Sacral agenesis is a term that applies to a wide range of developmental disorders of the lower portions of the spine and pelvis. Hemisacrum patients with all sacral segments present on one side of the spine, and decompensated lumbar rotoscoliosis, whit instability torac-pelvic that had transiliac lengthening of the lower extremity, accomplished by an innominate osteotomy with interposition of a rectangular iliac-bone graft in the osteotomy site, besides a posterior lumbar-iliac percutaneous fusion. We reported 5 adolescent patients, 2 men and 3 women, treated from 2000 to 2009, associated with average pelvic imbalance of 3.2 cm (2.5–4.5 cm) without other associated congenital anomalies. Patients classified as Vergara (Acta Ortop Mex 19:6–12, 2005) type IB unilateral partial agenesis of the sacrum, asymmetry of the pelvic ring there's a torac-pelvic cifoscoliotic deformity. Mean age was 12.2 years-old (range from 8.2 to 13.7). The mean follow-up was 7.2 years (from 2 to 8). The consolidation process of the osteotomy site was in an average of 6.4 (5–8.7 weeks) (P = 0.036). None of the patients presented family medical history of diabetes on their mothers. None residual femoral nerve palsy. The procedure offers postural correction at the level of the pelvis, low morbidity and no additional operations were required to achieve the surgical objective. Level of evidence Level IV, therapeutic study: Case series (no, or historical, control group), Prospective: The study was started before the first patient was enrolled.