Worrisome and Incidental Signs on Knee Radiographs SA–CME REVIEW head of the gastrocnemius tendons. Typically, joint contents travel into the Baker cyst through a mecha- nism resembling a one-way valve. 35 Displaced osteochondral bodies, and even meniscal fragments, are known to collect in Baker cysts. Radiographically, single or multi- ple well-defined osteochondral bod- ies appear as one or more mineral- ized masses in the soſt tissues behind the knee (Figure 10). Identifying additional findings associated with osteoarthritis — osteophytes, joint space loss, geodes, and/or subchon- dral sclerosis — should allow more confident diagnosis of degenerative osteochondral bodies in a Baker cyst without the need for follow up. Radiographs that lack any other signs of osteoarthritis, have an ill-defined or stippled pattern of mineralization, or show an unexplained mineralized soſt-tissue mass in a location not consistent with a Baker cyst should undergo cross-sectional imaging to exclude malignancy or other worri- some conditions. 35,40 Miscellaneous (Incidental) Multi-partite Patella Developmental anomalies of the patella are common. The patella is the largest sesamoid bone in the body with variable fusion patterns of secondary ossification centers. The most common location is the superolateral pole. 41,42 Particularly in the setting of trauma, multi-partite patella can create diagnostic uncer- tainty on radiographs by mimicking the appearance of acute fracture. Multi-partite patella can be differ- entiated from a comminuted fracture by identifying two or more smooth, well-defined, and non-united round or ovoid secondary ossification centers located at the superolater- al pole and separated from each other and the larger patellar body by well-defined curvilinear lucen- cies (Figure 11). 41-43 In the absence of associated bony tenderness with direct palpation at the site of a classi- cally-appearing multi-partite patella on physical examination, no follow up is necessary. Conclusion Knee radiography is common in daily clinical practice. Knowl- edge of worrisome signs related to difficult-to-detect traumatic knee pa- thology informs radiologists when to expeditiously recommend additional imaging and/or clinical evaluation. Familiarity with less-common incidental signs of degenerative joint disease and developmental anomaly allow for definitive diagnosis and confidence that no further evalua- tion is required. References 1) Kim YW, Mansfield LT. 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Applied Radiology 15 January / February 2023