2019 ISAKOS Biennial Congress ePoster #1811
Relationship between Posterior Instability of the Shoulder and Scapula Dyskinesis: Does the Scapular Manual Fixation Have a Great Effect on the Result of the Jerk Test?
Yasunari Fujii, MD, Kanoya JAPAN
Hironori Kakoi, MD, Kagoshima, Kagoshima JAPAN
Izumi Toshihiko, MD, Kagoshima, Kagoshima JAPAN
Kaieda Mitsuyoshi, MD, Kagoshima, Kagoshima JAPAN
Taniguchi Noboru, MD, Kagoshima, Kagoshima JAPAN
Orthopaedic Surgery, Kagoshima University, Kagoshima, Kagoshima, JAPAN
FDA Status Not Applicable
Our results showed that in about one third of the 182 shoulders without no posterior instability, temporal scapular dyskinesis created by passive scapular fixation during the jerk test caused the result of the jerk test to change from negative to positive, which meant that scapular dyskinesis had a great influence on the development of shoulder posterior instability.
Scapular dyskinesis is highly correlated with shoulder posterior instability. The purpose of this study is to examine how role temporal scapular dyskinesis produced by preventing the scapular movement during the jerk test passively plays in making shoulders change from stable to unstable, especially as to posterior instability.
We evaluated 182 shoulders with the negative jerk test result with a mean age of 18.5 years. We performed the jerk test fixing the scapula passively to create temporal scapular dyskinesis. We evaluated whether temporal scapular dyskinesis could change the jerk test result from negative to positive in all shoulders with the negative jerk test result. Results: In 114 of 182 shoulders (62.6%), regardless of fixing the scapula passively during the jerk test, the jerk test result remained negative, while in the other 68 shoulders (37.4%) the result changed from negative to positive, which meant that temporal scapular dyskinesis could cause shoulder posterior stability change from stable to unstable.
Our results showed temporal scapular dyskinesis created by passive fixation of the scapula during the jerk test worked on about one third of the 182 shoulders with the negative jerk test result to change it from negative to positive. Our study proved that scapular dyskinesis such as minimal or no abduction of scapula movement during the jerk test had a great influence on the development of shoulder posterior instability.