Two-stage knee arthroplasty in a patient with chronic osteomyelitis and an extensive metaphyseal-diaphyseal femoral bone defect: A case report.

High-energy open fractures are frequently complicated by osteomyelitis and femoral nonunion. Treatment of these conditions poses a significant challenge for surgeons and often results in limb amputation. A case of an infected nonunion of open distal femoral fracture, complicated by osteomyelitis and septic arthritis of the knee caused by a multidrug-resistant strain of Acinetobacter baumannii and methicillin-resistant Staphylococcus epidermidis with the initial Oxford knee score (OKS) of 7/48 is presented. The report demonstrates the use of a two-stage arthroplasty technique with an articulating spacer during the first stage for a metaphyseal-diaphyseal femoral defect of 8 cm, preserving the weight-bearing capacity and function of the knee joint (OKS of 18); whereas at the second stage, the segmental defect was repaired with an allograft and a tantalum cone (OKS of 32). This case serves as a valuable reference for medical professionals dealing with chronic osteomyelitis involving the knee joint and arthroplasty. Further research on this technique is necessary to improve clinical outcomes.