Tal Laor, MD Galen F. H. Chun, MD Bernard J. Dardzinski, PhD Judy A. Bean, PhD David P. Witte, MD Index terms: Bones, growth and development Femur, MR, 451.121411, 451.121412, 451.121413, 451.121416, 451.12143 Fibrous cortical defect, 451.3131 Knee, anatomy, 45.92 Tibia, 454.121411, 454.121412, 454.121413, 454.121416, 454.12143 Published online before print 10.1148/radiol.2243011259 Radiology 2002; 224:669 – 674 1 From the Departments of Radiology (T.L., B.J.D., G.F.H.C.), Biostatistics (J.A.B.), and Pathology (D.P.W.), Chil- dren’s Hospital Medical Center, Uni- versity of Cincinnati College of Medi- cine, 3333 Burnet Ave, Cincinnati, OH 45229. Received July 23, 2001; revi- sion requested August 27; final revi- sion received January 8, 2002; accepted January 29. Address correspondence to T.L. (e-mail: laor@chmcc.org). Author contributions: Guarantors of integrity of entire study, T.L., G.F.H.C., B.J.D.; study concepts and design, T.L., G.F.H.C., B.J.D.; liter- ature research, T.L.; clinical studies, T.L., G.F.H.C., B.J.D.; data acquisition, T.L., G.F.H.C., D.P.W.; data analysis/ interpretation, all authors; statistical analysis, T.L., B.J.D., J.A.B.; manuscript preparation, definition of intellectual content, and editing, T.L., G.F.H.C., B.J.D.; manuscript revision/review and final version approval, all authors. © RSNA, 2002 Posterior Distal Femoral and Proximal Tibial Metaphyseal Stripes at MR Imaging in Children and Young Adults 1 PURPOSE: To determine the frequency and distribution of the hyperintense stripe seen along the posterior surface of distal femoral and proximal tibial metaphyses at magnetic resonance (MR) imaging. MATERIALS AND METHODS: One hundred forty-two MR imaging studies ob- tained in 139 children and young adults were reviewed. The authors recorded the presence and distribution of posterior distal femoral and proximal tibial metaphyseal stripes. Presence of stripe was correlated with patient age and sex and with patency of the adjacent physis. Fifty-nine studies of adults were reviewed similarly. Two-way analysis of variance was performed to compare mean patient age for sex among four different categories that were based on stripe presence and physeal patency. Or- thogonal contrasts were used to determine whether a linear trend across the categories existed. In one cadaveric femur, imaging and histologic analysis were performed. RESULTS: A metaphyseal stripe was seen in all patients with a completely or partially open physis (110 femora, 102 tibiae) and in 56 femora and 60 tibiae in the patients with fused physes. Thirty-five femora and 35 tibiae showed no stripe; all patients were skeletally mature. Correlations between metaphyseal stripe visualiza- tion and physeal patency were significant (P  .001). Differences in mean patient age among the four categories were significant for both (femoral and tibial) loca- tions (P  .001), and a linear trend with age (P  .001) was demonstrated. This linear trend was also observed in both sexes (P  .001). Histologic analysis revealed highly vascular loose fibrous tissue. CONCLUSION: A posterior metaphyseal stripe is seen at MR imaging of the skele- tally immature knee and likely reflects normal bone growth. © RSNA, 2002 The increasing use of magnetic resonance (MR) imaging to evaluate musculoskeletal disorders of the knee in children requires recognition of the normal developmental appearance. This knowledge can facilitate differentiation between the appearance of skeletal growth and that of disease. The MR imaging characteristics of normal cartilaginous epiphyses, physes, and metaphyseal marrow during growth have been studied (1– 6). When interpreting MR images of the lower extremities of children for a variety of clinical indications, we consistently observe a high-signal-intensity stripe along the posterior surface of the distal femoral metaphysis on images obtained with all routine sequences except T1-weighted sequences (Fig 1). To our knowledge, this has not been described as a finding of MR imaging of the knee in pediatric patients. We hypothesize that this me- taphyseal stripe is normal and related to the dynamic bone modeling that occurs during skeletal growth. Therefore, the purpose of this study was to determine the frequency and distribution of the high-signal-intensity stripe seen along the posterior surface of the distal femoral and proximal tibial metaphyses at MR imaging. Pediatric Imaging 669 R adiology