腰椎椎間盤退化性疾病與終生累積負重之相關性研究

Relationship between Lumbar Disc Degeneration Diseases and Life Time Cumulative Lifting Load

洪瑜嬬(Yu-Ju Hung)

指導教授 ： 郭育良

共同指導教授 ： 黃耀輝(Yaw-Huei Hwang)

國立臺灣大學/公共衛生學院/職業醫學與工業衛生研究所/博士(2015年)

https://doi.org/10.6342/NTU.2015.02630

摘要

前言：
腰椎椎間盤退化性疾病是導致下背疼痛的重要原因之一，在台灣與歐美各國的職業補償統計顯示其高盛行率與發生率所導致的相關失能，造成了醫療與產業成本提高，對於國家的經濟發展是一項沉重的負擔。過去的研究結果顯示職業性負重是椎間盤退化的重要危險因子之一，然而，因為其影響因子之多重性，職業暴露劑量之定量仍有其困難，與椎間盤退化之劑量反應關係尚無定論。因此本研究針對特定高危險性暴露的工作族群，進行詳細的終生累積負重調查，嘗試定量究竟多少終生暴露劑量的搬運重量會造成傷害;且更進一步的調查是否過去所有的負重皆對於傷害的發生有影響? 抑或單次負重中存在有著閾值, 超過此值後的累積負重才具危害效應? 男女性的閾值是否不同? 除了負重之外，椎間盤的形態學(高度與寬度)與椎間盤突出是否具有相關性?若有，是否可以藉由量測椎間盤的高度與寬度來預測椎間盤突出? 本研究期望能以此結果應用於職場上作為制定保護勞工健康的累積負重參考基準和預防疾病的發生。
方法：
本研究設計為橫斷性研究，個案來源為20-65歲之間的果菜市場搬運工作人員，作為高危險性暴露的工作族群，以及以國立台灣大學附設醫院內科的門診感冒病患，作為一般工作族群。每位受試者均接受一份問卷調查、腰椎
磁共振攝影(MRI)與工作姿勢的模擬取相。為了獲得個案的終身累積負重暴露，研究人員詳細詢問個案過去工作中的搬運重量與時間，現場取相個案所示範的搬運動作，並應用腰椎受力評估軟體(3D SSPP)預測每一個搬運姿勢下的腰椎受力，最終相加所有的腰椎受力與執行搬運的時間乘積，此總和值即為個案的終身累積負重暴露，單位為牛頓×小時(Newton×hour (Nh))。腰椎核磁共振攝影的檢查項目包括五節腰椎之椎間盤缺水(Dehydration)、纖維盤破裂(Annulus tear)、椎間盤變薄(Disc height narrowing)、突出(Bulging or protruding)與脊椎滑脫症(Degenerative spondylolithesis、 Spondylolytic spondylolithesis)、椎間孔狹窄(Foramina narrowing)、神經根壓迫(Nerve root compression)，和椎間盤的高度與寬度。統計分析方法以邏輯斯迴歸模式檢視終生累積負重暴露與每一節腰椎之椎間盤退化疾病的相關性。以四種檢驗最適配方程式的統計法來比較各項負重閾值計算下的終生累積負重對椎間盤突出的發生有最佳的預測力。以ROC曲線下的面積大小比較二種預測椎間盤突出的預測力: Model 1以年齡、性別、身高、體重作為危險因子，Model 2以椎間盤的高度、寬度、年齡、性別、身高、體重作為危險因子。
結果：
共有715位自願者參與本研究，最後進行資料分析者為553位。研究結果顯示，終身累積負重與腰椎椎間盤退化疾病之間具有顯著相關，同時並呈現有暴露劑量-效應模式。其中，高負重暴露者(> 8.9×106Nh)相較於低負重者(< 4×105Nh)其第五節腰椎發生椎間盤缺水的危險性是2.5倍(AOR=2.5,
CI=1.5,4.1)，椎間盤變薄的危險性是4.1倍(AOR=4.1,95% CI=1.9,10.1);中度負重暴露者(4×105-8.9×106Nh)相較於低負重者發生椎間盤突出(Bulging)的危險性是2.1倍(AOR=2.1,95% CI=1.3,3.3)。超過閾值以上的負重才計入終生累積暴露的計算下，男性使用單次負重3000 牛頓，女性2800 牛頓，作為閾值的終生累積暴露值對L4-S1椎間盤突出有最好的預測度。針對腰椎後三節，椎間盤的高度、寬度與椎間盤突出具有相關性; 比較以年齡、性別、身高、體重作為危險因子的預測方程式(Model 1)和再加入椎間盤的高度、寬度作為危險因子的預測方程式(Model 2) ，發現後者的預測力較佳。
結論：
本研究顯示終生累積負重與椎間盤退化疾病之間具有劑量–效應關係，並定量出特定終生累積負重值對椎間盤退化的發生具有危險性; 男性單次負重閾值3000 牛頓，所計算的終生累積暴露值對L4-S1椎間盤突出有最好的預測度，女性為2800 牛頓。以椎間盤的高度、寬度、年齡、性別、身高、體重等危險因子構成的預測方程式可以用來預測椎間盤突出的發生。本研究計算腰椎終生累積負重的模式與預測椎間盤突出之方程式可作為職場上累積負重暴露與預防疾病發生的參考。

