Cervical ossification of the posterior longitudinal ligament: factors affecting the effect of posterior decompression

Objective: Decompression procedures for cervical myelopathy of ossification of the posterior longitudinal ligament (OPLL) are anterior decompression with fusion, laminoplasty, and posterior decompression with fusion. Preoperative and postoperative stress analyses were performed for compression from hill-shaped cervical OPLL using 3-dimensional finite element method (FEM) spinal cord models.

Methods: Three FEM models of vertebral arch, OPLL, and spinal cord were used to develop preoperative compression models of the spinal cord to which 10%, 20%, and 30% compression was applied; a posterior compression with fusion model of the posteriorly shifted vertebral arch; an advanced kyphosis model following posterior decompression with the spinal cord stretched in the kyphotic direction; and a combined model of advanced kyphosis following posterior decompression and intervertebral mobility. The combined model had discontinuity in the middle of OPLL, assuming the presence of residual intervertebral mobility at the level of maximum cord compression, and the spinal cord was mobile according to flexion of vertebral bodies by 5°, 10°, and 15°.

Results: In the preoperative compression model, intraspinal stress increased as compression increased. In the posterior decompression with fusion model, intraspinal stress decreased, but partially persisted under 30% compression. In the advanced kyphosis model, intraspinal stress increased again. As anterior compression was higher, the stress increased more. In the advanced kyphosis +?intervertebral mobility model, intraspinal stress increased more than in the only advanced kyphosis model following decompression. Intraspinal stress increased more as intervertebral mobility increased.

Conclusion: In high residual compression or instability after posterior decompression, anterior decompression with fusion or posterior decompression with instrumented fusion should be considered.     

Does the Modification of the Apical Geometry of a Dental Implant Affect Its Primary Stability? A Comparative Ex Vivo Study

(1) Background: Primary stability—one fundamental criterion for the success of dental implants—is influenced by implant geometry even if the effect of apical shape modifications on implant primary stability has not yet been examined. Therefore, the aim of the ex vivo study was to compare primary stability of implants differing in apically located screw threads (J-line) or a flat tip (K-line) only. (2) Methods: 28 implants of each group of the same diameter (4.3 mm) were randomly inserted into porcine bone blocks. The first group (9, 11 and 13 mm) was inserted into “hard”, the second (11 mm) into “soft” bone, here using a normal and an undersized drilling protocol. Insertion torque (Ncm), Periotest^® value, resonance frequency (implant stability coefficient, ISQ) and push-out force (N) were measured. (3) Results: In “hard” bone, primary stability increased with increasing length in both groups but it was significantly higher in J-line (p < 0.03). An undersized preparation of the implant bed in “soft” bone resulted in a significant increase in primary stability in both groups. Here, J-line also showed a significantly increased primary stability when compared to equally prepared K-line (insertion torque: 37 Ncm vs. 26 Ncm; Periotest^®: −6.5 vs. −4.3; push-out force: 365 N vs. 329 N; p < 0.05 each). (4) Conclusions: Primary stability is significantly higher with increasing implant length and apically located screw threads as well as with undersized drilling protocols. When preparing the implant site and subsequently selecting the implant system, modifying factors such as implant geometry (also at the tip) should be taken into account.     

术前K线对棘突纵割式椎管扩大成形术治疗颈椎后纵韧带骨化症疗效的影响

目的 探讨术前K线对棘突纵割式椎管扩大成形术治疗颈椎后纵韧带骨化症(C-OPLL)患者疗效的影响.方法 对2017年1月至2018年6月北京积水潭医院脊柱外科行棘突纵割式颈椎后路椎管扩大成形术治疗的C-OPLL患者157例的临床资料进行回顾性分析.根据术前K线结果将患者分为K线(+)组和K线(-)组,分别包括99例和5...     

