Talar Dome Osteochondral Lesion: AI-Powered MRI Staging

Coronal and sagittal proton-density fat-saturated sequences at 3 T provide the highest sensitivity for articular cartilage defects and subchondral bone signal changes. Gradient-echo T2* sequences improve cartilage delineation by detecting collagen matrix disruption. The presence of a high T2 signal rim beneath the subchondral bone plate — indicating fluid undercutting — is the critical sign of fragment instability, differentiating stable lesions managed conservatively from unstable lesions requiring arthroscopic fixation or microfracture.

The Anderson MRI staging (I–IV) is most widely applied: Stage I shows subchondral compression with marrow edema and intact cartilage; Stage II demonstrates subchondral cyst or partially detached fragment; Stage IIA adds a cyst beneath the fragment; Stage III shows complete detachment without displacement; Stage IV is a displaced loose body. Stages I–II are typically managed with non-weight-bearing and bone stimulation. Stage III–IV require arthroscopic intervention. AI quantification of lesion volume (length × width × depth in mm) refines prognosis beyond categorical staging.

Bone contusions appear as ill-defined STIR hyperintensity within the talar dome trabecular marrow without articular cartilage disruption or subchondral fracture line on T1-weighted images. Osteochondral lesions show a discrete subchondral fracture line (low T1/high T2), articular surface irregularity, or cartilage thinning on high-resolution PD-FS sequences. AI models trained on ankle MRI datasets identify the cartilage-bone interface disruption with high specificity, reducing the rate of missed OCD lesions that present initially as apparent contusions on acute MRI.