貝克氏囊腫在類風濕性關節炎中的盛行率：一超音波研究

Baker's cyst in rheumatoid arthritis: a musculoskeletal ultrasound study

目的：研究貝克氏囊腫在類風濕性關節炎病患中的盛行率。方法：回溯分析150位類風濕性關節炎病患的臨床症狀與骨骼肌肉超音波發現，並分析（1）年齡與貝克氏囊腫發生率相關性，（2）貝克氏囊腫大小與破裂的相關性，（3）貝克氏囊腫大小與膝關節積液多寡的相關性。結果：經由超音波發現150位類風濕性關節炎病患中有39位具有貝克氏囊腫（26%），亦即在300個膝關節中有48個膝關節有貝克氏囊腫（16%）。在48個貝克氏囊腫中，有11個破裂。統計上年齡與貝克氏囊腫發生率相關性（p=0.4554），貝克氏囊腫大小與破裂的相關性（p=0.5342），貝克氏囊腫大小與膝關節積液多寡的相關性（p=0.3910）均未達統計學上的關聯性。結論：在類風濕性關節炎病患中，貝克氏囊腫是相當常見的且很容易被臨床所低估。在針對貝克氏囊腫相關併發症以及治療，骨骼肌肉超音波對於臨床醫師是相當實用的。

Objectives: To investigate the frequency of Baker’s cysts in rheumatoid arthritis (RA). Methods: We retrospectively analyzed the clinical and musculoskeletal ultrasound (MUS) findings of 150 patients diagnosed with RA according to the American College of Rheumatology revised criteria. We used logistic regression to analyze the relationship between (1) patient age and incidence of Baker’s cyst and (2) diameter of the cyst and incidence of rupture. In addition, we used analysis of variance (ANOVA) to analyze the relationship between knee effusion grading and the diameter of the Baker’s cyst. Results: Baker’s cyst was detected in 39 patients with RA (26%) and in 48 of the 300 examined knees (16%). Eleven of the 48 cysts ruptured. Age was not correlated with the incidence of Baker’s cyst (p = 0.4554), and cyst diameter was not correlated with the incidence of rupture (p = 0.3910). Knee effusion grading was not correlated with cyst diameter (p = 0.5342). Conclusion: Although Baker’s cyst is common in RA, it is not easy to diagnose. Ultrasound should be widely employed to diagnose Baker’s cyst. Furthermore, clinicians should be alert in identifying this common complication of RA, which may be accompanied by considerable morbidity.