Revision total knee arthroplasty: Management of bone loss

Abstract

Bone loss is a common problem in revision total knee arthroplasty (TKA). The potential causes of bone loss are numerous, including osteolysis, septic loosening, direct mechanical bone loss, stress shielding, or iatrogenic from implant removal. Each revision TKA presents a unique challenge, depending on the magnitude of bony deficiency and the combination of etiologies. Preoperative and intraoperative evaluation of bone deficiency can predict the options for reconstruction. In the management of bone loss in revision TKA, it is imperative to consider not only the defect size and the extent of metaphyseal involvement but also patient demographics, including age, BMI, activity level, and life expectancy. The armamentarium of available treatment options is broad and includes polymethylmethacrylate (PMMA) with or without reinforcing screws; morselized or structural allograft; modular TKA systems including stems, wedges, and metal augments; and orthopedic salvage systems such as mega- or tumor prostheses. While morselized allograft is a suitable option for smaller, contained defects, use of allograft has inherent disadvantages, including risk of disease transmission, late resorption, and fracture/nonunion in the case of bulk allografts. The introduction of ultraporous metal augments and cones offers additional options to address structural defects in revision TKA, even in the face of metaphyseal compromise. Each revision is unique, and the degree of bone loss can be widely variable, making a strict treatment algorithm often impractical. Hence, proper treatment of bone loss entails understanding the multitude of management options in addition to the defect and patient being treated.