脊椎牽引對於嚴重退化椎間盤之養分傳輸影響

Abstract

目的：利用活體椎間盤培養系統探討牽引治療對於退化型椎間盤的養分傳輸之影響。 背景介紹：對於患有退化性椎間盤但尚未需要手術治療的病人而言，牽引治療是復健醫學上使用普遍且安全性高的技術之一。隨著椎間盤老化，其保水能力會被破壞，椎間盤高度會嚴重下降，導致椎間孔狹窄壓迫到神經根，引發下背痛及四肢痛麻等現象。牽引治療可回復縮小的椎間孔，緩解病人痛麻的神經根症狀。牽引治療短期內可疏緩縮小的椎間孔，但就長期而言，是否可有效增加椎間盤內的養分供給以持續保持其厚度則不無疑問。本研究的目的在研究牽引治療對椎間盤內養分傳輸影響，並探討牽引治療是否有利於椎間盤之生長與修復。 材料與方法：使用六個月大、體重約為140公斤的年輕豬隻，在屠宰後4~6小時內取回實驗室進行無菌操作之試樣處理，從上下椎間盤之椎骨中央取下胸椎第四節到第七節的椎間盤單元，將椎骨外的肌肉、韌帶以及後脊突去除，用生理食鹽水清洗後準備後續處理。本實驗將椎間盤分為三組：健康組、嚴重退化組、牽引治療組。健康組為椎間盤沒有受到任何損傷者；嚴重退化組的試樣處理後於第一天在椎間盤內注射0.25%胰蛋白酶0.5ml，並於第二天接受5小時2.0Hz的疲勞負載；牽引治療組的椎間盤則在注射胰蛋白酶和疲勞負載結束後，於第四天起介入連續三天的牽引治療，牽引力量為20kg，時間30分鐘，牽引過程中拉伸30秒、放鬆10秒為一個循環。所有試樣在持續給予正常生理負載的環境下培養一週，一週後探討其椎間盤高度變化量、細胞存活狀態、椎終板厚度、椎間環凸出量與表徵變化。另外為研究牽引治療完內部養分傳輸的即時效應，牽引治療組之椎間盤在最後一次治療結束後即給予螢光染劑循環，並與其他兩組比較一小時內擴散強度之差異。 結果：模擬中、老年人老化程度的嚴重退化性椎間盤與健康組相比，在七天培養後，椎間盤高度變化量增加、椎終板厚度降低、椎間環外突位移量增加，且螢光擴散趨勢大幅下降、椎間核和椎間環內細胞死亡。牽引治療則能恢復上述椎間盤因嚴重退化所造成的破壞，牽引治療組中椎間盤其高度變化量顯著性減少、椎終板厚度增加、椎間環明顯回縮，螢光擴散亮度在各部位均勻地顯著性上升，其中牽引治療在縱向運輸的恢復性較橫向運輸為優，另外促使椎間核和椎間環的活細胞再生，細胞存活比大為提升。 結論：牽引治療能有效回復部分退化時椎終板和椎間環被破壞的結構特性，幫助增加其對液體的滲透度、重建內部養分傳輸系統，讓椎間盤高度維持住且椎間盤細胞獲得養分來源而能自體修復生長，有助於延緩和改善嚴重退化椎間盤內部的惡性環境。

Objective: To investigate the effect of spinal traction on nutrition supply of simulated severe degenerative discs using a whole disc culture system. Summary of background data: Spinal traction is a well-recognized and safe physical therapy for patients with degenerative disc diseases before surgical remedies. Disc degradation leads to disc height loss and intervertebral foramen narrowing, which compress nerve root and thus induce low back pain and limb numbness. It was proved that traction treatment could expand the intervertebral foreman, so as to reduce radiculopathy in the short-term. Nevertheless, there was lack of knowledge on long-term benefits on nutrition supply for maintaining disc height. Hence, the purpose of this study was to investigate the effects of spinal traction treatment on disc nutrition supply and discover the efficiency of this method on disc regeneration. Methods: Thoracic spinal segments (T4-T7) were harvested from six-month-old pigs with average weight of 140 kg in 4~6 hours after sacrifice. Each disc was dissected out by parallel cutting through the transverse midline of cranial and caudal vertebra. The muscles, ligaments, and posterior process were removed before PBS irrigation. Specimens were assigned to the Intact, Severe-degeneration, and Traction group. All discs were physiologically loaded and incubated in an in-house whole organ culturing system for one week. To mimic severe degeneration discs, discs of Severe-degeneration and Traction group were applied with trypsin solution (0.5ml, 0.25%) injection and 5-hour fatigue loading (Frms: 420N, frequency: 2.0Hz) on the first and second day of the incubation period. Discs of Traction group were then treated with spinal traction (traction force: 20kg, duration: 30mins, one cycle: 30 s traction and 10 s relaxation) once per day from the 4th to 6th day of incubation period. Molecular transportation, disc height, cell viability and histology were observed at the end of incubation period. Molecular transportation was evaluated by fluorescence intensity of fluorescein sodium (FS) within discs, which was circulated in the culture system for 1 hr. One-way ANOVA was conducted to compare all measurements. Statistical difference was considered at p<0.05. Result: Severe degenerated discs were found to be with lower disc height, thinner endplate, anulus bulging, lower FS fluorescence intensity within disc and more dead cells in both nucleus pulposus and anulus fibrosus. In Traction group, it was shown that disc height and endplate thickness increased, AF retracted, fluorescent intensity elevated and cells relived. Conclusion: Spinal traction is capable to recover endplate thickness and excessive AF bulging, which successfully opens the blocked nutrition pathways in severe degenerative discs. Improved nutrition supply not only maintains disc height, but also facilitates disc cell growth and thus decelerates degeneration process.