Examiners’ influence on the measured active and passive extension deficit in finger joints affected by Dupuytren disease

BACKGROUND: The most commonly reported outcome measure in Dupuytren disease is the extension deficit in finger joints. This study aimed to investigate the examiners’ influence on the measured difference between active and passive extension deficit. METHODS: A prospective cohort study was conducted on 157 consecutive patients (81% men, mean age 70 years) scheduled for collagenase treatment for Dupuytren disease. Before injection, one of three experienced hand therapists measured active extension deficit (AED) and passive extension deficit (PED) in the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of the affected fingers using a hand-held metal goniometer. We included joints with ≥10° AED, and calculated mean AED and PED in MCP and PIP joints measured by each examiner. For adjusted analysis we used a mixed effects model to determine the relationship between the examiner and the AED-PED difference. RESULTS: For all 291 joints measured, mean AED was 46° (SD 21) and mean PED was 37° (SD 23). Mean difference between AED and PED measured by examiner 1 was 6° (SD 6), by examiner 2 was 9° (SD 9), and by examiner 3 was 12° (SD 9). The mixed effects model analysis showed that the identity of the examining therapist was a significant determinant of the AED-PED difference. CONCLUSIONS: In Dupuytren disease measurement of active and passive extension deficit in finger joint contractures may vary significantly between different examiners. This must be taken into consideration when designing clinical studies and comparing outcomes between studies.