MR imaging and metallic implants for anterior cruciate ligament reconstruction: assessment of ferromagnetism and artifact.

Magnetic resonance (MR) imaging is contraindicated for patients with certain ferromagnetic implants, primarily because of potential risks related to movement or dislodgment of the devices. An additional problem with metallic implants is the potential image distortion that may affect the interpretation of the MR study. Since MR imaging is frequently useful for the evaluation of postoperative anterior cruciate ligament (ACL) reconstruction, the ferromagnetic qualities and artifacts associated with MR imaging were determined for five metallic orthopedic implants commonly used for this surgery. Only the Perfix interference screw displayed a substantial deflection force and caused extensive signal loss. Images of the knee of one patient with two Perfix screws in place were not interpretable because of the image distortion caused by these implants. Therefore, alternative nonferromagnetic implants should be considered for reconstruction of the ACL.