MR arthrography of anterior cruciate ligament reconstruction grafts.

OBJECTIVE: Our objective was to determine the accuracy of MR arthrography for identification of tears of anterior cruciate ligament reconstruction grafts and for detection of localized anterior arthrofibrosis and impingement. MATERIALS AND METHODS: We retrospectively identified 27 patients (mean age, 31 years; range, 18-45 years) with anterior cruciate ligament reconstruction who had undergone MR arthrography followed by arthroscopy within 1 year. Three radiologists independently reviewed the MR arthrograms for the presence or absence of graft tear, localized anterior arthrofibrosis, and impingement. RESULTS: Graft tears were identified with 100% sensitivity by all three reviewers with specificities of 100%, 89%, and 94%. Localized anterior arthrofibrosis was identified with 100% sensitivity by all reviewers, with specificities of 79%, 71%, and 38%. Impingement was detected with sensitivities and specificities of 83% and 100%, 83% and 52%, and 33% and 90% by the three reviewers, respectively. Interobserver agreement was almost perfect for detection of graft tear (kappa = 0.83, 0.92, and 0.83), was fair to moderate for detection of localized anterior arthrofibrosis (kappa = 0.50, 0.32, and 0.22), and was slight to fair for detection of impingement (kappa = 0.40, 0.08, and 0.35). CONCLUSION: MR arthrography can accurately depict the presence of anterior cruciate ligament graft tears. Localized anterior arthrofibrosis and graft impingement were less accurately detected and showed greater observer variability.

MR Arthrography of the Knee.

The role of magnetic resonance imaging (MRI) in the evaluation of musculoskeletal injuries has been well documented during the last decade. There remain several important clinical situations in which noncontrast MRI has been disappointing. In the knee, magnetic resonance arthrography (MRA) can supplement noncontrast MRI in the evaluation of specific conditions, such as postoperative meniscus and osteochondritis dissecans. MRA significantly increases accuracy in the diagnosis of meniscal retear, as is seen in cases in which there has been a meniscal resection of more than 25% or after meniscal suturing. Also, in the evaluation of osteochondritis dissecans, the addition of intra-articular contrast has proved beneficial. Aside from assessing the integrity of the articular cartilage surface and documenting loose bodies, the contrast allows the clinician to distinguish fibrovascular granulation tissue from fluid partially or completely surrounding the osteochondritic fragment. These topics are discussed in this article.