A preliminary exploration of plain-film radiography in scapular dyskinesis evaluation

Abstract

Evaluation of scapular dyskinesis is of clinical interest because it is believed to be associated with pathologies of the shoulder. This study investigated the feasibility of plain-film radiography in evaluating scapular dyskinesis. Subjects with unilateral disorders of the shoulder (n = 186) who underwent plain-film radiography of bilateral scapulae were divided into 4 categories of scapular dyskinesis patterns according to the Kibler classification and analyzed. Coracoid upward shift distance (CUSD), length of the scapular spine line (LSS), and scapular upward rotation angle (SURA) were measured on the radiographs. Intrarater and inter-rater reliability were tested, and the characteristics of these parameters in each type were analyzed. The differences (d) between bilateral scapulae (d-CUSD, d-LSS, and d-SURA) among the 4 categories were compared. Intrarater and inter-rater reliability were excellent for all parameters. Significant differences between the scapulae were observed in CUSD in type I and in LSS in type II categories. No significant difference in any of the parameters was found in type III. Compared with the other categories, d-CUSD in type I and d-LSS in type II were significantly larger. The cutoff values of d-CUSD and d-LSS were 1.1 mm and 1.2 mm, respectively. No significant difference in d-SURA was found among the 4 categories. The measurement of CUSD, LSS, and SURA on plain-film radiography had excellent reliability. d-CUSD and d-LSS were characteristic parameters of type I and type II, respectively; however, type III had no distinguishing characteristics among the parameters.