Soft tissue and bone sarcomas of the lower extremity pose significant challenges for affected individuals, often associated with considerable burden. Chemotherapy, load restrictions, and surgery frequently result in long-term physical limitations, causing structural and functional deterioration. These challenges are particularly pronounced in childhood and adolescence, as they affect physiological development, resilience, and autonomy. Yet, it remains unclear whether these deficits can be fully compensated after treatment or if they result in long-term limitations, as this has not been sufficiently studied.

This bicentric study includes children and adolescents undergoing follow-up care for soft tissue or bone sarcoma of the lower extremity within 1 to 5 years since end of therapy. The cohort did not receive any specific prehabilitative training during neoadjuvant therapy. Participants will be divided into two subgroups based on the study site: (1) participants who participated in a non-specific exercise program during acute therapy and (2) participants who did not receive any exercise promotion during acute therapy. Target sample size is n=16. The study has been consented by the local ethics committee.

Several structural and functional parameters are measured to document the natural status of muscular structures and functional abilities after the treatment of a solid tumor in the lower extremities, with a focus on identifying specific deficits and the associated long-term limitations in daily life. The measurements include psoas muscle area, body composition, strength, mobility, balance ability, gait analysis, two questionnaires on physical activity and quality of life, and quantitative measures of the clinical course during acute treatment (days of hospitalization, infection rates, etc.).

For children and adolescents, daily functionality and the experience of autonomy are crucial for physiological development and contribute significantly to quality of life. Therefore, these factors should be investigated and supported in this cohort, a group that is currently underrepresented in scientific research.

Inclusion Criteria:

• Cessation of treatment for a bone tumor or soft tissue sarcoma of the lower extremity 1-5 years ago
• Age Range of 6 to 18 years
• Treatment has been conducted at one of the two designated study sites

Exclusion Criteria:

• Medical contraindications for testing (e.g. injury, pain, dizziness, lack of orthopedic clearance for weight-bearing in the tumor region, other acute orthopedic limitations unrelated to the underlying condition, etc.)
• Language barriers that prevent understanding of the instructions for study participation
• Cognitive impairment or developmental delay that hinders comprehension of the instructions in the testing situation, thereby preventing standardized diagnostic data collection

Participants include children and adolescents during follow-up in Munich/Germany for soft tissue sarcoma or bone tumor at the lower extremity currently 1-5 years after cessation of treatment.