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Background The Instability Severity Index Score (ISIS) was developed to help determine the prognosis for recurrent shoulder instability and to assist surgical decision-making. The radiographic portion of the ISIS represents a substantial portion of the total score. The present study examined the intra- and inter-rater agreement, reliability and accuracy of the radiographic components of the ISIS. Methods Four assessors evaluated 49 blinded shoulder radiographs. Assessors documented their observation of the presence of a Hill–Sachs lesion and/or a loss of glenoid contour. Radiographs were reviewed twice in random order over two sessions. Intra- and inter-rater reliability and accuracy were calculated. Results Intra-rater agreement ranged from 71% to 94% for the presence of a Hill–Sachs lesion and 85% to 94% for a loss of glenoid contour. Intra-rater kappa values ranged from 0.41 to 0.86 and 0.56 to 0.74, respectively. Inter-rater agreement was found to be 63% to 78% and 78% to 90% for Hill–Sachs and glenoid lesions, respectively. Corresponding kappa values were 0.31 and 0.48. Accuracy ranged from 29% to 57% for Hill–Sachs and 65% to 73% for glenoid lesions. Conclusions In the present study, intra- and inter-rater reliability of the radiographic portion of the ISIS demonstrated limited kappa and accuracy. We suggest that the ISIS should be used with caution as a guide for surgical management.

BackgroundThere are no current North American population-based incidence studies of elbow dislocations. This creates further challenges in assessing associated outcomes and complication rates. The present study aimed to determine the population-based incidence of elbow dislocations in a large Canadian city.MethodsFrom April 2002 to March, 2005, consecutive cases of elbow dislocation were documented. Age-specific, gender-specific and age-adjusted rates for simple and complex dislocations were calculated according to patient demographic and 2001 Canadian census data. All rates were reported per 10,000 persons per year.ResultsOne hundred thirty-seven dislocations (53 simple and 84 complex) were identified. Simple dislocations occurred at a rate of 0.262 (95% confidence interval [CI] = 0.191 to 0.332). Fracture-dislocations occurred at a rate of 0.415 (95% CI = 0.326 to 0.504). The overall age-adjusted incidence was 0.671 (95% CI = 0.638 to 0.704). With the exception of the 18 years to 29 years (rate = 0.916, 95% CI = 0.648 to 1.183) and ≥80 years groups (rate = 0.906, 95% CI = 0.112 to 1.700), all age groups had an approximate rate of 0.600.DiscussionThe results obtained in the present study are similar to those obtained in a previous European study. True population-based estimates of elbow dislocation incidence are provided, which may facilitate the assessment of outcomes and complication rates of such injuries.