Femoral Extra-articular Deformity in the Context of Prosthetic Knee Surgery and Application of Customized Treatment Using 3D Planning and Printing Techniques.

Introduction: Extra-articular deformity is that located proximal to the femoral epicondyles or distal to the neck of the fibula. In patients with gonarthrosis associated with extra-articular deformity, a different evaluation and approach will be necessary at the time of planning the arthroplasty. 3D planning and printing techniques have had a major impact on pre-operative planning, allowing the production of custom guides at low cost and in an accessible way. To our knowledge, this is the first report of combined 3D-guided extra-articular femoral osteotomy and total knee arthroplasty (TKA) for the treatment of extra-articular deformity and knee osteoarthritis.

Case report: We present the case of a 48-year-old caucasian male with gonarthrosis and a history of supracondylar femoral fracture with vicious consolidation. The pre-operative scan images were used for planning in collaboration with the engineers of the 3D planning and printing unit of our hospital. Two guides were designed and printed using biocompatible resin. The first one has a cannulated cylinder attached to a template of the patient's distal femoral surface to locate the entry point to the intramedullary canal. The second one fits the anterior cortex of the femur, over the fracture callus, and has six cannulated cylinders attached; four of them guided K-wires through the plane of the osteotomy and the other two guided position K-wires that would ensure canal alignment in the next step. A fixation and control plate was designed to maintain the corrected alignment until the definitive fixation with a retrograde femoral nail. After corrective osteotomy and fixation, TKA was performed. Six months after surgery, the patient is independent, pain-free, and does not use mechanical aids for walking. X-ray shows consolidation of the osteotomy and restoration of the mechanical axis of the limb.

Conclusion: The use of home 3D printers and open-source software, as well as the creation of a multidisciplinary 3D unit with orthopedic surgeons and bioengineers, makes it possible to obtain customized guides or implants with satisfactory clinical results at minimal cost.