8 Rationale and Biomechanics of the Reverse Shoulder Prosthesis: The American Experience

In this work a commercial reverse shoulder prosthesis has been redesigned to improve performances in terms of range of movements of the implant and stability to dislocation. A kinematic and mechanic study has been performed using a realistic solid model of the prothesised shoulder: in particular, all the components of the prosthesis have been acquired via a 3D laser scanner and inserted in a virtual humerus-glenoid system by reproducing the common surgical procedure. The final model has been used to measure the maximum angles of abduction and rotation of the arm and the shear forces that cause dislocation. Modifications proposed to the commercial prosthesis are: a different orientation of the cutting plane of the glenoid component and the interposition of a spacer to move the center of rotation of the arm.

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Reverse shoulder prosthesis combined with latissimus dorsi and teres major transfer for a lack of active elevation and external rotation

Tendon transfer for irreparable cuff tear ◽

10.1007/978-2-8178-0049-3_10 ◽

2011 ◽

pp. 111-124

Author(s):

Ph. Valenti ◽

A. Kilinc ◽

L. Thomsen

Keyword(s):

Latissimus Dorsi ◽

External Rotation ◽

Shoulder Prosthesis ◽

Reverse Shoulder Prosthesis ◽

Teres Major

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Biomechanical Evaluation of Different Designs of Glenospheres in the SMR Reverse Shoulder Prosthesis: Micromotion of the Baseplate and Risk of Loosening

Shoulder & Elbow ◽

10.1111/j.1758-5740.2010.00059.x ◽

2010 ◽

Vol 2 (2) ◽

pp. 94-99 ◽

Cited By ~ 8

Author(s):

Peter C. Poon ◽

Justin Chou ◽

Darryl Young ◽

Sharif F. Malak ◽

Iain A. Anderson

Keyword(s):

Shear Force ◽

Reverse Shoulder Arthroplasty ◽

Biomechanical Study ◽

Shoulder Prosthesis ◽

Reverse Shoulder Prosthesis ◽

Scapular Notching ◽

Uncemented Prosthesis ◽

Biomechanical Evaluation ◽

Glenoid Baseplate

Background Early outcomes of reverse shoulder arthroplasty have been encouraging. Scapular notching remains a major concern. In an attempt to reduce this problem, newer glenospheres are available. This biomechanical study performed in vitro, assessed the micromotions of baseplate in different designs of glenospheres and the relative risk of loosening. Methods A dynamic shear force was applied to each type of glenosphere in various angles of abduction. The micromotion of the glenoid baseplate after 1000 cycles of dynamic loading was measured and compared. Results Eccentric glenospheres were shown to have increased micromotion compared to the concentric designs of the same size. The greatest baseplate micromotion (26.83 μm) was well within the accepted limit for osseous in growth into uncemented prosthesis. Discussion We therefore conclude that the magnitude of the increased micromotion is small and is not expected to adversely affect osseous in growth onto the glenoid baseplate.

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