Zaid Jibri MBCHB, MRCS, Presenter: Nothing to Disclose

David John Martin, Abstract Co-Author: Nothing to Disclose

Ramy Mansour, Abstract Co-Author: Nothing to Disclose

Sridhar Kamath, Abstract Co-Author: Nothing to Disclose

To look for any association between edema in the superolateral portion of the infrapatellar fat pad and patellar maltracking indicators.

We retrospectively compared five patellar maltracking indicators between two groups of knee MRI scans. The first group included 100 knees with evidence of edema in the superolateral aspect of the infrapatellar fat pad (the study group). The second group included another 100 knee MRI scans that had normal infrapatellar fat pad (the control group). The five patellar maltracking indicators assessed were the trochlear depth, tibial tuberosity-trochlear groove distance (TTTG), patellar translation, patellofemoral angle (PFA) and the Insall-Salvati index.

The Insall-Salvati index, patellar translation and PFA were significantly higher in the study group (p-value of < 0.001, < 0.001 and 0.004 respectively, Student’s t-test). There was a higher prevalence of patella alta, lateral patellar displacement (LPD) and lateral patellar tilt in the study group (p-value of < 0.001, < 0.001 and 0.011 respectively, Fisher’s exact test). Sixty out of 100 knees in the study group had at least one abnormal patellar maltracking indicator in comparison to 16 out of 100 knees in the control group (p < 0.001, Fisher’s exact test).

Edema in the superolateral portion of Hoffa’s fat pad, the MRI feature of fat pad impingement, is associated with patellar maltracking.

The presence of edema in the superolateral aspect of Hoffa’s fat pad on MRI should prompt the radiologist to look for evidence of patellar maltracking. This can influence patient management.

Jibri, Z, Martin, D, Mansour, R, Kamath, S, The Association of Infrapatellar Fat Pad Edema with Patellar Maltracking: A Case Control Study.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11012573.html