Revision total knee arthroplasty: the end of the allograft era?

Abstract

Total knee arthroplasty (TKA) is highly successful, with an exponential increase expected in the near future [1, 2]. More importantly, a fivefold increase in the number of revision TKAs is expected by 2030 [1, 2]. In the latest studies, the top seven reasons for revision TKA include aseptic loosening (23.1 %), infection (18.4 %), polyethylene wear (18.1 %), instability (17.7 %), pain/stiffness (9.3 %), osteolysis (4.5 %), and malposition/misalignment (2.9 %) [1, 3]. With modern implants, constraint can be effectively managed [4]. However, one of the remaining challenges in revision TKA is the management of severe bone loss [4]. Traditionally, allografts have been widely utilized to manage bone loss, with a significant failure rate at only mid-term follow-up [4]. New techniques with restoration of the metaphysis have been developed to optimize the results of revision TKA [4–8]. In this editorial, it was our aim to present contemporary management solutions for severe bone loss encountered at the time of revision TKA. The main goal of revision TKA is to restore patient function with a stable, painless, and mobile knee. As such, the surgeon must overcome three basic challenges: (1) implant fixation, (2) alignment in all planes, and (3) proper patellofemoral tracking. The unifying principle that often limits achieving these goals is marked bone loss. In modern revision TKA systems, stems and augments are very helpful. However, the main challenge remains long-lasting stability of the implants despite a significant bone loss [4]. Two types of bone defects can be observed in revision TKA: cavitary defects or segmental defects [4]. Classifications [such as the American Academy of Orthopaedic Surgeons (AAOS) and Anderson Orthopaedic Research Institute (AORI) classification] have been created to categorize the bone loss, which may be difficult to determine preoperatively, particularly when implants must be first removed [4]. In reality, preoperative radiographic assessment helps determine whether the defect is segmental, cavitary, or combined [4]. This is important because segmental defects should be re-constructed to properly support the implant. In addition, the level of constraint should be adapted accordingly if the bony insertion of the collateral ligaments is not present or functional [4]. Unfortunately, utilizing undersized press-fit stems and adding more bone cement are still utilized to manage many large bony defects [4]. Morcellized allograft still has a role & Sebastien Parratte sebparratte@gmail.com; sebastien@parratte.fr