踝关节泪滴征(Teardrop Sign)：踝关节积在侧位平片上的x线征象，正常踝关节关节囊前壁和后壁表现出脂肪样密度，当踝关节积液时，关节囊肿胀，并表现出液体样密度，呈泪滴样改变。
Causes
- trauma 外伤
- gout 痛风
- rheumatoid arthritis 类风湿关节炎
- synovitis 滑膜炎
- infectious arthritis 感染性关节炎
Carke等报道：外伤病人踝关节肿胀>=13mm（d1+d2）预示骨折的阳性率为82%；进行进一步影像学检查的合理阈值。
Carke et al (2) reported that ‘An ankle effusion of 13 mm (d1 + d2) or greater in total capsular distension has a positive predictive value of 82% for occult fracture and is a reasonable threshold to prompt additional imaging.’