**10. Musculoskeletal effects**

Musculoskeletal toxicity may occur from RT in young children, the severity of which depends on the patient's age at treatment, RT dose, fractionation and RT fields. Growth of normal tissues can be impaired, resulting in reduced spinal growth and sitting height after RT for WT [43]. Scoliosis and kyphosis are other possible complications WT therapy, which may be a result of reactive myocontracture and shortened soft tissues from RT [44, 45], or nerve injury related to surgery [46]. At a median follow-up of 12–13 years, WT survivors have reported scoliosis in 54–67% and kyphosis in 14%, with 10–20% experiencing symptoms or requiring intervention [46, 47]. A higher scoliosis rate of 88% was observed by Mäkipernaa et al., potentially related to a longer median follow-up of 19 years and more complete radiologic followup; nevertheless, the vast majority of patients were still mild and asymptomatic, with 3 of 21 having a scoliosis curvature greater than 10° and only 1 being symptomatic. It is noteworthy that the available data on musculoskeletal complications involved WT patients treated to higher RT doses (median doses >30Gy) than are typically used in the current era [46–48]. Thus, it is likely that the incidence and severity of scoliosis after modern WT therapy are lower than previously published. Slipped femoral capital epiphyses can occur after RT for WT that includes the hip joint. The incidence is higher in children <4 years of age and after RT doses >25 Gy to the hip [49].
