Arthroscopic removal of intra-articular osteoid osteoma in the knee: case report and review of the literature

Osteoid osteoma is a relatively common benign bone tumor first described by Jaffe [1]. It most frequently arises in the long bones and exhibits a characteristic X-ray appearance, that is, a small radiolucent zone surrounded by reactive circumferential sclerosis (nidus) [2, 3]. Nocturnal pain, which can be alleviated by aspirin, is one of the characteristic clinical manifestations of this bone tumor [4]. Although it is relatively rare, osteoid osteoma can also arise in the intra-articular regions, and we found 14 such cases arising in the knee joint in the literature [5-18]. Patients with intra-articular osteoid osteoma often present with joint pain, intracapsular effusion, restricted motion, and muscle atrophy in the affected limb, which can be mistaken for more common entities, such as traumatic or degenerative pathologies of the joint. Furthermore, X-ray examination often fails to show the characteristic nidus that is typically seen in extra-articular osteoid osteoma and therefore can result in a delayed diagnosis. We herein present a case of intra-articular osteoid osteoma arising in the knee joint, which was successfully treated by arthroscopy, and review the reported cases of intra-articular osteoid osteoma arising in the knee.