424 AJR:196, February 2011 All patients underwent MRI with a 1.5-T system (Magneton Vision, Siemens Healthcare; Signa, GE Healthcare). The MRI protocol consisted of axial proton density (TR/TE, 2,000/32), axial T2-weight- ed fat-suppressed (3,800/56), coronal proton densi- ty (2,300/12), coronal fat-suppressed T2-weighted (2,400/56), sagittal proton density (2,900/21), and sagittal fat-suppressed T2-weighted (2,750/56) im- ages of the knee. All MRI sections were obtained with a slice thickness of 3–4 mm, field of view of 14–16 cm, and matrix size of 256 × 256. Eleven cortical desmoids were characterized on the basis of the following MRI findings: size and signal characteristics of the cortical irregular- ity in the medial supracondylar femur, presence of associated periosteal or subperiosteal edema and medial supracondylar marrow edema, and rela- tions between the cortical irregularity and the ori- gin of the medial head of the gastrocnemius ten- don and the adductor magnus tendon insertion. The presence of associated traumatic injuries of the menisci, ligaments, extensor mechanisms, and bone was evaluated. Results All 11 patients (Table 1) had a history of substantial acute trauma and knee pain within 4 weeks before MRI. The size range of the cortical desmoids was 8–12 mm (Figs. 2–4). In all cases, the defects were predominantly hypointense or isointense on proton density– weighted images and hyperintense on T2- weighted fat-suppressed images. Nine of the 11 patients had associated bone marrow ede- ma centered in the posteromedial femoral metaphysis or epiphysis. All patients had pe- riostitis, swelling, and edema at the origin of the medial head of the gastrocnemius tendon (Figs. 2 and 3). One patient had additional MRI Features of Cortical Desmoid in Acute Knee Trauma Renata La Rocca Vieira 1 Jenny T. Bencardino 1 Zehava Sadka Rosenberg 1 George Nomikos 2 La Rocca Vieira R, Bencardino JT, Rosenberg ZS, Nomikos G 1 Department of Radiology, New York University Hospital for Joint Diseases, 301 E 17th St., 6th Fl., New York, NY 10003-3899. Address correspondence to R. La Rocca Vieira (relarocca@gmail.com). 2 Department of Radiology, Georgetown University Hospital, Washington, DC. Musculoskeletal฀Imaging฀•฀Clinical฀Perspective AJR 2011; 196:424–428 0361–803X/11/1962–424 © American Roentgen Ray Society C ortical desmoids, also known in the medical literature as distal femoral cortical irregularities, are benign self-limiting fibrous or fi- broosseous lesions that most frequently occur in the medial supracondylar femur (Fig. 1). They are most prevalent among boys 10–15 years old and are believed to be tug lesions secondary to traction injury at the insertion of the adductor magnus aponeurosis or at the or- igin of the medial head of the gastrocnemius tendon [1–4]. Although it has been considered a chronic and repetitive injury, this process also may be related to an episode of acute knee trauma, not well recalled by physically active children. The purposes of this study were to describe the MRI features of cortical desmoid of the medial supracondylar femur associated with acute knee trauma and to re- view the literature on this entity. Materials and Methods Institutional review board approval for this ret- rospective study was obtained with waiver of in- formed consent. In a 1-year period we collected images from 11 1.5-T MRI examinations of 11 pa- tients (six boys, five girls; age range, 9–16 years; mean, 14.9 years) with a clinical history of acute knee trauma within 4 weeks before MRI and find- ings consistent with a cortical desmoid in the me- dial supracondylar femur. Cortical desmoid was defined as a focal intracortical defect of the medi- al supracondylar femur at the site of origin of the medial head of the gastrocnemius tendon or the site of insertion of the adductor magnus tendon. The MRI studies were retrospectively reviewed in consensus by two musculoskeletal radiologists with 12 and 25 years of experience. The patients’ medical records were reviewed. Keywords: cortical desmoid, distal femoral cortical irregularities, femur, knee, MRI, trauma DOI:10.2214/AJR.10.4815 Received April 16, 2010; accepted after revision June 16, 2010. OBJECTIVE. The purpose of this study was to describe the MRI features of cortical des- moids associated with acute trauma. CONCLUSION. Marrow edema, periostitis, and adjacent soft-tissue edema can be seen in cases of cortical desmoid associated with acute trauma. La Rocca Vieira et al. MRI of Cortical Desmoid Musculoskeletal Imaging Clinical Perspective Downloaded from www.ajronline.org by 52.73.204.196 on 05/16/22 from IP address 52.73.204.196. Copyright ARRS. For personal use only; all rights reserved