Decrease in peripheral muscle strength and ankle dorsiflexion as long-term side effects of treatment for childhood cancer

Background. This study investigated muscle strength, passive ankle dorsiflexion, and their association with motor performance in children after treatment for acute lymphoblastic leukemia, Wilms tumor, B-non-Hodgkin lymphoma, and malignant mesenchymal tumors. Procedure. Muscle strength was assessed with a hand-held dynamometer and ankle dorsiflexion with a goniometer in 92 and 64 survivors, respectively. Motor performance was measured with the Movement Assessment Battery for Children (movement-ABC). Age at testing: 6.1-12.9 years. Mean time since completing treatment: 3.3 years. Results were compared to 155 healthy controls. Results. Muscle strength of the survivors was reduced in ankle dorsiflexors on both sides (P < 0.001), wrist dorsiflexors on the non-dominant side (P < 0.001), and pinch grip on the non-dominant (P = 0.001) and dominant side (P = 0.01). Passive ankle dorsiflexion of the survivors was significantly less on both sides (P < 0.01). Movement-ABC percentile score was affected by pinch grip strength on the non-dominant (P < 0.004), and dominant side (P = 0.024) but not by strength of other muscle groups or by passive ankle dorsiflexion. Conclusion. Peripheral muscle strength and ankle dorsiflexion are reduced in the long-term in children treated for cancer with chemotherapy. However, neither decreased muscle strength nor reduced ankle dorsiflexion could completely explain reduced scores on the movement-ABC.