Complex regional pain syndrome following Cedell fracture

Frontal: comminuted fracture of the posteromedial talar tubercle (medial tubercle of the posterior talar process).

Oblique: Small bony fragments at adjacent to the tip of the lateral malleolus reflect injury of the lateral ankle ligaments.

Lateral: cortical flake of bone at dorsal talar head reflects avulsion of the dorsal talonavicular ligament.

Improved depiction of the intra-articular, comminuted, Cedell fracture.

Fragments at the tip of the lateral malleolus likely due to avulsion by CFL and inferior peroneal retinaculum.

Proximal avulsion of the dorsal talonavicular ligament should prompt suspicion of midtarsal (Chopart) sprain. No fracture of the anterior calcaneal process, nor obvious fat stranding around the bifurcate ligament. Tiny os peroneum; no appreciable ligamentocapsular injury of the calcaneocuboid joint.

Small fracture fragments vs chondrocalcinosis in the posterior subtalar joint.

Small bone fragments at the aforementioned sites of fracture, with small loose body in the posterior joint recess.

Generalized osteopenia, particularly subchondral/peri-articular.
Surrounding soft tissue edema is non-specific.
Disuse osteopenia, or other cause??

Bones are diffusely demineralized, particularly of the subchondral bone in the midfoot (peri-articular osteopenia). Joint spaces are preserved and congruent. Cortex appears thinned; no acute or stress fracture. No osseous destruction to suggest osteomyelitis.

Widespread patchy marrow hyperintensity with a subchondral predilection. No fracture.
Small non-specific ankle and posterior subtalar joints. All ligaments intact.
Non-specific fluid in the peroneal tendon sheath. All tendons intact.
Generalized subcutaneous edema; no focal collection/abscess.
Minor non-specific edema signal in muscles, reactive/sympathetic. No fatty atrophy (denervation unlikely).
 

Tc-99m MDP limited bone scan with SPECT/CT.

Early images: mildly increased blood flow and blood pool to the left foot, with foci of more markedly increased blood pool in the hindfoot and medial midfoot. 

Delayed images: markedly increased osteoblastic activity adjacent to the posterior subtalar joint, adjacent to the articulation between the medial and middle cuneiform bones, and adjacent to the 1st TMTJ. 
Moderately increased osteoblastic activity adjacent to the 1st MTPJ, and mildly increased periarticular osteoblastic activity elsewhere in the left foot. 

Conclusion: Findings are suggestive of reflex sympathetic dystrophy/complex regional pain syndrome of the left foot, with superimposed arthropathy involving the posterior subtalar, intercuneiform and first TMT joints.