Background <p>Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disorder caused by homozygous deletion or mutation of the SMN1 gene. Scoliosis is a common complication in patients with SMA type 2, often leading to impaired sitting balance, reduced respiratory function, and poor quality of life. We report a case of SMA type 2 with severe kyphoscoliosis successfully treated with posterior spinal fusion.</p> Case presentation <p>A 16-year-old Chinese male presented with progressive spinal deformity and a 14-year history of lower limb weakness. He had never walked independently and was wheelchair bound. Clinical examination revealed hypotonia, areflexia, and a severe thoracolumbar kyphoscoliosis. Genetic testing demonstrated homozygous deletion of SMN1 exon 7, three copies of SMN2, and one copy of NAIP, confirming SMA type 2. Preoperative supine radiography showed a Cobb angle of 83°. The patient underwent posterior spinal fusion with pedicle screw instrumentation from T1 to S2 using S2 alar–iliac screws (S2AIS) for distal fixation. No spinal osteotomy was performed, and deformity correction was achieved by concave distraction and convex compression. Interlaminar artificial bone grafting combined with bone morphogenetic protein (BMP) was used for fusion. Postoperatively, the Cobb angle was corrected to 42°, and he was able to sit upright independently. At 1-year follow-up, the correction was well-maintained and his quality of life was markedly improved. Longer follow-up is needed to confirm the durability of the results.</p> Conclusions <p>Posterior spinal fusion with S2AIS fixation achieved satisfactory deformity correction and improved quality of life in this skeletally mature SMA type 2 patient with severe kyphoscoliosis. Early diagnosis and multidisciplinary management are critical, and larger studies are needed to confirm long-term outcomes.</p>