The association of infrapatellar fat pad oedema with patellar maltracking: a case-control study.
OBJECTIVE
To look for any association between oedema in the superolateral portion of the infrapatellar fat pad and patellar maltracking.


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


RESULTS
There was a statistically significant difference in the Insall-Salvati index, patellar translation and PFA between the two groups (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 parameter in comparison to 16 out of 100 knees in the control group (p < 0.001, Fisher's exact test).


CONCLUSIONS
Oedema in the superolateral portion of Hoffa's fat pad, the MRI feature of fat pad impingement, is associated with patellar maltracking.
Department of Radiology, University Hospital of Wales, Cardiff, United Kingdom. zjibri@doctors.org.uk
Zaid
Z
Jibri
David
D
Martin
Ramy
R
Mansour
Sridhar
S
Kamath
D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D016022:Case-Control Studies; D015897:Comorbidity; D003240:Connective Tissue Diseases / Q000453:epidemiology* / Q000473:pathology*; D004487:Edema; D006801:Humans; D007592:Joint Diseases / Q000453:epidemiology* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D017847:Patellar Ligament / Q000473:pathology*; D015995:Prevalence; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D006113:United Kingdom