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What About Superior Erosion?

Stephanie Muh, MD

Read Complete Study: Reverse Total shoulder Arthroplasty with a Superior Augmented Glenoid Component for Favard Type – E1, E2 and E3 Glenoids

Superior glenoid wear is often under-appreciated when planning for a reverse Total Shoulder Arthroplasty (rTSA). It is the result of gradual erosion of the superior glenoid from humeral head migration due to rotator cuff tears. If superior erosion is not corrected during a Reverse Shoulder Arthroplasty (RSA), the implant may be placed in superior tilt and lead to early failure. While there have been numerous papers describing posterior glenoid erosion associated with long-standing shoulder arthritis, few papers discuss superior erosion. There are even fewer papers that discuss correction of superior erosion either with “high side” reaming, bone graft or metal augments.

This retrospective review looks at 68 rTSA patients who had either superior (33) or posterior-superior (35) augments for superior glenoid erosion with two years follow-up.1 There was significant improvement in SST, UCLA, ASES, Constant, and SPADI scores for both groups post-operatively. There were also significant improvements in flexion, abduction, internal rotation, and external rotation. Overall, over 88% exceeded the Minimal Clinically Important Difference (MCID) and 76% exceeded the Substantial Clinical Benefit (SCB). Radiographically, there was a 6% incidence of scapular notching. There were 5 complications (2 acromial stress fractures, 1 scapular spine fracture, 1 aseptic loosening, and 1 persistent pain). Of note, all of these complications were in patients with Favard type E3 glenoids.

This article presents one of the largest cohorts of superior metal augments in rTSA with an average of two years follow-up.1 In my opinion, the data supports the use of metal augments for treatment of superior glenoid erosion. Correcting superior erosion is important to avoid placing the glenoid baseplate in superior tilt to prevent early failure or loosening. Alternative options, including high side reaming (i.e. reaming of inferior glenoid) and the use of bone grafts, are a concern. Eccentric reaming may violate inferior subchondral bone leading to inadequate fixation of the baseplate due to loss of structural support and subsequent glenoid loosening. The use of bone graft can be difficult to find stable fixation as well as post-operative bone resorption, which also leads to loss of support and early loosening.

For me, metal augments are a reliable solution to address glenoid erosion. First, the technique to prepare for the superior augment allows for off-axis reaming which causes minimal bone loss.1,2 Secondly, there is no concern for bone resorption with metal augments. Finally, this data supports the usage of superior metal augments with good patient subjective and objective outcomes.1 In conclusion, with a low complication rate and good clinical outcomes, the superior and superior-posterior augments have become a staple in my practice to address the issue of superior glenoid erosion.

Reference

  1. Liuzza L, Mai DH, Grey S, Wright TW, Flurin PH, Roche CP, Zuckerman JD, Virk MS. Reverse Total Shoulder Arthroplasty with a Superior Augmented Glenoid Component for Favard Type-E1, E2, and E3 Glenoids. J Bone Joint Surg Am. 2020 Nov 4;102(21):1865-1873. doi: 10.2106/JBJS.19.00946.
  2. Lindsey G. Liuzza, Christopher Roche, Mandeep S. Virk, Joseph D. Zuckerman. Paper #29 – Outcomes using superior and posterior-superior augmented baseplates in reverse total shoulder arthroplasty for glenoid wear: short term follow up compared to match control. J Shoulder Elbow Surg.,Volume 28, Issue 6,2019,Pages e214-e215,ISSN 1058-2746,doi.org/10.1016/j.jse.2018.11.030.

Stephanie Muh, MD, is deputy chief of service in the department of orthopaedics at Henry Ford Hospital West Bloomfield where she specializes in shoulder and elbow reconstruction, rotator cuff repair and arthritis. Dr. Muh completed her residency in orthopaedic surgery at the Henry Ford Hospital and shoulder and elbow fellowship at Case Western Reserve University/University Hospitals of Cleveland.

Visit www.exac.com/extremities to learn about Exactech’s Equinoxe® Shoulder System, the most studied and published system in the industry.

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