Total knee arthroplasty for severe valgus deformity of the knee with extra-articular deformities of the femur and tibia using a 3-dimensional image matching software system

INTRODUCTION AND IMPORTANCE: Knee osteoarthritis with femoral and/or tibial extra-articular deformities makes total knee arthroplasty (TKA) technically difficult to perform, especially using intramedullary-based instrumentation systems. The Athena Knee 3-dimensional (3-D) image matching software is effective for TKA with an extra-articular deformity, especially in case of using a long-stem prosthesis or not available computer-assisted navigation systems. CASE PRESENTATION: A 79-year-old woman presented with right knee pain secondary to a progressive valgus deformity and gait disturbance. She had experienced a supracondylar femoral fracture fifteen years ago, and a tibial shaft fracture ten years ago on the same side; both of fractures were treated surgically. She had a severe valgus knee deformity and extra-articular deformity of femur and tibia, and valgus stress test detected medial knee instability. The range of motion was 0° in extension and 75° in flexion. Severe medial knee laxity compelled us to use a constrained and long-stem prosthesis, resulting in the use of an intramedullary guided system. The 3-D software system helped us to determine the amount of bone to cut as well as the appropriate entry points for the intramedullary rods and mechanical axis restoration. At two years after surgery, knee range of motion improved to 90° in flexion, and walking ability had also advanced from the use of two crutches to that of a T cane. CONCLUSION: The 3-D image matching software system for preoperative planning was useful for TKA with extra-articular deformity, especially in the case of a long-stem prosthesis without using a navigation system.