The paravicular bone of the foot is a congenital anomaly of the second ossification center of the navicular tuberosity, forming a separate paravicular bone at the navicular tuberosity. The paravicular bone is mostly bilateral. There are two types: one is round with no contact surface with the navicular bone and grows on the posterior tibial tendon like the patella, and its base is a cartilaginous surface composed of hyaline cartilage. It slides in a canal that runs along the posterior tibial tendon. This type is usually asymptomatic. The other type is round or triangular and is part of the navicular bone, but is separated from the navicular tuberosity by fibrocartilage. This type is more likely to be symptomatic. Normally 10% to 14% of people have a pars plana, which is a structural defect of the foot that affects the stability of the foot. Normally, the posterior tibial tendon passes under the medial end of the navicular bone and ends at the base of the second and third two medial cuneiform bones and the base of the second and third two metatarsals. In the presence of the pars plana, the posterior tibial tendon travels above the medial surface of the pars plana and terminates more permanently on the pars plana. This change in the direction of travel and stopping point destroys the inherent role of the posterior tibial tendon in raising the longitudinal arch of the foot and causing the foot to turn inward. As a result, it is very easy to cause flat feet, and easy to strain and cause symptoms. In some patients, although there is no paronychium, the navicular tuberosity is excessively enlarged and the attachment point of the posterior tibial muscle is abnormal, which can also cause similar functional disorders and symptoms. In addition, when walking, the medial projection of the longitudinal arch of the foot, the hypertrophy of the navicular tuberosity rubs against the edge of the shoe, local bursitis occurs, and tenosynovitis can occur in the posterior tibial muscle, producing symptoms such as swelling and pain. Patients are more common in young women. When standing for a long time or walking for a long time, the pain is felt on the medial side of the bottom of the foot. The medial navicular bone is elevated and there is pressure pain. The pain in the medial side of the foot increases when the foot is turned inward against resistance. Localized bursitis may be present. Sometimes, there is also pressure pain in the posterior tibial tendon. X-rays show small bony blocks with neat edges in the posterior part of the navicular bone, with the same density as the navicular bone, and some irregularities in the joint with the navicular bone or with osteosclerosis and cystic changes. In children with mild symptoms, activities can be reduced appropriately, and orthopedic shoes or plaster fixation can be worn to reduce symptoms. If there is bursitis or posterior tibial tendonitis, local hormone closure can be used. If the symptoms are serious and non-surgical treatment is ineffective, surgical treatment can be performed. After lumbar anesthesia or epidural anesthesia, the patient is placed supine with a tourniquet. A longitudinal incision is made on the medial side of the foot with the navicular tuberosity as the center, and the skin and subcutaneous tissue are incised to reveal the posterior tibial tendon, and at the distal end of the posterior tibial tendon, the tendon may stop at the navicular bone or the pars plana, and the anterior edge of the posterior tibial tendon is separated. If the posterior tibial tendon mainly stops at the navicular bone, the posterior tibial tendon can be split longitudinally from the middle. This allows the paracarpal beneath it to be seen. The pars plana is clamped and pulled to examine the junction between the pars plana and the navicular tuberosity. The pars plana is removed from this junction. The split posterior tibial tendon is indirectly sutured with a silk suture. If the posterior tibial tendon stops primarily at the pars plana, removal of the pars plana may also sever the stop of the posterior tibial tendon. In this case, a rough bone surface can be made on the medial side of the navicular tuberosity and two bone holes can be drilled, and the distal end of the posterior tibial tendon can be sutured and fixed through the bone holes. Kidner advocates that after removal of the pars plana, the flat foot should be corrected at the same time by displacing the posterior tibial tendon outward and downward to the metatarsal surface of the navicular and suturing it to the periosteum or fascia on the metatarsal side to reestablish the posterior tibial muscle and its suspensory role. After resection of the navicular bone alone, the wound is bandaged with pressure and the stitches are removed two weeks after surgery, and after three weeks, if there is no foot discomfort, the foot can be gradually moved down to the ground. It is best to pad the medial side of the foot to support the medial arch of the foot. If the posterior tibial muscle is reconstructed anteriorly or shifted to the metatarsal side, a cast should be applied to immobilize the metatarsal of the foot with inversion for six weeks. No weight-bearing activities with crutches, and gradual weight-bearing activities after removal of the cast. The medial pad of the foot can be padded to reduce the strain on the tendons of the foot during walking.