验证腋囊厚度与查体角度的相关性及超声与磁共振成像测量腋囊厚度的相关性。

本研究纳入30名健康志愿者进行超声及体格检查，并纳入36例在本院门诊确诊为单侧粘连性肩关节囊炎（adhesive capsulitis，AC）的患者进行超声、磁共振成像及体格检查，收集个人信息、腋囊厚度与查体角度（包括外展、外旋、内旋），进行相关性分析及测量一致性分析。

数据显示，尽管健康志愿者与患者健侧肩关节的数据在年龄、BMI、腋囊厚度等参数上差异无统计学意义，但在内旋的差异上具有统计学意义（P =0.042）。患侧腋囊与外旋（r =-0.360，P = 0.031）和内旋（r =-0.497，P =0.002）呈显著负相关，而与身高（r =0.429，P =0.009）和体重（r =0.361，P=0.030）呈显著正相关。在排除健侧影响后，腋囊厚度差值与外旋差值（r =-0.373，P=0.025）呈显著负相关，相关性有所提升，与内旋差值（r =-0.383，P =0.021）呈显著负相关，相关性有所减弱。另外本研究发现，超声测量腋囊厚度（4.39±1.19）mm显著低于磁共振成像（9.08±2.03）mm，且超声与磁共振成像测量呈显著正相关（r =0.676，P<0.001）。

本研究通过横断面研究，充分证实了腋囊厚度与查体角度（外旋、内旋）之间存在显著负相关，超声与磁共振成像测量腋囊的一致性中等，磁共振成像测量厚度明显大于超声（P<0.001）。同时通过与健康志愿者的对比，发现内旋受限可能是AC的早期提示因素。

Adhesive capsulitis (AC) is a disease in which the range of motion (ROM) of the shoulder joint is limited due to chronic inflammation and fibrosis of the joint capsule. It is usually manifested as thickening of the glenohumeral ligament or axillary capsule, joint capsule contracture, and reduced joint volume. The axillary capsule is the most relaxed part of the joint capsule, allowing for sliding when the shoulder joint is abducted and rotated. When chronic inflammation and fibrosis of the joint capsule cause contracture and thickening, the abduction, external rotation (ER), and internal rotation (IR) angles of the shoulder joint will also be restricted. For AC patients, the current imaging examination methods mainly include ultrasound and magnetic resonance imaging. Relevant studies have shown that the normal thickness of the axillary sac under ultrasound is approximately 1.3-2.8 mm, and the threshold for diagnosing AC is about 3.2-3.34 mm. The normal axillary sac thickness under magnetic resonance imaging is approximately 2.9 mm, and the threshold for diagnosing AC is about 4.0-5.0 mm. Ultrasound has the advantages of being non-invasive, convenient, and real-time. It can also dynamically observe the morphological changes of the axillary sac during joint movement, making it more suitable for pre-treatment assessment and post-treatment follow-up of AC. Magnetic resonance imaging (MRI) can simultaneously assess lesions in the axillary sac, rotator cuff tendons, and surrounding soft tissues, making it more suitable for preoperative evaluation. However, to date, most scholars have focused mainly on the threshold for diagnosing AC, the therapeutic effect of AC treatment, and the consistency of axillary capsule measurement by ultrasound and MRI. However, few scholars have compared ultrasound-measured axillary capsule thickness with shoulder joint ROM.

To verify the correlation between axillary capsule thickness and physical examination angle, as well as the correlation between the measurement of axillary capsule thickness by ultrasound and magnetic resonance imaging.

In this study, 30 healthy volunteers were included for ultrasound and physical examination, and 36 patients diagnosed with unilateral AC in the outpatient department of our hospital were included for ultrasound, MRI, and physical examination. Personal information, axillary sac thickness, and physical examination angles (including abduction, external rotation, and internal rotation) were collected for correlation analysis and measurement consistency analysis.

Data show that, in healthy shoulder joints, there is no statistically significant difference in parameters such as age, BMI, and axillary sac thickness between healthy volunteers and patients; however, there is a statistically significant difference in internal rotation (P=0.042). The axillary sac on the affected side was significantly negatively correlated with external rotation (r=-0.360, P=0.031) and internal rotation (r=-0.497, P=0.002), while significantly positively correlated with height (r=0.429, P=0.009) and weight (r=0.361, P=0.030). After controlling for the healthy side, the difference in axillary capsule thickness was significantly negatively correlated with the difference in external rotation (r= -0.373, P = 0.025), and the correlation improved. It was significantly negatively correlated with the difference in internal rotation (r = -0.383, P = 0.021), and the correlation was weakened. In addition, this study found that the thickness of the axillary capsule measured by ultrasound (4.39±1.19) mm was significantly lower than that measured by MRI (9.08±2.03) mm, and there was a significant positive correlation between ultrasound and MRI measurements (r=0.676, P<0.001) .

This cross-sectional study fully confirmed a significant negative correlation between axillary cyst thickness and physical examination angles (external and internal rotation). The consistency of axillary cyst measurement by ultrasound and magnetic resonance imaging was moderate, and the thickness measured by magnetic resonance imaging was significantly greater than that measured by ultrasound. Meanwhile, comparing healthy volunteers with those with limited IR revealed that limited IR might be an early warning factor for AC.