) in the thoracic spine can result in serious myelopathy, leading to circumferential compression of the spinal cord in advanced stages of the disease. The authors performed circumspinal decompression (circumferential decompression of the spinal cord) on these patients. This operation consists of two steps: posterior and lateral decompression of the spinal cord by removal of the OLF (first step) and anterior removal of the OPLL for anterior decompression (second step), followed by interbody fusion. In the first step, two deep parallel gutters, covering the extent of the OPLL to be removed anteriorly, are drilled down from the rear into the vertebral body along both sides of the dura to easily and safely remove the OPLL anteriorly at the second step. In the second step, the surgical approach varies according to the affected level; costotransversectomy in the upper thoracic spine and standard thoracotomy in the middle or lower thoracic spine. According to the authors, circumspinal decompression is not an easy procedure, but from their results in 10 patients, they identify it as a radical and promising surgical procedure.     

胸椎黄韧带骨化症的治疗方法选择

目的研究胸椎黄韧带骨化症（ｏｓｓｉｆｉｃａｔｉｏｎｏｆｌｉｇａｍｅｎｔｕｍｆｌａｖｕｍ,ＯＬＦ）诊断与手术治疗的特点。方法采用回顾性研究方法对手术治疗的胸椎ＯＬＦ的病例进行总结分析。结果总计７２例ＯＬＦ,其中局灶型１５例,连续型４１例,跳跃型１６例;３７．５％合并颈椎后纵韧带骨化症（ｏｓｓｉｆｉｃａｔｉｏｎｏｆｐｏｓｔｅｒｉｏｒｌｏｎｇｉｔｕｄｉｎａｌｌｉｇａｍｅｎｔ,ＯＰＬＬ）,１９．４％合并胸椎ＯＰＬＬ,９．７％合并胸椎间盘突出,１．４％同时合并颈、胸、腰椎ＯＰＬＬ,９．７％合并腰椎间盘突出。结论上述特点是胸椎ＯＬＦ诊断及选择治疗方法时要特别考虑的因素。“揭盖式”椎管后壁切除减压是治疗本病安全、有效的手术方法。     

Management of thoracic myelopathy caused by ossification of the posterior longitudinal ligament combined with ossification of the ligamentum flavum—a retrospective study

Background contextOssification of the posterior longitudinal ligament (OPLL) or ossification of the ligamentum flavum (OLF) is being increasingly recognized as a cause of thoracic myelopathy and is relatively common in the Japanese population and literature. However, no series of OPLL combined with OLF has been previously published. Many different surgical procedures have been used for the treatment of thoracic OPLL or OLF. However, the possibility of postoperative paraplegia remains a major risk, and consistent protocols and procedures for surgical treatment of thoracic OPLL combined with OLF have also not been established.PurposeTo compare the effect of thoracic myelopathy treatment and safety of posterior decompression with or without instrumented fusion and circumferential spinal cord decompression via a posterior approach in Chinese patients of OPLL combined with OLF at a single institution.Study designThis retrospective clinical study of 31 cases was conducted to investigate the clinical outcomes of three kinds of surgical procedures for thoracic myelopathy caused by OPLL combined with OLF in Chinese population.Patient sampleProcedure was performed in 31 patients.Outcome measuresNeurologic status was evaluated using the Japanese Orthopaedic Association (JOA) score and Hirabayashi recovery rate before and after surgery.MethodsA total of 31 patients who underwent surgery for thoracic OPLL combined with OLF were classified into three groups: posterior decompression group (13 patients); circumferential decompression group (seven patients), which included four who underwent extirpation and the other three underwent the floating procedure; and posterior decompression and fusion group (11 patients), all of whom underwent laminectomy with posterior instrumented fusion. In each group, JOA score was used to evaluate thoracic myelopathy, and Hirabayashi recovery rate was calculated 1 year after surgery and at final examination.ResultsMean recovery rate at the final follow-up was 46.5% in the posterior decompression group, 65.1% in the circumferential decompression group, and 62.7% in the posterior decompression and fusion group. Postoperative paralysis occurred in three patients in the posterior decompression group, one in the circumferential decompression group, and one in the posterior decompression and fusion group. In the circumferential decompression group, leakage of cerebrospinal fluid occurred in four patients. Urinary tract infection occurred in two patients, and superficial wound disruption occurred in one patient. Late neurologic deterioration occurred in four patients in the posterior decompression group. There were no cases of postoperative paralysis or late neurologic deterioration in the posterior decompression and fusion group.ConclusionsThoracic OPLL combined with OLF is an uncommon cause of myelopathy in the Chinese population. It can present acutely after minor trauma. A considerable degree of neurologic recovery was obtained by posterior decompression with instrumented fusion, despite the anterior impingement of the spinal cord by the remaining OPLL. In addition, the rate of postoperative complications was low with this procedure. We consider that one-stage posterior decompression and instrumented fusion be selected for patients in whom the spinal cord is severely damaged before surgery and/or when circumferential decompression is associated with an increased risk.     

