Objective To investigate the therapeutic effect of an improved type of cranial vault reconstruction surgery

combined with helmet correction after surgery for unilateral lambdoid craniosynostosis in infants. Methods Clinical data of patients with unilateral lambdoid craniosynostosis from July 2021 to September 2025 were retrospectively analyzed. An improved type of skull reconstruction was used for surgical treatment. The patient was placed in a prone position， and the affected parietal bone at 1.5 cm beside the midline was removed and subjected to an “X” osteotomy， which was remodeled to make it bulge. On the contralateral side， a “C”-shaped osteotomy was performed along 1.5 cm posterior to the coronal suture and beside the midline to 0.5 cm anterior to the lambdoid suture. A transverse osteotomy about 1.5-2 cm wide posterior to the sagittal suture was performed to completely disconnect the midline bone strip from the occipital bone. After the plastic reconstruction， the affected side of the parietal bone was reduced and fixed， and the contralateral “C”-shaped osteotomy bone flap was fixed on the remaining midline bone strip to make the compensatory side of the parietal bone contract. Orthotic helmets were worn from 2 to 4 weeks postoperatively for 6 to 12 months，20 to 22 hours per day. The patients were followed up regularly to observe the head shape， measure the cranial vault asymmetry index （CVAI） and the volume of left and right  posterior cranial cavity. The results were satisfactory if CVAI<3.5. Results A total of 7 patients with unilateral lambdoid craniosynostosis were enrolled， including 3 males and 4 females， aged from 5 to 18 months， with preoperative CVAI 6.15± 2.82. The hospital stay was （11.57±1.62） days， and the intraoperative blood loss was （105.71±23.0） mL. The operation was safe， only scalp swelling and fever occurred after operation， and no serious complications occurred. All patients were followed up for 6 to 12 months， and the head asymmetry was significantly corrected. At 6 months after surgery， the CVAI of helmet correction was 1.45±1.19， all less than 3.5， which reached the satisfactory standard. The preoperative CVAI， postoperative CVAI and postoperative helmet correction CVAI at 6 months were statistically different （P<0.05）. There was a significant difference in the volume difference between the left and right posterior cranial cavity before operation and 6 months after operation （P<0.05）. Conclusion Modified type of cranial vault reconstruction surgery combined with helmet correction for the treatment of unilateral lambdoid craniosynostosis in infants is safe and has few complications. This surgical method can effectively correct the head asymmetry of such patients， and after the helmet correction for 6 months， the head asymmetry was further corrected. The correction effect of unilateral lambdrage synostosis is satisfactory.

Craniosynostosis, Cranial vault reconstruction surgery, Lambdoid craniosynostosis, Orthopedic