I work as a graduate research assistant in the DeFrate Musculoskeletal Bioengineering Laboratory under Dr. Lou DeFrate. My research focuses on quantifying cartilage deformations in the human knee, shoulder, and hip joints in vivo, using magnetic resonance imaging (MRI) and 3D solid modeling techniques. I also use novel quantitative MRI methods, such as T1rho and T2 mapping, to analyze the structure and composition of cartilage non-invasively to assess overall tissue health. Most recently, I have been working to develop image processing techniques to automatically isolate bones from MR images.


  1. Heckelman LN, Riofrio AD, Vinson EN, Collins AT, Gwynn OR, Utturkar GM, Goode AP, Spritzer CE, DeFrate LE (2020). Dose- and Recovery-Response of Patellofemoral Cartilage Deformations to Running. Orthopaedic Journal of Sports Medicine, 8(12).

  2. Heckelman LN, Smith WAR, Riofrio AD, Vinson EN, Collins AT, Gwynn OR, Utturkar GM, Goode AP, Spritzer CE, DeFrate LE (2020). Quantifying the biochemical state of knee cartilage in response to running using T1rho magnetic resonance imaging. Scientific Reports, 10(1870).

  3. Owusu-Akwaw KA, Heckelman LN, Cutcliffe HC, Sutter EG, Englander ZE, Spritzer CE, Garrett WE, DeFrate LE (2018). A Comparison of Patellofemoral Cartilage Morphology and Deformation in Anterior Cruciate Ligament Deficient versus Uninjured Knees. Journal of Biomechanics, 67, 78-83.

  4. Taylor KA, Collins AT, Heckelman LN, Kim SY, Utturkar GM, Spritzer CE, Garrett WE, DeFrate LE (2018). Activities of Daily Living Influence Tibial Cartilage T1rho Relaxation Times. Journal of Biomechanics, 82, 228-233.

  5. Zhang H, Heckelman LN, Spritzer CE, Owusu-Akyaw KA, Martin JM, Taylor DC, Moorman CT, Garrigues GE, DeFrate LE (2018). In Vivo Assessment of Exercise-Induced Glenohumeral Cartilage Strain. Orthopaedic Journal of Sports Medicine, 6(7).

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Figure 1. Exercise decreased cartilage thickness in the patella, as demonstrated in an ACL deficient knee. Red regions represent thicker cartilage, while blue regions represent thinner cartilage. (S = superior; I = inferior; M = medial; L = lateral).

*Figures above from Owusu-Akyaw et al. (2017).

Figure 2. Patellofemoral cartilage was sampled within 2.5 mm radius regions spanning the cartilage surfaces, enabling site-specific comparisons of cartilage thickness before and after exercise and between ACL deficient and intact knees. (A) Patellar cartilage. (B) Trochlear cartilage.