The superior migration of the humeral head is often recognized on plain X-rays on rotator cuff tear. We evaluated the superior migration of the humeral head on X-rays in the supine position on massive rotator cuff tear. The aim of this study was to evaluate the relationship between superior migration of the humeral head on X-rays in the supine or standing position and the size of torn tendons on various rotator cuff tear. We studied 32 shoulders in 32 patients who underwent rotator cuff repair from January to December 2007 retrospectively. There were 23 men and 9 women, their mean age was 63.4 years old (range, 52-75 years old). We evaluated grading of superior migration of the humeral head by anteroposterior radiograph in external rotation in the supine and standing position reported by Oizumi. We measured torn tendon size on MRI and identified torn tendons on arthroscopy. Almost all cases on each torn size migrated superiorly by grade I in the standing position. The larger the size of torn tendons were, the more progressive grade of superior migration were in the supine position. Almost all cases in the small and medium tear were migrated by grade I. In large and massive tear, almost all cases were grade II or III. We cannot predict torn size by routine radiograph in the standing position, but can predict it in the supine position as an additional check. Examination of plain X-rays in the supine position may be useful to predict torn size of rotator cuff.
