Table 1.

Demographic information, clinical presentation, preoperative and postoperative features of the patients treated by arthroscopic removal of intra-articular osteoid osteoma of the knee

Age (yr)/gender	Side	Symptoms	Pain alleviating on NSAIDs	Duration of symptoms until the accurate diagnosis (mo)	Trauma history	Location	Diagnostic imaging	Arthroscopic portals	HPA confirmed osteoid osteoma	Follow-up (mo)	Recurrence
16/F	L	Persistent knee pain worsening at night	Yes	15	Yes	Anterolateral part of the femur above the cartilage border of the trochlea	CT, bone scan	AM, AL, SL	Yes	171	No
23/M	L	Persistent knee pain worsening in activity and at night	Partially	24	No	Anteromedial part of the femur on the cartilage border of the trochlea	MRI (2)1, bone scan	AM, AL	Yes	24	No
17/F	L	Persistent knee pain worsening in activity and at night	Yes	6	No	Anterolateral part of the femur above the cartilage border of the trochlea	MRI, CT	AM, AL, SL	Yes	55	No
37/F	R	Persistent knee pain and swelling	Yes	12	No	Posterior aspect of the lateral femoral condyle	MRI, CT, bone scan	AM, AL, PM, PL	Yes	24	No

¹Patient had a first magnetic resonance imaging (MRI) performed, after which another physician performed an open biopsy at our department. As the symptoms persisted over the course of 10 mo, the patient was referred to the senior author to re-evaluate the case. After detailed analysis, the senior author suspected of intra-articular osteoid osteoma (iaOO) of the knee and issued a bone scan and a follow-up MRI, which confirmed the diagnosis of iaOO of the knee. NSAIDs: Non-steroidal anti-inflammatory drugs; HPA: Histopathologic analysis; F: Female; M: Male; CT: Computerized tomography; MRI: Magnetic resonance imaging; AM: Anteromedial; AL: Anterolateral; SL: Superolateral; PM: Posteromedial; PL: Posterolateral.