Medial Center of Rotation Is Best for Reverse Total Shoulder Arthroplasty

Educational Objectives

The goal of this program is to improve the overall management of total shoulder arthroplasty. After hearing and assimilating this program, the clinician will be better able to:

1. Discuss the evolution of the reverse shoulder arthroplasty technique.

Summary

Background: 1970s reverse shoulder arthroplasty (RSA) design very lateralized (ie, center of rotation [COR] located outside bone); glenoid loosening resulted in failures

Grammont RSA: design medialized COR and lowered humerus, thereby eliminating lever arm on glenoid implant; solved issue of glenoid loosening

Problems with medialization: inferior scapular notching; (contributes to polyethylene wear and loosening); limited rotation (impingement of humeral cap on glenoid neck); instability; loss of shoulder contour

Metallic lateralization: early solution to medialization problems; moves COR outside prosthesis; avoids scapular impingement; creates better stability and rotation; however, increases lever arm and therefore risk for glenoid loosening from sheering force on implant

Bony increase-offset (BIO)-RSA: creates bony lateralization

Technique: use longer peg and screws to incorporate graft into base plate; place cancellous bone on glenoid surface to ensure healing of bone graft with scapula; example — cuff tear with arthritis reveals no infraspinatus or supraspinatus; detach remaining subscapularis in front; use guide aligned to forearm; place guide wire in center of humeral head; prepare pure cancellous bone graft; drill center hole; make bone cut parallel or oblique for asymmetric superior glenoid wear; place cancellous bone graft on long peg of base plate; prepare glenoid surface as low as possible; ream more than normal to reach cancellous bone; impact base plate with bone graft; fix with anterior and posterior compressive screws, and superior and inferior locking screws; ream 29 mm in length; choose 36 to 42 mm head based on patient size; prepare humerus for reverse prosthesis; place transosseous sutures to reattach subscapularis before reduction; COR remains inside scapula; results in no risk for glenoid loosening and less notching (inferior, anterior, and posterior)

Study: prospective monocentric study; included all patients with humeral bone grafts; follow-up >2 yr; ordered computed tomography (CT); hypotheses — bone grafts heal in elderly patients; low rate of inferior scapular notching; functional results unchanged from Grammont RSA; design — 42 patients (mainly women) followed >2 yr; mean 72 yr of age; pathology included cuff tear arthritis, rotator cuff failure, and fracture sequelae; presence of glenoid bone loss constituted exclusion criterion; results — procedure decreased anterior and posterior impingement (increased rotation); greater internal and external rotation achieved than with Grammont RSA; Constant scores similar to Grammont RSA; improved cosmesis; radiographs and CT demonstrated incorporation of bone graft in all patients; no anterior impingement; no implant loosening, screw breakage, or radiolucent line; no change to COR (main advantage); improved stability with no dislocation or subluxation; conclusions — procedure results in equal or improved mobility, lower incidence of scapular notching, and less instability, compared to Grammont RSA

Readings

Suggested Reading

Boileau P et al: Bony increased-offset reversed shoulder arthroplasty: minimizing scapular impingement while maximizing glenoid fixation. Clin Orthop Relat Res, 2011 Sep;469(9):2558-67; Boileau P et al: Grammont reverse prosthesis: design, rationale, and biomechanics. J Shoulder Elbow Surg, 2005 Jan-Feb(1 Suppl S):147S-161S; Edwards TB et al: The influence of rotator cuff disease on the results of shoulder arthroplasty for primary osteoarthritis: results of a multicenter study. J Bone Joint Surg Am, 2002 Dec;84-A(12):2240-8; Gerber C et al: Subscapularis muscle function and structure after total shoulder replacement with lesser tuberosity osteotomy and repair. J Bone Joint Surg Am, 2005 Aug;87(8):1739-45; Hammond JW et al: Surgeon experience and clinical and economic outcomes for shoulder arthroplasty. J Bone Joint Surg Am, 2003 Dec;85-A(12):2318-24; Hasan SS et al: The distribution of shoulder replacement among surgeons and hospitals is significantly different than that of hip or knee replacement. J Shoulder Elbow Surg, 2003 Mar-Apr;12(2):164-9; Jain N et al: The relationship between surgeon and hospital volume and outcomes for shoulder arthroplasty. J Bone Joint Surg Am, 2004 Mar;86-A(3):496-505; Kempton LB et al: A complication-based learning curve from 200 reverse shoulder arthroplasties. Clin Orthop Relat Res, 2011 Sep;469(9):2496-504; LaFosse L et al: Primary total shoulder arthroplasty performed entirely thru the rotator interval: technique and minimum 2-year outcomes. J Shoulder Elbow Surg, 2009 Nov-Dec;18(6):864-73; McFarland EG et al: The reverse shoulder prosthesis: A review of imaging features and complications. Skeletal Radiol, 2006 Jul;35(7):488-96; Miller SL et al: Loss of subscapularis function after total shoulder replacement: A seldom recognized problem. J Shoulder Elbow Surg, 2003 Jan-Feb;12(1):29-34;29-34; Nicholson GP et al: Scapular notching: Recognition and strategies to minimize clinical impact. Clin Orthop Relat Res, 2011 Sep;469(9):2521-30; Rockwood CA Jr: The reverse total shoulder prosthesis. The new kid on the block. J Bone Joint Surg Am, 2007 Feb;89(2):233-5; Savoie FH 3rd et al: Arthroscopic management of posterior instability: evolution of technique and results. Arthroscopy, 2008 Apr;24(4):389-96

Disclosures

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the following has been disclosed: Dr. Boileau is a consultant for Smith & Nephew and receives royalties from Tornier. The planning committee reported nothing to disclose.

Acknowledgements

Dr. Boileau was recorded at Arthroscopy/Arthroplasty/Fractures: 28th Annual San Diego Meeting, held June 22-25, 2011, in San Diego, CA, and presented by San Diego Shoulder Institute. For information on Arthroscopy/Arthroplasty/Fractures: 29th Annual San Diego Meeting, presented by San Diego Shoulder Institute, visit their website at www.shoulder.com. The Audio-Digest Foundation thanks the speaker and the sponsor for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

OR351401

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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