Background: Substantial differences between disability and impairment are commonplace and puzzling. Subjective (psychosocial) factors may be paramount given that pain is a more important determinant of perceived overall arm-specific disability than is objective elbow impairment. To further evaluate the relationship between impairment and disability, we tested the hypothesis that objective loss of elbow motion predicts perceived elbow-related task-specific disability better than does pain after elbow trauma.
Methods: One hundred and fifty-eight patients were evaluated at a median of twenty-six months after a traumatic elbow injury and completed the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. Predictors of the total DASH score and of the scores for individual DASH items that were expected to be related to elbow function were evaluated with univariate and multivariate analyses.
Results: Motion accounted for 35% of the variability in the total DASH score, for 11% to 12% of the variability in the responses to questions specific to hand-based activities, and for 24% to 33% of the variability in the scores for tasks depending on elbow motion. Pain accounted for 41% of the variability in the total DASH score and was a better predictor than motion of disability associated with three tasks: opening a tight jar (with pain and motion accounting for 24% and 11% of the variability, respectively), pushing open a door (25% and 12%, respectively), and placing an object overhead (28% and 25%, respectively). None of the multivariate models explained more than 53% of the variability in the DASH scores.
Conclusions: Objective physical elbow impairment correlated with self-reported disability with respect to specific tasks, but a large proportion of disability remains unexplained. Further research is needed to better understand the differences between objective impairment and perceived disability.