關鍵字

椎間盤退化性疾病 ； 終生累積負重 ； 椎間盤突出 ； 閾值 ； 橫斷性研究 ； 腰椎核磁共振攝影 ； 預測方程式

並列摘要

Background and Objective: Lumbar disc degeneration (LDD) has been related to heavy physical loading. However, the quantification of the exposure has been controversial and the dose-response relationship with the LDD has not been established. It is also unclear whether a specific threshold value exists in each lifting load, the accumulation above which best predicts lumbar disc protrusion, or on the other hand, all lifting load should be accumulated. In a clinical setting, the radiographic diagnosis of disc condition typically requires magnetic resonance imaging (MRI), which is less readily available than plain radiograph is in most primary care facilities. If the relationship between reduced disc height and disc bulging or protrusion was existed, useful insight can be obtained to guide further direction of patient evaluation. The purposes of this study are to investigate the dose-response relationship between lifetime cumulative lifting load and LDD; to determine the optimal threshold value of lumbar compression load in each lifting, which allowed for best prediction for disc protrusion while lifetime cumulative load was calculated; and to determine the association between disc morphology and disc bulging or protrusion.

Method: This is a cross-sectional study. Every participant received assessments with a questionnaire, MRI of the lumbar spine and lumbar disc compression load. MRI assessments included disc dehydration, annulus tear, disc height narrowing, bulging, protrusion, extrusion, sequestration, degenerative and spondylolytic spondylolisthesis, foramina narrowing, and nerve root compression on each lumbar disc level. The compression load was predicted by a biomechanical
software system. We sum up all lifting exposure to the calculation for examining the association between lifetime cumulative lifting load and LDD; and sum up only lifting load greater than proposed thresholds for determining the optimal threshold value of lumbar compression load in each lifting .For accumulation above different thresholds, predictive capabilities for disc protrusion were compared using four statistical values, (1) Area under the curve of a receiver operating characteristic curve, (2) R2, (3) Akaike information criterion, and (4) Bayesian information criterion. The intervertebral disc height and disc depth were measured. Logistic regression analysis was applied to identify the association between anthropometric factors, disc morphology factors, and disc bulging/protrusion. Model 1 was constructed using anthropometric variables to investigate the capacity for predicting disc bulging/protrusion. Model 2 was constructed using anthropometric variables and disc morphology variables. The ability of the models to discriminate between participants with and without disc bulging/protrusion was evaluated using a receiver operating characteristic curve.

Result: A total of 553 participants were recruited in this study and categorized into tertiles by cumulative lifting load, i.e., <4.0 × 105, 4.0 × 105–8.9 × 106, and >= 8.9 × 106 Newton× hours. The risk of LDD increased with cumulative lifting load. The best dose-response relations was found at the L5–S1 disc level, in which high cumulative lifting load was associated with elevated odds ratios of 2.5 (95% CI 1.5–4.1) for dehydration, and 4.1(95% CI 1.9–10.1)for disc height narrowing comparing to low lifting load. Participants exposed to intermediate lifting load had increased odds ratios of 2.1(95% CI 1.3–3.3) for bulging comparing to low lifting load. The tests for trend were significant. For men, 3000 Newton for each lifting
task was the optimal threshold value for predicting L4-S1 disc protrusion, whereas for women, 2800 Newton was optimal. Total of 452 MRI scans were analyzed for the morphology study. Age, body weight, body height, disc height, and disc depth were significantly associated with disc bulging/protrusion. The area-under-the-curve (AUC) statistics of Model 2 were significantly better than Model 1 at the L3-L4 (p<.05) and L4-L5 level (p<.05) but not at the L5-S1 level.

Conclusions: The results suggest a dose-response relationship between cumulative lifting load and LDD. Cumulative lifting load predicted L4-S1 disc protrusion best when the threshold value was set at 3000 Newton for men, and 2800 Newton for women. The results showed an association between disc morphology and disc bulging/protrusion at the L3-L4, L4-L5, and L5-S1 level. We also developed a model by using anthropometric factors and disc morphology to predict disc bulging/protrusion.

並列關鍵字

Lifetime cumulative lifting load ； Lumbar disc degeneration ； MRI ； Dose-response relationship ； disc morphology ； disc protrusion ； threshold value

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