Comparison of patient-specific instruments with the computer-assisted navigation in total knee arthroplasty for osteoarthritis in a patient with femoral fracture malunion

Extra-articular femoral deformity in total knee arthroplasty (TKA) is a challenge the surgeon must face when using the conventional cutting devices to perform distal femoral intra-articular resection. A variety of new instruments have sprung up to overcome this problem, including patient-specific instruments (PSI) and computer-assisted navigation (CAN). We compared these two instruments in guiding the coronal resection in TKA for osteoarthritis in a 58-year-old woman with a femoral fracture malunion. The patient demonstrated a satisfactory functional outcome and neutral lower limb alignment. Both of PSI and CAN are promising alternatives to conventional devices in the present of extra-articular deformity. The preoperative preparation of PSI is time-consuming but the resection procedure is simple. CAN has the contrary characteristics and it is more reliable than the PSI.