Anteromedial Tibial Tubercle Osteotomy (Fulkerson Osteotomy)

The tibial tubercle (interchangeable with tuberosity) is the most distal anchor of the extensor mechanism and can serve as a tool in altering patellofemoral (PF) mechanics. Known collectively as distal realignment procedures, osteotomies of the tibial tubercle are a useful method to treat a variety of PF conditions by allowing coronal, axial, and sagittal plane adjustments of the patellofemoral articulation which redistribute patellar contact pressures (force and contact area) and potentially improve tracking. Numerous tibial tubercle osteotomies have been described in the literature to treat PF pain, chondrosis, and instability. The most notable include medialization, initially described by Roux and later popularized by Elmslie and Trillat, for the treatment of PF instability and anteriorization of the tibial tubercle described by Maquet performed to treat PF pain associated with arthritis. Each of these procedures takes advantage of important technical alterations in patellar kinematics. Anteriorization of the tubercle elevates the distal extensor mechanism and serves to shift patellar contact forces proximally, while medialization results in a decrease of the lateral force vector. In an effort to avoid complications associated with the Maquet procedure, Fulkerson designed a tubercle osteotomy known as the anteromedialization (AMZ) technique to address PF pain in conjunction with patellar maltracking. The oblique nature of the Fulkerson osteotomy allows for simultaneous anteriorization and medialization of the tibial tubercle. By varying the angle of the osteotomy, the tubercle can be biased to a more anterior or more medial position. Since his initial description, the indications for this procedure have evolved significantly and continue to be refined. This has been primarily driven by the evolution and outcomes of patellofemoral resurfacing procedures as well as improved objective measures of patellar alignment, contact area, and forces. The tibial tuberosity to trochlear groove (TT–TG) distance, popularized by Dejour et al. as an objective measure of tuberosity position, has helped quantify abnormal tuberosity position and enhanced appropriate candidate identification for all tuberosity osteotomies including the AMZ. This becomes important because patellar contact pressures are very sensitive to distal realignment. In addition, combining AMZ with PF cartilage restorative procedures such as autologous chondrocyte implantation and osteoarticular grafting procedures within the PF compartment have demonstrated superior results to either procedure performed independently.