Relevancia biomecánica de la posición del componente glenoide…(Inglés)

"Relevancia biomecánica de la posición del componente glenoide en la prótesis total de hombro delta III inverso."

Richard W. Nyffeler MDa, , , Clément M.L. Werner MDb and Christian Gerber MDb

aOrthopaedic Hospital, University of Lausanne, Lausanne, Switzerland bDepartment of Orthopaedic Surgery, University of Zurich, Balgrist, Zurich, Switzerland

The presence of a notch at the inferior part of the scapular neck is a common radiographic finding in patients treated with a reverse Delta III shoulder prosthesis. It is thought that this notch is a result of mechanical contact between the polyethylene cup of the humeral implant and the inferior glenoid pole during adduction of the arm. This in vitro study assessed the effect of glenoid component positioning on glenohumeral range of motion in 8 shoulder specimens. Four different positions of the glenosphere were tested: glenosphere centered on the glenoid, leaving the inferior glenoid rim uncovered (configuration A); glenosphere flush with the inferior glenoid rim (configuration B); glenosphere extending beyond the inferior glenoid rim (configuration C); and glenosphere tilted downward 15° (configuration D). The respective mean adduction and abduction angles in the scapular plane were −25° and 67° for configuration A, −14° and 68° for configuration B, −1° and 81° for configuration C, and −9° and 75° for configuration D. Placing the glenosphere distally (test configuration C) significantly improved adduction and abduction angles compared with all other test configurations (P < .001).

Journal of Shoulder and Elbow Surgery Volume 14, Issue 5 , September-October 2005, Pages 524-528.