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    How to Avoid the Top 3 Mistakes in Reverse Total Shoulder Arthroplasty

    In the first few years after the reverse total shoulder arthroplasty (RTSA) implant was approved for use in the US, Joaquin Sanchez-Sotelo, MD, PhD, would see referral patients with poor baseplate positioning, dislocations, and glenoid loosening.

    With surgeons gaining greater experience in RTSA techniques, plus advances in the reverse implant, those problems have gone away – only to be replaced with 3 new issues:

    • Pseudoparalysis in external rotation
    • Perimeter impingement
    • Excessive lengthening and lateralization

    Dr. Sanchez-Sotelo – who will chair ICJR’s upcoming 10th Annual Shoulder Course with Grant E. Garrigues, MD – discussed why these mistakes occur and what surgeons can do to avoid them in a presentation at ICJR’s 7th Annual Shoulder Course.

    Pseudoparalysis in external rotation, he said, is the result of atrophy and fatty infiltration of the supraspinatus, the infraspinatus, and the teres minor, which causes  severe weakness of the entire posterior rotator cuff. CT scan is helpful in identifying patients at risk for pseudoparalysis, as it will show the surgeon the condition of these tendons. The results of testing performed during the physical exam also provide clues to at-risk patients, such as a marked external rotation lag sign and a lack of active external rotation in abduction (Hornblower’s sign).

    RELATED: Register for ICJR’s 10th Annual Shoulder Course, October 7-9 in Las Vegas

    Identifying at-risk patients and then restoring the posterior cuff can help the surgeon prevent pseudoparalysis in external rotation. This is achieved by ensuring adequate lateralization of the greater tuberosity offset and selectively performing tendon transfer procedures; Dr. Sanchez-Sotelo typically transfers the latissimus dorsi when needed. In patients who are undergoing RTSA because of a fracture, it is crucial for the surgeon to reconstruct the greater tuberosity to restore function of the posterior cuff.

    Perimeter impingement is caused by contact between the implant’s polyethylene and the medial scapula, resulting in wear, debris, and bone loss. Impingement can also occur at the acromion and, to a lesser extent, at the coracoid. The notching that results from perimeter impingement is important, Dr. Sanchez-Sotelo said: The French literature has shown that it correlates with glenoid and humeral loosening.

    To prevent perimeter impingement, Dr. Sanchez-Sotelo recommends that surgeons:

    • Use a more vertical opening angle for the polyethylene
    • Add more lateralization, and/or inferior overhang, and/or posterior eccentricity to move the glenosphere away from the scapula, which limits impingement
    • Consider tuberosity trimming, if necessary, to avoid impingement with the acromion and coracoid

    Excessive lengthening and lateralization commonly cause arthroplasty pain because the shoulder is too tight. This tightness – which can result in stiffness, brachial plexus stretch, deltoid pain and failure, and acromion/scapular spine fracture – can be attributed to the evolution in reverse implant designs, Dr. Sanchez-Sotelo said.

    Many reverse implants are currently on the market, with great variability in the amount of glenoid, humeral, and global offset they provide. [1] The surgeon must understand the implications of each implant’s features to adapt their surgical technique and avoid adding too much lateralization and/or too much distalization.

    Click the image above to watch Dr. Sanchez-Sotelo’s presentation on avoiding mistakes in RTSA.

    Faculty Bio

    Joaquin Sanchez-Sotelo, MD, PhD, is a Consultant and Professor in the Department of Orthopaedic Surgery and Chair of the Division of Shoulder and Elbow Surgery at Mayo Clinic, Rochester, Minnesota.

    Disclosures: Dr. Sanchez-Sotelo has disclosed that he receives royalties and research support from and is a paid speaker for Stryker; that he receives royalties from, is a paid consultant for, and is a paid speaker for Wright Medical Technology; that he is a paid consultant for Exactech, Inc.; and that he is a paid speaker for Acumed.

    Reference

    1. Werthel J-D, Walch G, Vegehan E, Deransart P, Sanchez-Sotelo J, Valenti P. Lateralization in reverse shoulder arthroplasty: a descriptive analysis of different implants in current practice. Int Orthop . 2019 Oct;43(10):2349-2360. doi: 10.1007/s00264-019-04365-3. Epub 2019 Jun 28.