Surgical Technique for Anteromedialization of the Tibial Tubercle with the Tracker AMZ Guide System

realign the knee extensor mechanism. Proximally, Insall realignment or variations with imbrication of the vastus medialis obliquis (VMO) and medial patellar retinaculum, combined with a lateral release, have been used extensively to improve patellar tracking. Distal realignment, in which the tibial tubercle is typically moved medially to improve patellar alignment, is the other common approach to extensor mechanism realignment. Some tibial tubercle procedures, such as the Hauser technique, have moved the tibial tubercle posteriorly “down” the medial slope of the tibia as the tibial tubercle is moved medially. Unfortunately, this type of procedure can increase loads on an already compromised patella. Others, such as the Emslie-Trillat procedure, use a flat osteotomy cut behind the tibial tubercle and subsequent straight medial tibial tubercle displacement to realign the extensor mechanism. The importance of preventing overload on the realigned patella cannot be overemphasized. The frequently noted “benign” or “normal” chondrosis (often found in even asymptomatic individuals along the medial facet of the patella) may not be benign if it is subjected to increased forces after a straight medialization procedure. Furthermore, increased force onto a medial facet lesion sustained at the time of a dislocation may contribute to further chondral deterioration or increased symptoms. Bandi and Maquet described procedures to reduce contact stress on the patella by elevating the tibial tubercle anteriorly. This has been helpful to many patients with patellar arthrosis. The original procedure attempted to unload the patella in patients with arthrosis and was not specific for those with concomitant malalignment. The concept of anteromedial tibial tubercle transfer, as described by Fulkerson, combines the benefit of extensor mechanism realignment with unloading of the patellofemoral articulation through tibial tubercle elevation. An oblique osteotomy posterior to the tibial tubercle permits tibial tubercle displacement along a smooth osteotomy plane in an anterior and medial direction. Thus, anteromedialization (AMZ) is a natural evolution from those earlier procedures. In addition to combining realignment with elevation, distant bone graft harvest is avoided. The complication rate with anterior medialization has been lower than with straight anteriorization and Surgical Technique for Anteromedialization of the Tibial Tubercle with the Tracker AMZ Guide System