背景與目的：盂肱關節不穩定指肱骨頭無法穩定地維持在肩盂窩中心。臨床常用加載移位測試評估肱骨頭位移情形，以助評估及擬訂治療計畫。但徒手測試信度不佳，若使用線性位移器或膝關節動度計量化施力與位移量，信度則明顯提高，但這些儀器體積較大，臨床使用不易。本研究選用可攜式雷射距離檢測儀與手握式測力器為量化肱骨頭前向移位的工具，探討莫測試者內信度。方法：共收取15位受試者，以手握式測力器固定4磅與6磅施力，使用雷射距離檢測器測量肱骨頭前向位移量，於同日與隔天分別執行肱骨頭前向位移測試，每個磅數測試5次。以級內相關係數和測量標準誤呈現測試信度與精確度。結果與討論：使用4磅推力測試之平均位移為10.6─10.9公釐，再測試信度為0.86─0.98，測量標準誤為0.62─0.87公釐。使用6磅推力平均位移為13─13.9公釐，再測試信度為。0.88─0.95測量標準誤為0.8─1.2公釐。本研究測試信度達良好以上，不亞於過去儀器測試之信度。本研究施力較小，而位移量相近，推測可能因使用治具減少摩擦力，因此可用較小推力達到相似位移量。臨床應用：本研究建立了以雷射距離檢測器與手提式測力器量化肱骨頭前向移位的測試信度，此方式可助臨床評估量化盂肱關節前向不穩定或鬆弛程度，並監控肩關節穩定運動訓練成效。

Background and Purpose: Glenohumeral joint (GHJ) in stability is defined as inability to maintain the humeral head centered in the glenoid fossa. Accurate noninvasive c1inical tests for shoulder instability are important in clinical assessment and treatment planning for GHJ instability. However, manual tests for assessment of GHJ in stability often lack sound reliability. The purpose of this study was to determine intra-rater reliability of the humeral head anterior translation using a laser displacement meter and fixed displacement force. Methods: We recruited 15 healthy subjects and measured their humeral head anterior translation distance using a laser displacement meter that was known to have high accuracy. A hand-held dynamometer was used to quantify the manual force in displacing the humeral head. Subjects were tested their humeral head anterior translation 5 times on two separate days to determine within-day and between-day intra-rater reliability. Intraclass correlation coefficients (ICC) and standard error of measurements (SEM) were calculated to estimate intra-rater reliability and testing accuracy. Results: The average anterior translation of the humeral head for these subjects were 10.6-10.9 mm when applying a displacement force of 4 pounds and 13-13.9 mm when applying a force of 6 pounds during the tests. Good to excellent within-day and between-day reliabilities, with the ICC values between 0.86 and 0.98 in the 4-pound tests and 0.88-0.95 in the 6-pound tests. The SEM values were between 0.62-0.87 mm for the 4-pound tests and 0.8-1.2 mm for the 6-pound tests. Conclusions: The study has established measurement reliability in quantifying humeral head anterior displacement using a laser distance meter and a hand-held dynamometer. Clinical Relevance: An objective, quantitative, and highly reliable test like this could help clinicians to accurately assess subjects with shoulder instability or laxity and monitor their progress after neuromuscular stabilization training.