Objective：We conducted a new physical fitness test and assessed activity and social participation in pediatric cancer survivors who participated in our hospital events and examined its characteristics and issues.

Subjects：A total of 30 children aged 5 years or older (median age 9 years, 17 boys, 13 girls) were enrolled in the study. They were chosen from a pool of 44 pediatric cancer survivors who participated in our hospital's long-term follow-up events from August 2018 to August 2019.

Methods：Medical records and evaluations performed at the events were examined retrospectively. Survey items included sex, diagnosis, age at evaluation and onset, years since discharge, physical and cognitive functions, new physical fitness test results, and ability to perform basic physical activity.

Results：Regardless of the number of years since discharge from the hospital, physical fitness tended to be lower than the national average for both sexes and all ages, with a particular decline in endurance. Twenty-six of the 30 subjects (87%) were able to attend school all day and go out for a day. In addition, 11 (37%) participated in physical activities other than physical education and club activities.

Conclusions：Childhood cancer survivors may have a long-term, persistent decline in physical fitness, even if they are able to participate in academic, leisure, and social activities, such as exercise lessons. It is beneficial to provide continuous support for physical fitness during hospitalization and throughout life, as well as to accomplish activities and social participation in accordance with growth.

Heterotopic ossification (HO) is one of the complications of a cervical cord injury that results in limited range of motion, which can interfere with basic movements and activities of daily living. We encountered a case of a cervical cord injury patient with limited range of motion and mobility due to HO of the hip joint who experienced improvement in both as a result of early surgery and rehabilitation. A 17-year-old boy was diagnosed with a cervical cord injury due to an anterior fracture of the sixth cervical vertebrae following a fall into a pool. It was classified as bilateral C6BII according to the Zancolli's classification for cervical cord injury. The patient presented with limited range of motion in his left hip and was diagnosed with HO four months after the injury. Eight months after the injury, his hip range of motion deteriorated further；consequently, he required continuous transfer assistance. Therefore, surgical HO removal was performed during this period of convalescent rehabilitation. The patient underwent constant post-operative rehabilitation, and the range of motion in his left hip joint improved；thus, he became independent in transfer activities. A concomitant HO after a cervical cord injury can lead to functional impairment in convalescent rehabilitation. In addition, no practice guidelines have been developed that include recommendations on when to perform surgical procedures for HO. Treatment of HO with a combination of immediate surgery and aggressive rehabilitation can be expected to restore function and maximize activity and participation in patients with cervical cord injury with concomitant HO.