Accessory plantaris muscle can result in symptomatic hardware impingement following ACL reconstruction

Anatomic variants of lower extremity musculature, such as the gastrocnemius, popliteus, and the plantaris have been well described in the literature. The impact of these anatomical variations on clinical outcomes depends on their proximity to and effects on adjacent anatomical structures, particularly in the context of planned surgical procedures in the region. While the presence of the accessory plantaris is rare, no previous cases have described it negatively affecting surgical outcomes to our knowledge. We present a case of a 42-year-old patient who underwent an anterior cruciate ligament (ACL) reconstruction using a femoral Endobutton for graft fixation positioned just beneath an accessory plantaris, leading to impingement and persistent knee pain. This case highlights the importance of understanding anatomical variations when planning and performing surgical procedures and suggests the need for further research in this area.