According to study results, the MRI oblique trochlear view accurately evaluates trochlear morphology and better characterizes trochlear dysplasia in patients with patellofemoral instability compared with the standard MRI axial sequences.
“Standard axial MRI cuts are perpendicular to the femoral shaft and provide meaningful images of the proximal trochlea,” Jack Farr, MD, told Healio.com/Orthopedics. “However, for the mid and distal aspects, as the trochlea curves posteriorly, the cut becomes oblique and less clear. Using an oblique imaging cut improves the clarity of the mid and distal trochlea not only for morphology assessment, but also articular cartilage detail.”
Researchers retrospectively reviewed 73 patients with patellofemoral instability using the MRI oblique trochlear view and 73 control patients using standard MRI axial sequences. Investigators assessed the trochlear morphology on axial and oblique trochlear sequences at the following three levels: level 1 at 25%; level 2 at 50%; and level 3 at 75% of the length of the trochlear groove. They also measured the trochlear sulcus angle and sulcus depth at three levels. They compared measurements between the new trochlear sequences and the standard axial sequences.
Results showed that at all three levels, the trochlear sulcus angle and sulcus depth were statistically different between the axial and oblique trochlear views. The trochlear sulcus angle in the axial view for level one, level two and level three was 160°, 146.8° and 134.7°, respectively. In the oblique trochlear view, the sulcus angle was 154.7°, 151.08° and 148°, respectively. The sulcus depth in the axial view was 2.29, 3.97 and 6.25, respectively. In the oblique trochlear view, the sulcus depth was 3.2, 4.18 and 5.14, respectively. Investigators noted the oblique trochlear view showed more uniform sulcus angle and sulcus depth along the trochlea.
Farr said, “The clinical importance of trochlear dysplasia on patellar instability is well recognized, but historical classifications are now being reassessed to improve communication of the patient specific pathoanatomy. Understanding the shape of the mid and distal aspects (shallow, flat or convex) may allow a more precise classification that may impact clinical management. Future research on transferring 2D images into a 3D understanding will continue to evolve.”– by Monica Jaramillo
Disclosures: The researchers report no relevant financial disclosures.