Osteomyelitis of the patella is a very uncommon condition that occurs mostly in the pediatric population. In addition to its rarity, nonspecific and variable clinical presentations usually lead to postponement in making the correct diagnosis. Moreover, it is often missed as prepatellar bursitis or septic arthritis of the knee. Nonetheless making early diagnosis and initiating prompt treatment is most important to preventing this condition from becoming chronic. In this case report, the authors encountered this rare condition of the patella in a child that was first misdiagnosed with pyogenic arthritis or prepatellar bursitis of the knee. The delay in making the diagnosis led to intractable progression of the disease, and sequestrectomy was required to stabilize the condition.