Precise nail tip positioning after tibial intramedullary nailing prevents anterior knee pain

Anterior knee pain (AKP) is a common complication following intramedullary nailing of tibial shaft fractures. Our aim was, by analysing the postoperative lateral knee X-rays and clinical status (VAS score), to find the best intramedullary tip position of a non protruded nail that will provide the best postoperative outcome avoiding AKP. We evaluated the postoperative outcome of 221 patients, from the last four years, with healed fractures initially treated with intramedullary reamed nails with two or three interlocking screws proximally and distally through a medial paratendinous incision for nail entry portal. Our aim was to analyse a possible relationship between AKP according to the VAS scale, and nail position marked as a distance from tip of nail to tibial plateau (NP) and to tibial tuberosity (NT), measured postoperatively on lateral knee X-rays. Two groups of patients were formed on the basis of presence of pain related to AKP (the level of pain was neglected): group A were patients with pain and group B without pain. The difference between the two groups concerning NP and NT measurements appeared to be statistically significant concerning NT measurement (p < 0.05), with high accuracy according to the classification tree. We presume that the position of the proximal tip of the nail and its negative influence on the innervation pattern of the area dorsal to patellar tendon could be the key factor of AKP. We conclude that the symptoms of AKP will not appear if the tip of the nail position is more than 5.5 mm from the tibial plateau (NP) and more than 2.5 mm from the tibial tuberosity (NT).