Three-dimensional virtual modeling for lower limb deformity correction over intramedullary nail

The use of intramedullary nails (IMNs) for deformity correction and limb lengthening has become increasingly established. However, performing acute deformity correction over an IMN remains technically demanding. The purpose of this study was to describe the application of 3D virtual surgical planning and patient specific 3D-printed cutting guides for the management of complex lower-limb deformities in young patients.

This retrospective, single-center study included 21 patients (mean age: 12 years) who underwent surgery using IMNs for complex lower-limb deformities correction between May 2019 and June 2024. Virtual 3D femoral and tibial models were created for preoperative planning and used to design patient-specific cutting guides for the surgical correction. All patients were evaluated for preoperative and postoperative anteroposterior and lateral deformity angles, time to osteotomy union, and complications.

Twenty-one patients underwent correction of 23 extremities. According to an a priori classification, an excellent correction (residual angulation ≤5° in both planes) was achieved in 19/23 extremities (83%) and an acceptable correction (6-10° residual angulation, within the recognized tolerance for the growing skeleton) in 4/23 extremities (17%), no extremity demonstrated residual deformity >10°. Among the 20 patients available for follow-up, the mean time to radiographic union was 8.5 weeks (range, 4.5-18 weeks), excluding the cases treated with a PRECICE lengthening nail for combined limb deformity correction and bone lengthening. No major intraoperative or early postoperative complications occurred, two extremities (8.7%) developed delayed union that resolved without intervention, one planned secondary procedure was performed (4.3%), and one patient (4.8%) was lost to follow-up.

Three-dimensional virtual planning and patient-specific cutting guides represent effective adjuncts for correcting complex lower-limb deformities using intramedullary nails in pediatric patients. This approach enhances the accuracy of preoperative planning and facilitates more precise and controlled surgical execution.