Introduction There are not enough published studies on the impact of early isolated triceps lengthening operations in hemiparesis on the state of motor characteristics and on the development of orthopedic complications in children with GMFCS II.Purpose Analyze motor locomotion in children with spastic hemiplegia who had not previously been operated on and those who had undergone isolated surgical lengthening of the triceps at an early age.Material and methods Four groups of children with spastic hemiplegia according to Rodda et Graham types: I) type 2a gait (4 children), II) type 3 (3 children), III) type 4 (7 children), IV) type 4 with previous triceps lengthening (9 children).Results The features revealed in gait types 2a, 3 and 4 in the sagittal plane correspond to the characteristic and previously described features. In all groups, asymmetric rotational movements of the pelvis and tilt asymmetry in the frontal plane were observed. In the group of early isolated tricep lengthening, a decrease in the moment of force by pushing with the foot at the end of the single-support phase was revealed, in combination with an increase in the moment of forces of knee joint extension in the single-support phase.Discussion Early isolated triceps lengthening that weakens its function leads to a compensatory increase in the work of the knee extensors which is similar to the mechanism to of iatrogenic crouch gait, but does not result in a complete loss of walking function in the conditions of a contralateral healthy limb.Conclusions Movement pathology is present in all three measurement planes in gait types 2a, 3, 4 according to the Rodda et Graham classification. The most pronounced deviations were found in gait type 3. The rotational turn of the pelvis is an initially compensatory mechanism due to intratorsion femur deformity. Isolated triceps lengthening surgeries performed at an early age lead to reduced plantar push strength, increased compensatory work of the knee extensors, and probably do not prevent the orthopedic pathology found in Rodda et Graham's gait type 4.