Objective: In patients with Dupuytren contracture (DC), the extension deficit in the affected finger joints is an important measure of disease severity and treatment outcome. In the literature, extension deficit has been reported as either active extension deficit (AED) or passive extension deficit (PED). When different examiners measure joint contracture, examiner-related variability may affect measurement reliability. The objective was to investigate the influence of the examiner on the size of difference between AED and PED measured by different therapists. Materials and Methods: A prospective cohort study was conducted on patients with DC attending the orthopedic department’s outpatient clinic for treatment with collagenase injections. The indication for collagenase was presence of palpable cord and extension deficit of at least 20° in metacarpophalangeal (MCP) and/or proximal interphalangeal (PIP) joint. Before injection, the patients were examined by 1 of 3 experienced hand therapists; the assignment of therapists to the clinics followed their work schedule independent of patient scheduling. The examining therapist measured AED and then PED of the MCP and PIP joints of the affected fingers using a goniometer. A total of 157 consecutive patients (81% men), mean age 70 years (range, 50-87 years), were examined, each by 1 of the 3 therapists. AED of at least 10° was recorded in 291 joints (163 MCP and 128 PIP) and these were included in the analyses. The affected finger was the small (57%), ring (36%), middle (6%), and index (1%). Of the 291 joints, 115 were measured by therapist 1, 83 by therapist 2, and 93 by therapist 3. The difference between AED and PED for each joint was calculated and compared according to examining therapist, affected joint, affected finger, patient gender, and patient age. Analysis of covariance was performed to determine the relationship between the size of the difference between AED and PED and the identity of the examining therapist, adjusting for affected joint, finger, gender, age, and AED. Results: For all 291 joints, mean (SD) AED was 46 (21) and PED 37 (23) degrees. Mean difference (SD) between AED and PED measured by therapist 1 was 6 (6), by therapist 2 was 9 (9), and by therapist 3 was 12 (9) (P = .001 for therapist 1 vs therapist 2, P < .001 for therapist 1 vs therapist 3, and P = .03 for therapist 2 vs therapist 3). No statistically significant AED-PED differences were found according to joint (MCP mean 9 [SD 8], PIP 8 [8]), finger (small 9 [9], ring 9 [7]), gender (men 10 [10], women 9 [7]), or age (Spearman r = .002). The multivariate analysis showed the identity of the examining therapist was a significant determinant of the AED-PED difference (B = 6.3, 95% confidence interval [CI] 4.2-8.4, P < .001, and B = 3.0, 95% CI 0.7-5.3, P = .010, for therapist 3 vs therapists 1 and 2, respectively). Conclusions: When measuring extension deficit in finger joints affected by DC, the size of difference between measured active and passive deficit can vary significantly according to examining therapist. This should be taken into consideration when designing clinical studies and comparing results across studies.
