Abstract
Inflammatory femoroacetabular impingement (FAI) is a cam lesion caused by inflammation and is characterized by a distinct bone deformity. To date, no reports have described bone deformities resulting from juxta-articular osteoid osteomas that resemble those seen in inflammatory FAI. We report a case of a 15-year-old girl who presented with right hip pain, hip arthritis, and a cam deformity at the femoral head-neck junction. Computed tomography revealed a bone translucency with internal calcification, suggestive of a nidus, at the medial cortex of the right femoral neck. Based on these findings, we diagnosed inflammatory FAI caused by juxta-articular osteoid osteoma. Following resection, her pain resolved rapidly. This is a rare reported case of juxta-articular osteoid osteoma causing inflammatory FAI. Understanding the characteristics of inflammatory FAI can aid in distinguishing between inflammation and FAI as the source of pain.