What are some strategies for radiographically differentiating between erosions secondary to erosive osteoarthritis versus psoriatic arthritis involving the DIP joints?  

In erosive OA, DIP changes show central (or paracentral) erosions with gull-wing appearance. Gull-wing appearance is created by the sclerotic border of erosion in OA (sclerotic border is typically not present in PsA). In addition, at least DIPs are involved in OA (Ridley et al., PMID 30309145).In Ps...