Automatic Segmentation and Measurement on Knee Computerized Tomography Images for Patellar Dislocation Diagnosis

Figure 8

Key points, PTA, and PLS. As shown in (a), each bone has three key points selected: two central valley or peak points along the boundary and the middle of the leftmost and the rightmost boundary points (colored in purple). Key points of the two bone regions are colored in red and green, respectively. The definition of patella tilt angle (PTA) is illustrated in (b), which is the angle, θ, between the femur and the patella’s central planes which are colored in yellow and blue, respectively. The definition of patella lateral shift (PLS) is illustrated in (c), which is the distance, D, between the parallel approximate central planes of the femur and the patella.

(a)

(b)

(c)