退化性關節炎患者關節軟骨在動態負重後的變化

Abstract

背景: 膝關節退化性關節炎被定義為關節軟骨退化磨損伴隨硬骨不正常增生和滑液囊發炎，為老年人常見之慢性疾病，同時也是造成失能的一個重要成因。關節軟骨機械特性改變使動作過程中有更多壓力傳遞至軟骨下骨，被認為可能是此類型患者疼痛的來源之一。目前核磁共振影像相關研究大多是觀察此類型患者軟骨在靜態負重後的變化，無法呈現日常動態活動像是行走時軟骨承重後的變化。 目的: (一)比較退化性關節炎患者與沒有膝關節症狀之女性其關節軟骨性質與型態是否存在差異; (二)比較退化性關節炎患者與沒有膝關節症狀之女性其關節軟骨在十分鐘踏步測試後的性質與型態的變化。 方法: 本實驗收集膝關節退化性關節炎患者與沒有膝關節症狀之女性，在十分鐘踏步前後收取膝關節核磁共振影像，分析關節軟骨性質(橫向鬆弛時間)與型態(體積、厚度)的變化，此外會使用問卷(The Western Ontario and McMaster Universities Osteoarthritis index, WOMAC)來紀錄膝關節退化性關節炎患者的臨床症狀。利用獨立樣本t檢定(Independent t test)比較兩組基本資料及關節軟骨踏步前的狀態，雙因子混和設計變異數分析(Two-way mixed-design ANOVA)比較兩組在踏步前後關節軟骨性質與型態的變化，顯著水平定在0.05。若任何交互作用達顯著，將進行事後分析，並使用Bonferroni做調整。如果關節軟骨變化會因為組別不同而有所不同(group*time interaction)，則會採用Pearson相關係數評估軟骨性質與型態與問卷分數的相關性。 結果: 共十名退化性關節炎患者(年齡：61.3±9.4、身體質量指數：26.5±2.9)與十名沒有膝關節症狀之女性(年齡：55.2±6.51、身體質量指數：22.5±1.4)參與本試驗。退化性關節炎患者之身體質量指數顯著高於沒有膝關節症狀之女性(p<0.001)，沒有膝關節症狀之女性其外側脛骨軟骨則顯著較退化性關節炎患者厚(p=0.045)，在年齡、關節軟骨性質與其他區域之軟骨型態沒有顯著差異。十分鐘踏步後，關節軟骨的變化並沒有因為組別不同而有所不同，兩組在內側股骨區域的橫向鬆弛時間在踏步後與踏步前相比都呈現顯著下降(35.83±12.41ms vs. 29.17±10.9ms)，在內側脛骨體積於踏步後七分鐘與踏步後二十一分鐘呈現顯著增加(1.4±0.27mm vs. 1.45±0.26mm)，外側脛骨厚度與體積則存在組間差異。 結論: 退化性關節炎患者與沒有膝關節症狀之女性在十分鐘踏步前後膝關節軟骨在性質與型態上的變化並沒有顯著差異，但兩組在踏步十分鐘後內側股骨區域橫向鬆弛時間都有下降的趨勢。不同的身體質量指數可能是造成兩組症狀有無的原因。

Background: Knee osteoarthritis (OA) is characterized as a progressive loss of articular cartilage associated with bone hypertrophy and capsule thickening, which is commonly affecting elderly population and acting as a major cause of disability. Although articular cartilage is aneural and avascular in nature, mechanical property changes in degenerative cartilage may lead to an increase in joint stress transmitted to subchondral bone that causes pain during weight bearing activities. However, previous studies only used Magnetic Resonance Imaging (MRI) to investigate cartilage behavior after static loading which does not truly represent cartilage responses in daily activities. Purposes: (1) to evaluate articular cartilage morphology and property difference between knee OA patients and asymptomatic female controls (2) to compare articular cartilage morphology and property changes after ten minutes stepping exercise between knee OA patients and asymptomatic female controls Methods: Knee OA female and asymptomatic female controls were recruited in this study. Knee articular cartilage morphology (volume and thickness) and property (T2 relaxation time) before and after 10 min stepping exercise were measured and compared between control and knee OA individuals. WOMAC questionnaire was used to document clinical symptoms and functional deficits in knee OA population. Independent t test was used to compare demographic data and baseline cartilage condition between groups. Two-way mixed-design ANOVA were used to compare cartilage property and morphology changes before and after ten minutes stepping between groups. The alpha level was set at 0.05. Post hoc analysis with Bonferonni adjustment was performed if any significance effect was found. If cartilage changes were significance difference between group (group*time interaction), Pearson correlation coefficient were used to analyze correlation between cartilage changes and WOMAC score. Results: Ten knee OA patients(age：61.3±9.4、BMI：26.5±2.9) and ten asymptomatic female controls (age：55.2±6.51、BMI：22.5±1.4) were recruited in this study. BMI of the knee OA group was significant higher when compared to the control group (p<0.001). Baseline lateral tibial cartilage thickness was significant higher in asymptomatic controls compare to knee OA group (p=0.045). There were no significant difference in age, cartilage property and cartilage morphology in other regions between groups. Two-way mixed ANOVA revealed no significant differences on cartilage property and morphology changes before and after dynamic loading between groups. Both groups showed significant decreased T2 relaxation time in medial femoral cartilage region (35.83±12.41ms vs. 29.17±10.9ms) after stepping, increased medial tibial cartilage volume(1.4±0.27mm vs. 1.45±0.26mm) between M2 (post loading 7min) and M4 (post loading 21min). Lateral tibial cartilage volume and thickness were significant difference between knee OA group and control group. Conclusion: There were no significant differences in cartilage property and morphology between knee OA patients and asymptomatic controls before and after ten minutes stepping. Decrease T2 relaxation time in medial femoral cartilage region was identified in both group after ten minutes dynamic loading. Different BMI may cause symptoms in knee OA group.