In this FAQ, William Saalfeld, NP, breaks down why the modified van der Heijde–Sharp (mvdH-S) score remains the most widely used radiographic method in psoriatic arthritis (PsA) clinical trials. He highlights how the score delivers the strongest combination of reliability, sensitivity to change, and validation, making it ideal for detecting small but meaningful structural progression over typical trial timelines. Learn how its consistent use across randomized controlled trials—including recent NEJM studies—supports cross-trial comparability, regulatory acceptance, and its role as a trusted structural endpoint linked to long-term physical function and disability in PsA.