结合K线分析颈椎后纵韧带骨化患者的颈椎活动度与手术预后的关系

目的:结合K线(颈椎侧位X线片上C_2及C_7椎管中点的连线)分析颈椎后纵韧带骨化患者的颈椎活动度与手术预后的关系。方法:对2014年4月至2017年3月行颈椎后路单开门椎管扩大成形术的42例颈椎后纵韧带骨化(cervical ossification of the posterior longitudinal ligament,OPLL)患者进行回顾性分析。根据后纵韧带骨化与K线的位置关系,患者被分为K线(+)组及K线(-)组。后纵韧带骨化病灶未超过K线称为K线(+),反之,后纵韧带骨化病灶越过K线称为K线(-)。观察术前及术后3个月JOA(Japanese Orthopedic Association)评分,并计算术后3个月JOA改善率评估患者神经功能恢复情况。通过影像学资料测量术前及术后3个月后纵韧带骨化的侵占率(occupation ratio,OOR),颈椎生理曲度(cervical lordotic angles,CLA)和颈椎前凸值(cervical lordotic value,CLV)。评估不同的K线分组中,CLV0组和CLV≤0组之间患者的术后神经功能恢复之间的联系。结果:K线(+)组和K线(-)组患者的术前CLA分别为(14.7±9.6)°和(-6.4°±9.5)(P0.05),术后3个月分别为(14.0±8.0)°和(-1.4±10.4)°(P0.05);术前JOA评分分别为10.9±3.2和11.2±2.5(P0.05),术后3个月分别为14.2±1.8和12.6±2.2(P0.05),术后3个月JOA改善率分别为(54.7±17.6)%和(25.5±15.7)%(P0.05)。K线(+)组中,术后3个月CLV0组的患者29例,其术后3个月JOA改善率(52.3±17.2)%,术后3个月CLV≤0组的患者4例,其术后3个月JOA改善率为(72.2±7.8)%,术后3个月CLV≤0组患者JOA改善率明显优于术后3个月CLV0组(P0.05)。结论:无论患者颈椎后纵韧带骨化分类为K线(+)或K线(-),颈椎后路单开门椎管扩大成形手术都能够很好的改善患者的神经症状,尤其K线(+)组的患者,具有较好的预后效果。K线(+)组患者术后3个月CLV0时,其JOA改善率较CLV≤0的患者差。     

K线用于选择颈椎后纵韧带骨化症手术策略的回顾性分析

目的:验证颈椎侧位X线片上C2与C7椎管中点的连线(K线)用于颈椎后纵韧带骨化症(Ossification of postenior longitudinal ligament,OPLL)手术方式选择的作用.方法:2000年5月至2008年4月,我科通过后路减压手术治疗颁椎OPLL引起的脊髓病患者35例.男25例,女10例,手术时平均年龄为54.6岁(35～73岁).根据OPLL范围相对于K线的位置,将所有患者分为两组,OPLL范围未超过K线者为K线阳性组,超过K线者为K线阴性组.记录术前及术后1年时两组患者的日本骨科学会(Jalt)anese Onhopedic Association,JOA)评分,算出恢复率.结果:K线阳性组24例,K线阴性组11例.K线阳性组的JOA评分由术前平均8.6分提高到术后1年时的13.8分.平均提高5.2分;K线阴性组南术前的6.6分提高到术后1年时的9.8分,平均提高3.2分:K线阳性组的平均恢复率为64.2%,K线阴性组为30.8%.两组间有非常显著性差异(P(0.001).结论:术前利用K线这一简单实用的指标能有效预测OPLL后路减压手术的疗效,从而帮助医生选择合适的手术方式.     

后路手术治疗过伸位K线阳性颈椎后纵韧带骨化症的疗效

目的：观察后路减压手术治疗过伸位K线阳性颈椎后纵韧带骨化症（OPLL）的临床疗效。方法回顾性分析2005年2月至2012年1月第二军医大学附属长征医院收治的72例OPLL患者的临床资料,其中27例行椎板成型术、45例行椎板切除减压内固定术。根据OPLL骨化最高点相对于K线的位置,分为K线阳性组（标准侧位片K线阳性,39例）和过伸位K线阳性组（标准侧位片K线阴性但过伸位侧位片K线阳性,33例）。记录术前和术后1年两组患者的日本骨科学会（JOA）评分,计算恢复率。结果术后1年,K线阳性组JOA评分由术前的（11.3±2.9）分提高到（14.2±3.0）分（P＜0.05）,过伸位K线阳性组JOA评分由术前的（10.5±1.8）分提高到（13.3±2.7）分（P＜0.05）,但术前、术后JOA评分组间比较,差异无统计学意义（P＞0.05）;K线阳性组和过伸位K线阳性组恢复率分别为（51±22）%和（44±23）%,两组比较,差异无统计学意义（P＞0.05）。结论对过伸位K线阳性颈椎OPLL患者施行后路手术可以获得与K线阳性患者相当的临床疗效。