Reliability and reproducibility of radiographs of greater tuberosity displacement. A cadaveric study.

BACKGROUND

Classification of fractures of the greater tuberosity has shown poor reliability, in part as a result of an inability to assess fracture displacement accurately. We used fluoroscopic images of prepositioned osteotomized greater tuberosity fragments in cadavers to determine the accuracy of radiographic interpretation, the interobserver reliability, and the effect that radiographs might have on surgical decision-making.

METHODS

Twelve osteotomies of the greater tuberosity (three each with 2, 5, 10, and 15 mm of displacement) were created in whole-body cadavers. Six fluoroscopic images (anteroposterior views in external and internal rotation, anteroposterior views in neutral rotation with 15 degrees of cephalic and 15 degrees of caudal tilt, a lateral outlet view, and an axillary view) were made after each osteotomy. Four experienced orthopaedic surgeons measured displacement in millimeters on seventy-two randomized images. Four views in sequence (the anteroposterior view in internal rotation and the outlet view together, then the axillary view, and then the anteroposterior view in external rotation) of each osteotomy pattern were then viewed, and each surgeon was asked whether surgery would be indicated on the basis of each set of images.

RESULTS

No one fluoroscopic view was significantly more accurate than another. There was a trend toward increased accuracy of imaging of minimally displaced (</=5 mm) tuberosity fragments with the anteroposterior view in external rotation. When viewed sequentially, the anteroposterior view in external rotation, evaluated last, altered treatment in nine of forty-eight situations. There was substantial agreement (kappa = 0.71) among the surgeons with respect to their recommendations for treatment of the displaced greater tuberosities after they had inspected the four images.

CONCLUSIONS AND CLINICAL RELEVANCE: To our knowledge, we are the first to examine the accuracy and reliability of interpreting images of known displacements of the greater tuberosity. Multiple radiographic views are needed to evaluate displacement of the greater tuberosity appropriately. The anteroposterior view in external rotation can profile the greater tuberosity and help demonstrate small displacements. Treatment decisions should be consistent between surgeons when multiple views are used.