The complete type of suprapatellar plica in a professional baseball pitcher: consideration of a cause of anterior knee pain.

Abstract We report the case of a professional baseball pitcher who achieved complete relief of an anterior knee pain after resection of a complete type of suprapatellar plica under arthroscopy. The 27-year-old male professional baseball pitcher had complained of right anterior knee pain while pitching for more than 2 years. On physical examination, the mobility of his patella was limited and he complained of tenderness along the joint line of his lateral patellofemoral joint. The preoperative patellofemoral axial radiograph showed osteophyte formation on the lateral edge of the patella. On preoperative magnetic resonance imaging, a septum dividing the suprapatellar pouch was found. Arthroscopy revealed obvious cartilaginous damage on the lateral facet of the patella and facing trochlea of the femoral condyle. There was a complete type of suprapatellar plica. The suprapatellar plica seemed to be anchoring the patella, which reduced the mobility of the patella. After resecting the complete type of suprapatellar plica under arthroscopy, the mobility of the patella was improved. Because his anterior knee pain while pitching reduced rapidly postoperatively, he could return to regular baseball. We consider that the main cause of his anterior knee pain was cartilaginous damage on the patella and the trochlea, which might be accelerated by the existence of the suprapatellar plica that reduced the mobility of the patella.