Silvia Mariani MD, Presenter: Nothing to Disclose

Alice La Marra MD, Abstract Co-Author: Nothing to Disclose

Stefano Necozione MD, Abstract Co-Author: Nothing to Disclose

Vittorio Calvisi MD, Abstract Co-Author: Nothing to Disclose

Antonio Barile, Abstract Co-Author: Nothing to Disclose

Carlo Masciocchi, Abstract Co-Author: Nothing to Disclose

To prove that weight-bearing (WB)-MRI may unmask a patello-femoral maltracking with respect to standard-MRI and to define which measurement of patellar alignment is the most reliable.

Since November 2011 we collected 95 patients (age 16-26 years), divided, on the basis of clinical tests (patello-femoral grind, patellar tilt, patellar glide and patellar apprehension tests) in 2 groups: Group A (control group) of 20 patients clinically negative, and Group B of 75 patients clinically suspected of chronic patellar maltracking. All patients underwent a dedicated MRI (G-SCAN, Esaote, Italy), in supine and WB position, with a knee flexion of 12°-15°. The measurements (performed by Carestream Vue Solutions 11.3 system) according with literature were: Insall-Salvati index (IS), lateral patellar displacement (LPD), lateral patellofemoral angle (LPA) and lateral patellar tilt (LPT). We used, for statistical analysis, quantitative and qualitative tests (ANOVA, Friedman, Kappa of Cohen and Coefficient of variations from duplicate measurements) to compare before and after load all groups and all measurements.

Group A patients showed no statistically significant variations at all measurements both on standard and WB-MRI. On the basis of standard MRI-measurements, Group B patients were divided in Group B1 (23 pts) (negative or positive at 1 measurement) and in Group B2 (52 pts) (positive at 2 or more measurements). After WB-MRI, patients of Group B1 were divided in Group B1a (6 pts) if they remained positive at 0/1 measurement and in Group B1b (17 pts) if they became positive at 2 or more measurements). All patients of Group B2 confirmed to be positive at 2 or more measurements at WB-MRI. Qualitative statistical analysis (K-Cohen) demonstrated that LPT was the best predictive measurement (K=0.278) between standard and WB-MRI. Quantitative statistical analysis (Coefficient of variations from duplicate measurements) showed that LPT (for Group B1b=60.3%) and LPA (for Group B2=69%) were the most reproducible and clinically useful measurements.

The study demonstrates both the high diagnostic value of WB-MRI in unmasking PF-maltracking and the best predictive value of LPT measurement.

This study demonstrates that WB-MRI (using LPT measurement) may be very useful in unmasking patello-femoral maltracking in patients with negative standard MRI.

Mariani, S, La Marra, A, Necozione, S, Calvisi, V, Barile, A, Masciocchi, C, Anterior Knee Pain Syndrome: May One and Simple Measurement Using Weight-bearing MRI Unmask Patellar Maltracking in Your Patients Negative at Standard-MRI?.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044332.html