探討一節或兩節前路椎間融合手術暨幾何形態因子對於病人術後整體與椎節的運動行為之影響

Single- and Two-level Anterior Cervical Decompression and Fusion: Influence of Surgical Type and Morphological Factors on the Total and Segmental Cervical Range of Motion and Kinematics

林佳慶(Chia-Ching Lin)

指導教授 ： 王兆麟

國立臺灣大學/工學院/醫學工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.00470

摘要

研究目的：
研究前路頸椎減壓暨椎間融合手術病人術後頸椎運動行為，與探討頸椎幾何因子與運動行為之相關性。

背景介紹：
前路頸椎減壓暨椎間融合手術為目前臨床常用來治療頸椎神經脊髓病變的方法。研究報告指出此手術能有效減緩病患症狀且具有良好的手術成效，然而臨床追蹤報告也指出病人術後可能會有鄰近節椎間盤提早退化的情形，因此探討手術後的鄰近節病變為目前相關領域學者們討論的重點。
先前文獻指出性別、年齡與病症發生時間可能與術後鄰近節退化有關。在融合手術後，手術節活動度因為融合而降低，而鄰近節活動度則可能因為手術節的數目與術後時間的演進而有不同的代償變化。目前少有文獻量化探討融合手術節數與術後時間點演進對於鄰近節活動度與退化的關係，因此研究不同手術節數對於病患術後頸椎整體以及鄰近節運動行為是值得討論的重要議題。
此外，根據幾何運動學的概念，頸椎本身的幾何形態應該會對頸椎運動學有所影響，而目前尚未有足夠的文獻對頸椎的幾何形態與頸椎整體或椎節間的運動行為做一個詳盡的討論。因此，本研究將設計一套前瞻性臨床實驗，研究前路頸椎減壓暨椎間融合手術病人之術後頸椎運動行為，以及探討頸椎幾何因子與運動行為之相關性。

材料與方法：
本研究徵招了47位頸椎神經脊髓病變患者，且需進行一節或兩節前路椎間融合手術治療的病患。病人在術前、術後三個月、術後六個月以及術後十二個月時拍攝正中、前彎與後仰姿勢的側向X光影像。利用影像資料量測病人術前與術後的C2至C7頸椎整體活動度、手術節和上、下鄰近節的椎節間活動度。為了瞭解手術對於椎節活動品質的影響，此研究將分析手術節和上、下鄰近節的活動度貢獻百分比於手術前後的變化。
另外，病人也會在術前拍攝核磁共振影像並量測其椎體長度、椎體高度以及椎間盤高度等頸椎的幾何形態因子，並幾何形態因子與頸椎整體或椎節間的運動行為的關係。此外本研究根據病人的側向X光影像資料建立參數化有限元素模型，將病人實際的活動度當作負載條件進行分析，瞭解術前與術後頸椎的生物力學改變。
為探討手術形態(一節或兩節)以及時間變化(術前及術後三、六、十二個月)對病人的影響，統計分析採用混合模型變異數分析。單變量線性回歸分析則用來探討幾何因子與頸椎運動行為的相關性分析。

結果：
本研究徵召28位男性與19位女性病患，平均年齡約為55.4歲(範圍：30至79歲)，其中包含一節前路手術之病患共有30位，兩節前路手術則有17位。
一節手術的患者整體活動度在術後三個月顯著下降(p=0.002)，但在術後六個月就恢復至與術前無顯著差異；而兩節手術病患的整體活動度則是於術後顯著下降(p<0.02)，且於術後十二個月也無法回復至與術前相似的狀態。在手術節活動度貢獻百分比的部份，一節手術的病患與兩節手術的病患皆呈現下降的趨勢，但一節手術的病患在術後三個月就有顯著下降(p=0.012)，而兩節手術的病患則是在術後十二個月才與術前相比有顯著下降(p=0.047)。
一節手術病患的上鄰近節活動度貢獻百分比在術後各時間點皆顯著上升(p<0.05)；兩節手術的病患的上鄰近節活動度貢獻百分比則是在術後六個月時才達到顯著上升15%(p=0.042)。然而以手術型態來分析的話，在數據顯示兩節手術病患的上鄰近節活動度貢獻百分比相較於一節手術病患皆多出10-15%的貢獻度。在下鄰近節活動度貢獻百分比的部分，一節與兩節手術的病患皆有上升的趨勢，但皆無顯著的變化。
在頸椎幾何因子與活動度貢獻百分比的相關性探討中，於兩節手術病患的手術節上節後側椎間盤高度與上鄰近節活動度貢獻百分比有高度負相關(R=-0.717)，並有顯著的相關性(p=0.03)，於其他的參數則無發現顯著的關聯性。
在參數化有限元素的模擬中，兩節手術病患的上鄰近節椎間核壓力上升的幅度皆較一節手術大。在前彎姿勢，一節手術病患約上升20%，兩節手術病患約44%；後仰的姿勢，一節手術病患約上升23%，兩節手術病患約34%。

結論：
一節手術的病患在融合手術後，其整體頸椎活動於術後六個月即可恢復至術前水準，手術節的活動度也會在術後三個月時達到穩定。其上鄰近節的活動度貢獻百分比些微的上升，但在術後一年的追蹤內不會再有顯著變化，此現象可能為整體活動度回復的原因。相較於兩節手術的病患，由於融合的節數較多，手術節活動度需要在術後六個月到十二個月才有穩定的趨勢。此外上鄰近節活動度貢獻百分比在術後六個月前也有持續上升的情況，並在六個月與術前相比有顯著的差異，此現象也可能導致椎間盤壓力上升幅度也較一節手術來得大。研究結果也指出術前手術節上節的後側椎間盤高度將對其術後上鄰近節活動度貢獻百分比產生負面的影響。

關鍵字

頸椎神經脊髓病變 ； 活動度貢獻百分比 ； 頸椎幾何形態因子 ； 頸椎椎間盤壓力

並列摘要

Objective:
To investigate and better understand the influence of Anterior Cervical Discectomy and Fusion surgery on cervical kinematics and to elucidate possible relationships between cervical morphometrics and altered cervical biomechanics.

