Osteochondral fragements incarcerated in the hip joint during fracture-dislocation have been reported to be the cause of posttraumatic arthritis, and open reduction of the fracture or removal of the fragments during surgery is recommended. Locking symptoms developed during hip joint movement in a patient with a history of hip joint fracture-dislocation (Thompson and Epstein (T-E) type III) after undergoing internal fixation of the acetabular fracture. Computer tomographic (CT) scan revealed a bony fragment impinging on the acetabular weight-bearing portion. This bony fragment was removed using hip arthroscopy. We recommend that CT evaluation be performed after surgery for acetabular fractures. We also recommend arthroscopic removal as a treatment option for posttraumatic loose bodies in the hip joint.