Work

Misclassifying climber adaptation: dorsal PIP synovial thickening in asymptomatic rock climbers meets ultrasound criteria for synovitis

Year: 2026

Type: article

Abstract: Objectives: To establish normative sonographic values for proximal interphalangeal (PIP) joint synovium, effusion and cartilage in asymptomatic adult rock climbers and to assess whether rheumatoid arthritis-derived ultrasound criteria misclassify normal climber adaptation as pathology. Methods: Cross-sectional study of 160 asymptomatic adults (80 climbers with ≥5 years' experience, 80 non-climbing controls) recruited from a sports medicine clinic in Salt Lake City, USA. Long-axis greyscale ultrasound of the middle and ring finger PIP joints measured dorsal synovium at the middle phalangeal base and the proximal phalangeal neck (dorsal recess), dorsal effusion, volar cartilage and volar effusion at 0° and 90° flexion. Images were measured by a blinded investigator. Groups were compared by Welch's t-tests (Bonferroni threshold p<0.004); years of climbing were tested as an exposure proxy. Results: Groups were matched for age, sex and hand scanned. Climbers had greater synovial thickness and effusion at every landmark (all p<0.0001). The most discriminating measure was dorsal synovium at the proximal phalangeal neck: 2.08±0.29 mm in climbers versus 0.97±0.15 mm in controls (middle finger). Volar cartilage did not differ (both p=0.32), flexion to 90° produced a negligible (≤0.03 mm) increase in volar effusion and years of climbing were unrelated to synovial thickness. Conclusions: Asymptomatic climbers have baseline PIP synovial thickening meeting McNally greyscale criteria for grade 1-2 synovitis despite absent symptoms and preserved cartilage. The dorsal recess at the proximal phalangeal neck is the site at which standard criteria most consistently misclassify climbers and is proposed as the primary reference landmark; climber-specific thresholds are required.

Source: BMJ Open Sport & Exercise Medicine

DOI: 10.1136/bmjsem-2026-003509

Authors: Jedidiah Farley, Jared Vagy, Kevin Cowell, Xeber Iruretagoiena, Volker Rainer Schöffl, Paulo Miro