Introduction:
Anterior Cervical Decompression and Fusion (ACDF) is one of the most commonly employed surgical techniques to treat Cervical Spondylotic Myelopathy (CSM). Despite the reported high clinical success rates of ACDF, an increased rate of adjacent segment disease (ASD) post ACDF surgery has raised some significant concerns in the literature.
Many demographical factors such as gender, age and duration of symptoms have all been implicated to contribute to the development of ASD, however, limited studies have specifically attempted to quantify the relationship between over-compensatory adjacent segmental contribution to total cervical Range of Motion (ROM) and the development of ASD. Given the likely alternation of the cervical biomechanics due to the immobilization of a segment following ACDF, a better understanding of the postoperative kinematical change is well warranted.
Moreover, no study has conducted a morphometric analysis of the cervical vertebral column and its influence on the global and segmental ROM in the literature to date. Based on the immanent biomechanical relationship between vertebral morphology and resultant spinal kinematics, a better understanding of the potential influence using an in-vivo, prospective design is needed to fulfill this gap in our knowledge.
Materials and methods:
Forty-seven patients with clinically diagnosed CSM undergoing either a single- or two-level ACDF were recruited in the study.
Neutral, full active flexion and extension lateral radiographs were taken preoperatively and then at 3, 6 and 12 month follow-ups for all patients. Using the obtained radiographs, global ROM of C2-7, ROM of the treated functional spinal unit (FSU) as well as the superior and inferior segmental ROM were obtained using a computer based quantitative measurement analysis software. The relative contribution from the FSU and each of the adjacent segments to total cervical ROM were compared pre- and post-operatively. MRI scans conducted as part of the preoperative workup were also obtained in order to accurately determine the vertebral morphometric measurements, which included vertebral length, vertebral height, and disc height.
In order to investigate and simulate the cervical biomechanical properties during the movement, a number of parametric finite element models (FEM) were also constructed based on patients’ radiographs with the observed ROM inputted as the individual loading conditions.
Statistically, a mixed design repeated ANOVA analysis was used to determine the interaction and main effects of surgery type (single or two-level) and time (pre-, 3, 6, 12 month). A univariate linear regression analysis was then conducted to determine the relationship between morphological factors and the kinematical changes.

Results
Overall, 30 single-level and 17 two-level ACDF patients were recruited. The patients consisted of 28 males and 19 females with a mean age of 55.4 (range 30 to 79) years.
Single-cage patients demonstrated a significantly decreased total ROM at 3 months (p=0.002) but improved to pre-operative level by 6 months. In contrast, patients with two-cage ACDF demonstrated significantly decreased total ROM at all follow up assessments (p<0.02) and did not reach pre-surgery level even at 12 months post-surgery. Similar trend was observed for the FSU ROM where a significantly decreased contribution was found for the single-cage patients at all follow up assessments (p<0.01), however, the FSU contribution was only significantly decreased at 12 months (p=0.047) for the two-cage patients.
In terms of upper adjacent ROM contribution, it was found to be significantly increased at all follow up assessment points (p<0.05) for the single-cage patients but was only significantly increased at 6 months (p=0.042) for the two-cage patients when compared to pre-surgery. However, in terms of the raw contribution, it was noted that the two-cage patients demonstrated a 10-15% more in contribution to the total ROM when compared to the single-cage at the upper adjacent segments. No significant changes were found for both groups for the lower adjacent ROM contribution.
For the correlation of morphological factors and cervical kinematical change, in patients with two-cages, the posterior disc height of the FSU’s upper segment was found to have a strong (R=-0.717) and significant (p=0.03) negative correlation with an increased upper adjacent segmental contribution to total ROM. This was not the case for single-cage patients. No other morphological factors were found to have a significant correlation with the post-operative kinematical changes.
The FEM modeling illustrated that based on the obtained radiographs, the two-cage patients demonstrated a greater increase in upper adjacent intradiscal pressure (IDP) than the single-cage patients for both flexion (44% vs 20%) and extension (34% vs 23%) respectively.
Conclusion:
Single-cage patients regained their pre-operative total ROM by 6 months post-surgery and the fused segment demonstrated adequate fusion and immobility by 3 months. The results indicated that the regained total ROM were mostly due to a slight increase in the upper adjacent segment contribution at 3 months, which then remained unchanged throughout the study period. In contrast, due to the increased levels of fusion in the two-cage patients, the fused segment did not demonstrate adequate immobilization until 6 to 12 month post-surgery. Furthermore, patients with two-cages demonstrated a significant increase of upper segment contribution at 6 months and coupled with greater likelihood of an increase in IDP based on the FEM analysis. Lastly but not the least, the upper posterior disc height of the FSU was found to have an association with the increased upper adjacent segment contribution in patients with two-cages.

並列關鍵字

Cervical spondylotic myelopathy ； ROM contribution ； Morphological factors ； Cervical intradiscal pressure

參考文獻

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