Cervical myelopathy resulting from combined ossification of the ligamentum flavum and posterior longitudinal ligament: report of two cases and literature review

Background contextIn the cervical spine, the combination of ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament (OPLL) is rarely seen. There have been only four cases reported in the English literature.PurposeWe describe two more cases that exhibited cervical myelopathy resulting from the combination of cervical OLF and OPLL and required surgery. A literature review with a comparative analysis between previous reports and present cases was also performed.Study designCase report and literature review.Patient sampleTwo patients with combined OLF and OPLL.Outcome measuresPreoperative computed tomography, magnetic resonance imaging, and pathological findings from operative specimens were used to confirm the diagnoses.MethodsA 76-year-old man (Case 1) presented with disturbance of gait and fine finger movement. Magnetic resonance imaging showed severe spinal canal stenosis and cord compression at the C3–C4 level. Computed tomography showed OPLL at the C2–C6 levels (segmental type) and OLF at the left C3–C4 level. The patient underwent posterior decompression and OLF resection. A 75-year-old man (Case 2) presented with sensory disturbance and muscle weakness in his bilateral upper extremities and disturbance in fine finger movements. Magnetic resonance imaging showed severe spinal canal stenosis and cord compression at the C2–C3 and C3 levels. Computed tomography showed OPLL at the C3–C7 levels (mixed type) and OLF at the left C2–C3 and C3 levels. The patient also underwent posterior decompression and OLF resection.ResultsIn both cases, histological examination of the surgical specimens showed osseous tissue and enchondral ossification within the ligamentum flavum, and the diagnosis in each case was OLF. After surgery, both patients' symptoms immediately improved, and no recurrence was observed at 2 years after surgery.ConclusionsWe experienced two cases of cervical myelopathy resulting from the combination of OLF and OPLL in the cervical spine. The symptoms of myelopathy were treated successfully by laminectomy and laminoplasty with OLF resection in both cases. The literature review including the present two cases revealed that cervical OLF tended to occur adjacent or close to the margin of cervical OPLL, suggesting that the increased mechanical stress at the junction of OPLL may be a causative factor.     

经关节突减压融合治疗腹侧压迫型胸椎管狭窄症

目的 探讨经关节突减压融合治疗腹侧压迫型胸椎管狭窄症的手术疗效和安全性.方法 2005年4月至2009年4月,采用后方人路经关节突行椎管腹侧减压,同时行前路植骨后路内固定融合术治疗腹侧压迫型胸椎管狭窄症患者33例,其中获得12个月以上随访者19例,男10例,女9例;年龄33～77岁,平均55.9岁;胸椎后纵韧带骨化(ossification of posterior longitudinal ligament,OPLL)5例,胸椎间盘突出症(thoracic disc hemiation,TDH)11例,胸椎OPLL合并胸椎黄韧带骨化(ossification of ligamentum flavum,OLF)2例,TDH合并OLF 1例.采用改良日本骨科协会(Japanese Orthopaedic Association,JOA)评分法和Nurick分级评价神经减压效果.结果 手术时间180～480 min,平均299.5 min;术中出血量250～2200 ml,平均918.5 ml.7例胸椎OPLL患者(包括合并OLF)术中出现硬膜损伤1例,术后发现神经功能恶化2例.12例TDH患者(包括合并OLF),术后无神经功能恶化,未发现脑脊液漏及其他并发症.术后随访时间12～54个月,平均28.6个月.术前JOA评分2～11分,平均63分;末次随访时JOA评分5～11分,平均8.6分.术前Nurick分级0～5级的例数分别为:2、2、4、5、2、4例,术后Nurick分级0～5级的例数分别为:6、6、3、3、1、0例.结论 采用经关节突人路减压融合治疗腹侧压迫型胸椎管狭窄症可以获得充分的减压及满意的疗效,可以作为一种较为安全的胸椎管腹侧减压入路.     

An epidemiological survey on ossification of ligaments in the cervical and thoracic spine in individuals over 50 years of age

An epidemiological survey on ossification of the spinal ligaments was performed on a total of 1,058 subjects over the age of 50 years by means of roentgenography of the cervical and thoracic spine. Ossification of the posterior longitudinal ligament (OPLL) of the cervical spine was detected in 34 subjects (3.2%) with a predilection for men, whereas OPLL in the thoracic spine was found in 8 (0.8%). There were 325 cases (30.7%) of ossification of the anterior longitudinal ligament (OALL) of stage II or above by Forestier's classification in the region from the cervical to thoracic vertebrae, and these cases included a significantly greater number of men. Ossification of the ligamenta flava (OLF) was observed in 48 cases (4.5%). As for the coexistence of ossification of these ligaments, 364 individuals (34.4%) had at least one instance of OPLL and OALL (stage II or above) in the region from the cervical to thoracic spine, and OLF in the thoracic spine.     

Spinal canal size in ossification of the posterior longitudinal ligament of the cervical spine

BACKGROUND: The size of the spinal canal is a factor that contributes to the neurologic deficits associated with cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: Bone-window computed tomography (CT) examinations of the cervical spine in 64 patients with cervical OPLL were reviewed. Forty-two patients underwent surgical treatment (anterior decompression: 16 patients, posterior decompression: 26 patients). The remaining 22 patients were managed conservatively. Selection of the surgical approach, anterior or posterior, was based on the longitudinal extent of cord compression. RESULTS: The mean developmental size of the spinal canal in the posterior decompression group (10.7 mm at C4) was significantly smaller than the other 2 groups. The spinal canal was narrowed by OPLL to 2.9 to 10.0 mm. The proportion of the patients showing motor deficits of the lower extremities significantly increased when the sagittal canal diameter was narrowed to less than 8 mm. CONCLUSIONS: This study demonstrates critical values of CT-determined spinal canal stenosis. Developmental size of the spinal canal and the residual anterior-posterior canal diameters resulting from OPLL spinal cord compression are important factors influencing clinical management and the neurologic state.