Preoperative Virtual Planning Combined with 3D-Printed Surgical Guide Technology for Correction of Shepherd's Crook Deformity: A Case Report.

BACKGROUND Shepherd's crook deformity, a rare and severe skeletal malformation, is characterized by a distinctive shepherd's crook-like curvature of the proximal femur. This pathological condition manifests as a marked reduction in the femoral neck-shaft angle (typically measuring less than 90 degrees). The deformity is most frequently observed in patients with fibrous dysplasia (FD), where it is a hallmark skeletal manifestation of the disease. CASE REPORT A 12-year-old boy presented with progressive deformity of both lower limbs. Physical examination revealed a typical "shepherd's crook" deformity of both femurs with associated abnormalities of the left tibia and fibula. Radiographic findings confirmed polyostotic fibrous dysplasia affecting multiple bones and causing severe lower-limb malalignment. Preoperative three-dimensional (3D) CT reconstruction and digital planning were performed to design an individualized osteotomy, and a patient-specific surgical guide was fabricated to ensure accuracy. Postoperative imaging demonstrated restoration of anatomical axes and improved mechanical alignment. Measurements showed a right femoral neck-shaft angle of 125.7°, a left angle of 129.1°, and a residual limb length discrepancy of 9 mm. The patient recovered well without complications. CONCLUSIONS This case report demonstrates the integration of preoperative virtual surgical planning with 3D-printed patient-specific guides for precise correction of femoral shepherd's crook deformity, exemplifying the clinical application of digital orthopedic technologies in complex skeletal reconstruction.