摘要Background: Lower extremity bursae are very vulnerable to injury during strenuous physical exercises.Understanding the imaging characteristics of normal bursae is essential for early diagnosis of morphological abnormalities.Therefore, we evaluated the normal range of lower extremity bursae in healthy young men using high-resolution ultrasound (HR-US) imaging.Methods: Bursae in the lower extremities were examined by HR-US in 290 Chinese healthy young men with a median age of 18 years (range, 18-23 years).The bilateral suprapatellar bursa (SPB), deep infrapatellar bursa (DIPB), popliteal bursa (PB), and retrocalcaneal bursa (RCB) were imaged and measured for analysis.Results: The HR-US identification rates of the SPB, DIPB, PB, and RCB were 89.0％ (517/580), 55.0％ (319/580), 29.4％ (171/580), and 49.5％ (287/580), respectively.With the assumption that the bursae were normal in 95％ of the study participants, the length and width values at the maximal cross-section of the SPB, DIPB, PB, and RCB were ≤18.00 and 6.09 mm, 8.10 and 2.1 1 mm, 7.67 and 3.93 mm, and 7.82 and 2.04 mm, respectively.Conclusions: Using HR-US imaging, we were able to analyze lower extremity bursae with high detection rates in healthy young men.The normal ranges of lower extremity bursa dimensions in healthy young men measured by HR-US in this study could be used as reference values for evaluation of bursa abnormalities in the lower extremity.