## FINDINGS

### Bones / Alignment
- Findings compatible with **talocalcaneal coalition** at the **middle subtalar facet/sustentacular tali region**, likely osseous or fibrocartilaginous, with narrowing/irregularity and partial loss of the normal subtalar joint cleft.
- Associated **prominent dorsal talar beaking** and mild chronic hindfoot/midfoot remodeling.
- **Pes planus** alignment on this nonweightbearing MRI.
- **Focal marrow edema** in the inferior/central talar head-neck region adjacent to the sinus tarsi/middle subtalar region. No displaced fracture line, collapse, or aggressive marrow lesion identified.
- No acute dislocation.

### Tibiotalar / Subtalar Joints and Cartilage
- **Small-to-moderate tibiotalar joint effusion**, most evident in the anterior recess and medial/lateral gutters.
- **Small-to-moderate posterior subtalar joint fluid/effusion/synovitis**.
- Mild chronic marginal spurring/remodeling about the anterior tibiotalar/talar neck and subtalar/talonavicular regions.
- **Small osteochondral/subchondral abnormality of the central-to-medial/medial talar dome**, with focal subchondral low T1 signal and mild articular surface irregularity. No displaced osteochondral fragment or talar dome collapse identified.

### Sinus Tarsi / Ligaments
- Increased fluid/edema in the **sinus tarsi** with partial loss of normal fat signal, likely reflecting sinus tarsi inflammation and/or sprain of the cervical/interosseous talocalcaneal ligament complex.
- Mild peri-ligamentous edema about the lateral ankle. The ATFL region is somewhat indistinct with adjacent edema, suspicious for a low-grade sprain/partial tear. No definite complete ligament disruption or displaced avulsion fragment is seen.
- No definite deltoid or syndesmotic ligament tear identified on the provided sequences.

### Tendons
- **Prominent fluid in the flexor hallucis longus tendon sheath**, consistent with FHL tenosynovitis; tendon substance remains intact.
- Mild additional fluid/edema about the posteromedial flexor tendon bundle, possibly mild associated tenosynovitis.
- Achilles, peroneal, anterior extensor, and remaining visualized medial flexor tendons are grossly intact without definite rupture.

### Soft Tissues
- Mild diffuse periarticular/subcutaneous edema about the ankle and hindfoot, greatest laterally/anterolaterally and posteromedially near the tarsal tunnel.
- No focal soft-tissue mass or drainable fluid collection.

## IMPRESSION

1. **Talocalcaneal coalition at the middle subtalar facet/sustentacular region**, likely osseous or fibrocartilaginous, with associated dorsal talar beaking, chronic hindfoot remodeling, and pes planus. **High confidence.**

2. **Sinus tarsi edema/fluid** with adjacent focal talar head/neck marrow edema, favored reactive/stress-related in the setting of subtalar coalition and altered hindfoot mechanics; no displaced fracture or collapse. **High confidence for edema; medium confidence for etiology.**

3. **Small-to-moderate tibiotalar and posterior subtalar joint effusions/synovitis.** **High confidence.**

4. **FHL tenosynovitis**, with mild additional posteromedial flexor tendon sheath fluid; no tendon rupture. **High confidence.**

5. **Small central-to-medial/medial talar dome osteochondral lesion/subchondral abnormality** without displaced fragment or collapse. **Medium confidence.**

6. Mild lateral ankle peri-ligamentous edema with indistinct ATFL region, suspicious for **low-grade lateral ligament sprain/partial ATFL injury**; no definite complete tear. **Low-to-medium confidence.**