The most frequent first visits for pars plana deformity are in children 10-12 years of age. The child reports medial foot pain and some have a history of sprain with definite inversion of the ankle. Examination reveals a bony mass on the medial aspect of the foot, just below the anterior aspect of the medial ankle, and in cases with prolonged pain, it is often complicated by flat feet. This flat foot is characterized by an intact arch when not weight bearing and a collapsed arch when fully weight bearing.
The pars plana of the foot is a congenital abnormality of the second bony center of the navicular tuberosity, which forms a separate pars plana at the navicular tuberosity. The paravicular bone is mostly bilateral. Normal 10% to 14% of people have a paracarpal bone, which is a structural defect of the foot and affects the stability of the foot. Under normal circumstances, the posterior tibial tendon passes under the medial end of the navicular bone and ends at the base of the second and third medial cuneiform bones and the base of the second and third 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 easy to cause flat feet and strain and cause symptoms. The protruding paracarpal bone can cause damage to the posterior tibial tendon and aggravate the pain when the posterior tibial tendon is compressed during the inversion of the ankle joint.
Conservative treatment has been used in the past to treat the pars plana deformity. It is true: conservative treatment relieves pain in the vast majority of patients, but some patients have persistent pain in the foot, which affects sports, and patients with concurrent flatfoot are more imaged in sports such as running and jumping. It has an impact on the child’s sports performance, especially on the sports test items of the secondary school exam. Therefore, more and more parents and doctors are opting for surgical treatment. It is now advocated that after removing 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 bone and suturing it to the periosteum or fascia on the metatarsal side to reconstruct the posterior tibial muscle and play its suspension role.