Fig. 1 Force distribution on the native glenoid versus coracoid graft with variable levels of glenoid bone width restoration (via Latarjet) in 90-degree humerothoracic abduction in the scapular plane and neutral (0 degrees) rotation.
Courtesy of Ryan Rauck, MD

AAOS Now

Published 12/20/2023
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Rebecca Araujo

Less than 100 Percent Glenoid Bone Loss Restored through Latarjet Surgery Is Associated with Instability and Graft Complications

Patients with glenoid bone loss are at risk of recurrent shoulder instability if glenoid width is not properly restored. For those patients with significant anterior glenoid bone loss with recurrent instability, a coracoid transfer, or Latarjet procedure, may be required. However, the percentage of glenoid width restoration necessary to attain stability has not been identified, according to researchers of a biomechanical study presented at the AAOS 2023 Annual Meeting. The study sought to specify this “necessary percentage” by measuring anterior humeral head translation and force distribution on the coracoid graft.

The study was presented by Ryan Rauck, MD, assistant professor of orthopaedic surgery, sports medicine, and shoulder surgery at the Ohio State University Wexner Medical Center.

“Treatment of moderate to large glenoid bone loss is challenging,” Dr. Rauck told AAOS Now. “The Latarjet has an excellent track record for addressing anterior shoulder instability with glenoid bone loss, but what is the upper limit? And what are the goals of restoring native glenoid width restoration after Latarjet? Is it 110 or 100 percent? Is 90 percent sufficient? These are all unanswered questions, and this study was an attempt to provide biomechanical evidence to answer some of them.”

According to the findings, 100 percent glenoid width restoration was necessary to avoid an increased risk of not only recurrent instability but also graft complications, particularly when less than 90 percent of width is restored.

“From a biomechanical standpoint, analyzing anterior humeral head translation as well as distribution of contact force between the native glenoid and the coracoid graft, the goals for glenoid width restoration after Latarjet should be 100 percent of native,” Dr. Rauck summarized.

The study involved nine cadaveric specimens that were mounted on a shoulder simulator, which used pulleys and weights to load shoulder tendons. The researchers used a motion-tracking system to measure glenohumeral translations and force distributions on the scapula and humerus. The force-distribution sensor was secured to the glenoid and coracoid graft transfer.

Each specimen underwent coracoid osteotomy with a graft depth of 10 mm. In order to access the glenoid for removal of the appropriate amount of bone, the investigators performed a lesser tuberosity osteotomy (LTO). The lesser tuberosity and the attached subscapularis were then reflected medially to allow access to the glenoid. To establish benchmarks for restoring 110 percent, 100 percent, 90 percent, and 80 percent of native glenoid width, the researchers measured the widest point of the glenoid and used CT images to confirm accuracy. A burr was used to establish bone loss. Two screws were used for the coracoid graft transfer, and the LTO was repaired with Kirschner wires prior to each testing condition.

For the simulation, the supraspinatus was loaded with 18 N, and the subscapularis, infraspinatus, and conjoined tendons were loaded with 13 N each. Tests were carried out in the native joint, with repaired LTO, and with Bankart tear, then with 110 percent, 100 percent, 90 percent, and 80 percent of glenoid width restoration after Latarjet. Glenohumeral translation was measured with the application of an anteroinferior load of 44 N at 90-degree humerothoracic abduction and at 0 degrees or 45 degrees of glenohumeral external rotation. Force distribution was measured with the same rotator cuff loads without an anteroinferior load.

The investigators found that as the amount of glenoid width restored decreased, the amount of humeral head translation increased during anteroinferior load:

  • 110 percent restored: 3.0 mm translation (standard deviation, 2.7 mm)
  • 100 percent restored: 4.1 mm (2.6)
  • 90 percent restored: 10.8 mm (3.0)
  • 80 percent restored: 13.1 mm (4.7)

The amount of translation was similar between the intact joints and the LTO group (P = 0.372). The amount of translation significantly increased with only 90 percent glenoid restoration compared with 100 percent (P <0.001).>

The percentage of glenoid bone loss was also associated with the amount of force applied on the coracoid graft after Latarjet (Fig. 1). At 110 percent, 100, percent, 90 percent, and 80 percent restoration, force distributions on the coracoid graft relative to the native glenoid were 3.1 percent, 9.0 percent, 44 percent, and 64 percent, respectively. Again, the amount of force increased significantly with 90 percent glenoid width restored compared with 100 percent restoration (P <0.001).>

Notably, Dr. Rauck added, “One unexpected finding was how little force the coracoid graft sees with 110 percent or even 100 percent glenoid width restoration. This may have implications in graft resorption.”

The study findings confirmed that the goal of glenoid restoration should be 100 percent relative to the native glenoid width, the authors wrote. “Less than 100 percent glenoid width restoration puts the shoulder at risk for recurrent instability and places the majority of the contact forces on the coracoid graft, which could place the patient at risk for graft complications,” Dr. Rauck said.

When 100 percent restoration is not possible with a Latarjet procedure, surgeons “may consider using alternative graft sources,” Dr. Rauck advised.

The authors acknowledged several limitations of the study. Dr. Rauck commented: “This is a biomechanical study, so further study is needed to determine the clinical ramifications. Another limitation is we did not incorporate humeral-sided bone loss, so caution should be used when applying the findings of this study when bipolar bone loss is present.”

Based on the findings of this study, Dr. Rauck said that future studies are needed “to determine how this data looks using distal tibia allograft or other graft sources. One difference would be that there is no sling effect from the conjoined tendon in those cases.”

Dr. Rauck’s coauthors of “How Much Glenoid Bone Loss Needs to Be Restored with a Latarjet?” are Christopher Brusalis, MD; Amirhossein Jahandar, MS; Andreas Kontaxis, PhD; and Samuel Arthur Taylor, MD.

Rebecca Araujo is the managing editor of AAOS Now. She can be reached at raraujo@aaos.org.