Shoulder Injuries in the Overhead-Throwing Athlete: Epidemiology, Mechanisms of Injury, and Imaging Findings

PROLOGUE: Several years ago, when we began to question microinstability as the universal cause of the disabled throwing shoulder, we knew that we were questioning a sacrosanct tenet of American sports medicine. However, we were comfortable in our skepticism because we were relying on arthroscopic insights, clinical observations, and biomechanical data, thereby challenging unverified opinion with science. In so doing, we assembled a unified concept of the disabled throwing shoulder that encompassed biomechanics, pathoanatomy, kinetic chain considerations, surgical treatment, and rehabilitation. In developing this unified concept, we rejected much of the conventional wisdom of microinstability-based treatment in favor of more successful techniques (as judged by comparative outcomes) that were based on sound biomechanical concepts that had been scientifically verified. Although we have reported various components of this unified concept previously, we have been urged by many of our colleagues to publish this information together in a single reference for easy access by orthopaedic surgeons who treat overhead athletes. We are grateful to the editors of Arthroscopy for allowing us to present our view of the disabled throwing shoulder. Part I: Pathoanatomy and Biomechanics is presented in this issue. Part II: Evaluation and Treatment of SLAP Lesions in Throwers will be presented in the May-June issue. Part III: The "SICK" Scapula, Scapular Dyskinesis, the Kinetic Chain, and Rehabilitation will be presented in the July-August issue. We hope you find it thought-provoking and compelling.

Glenohumeral internal rotation deficit (GIRD) indicates a 20° or greater loss of internal rotation of the throwing shoulder compared with the nondominant shoulder.

The purpose of this study was to compare the diagnostic accuracy of MRI, MR arthrography, and ultrasound for the diagnosis of rotator cuff tears through a meta-analysis of the studies in the literature. Articles reporting the sensitivities and specificities of MRI, MR arthrography, or ultrasound for the diagnosis of rotator cuff tears were identified. Surgical (open and arthroscopic) reference standard was an inclusion criterion. Summary statistics were generated using pooled data. Scatterplots of the data sets were plotted on a graph of sensitivity versus (1 - specificity). Receiver operating characteristic (ROC) curves were generated. Sixty-five articles met the inclusion criteria for this meta-analysis. In diagnosing a full-thickness tear or a partial-thickness rotator cuff tear, MR arthrography is more sensitive and specific than either MRI or ultrasound (p 0.05). Summary ROC curves for MR arthrography, MRI, and ultrasound for all tears show the area under the ROC curve is greatest for MR arthrography (0.935), followed by ultrasound (0.889) and then MRI (0.878); however, pairwise comparisons of these curves show no significant differences between MRI and ultrasound (p > 0.05). MR arthrography is the most sensitive and specific technique for diagnosing both full- and partial-thickness rotator cuff tears. Ultrasound and MRI are comparable in both sensitivity and specificity.