Judong Pan MD, Presenter: Nothing to Disclose

Christoph Stehling MD, Abstract Co-Author: Nothing to Disclose

John A. Lynch PhD, Abstract Co-Author: Nothing to Disclose

Michael C. Nevitt PhD, Abstract Co-Author: Nothing to Disclose

Thomas M. Link MD, Abstract Co-Author: Consultant, General Electric Company

To study knee morphological abnormalities and cartilage T2 changes with 3T MRI in non-symptomatic, middle-aged subjects and investigate the role of vastus lateralis/vastus medialis cross-sectional area ratio (VL/VM) in preclinical knee osteoarthritis (OA).

174 non-symptomatic individuals (76 men and 98 women) aged 45-55 years with OA risk factors were selected from the Osteoarthritis Initiative (OAI) incidence cohort. OA-related knee abnormalities were analyzed using the whole-organ MR imaging score (WORMS) by two musculoskeletal radiologists. Knee cartilage T2 maps and cross-sectional area of vastus lateralis/medialis were obtained using standardized segmentation techniques. Muscle measurements were normalized to body size using body surface area (BSA). Statistical significance was determined using Student’s t-test, ANOVA, multivariate correlation tests, and multiple regression models.

Our data showed that male subjects had significantly larger cross-sectional area of quadriceps, hamstring, and vastus medialis than women. However, after normalizing for body size using BSA, the significant gender difference in muscle size was no longer observed except for vastus medialis. Larger muscle demonstrated greater maximal flexion and extension forces (p < 0.0001). Male and female subjects with lower VL/VM ratio demonstrated significantly higher mean cartilage T2 values (all compartments combined, mean 45.17 ± 2.52 versus 44.10 ± 2.12, p = 0.0017) and showed also significantly higher WORMS scores (all compartments combined, mean 18.68 ± 17.05 versus 14.12 ± 15.47, p = 0.0316). Regression analyses of combined mean cartilage T2 using VL/VM ratio as the predictor revealed significant linear and second degree polynomial relationship between these two variables (p = 0.0109 and 0.0082 respectively).

A significant gender difference in muscle size is observed, which is at least in part related to gender difference in body size. Non-symptomatic, middle-aged subjects with lower VL/VM ratio may be at increased risk for cartilage degeneration as evidenced by cartilage T2 elevation and increased OA-related morphological abnormalities.

Vastus lateralis/medialis imbalance may predispose to pathogenesis of early OA. Cartilage T2 correlates with morphological changes and may potentially be used as a biomarker for preclinical OA.

Pan, J, Stehling, C, Lynch, J, Nevitt, M, Link, T, Knee Morphological Abnormalities and Cartilage T2 Changes Determined with 3T MRI in Relation to Vastus Lateralis/Vastus Medialis Cross Sectional Area Ratio in Nonsymptomatic Subjects from the Incidence Cohort of the Osteoarthritis Initiative.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9005460.html