Axial MRI index of patellar engagement: A new method to assess patellar instability

Abstract

AEI is a new index to measure LPD. It can be obtained in all cases because it is obtained from two different MRI views. The normal value is close to 1. It can be used to measure patellar instability on the axial plane in patients with OPI, especially in the most severe cases.

Anatomical patella instability risk factors on MRI show sensitivity without specificity in patients with patellofemoral instability: a systematic review

“…Within the control group, four of five data sets do not cross the mean of the combined control group. The study by Guilbert et al 15 has the largest cohort (n=180) in the control and PFI groups. Their PFI group has no values crossing the traditional threshold of pathological lateral patella tilt, that is, 20°.…”

“…For the TT-TG distance, 16 studies were excluded for either using the tibial tubercle as an osseous landmark (5 studies),18 30–33 or no clear description of measurement parameters reported (11 studies) 9–11 14 15 27 34–38…”

“…All of the control data were from patients with knee symptoms other than PF; for example, meniscal, cartilage and/or ligamentous injuries 6 9–12 15 17 30 37 38 42–44. Only two papers used a strict definition of normals (asymptomatic volunteers) 41 45.…”

Biplanar ascending opening-wedge high tibial osteotomy increases tibial tubercle–trochlear groove distance and decreases patellar height

“…Described by Guilbert et al , the PF AEI represents the percentage of the patellar cartilage that is actually engaged in the trochlear cartilage measured on a patellar and a trochlear axial cut using a line tangent to the posterior femoral condyles as reference (figure 3A). 13 The normal value is close to 1.…”

The patellofemoral joint: from dysplasia to dislocation

“…7b): 15 this is a new index of measurement for lateral patellar displacement and is a direct reflection of this entity. Measurement of AEI can be obtained with two different axial MRI views, using the cartilaginous and posterior condylar landmarks as references.…”