Posterior ankle impingement–an underdiagnosed cause of ankle pain in pediatric patients

Figure 1 Fifteen-year old male with posterior ankle pain with os trigonum seen on lateral ankle radiograph.

Figure 2 Magnetic resonance imaging-sagittal image demonstrating edema-like signal intensity adjacent to the os trigonum in the previously mentioned 15-year-old patient in Figure 1.

Figure 3 Arthroscopic appearance of the os trigonum of the same patient in Figures 1 and 2 before excision.