Unreamed tibia nail (UTN) bending: case report and problem solution

An unreamed tibia nail (UTN), implanted for operative stabilization of the tibia after a distal shaft fracture of the lower leg, was bent by excessive load prematurely applied during the healing process, whereby the cross-section-dependent maximum torque permitted in the edge fiber of the UTN during bending load was exceeded. Straightening of the bent, not broken UTN by hand was impossible. Therefore, the bent UTN could only be removed by causing additional damage to the tibia, which is why bending of the nail must be avoided. Our analysis shows that modification of the arrangement of the locking holes by 45 degrees increases bending load capacity of the UTN, which can minimize the probability of the occurrence of a bent nail.