Heterogeneous popliteal cyst in an 89-year-old woman with known total knee arthroplasty presenting with a palpable mass. Sagittal T2-weighted MRI shows a few septa and hypointense internal debris in an otherwise common Baker’s cyst. Despite the severity of artifact due to metallic hardware, it is still possible to appreciate its relationship to the medial gastrocnemius and the semimembranosus tendons. Absence of enhancement after gadolinium intravenous administration was confirmed in the same study (not shown). MGc, medial gastrocnemius; Sm, semimembranosus