Use of CT in the management of anterior cruciate ligament revision surgery.

Anterior cruciate ligament (ACL) injuries occur most commonly in individuals between 18 and 29 years of age and are strongly correlated with sporting activity, with female athletes being at higher risk of ACL rupture than their male counterparts. ACL reconstruction is one of the most frequently performed procedures in orthopaedic surgery, having a reported incidence of 85 per 100,000 head of population in the at-risk age group. Subsequent graft failure is most commonly caused by recurrent trauma, followed by tunnel malpositioning, although the choice of graft type does not appear to affect outcome. The Danish ACL registry reported that ACL revisions accounted for 7.5% of all ACL reconstruction surgery performed between 2005 and 2008. Revision of ACL reconstruction is recognized to carry a worse outcome than primary reconstruction. Preoperative imaging has become a crucial part of surgical planning in these patients, with great reliance placed on computed tomography (CT). The radiologist should be able to recognize the types of primary repair and must be able to assess for the complications of primary surgery, such as tunnel malpositioning, tunnel widening, and fixation device failure. Revision is commonly a two-stage procedure with bone grafting of the tunnels prior to the definitive ligament repair. The radiologist should be able to asses for adequate bone graft incorporation. The purpose of this article is to present a review of the use of CT in the management of ACL revision surgery with examples of commonly used fixation devices; complications, such as tunnel widening and tunnel malpositioning; and bone graft incorporation.