Patellar instability: CT and MRI measurements and their correlation with internal derangement findings.
OBJECTIVE
To test the inter-observer and inter-method reliability among the measures suggesting patellofemoral joint disorder on both CT and MRI in the same subject and find possible association with internal derangements of the patellofemoral joint on MRI.


METHODS
Institutional review board approval was obtained with waiver of the informed consent in this HIPPA-compliant study. CT and MRI were evaluated in 32 knees in 32 respective subjects (10 men/22 women, mean age 38 ± 19 years). Three trained observers assessed tibial tuberosity-trochlear groove (TT-TG) distance, trochlear angle and trochlear depth on both CT and MRI. Intra-class correlation coefficient (ICC) was used to evaluate inter-observer and inter-method reliability. Two radiologists' consensus reading was used to evaluate their association with soft tissue abnormalities of the patellofemoral joint. Chi-square test was used to assess the statistical significance of the qualitative variables.


RESULTS
There was an excellent inter-observer reliability (ICC for CT >0.89 and for MRI >0.90) and inter-method reliability (ICC >0.86) for all the quantitative measurements. There was a significant association between increased TT-TG distance value on MR imaging and lateral facet patellar cartilage abnormality and joint effusion (p < 0.05).


CONCLUSIONS
Quantitative trochlear parameters can be reliably calculated on MRI, and an abnormal TT-TG distance is the most useful measurement among various static MR imaging parameters to correlate with patellar chondrosis and joint effusion. TT-TG distance should be reported in patellofemoral pain syndrome patients.


METHODS
IV.
The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, 601 N. Caroline Street, Baltimore, MD, 21287, USA.
Rashmi S
RS
Thakkar
The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, 601 N. Caroline Street, Baltimore, MD, 21287, USA.
Filippo
F
Del Grande
Department of Radiology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
Vibhor
V
Wadhwa
The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, 601 N. Caroline Street, Baltimore, MD, 21287, USA.
Majid
M
Chalian
Department of Radiology, University Hospital, Zurich, Switzerland.
Gustav
G
Andreisek
The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, 601 N. Caroline Street, Baltimore, MD, 21287, USA.
John A
JA
Carrino
The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, 601 N. Caroline Street, Baltimore, MD, 21287, USA.
John
J
Eng
The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, 601 N. Caroline Street, Baltimore, MD, 21287, USA. avneesh.chhabra@utsouthwestern.edu.
Avneesh
A
Chhabra
D000328:Adult; D002357:Cartilage Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D015588:Observer Variation; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D046788:Patellofemoral Pain Syndrome / Q000000981:diagnostic imaging / Q000503:physiopathology; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed
Patella maltracking; Patellofemoral disorder; TT–TG; Tibial tuberosity–trochlear groove distance; Trochlear dysplasia