Juvenile Particulate Osteochondral Allograft for Treatment of Osteochondral Lesions of the Talus: Detection of Altered Repair Tissue Biochemical Composition Using 7 Tesla MRI and T2 Mapping Shaleen Vira, MD 1 , Austin J. Ramme, MD, PhD 1 , Cary Chapman, MD 2 , Ding Xia, MS 3 , Ravinder R. Regatte, PhD 4 , Gregory Chang, MD 5 1 Resident Physician, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY 2 Assistant Professor, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY 3 Research Scientist, Center for Biomedical Imaging, Department of Radiology, NYU Langone Medical Center, New York, NY 4 Professor, Center for Biomedical Imaging, Department of Radiology, NYU Langone Medical Center, New York, NY 5 Associate Professor, Center for Biomedical Imaging, Department of Radiology, NYU Langone Medical Center, New York, NY article info Level of Clinical Evidence: 4 Keywords: cartilage collagen magnetic resonance talus tibia abstract During the previous 2 decades, numerous surgical procedures have become available to treat osteochondral lesions of the talus. The objective of the present study was to use 7 Tesla (7T) magnetic resonance imaging (MRI) to quantify and compare T2 values (a marker of collagen architecture) of native tibiotalar cartilage and cartilage repair tissue in patients treated with a juvenile particulate allograft for osteochondral lesions of the talus. The institutional review board approved the present study, and all subjects provided written informed consent. We scanned the ankles of 7 cartilage repair patients using a 7T MRI scanner with a multi-echo spin- echo sequence to measure the cartilage T2 values. We assessed the cartilage T2 values in the talar repair tissue, adjacent native talar cartilage, and overlying tibial cartilage. We compared the differences between groups using the paired t test. The talar cartilage repair tissue demonstrated greater mean T2 relaxation times compared with the native adjacent talar cartilage (64.88  12.23 ms versus 49.56  7.82 ms; p ¼ .043). The tibial cartilage regions overlying these talar cartilage regions demonstrated a trend toward greater T2 relax- ation times (77.00  31.29 ms versus 59.52  7.89 ms; p ¼ .067). 7T MRI can detect differences in T2 values in cartilage repair tissue compared with native cartilage and could be useful for monitoring the status of cartilage health after surgical intervention. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. Osteochondral lesions of the talus occur in the setting of ankle trauma or instability (1) and are characterized by a defect of the articular cartilage and the adjacent subchondral bone (2). The chal- lenge of treating lesions of the avascular cartilage was first appreci- ated in 1743 by Dr. Hunter, who stated that an articular cartilage lesion is a “troublesome thing and once destroyed, it is not repaired” (3).A high failure rate is seen with nonoperative treatment, with <45% of lesions responding favorably (4). Because of the high load per unit area of the tibiotalar joint (5), these patients are at a significant risk of developing debilitating osteoarthritis (5). To relieve symptoms, restore mobility, and prevent long-term arthritic sequelae, various operative treatment options have been developed, including micro- fracture/drilling, autologous osteochondral transplantation, osteo- chondral allograft transplantation, and autologous chondrocyte transplantation. No technique appears to be superior to the others (6), and each option has associated strengths and weaknesses (6). Currently, surgeon preference has a significant role in decision making. Recently, a juvenile articular cartilage graft (DeNovo Ò NT Graft, Zimmer, Warsaw, IN) (7,8) has been proposed for the treatment of talar osteochondral lesions of the talus <5 cm 2 for patients in whom microfracture chondroplasty failed (9). The DeNovo Ò NT Graft (Zim- mer) is a particulate juvenile articular cartilage obtained from juvenile allograft donors 13 years old but typically <2 years old (9). Because of preparation from immature articular cartilage, the DeNovo Ò NT Graft has a much greater cellular density, cell proliferation rate, cell outgrowth, and glycosaminoglycan content than mature articular cartilage (10). First tested in rabbit models in 1983 (11) and initially Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Gregory Chang, MD, The Bernard Irene Schwartz Center for Biomedical Imaging, Department of Radiology, NYU Langone Medical Center, 660 First Avenue, 3rd Floor, Room 334, New York, NY 10016. E-mail address: gregory.chang@nyumc.org (G. Chang). 1067-2516/$ - see front matter Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2016.09.012 Contents lists available at ScienceDirect The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org The Journal of Foot & Ankle Surgery 56 (2017) 26–29