背景與目的：肌肉骨骼系統超音波影像在臨床診斷上由於非侵入性、可立即顯示影像且價格便宜，所以普遍性很高。但到目前為止仍未有以超音波評估退化性膝關節炎患者滑膜囊厚度之研究；也缺乏超音波應用在此之信度。方法：二位受過訓練之評估者，以8位（共10膝）退化性膝關節炎患者為研究對象；受試者先後接受二位評估者之評估，其間間隔為20分鐘，此為評估者間再測信度之測試；另20分鐘之後由第一位評估者再次重覆評估，此為評估者內再測信度之測試。測試時，受試者平躺放鬆，受試腳放在固定用之三角架上，利用關節量角器確認膝關節擺位在彎曲30度之姿勢接受檢查，將超音波探頭輕輕擺放在傳導膠上，控制探頭以不碰到皮膚為原則；總共有四個測量部位：髕骨上、下及內、外側滑膜囊四部位。結果：髕骨上方及下方滑膜囊，不論評估者間或評估者內都有極高之重測信度（相關係數：0.93-0.99），雖然髕骨內側及外側之相關係數值落在高度信度（相關係數：0.82-0.88），但95%信賴區間的範圍較大。本研究之結果顯示評估者間及評估者內再測信度很高，其原因除了評估者事前充分的熟悉膝關節的解剖構造和超音波影像，在測試方法中明確定義及標示出骨突點當做量取指標有很大的關係。另外，本研究中膝關節量測部位在超音波影像的判讀上較單純，也可能是信度高的原因。結論：超音波影像評估應用在退化性膝關節滑膜囊之檢測具極高度之再測信度。

Background and purposes: Musculoskeletal sonography is a simple, rapid, inexpensive tool and widely used for clinical diagnosis. Review literature there has not yet been a study to assess the joint synovitis of osteoarthritic knee and to determine its reliability Methods: Eight subjects (10 knees) who had osteoarthritic knees were included. All subjects were assessed by to observers in the same day, but taking twenty minutes interval. This study aimed to declare the reliability of interrater and intrarater. Subject was supine with the knee in 30° flexion and the measurments of synovium were done around patella at superior, inferior and lateral, medial portion Results: The reliability of interrater and intrarater were very high in all four parts of patellar region However, the 95% confidence interval of the medial and lateral parapatellar reliability were wider than those of the supra- and infrapatellar reliability. Conclusions: The high reliability of synovitis assessed by sonographic image may be due to well trained observer and easy to perform sonography on knee joint.