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Chronic posttraumatic shoulder instability is characterized by trauma-associated, recurrent dislocations. Surgical treatment is indicated in most cases but it remains controversial how risk factors should be weighted to decide between arthroscopic Bankart repair (ABR), Latarjet or alternative procedures. Known risk factors for recurrence are patient age, hyperlaxity, sports profile and bone loss. Surgical techniques are discussed in detail. The ABR leads to high patient satisfaction and return to sports; however, in association with risk factors, recurrent dislocations are seen even several years later. Latarjet or bone block procedures lead to high patient satisfaction, sustainable stability as a revision procedure, but can also be primarily indicated for chronic instability depending on risk factors. Early complications are more frequent but of a minor nature in most cases. All techniques are known for a serious learning curve. If performed well, they do not seem to increase the risk of arthritis, which is most affected by the number of lifetime dislocations and higher energy trauma.

Chronic traumatic anterior shoulder instability can be defined as recurrent trauma-associated shoulder instability requiring the assessment of three anatomic lesions: a capsuloligamentous and/or labral lesion; anterior glenoid bone loss and a Hill-Sachs lesion. Surgical treatment is generally indicated. It remains controversial how risk factors should be evaluated to decide between a soft-tissue, free bone-block or Latarjet-type procedure. Patient risk factors for recurrence are age; hyperlaxity; competitive, contact and overhead sports. Trauma-related factors are soft tissue lesions and most importantly bone loss with implications for treatment. Different treatment options are discussed and compared for complications, return to sports parameters, short- and long-term outcomes and osteoarthritis. Arthroscopic Bankart and open Latarjet procedures have a serious learning curve. Osteoarthritis is associated with the number of previous dislocations as well as surgical techniques. Latarjet-type procedures have the lowest rate of dislocation recurrence and if performed correctly, do not seem to increase the risk of osteoarthritis.

Supplemental material, sj-docx-1-ajs-10.1177_03635465221148494 for Effect of PARP-1 Inhibition on Rotator Cuff Healing: A Feasibility Study Using Veliparib in a Rat Model of Acute Rotator Cuff Repair by Michael B. Künzler, Michelle H. McGarry, Masaki Akeda, Hansel Ihn, Agnieszka Karol, Brigitte von Rechenberg, Michael O. Schär, Matthias A. Zumstein and Thay Q. Lee in The American Journal of Sports Medicine

BACKGROUND Navigated augmented reality (AR) through a head-mounted display (HMD) may lead to accurate glenoid component placement in reverse shoulder arthroplasty (RSA). The purpose of this study is to evaluate the deviation between planned, intra- and postoperative inclination, retroversion, entry point, depth and rotation of the glenoid component placement assisted by a navigated AR through HMD during RSA. METHODS Both shoulders of six fresh frozen human cadavers, free from fractures or other bony pathologies, were used. Preoperative computed tomography (CT) scans were used for the three-dimensional (3D) planning. The glenoid component placement was assisted using a navigated AR system through a HMD in all specimens. Intraoperative inclination, retroversion, depth and rotation were measured by the system. A postoperative CT scan was performed. The pre- and postoperative 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postoperative inclination, retroversion, entry point, depth and rotation of the glenoid component placement. Additionally, a comparison between intra- and postoperative values was calculated. Outliers were defined as >10° inclination, >10° retroversion, >3 mm entry point. RESULTS The registration algorithm of the scapulae prior to the procedure was correctly completed for all cases. The deviations between planned and postoperative values were 1.0 ± 0.7° for inclination, 1.8 ± 1.3° for retroversion, 1.1± 0.4mm for entry point, 0.7 ± 0.6mm for depth, and 1.7 ± 1.6° for rotation. The deviation between intra- and postoperative values were 0.9±0.8° for inclination, 1.2±1.1° for retroversion, 0.6±0.5mm for depth, and 0.3±0.2° for rotation. There were no outliers between planned and postoperative parameters. CONCLUSION In this study, the use of a navigated AR system through a HMD for RSA led to low deviation between planned and postoperative values and between intra- and postoperative parameters.

Rotator cuff tears (RCT) are one of the most common sources of shoulder pain. Many factors can be considered to choose the right surgical treatment procedure. Of the most important factors are the tear retraction and tear width, assessed manually on preoperative MRI.A novel approach to automatically quantify a rotator cuff tear, based on the segmentation of the tear from MRI images, was developed and validated. For segmentation, a neural network was trained and methods for the automatic calculation of the tear width and retraction from the segmented tear volume were developed.The accuracy of the automatic segmentation and the automated tear analysis were evaluated relative to manual consensus segmentations by two clinical experts. Variance in the manual segmentations was assessed in an interrater variability study of two clinical experts.The accuracy of the tear retraction calculation based on the developed automatic tear segmentation was 5.3 mm ± 5.0 mm in comparison to the interrater variability of tear retraction calculation based on manual segmentations of 3.6 mm ± 2.9 mm.These results show that an automatic quantification of a rotator cuff tear is possible. The large interrater variability of manual segmentation-based measurements highlights the difficulty of the tear segmentations task in general.