ObjectiveTo explore the surgical technique and effectiveness of limited bone and soft tissue surgery combined with Ilizarov technique in the treatment of adolescents severe cerebral palsy with flattened valgus foot and lower leg external rotation deformity. MethodsA retrospective analysis was conducted on 12 patients with severe cerebral palsy with flattened valgus foot and external rotation deformity of the lower leg, totaling 16 feet, admitted between January 2022 and January 2025. There were 5 males with 7 feet and 7 females with 9 feet, the age ranged from 12 to 18 years, with an average of 15 years. There were 10 cases on the left foot, 6 cases on the right foot, and 4 cases on both feet. The preoperative external rotation angle of the lower leg ranged from 20° to 35°, with an average of 26°. The preoperative visual analogue scale (VAS) score was 4.9±0.9, the American Orthopaedic Foot & Ankle Society (AOFAS) score was 68.7±12.0, the calcaneal tilt angle was (12.69±1.78)°, and the hindfoot angle was (18.69±3.55)°. Patients with bilateral lower leg deformities underwent surgery in two phases, with an interval of 3-6 months between surgeries. Select soft tissue surgery (Achilles tendon elongation, release or transposition of joint capsule and ligaments) and bone surgery (joint fusion, calcaneal osteotomy, medial wedge osteotomy, etc.) combined with tibiofibular internal rotation osteotomy and Ilizarov external fixation were selected according to the patient’s condition. At 1 week after operation, the external fixators of the lower leg and ankle were slowly adjusted, and the deformities that were not completely solved in the three-dimensional correction operation were corrected. Postoperative pain relief and functional recovery were evaluated by VAS and AOFAS scores, and the improvement of foot deformity was evaluated by calcaneal tilt angle and hindfoot angle on radiographic data, and the postoperative effctiveness was evaluated according to the International Clubfoot Study Group (ICFSG). Results At 2 weeks after operation, the foot deformity of the patient was basically adjusted. All patients were followed up 6-36 months, with an average of 18 months. The incisions healed by first intention without nerve injury, infection, or other complications. At last follow-up, the patients recovered satisfactorily, the osteotomy sites healed, and the external rotation of the lower leg was corrected. The VAS score was 1.2±0.1 and AOFAS score was 86.7±6.8, which were significantly different from those before operation (P<0.05). The calcaneal tilt angle was (18.38±1.15)° and the hindfoot angle was (10.06±2.93)°, which were significantly different from those before operation (P<0.05). According to the ICFSG scoring standard, 13 feet were excellent and 3 feet were good, and the excellent and good rate was 100%. ConclusionThe combination of bone and soft tissue limited surgery and Ilizarov technique is a safe, minimally invasive, and effective method for treating severe cerebral palsy in adolescents with flattened valgus foot and external rotation deformity of the lower leg. It conforms to biological principles and follows the concept of natural bone reconstruction.