ABSTRACT
Objective To investigate the shape of the infrapatellar plica of the knee and its anatomical relationship with the femoral insertion of posterior cruciate ligament(PCL).Methods Thirteen fresh frozen adult cadaveric knee joints(6 left knees and 7 right knees) were dissected to explore the shape of the infrapatellar plica and its anatomical relationship with the femoral insertion of PCL.According to the HE staining,The junction of the femoral insertion of the infrapatellar plica and PCL was also observed using the hematoxylin-eosin staining.Results There was an infrapatellar plica in the knee,the anterior of which was connected to the fat pad.And then it passed the PCL at the lateral side,posteriorly connected to the middle part of the sagittal septum located between the anterior and posterior cruciate ligament.The posterior part of the sagittal septum formed the posterior septum of the knee.It was found that the infrapatellar plica could be classified into the complete type(membrane type) of 15.4％ (2/13),the incomplete type (separate type) of 76.9％ (10/13) and the absent type of 7.7％ (1/13) according to their morphologic characteristics.Moreover,the femoral insertion of the infrapatellar plica and the PCL was very close histologically.Conclusion The anatomical relationship between the infrapatellar plica of knee and the femoral insertion of PCL was very close in the anatomical structure.The infrapatellar plica is morphologically classified the complete type(membrane type),incomplete type(separate type) and absent type.