Bilateral weighted radiographs are required for accurate classification of XXXX : an observational study of 59 cases.

@entity1 @entity1172 @entity130
INTRODUCTION: Misinterpretation of the Rockwood classification system for acromioclavicular joint (ACJ) separations has resulted in a trend towards using unilateral radiographs for grading. Further, the use of weighted views to 'unmask' a @entity130 has fallen out of favour. Recent evidence suggests that many radiographic @entity130 represent only a partial injury to the stabilising ligaments. This study aimed to determine (1) whether accurate classification is possible on unilateral radiographs and (2) the efficacy of weighted bilateral radiographs in unmasking higher-grade injuries. METHODS: Complete bilateral non-weighted and weighted sets of radiographs for @entity1 presenting with an @entity1172 over a 10-year period were analysed retrospectively, and they were graded I-VI according to Rockwood's criteria. Comparison was made between grading based on (1) a single antero-posterior (AP) view of the injured side, (2) bilateral non-weighted views and (3) bilateral weighted views. Radiographic measurements for cases that changed grade after weighted views were statistically compared to see if this could have been predicted beforehand. RESULTS: Fifty-nine sets of radiographs on 59 @entity1 (48 male, mean age of 33 years) were included. Compared with unilateral radiographs, non-weighted bilateral comparison films resulted in a grade change for 44 @entity1 (74.5%). Twenty-eight of 56 @entity1 initially graded as I, II or III were upgraded to grade V and two of three initial grade V @entity1 were downgraded to grade III. The addition of a weighted view further upgraded 10 @entity1 to grade V. No @entity130 was changed to grade III and no injury of any severity was downgraded by a weighted view. Grade III injuries upgraded on weighted views had a significantly greater baseline median percentage coracoclavicular distance increase than those that were not upgraded (80.7% vs. 55.4%, p=0.015). However, no cut-off point for this value could be identified to predict an upgrade. CONCLUSIONS: The accurate classification of ACJ separation requires weighted bilateral comparative views. Attempts to predict grade on a single AP radiograph result in a gross underestimation of severity. The value of bilateral weighted views is to 'unmask' a grade V injury, and it is recommended as a first-line investigation.
