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Editorial Commentary: Anchor Position Affects Glenoid Resorption Rates After Arthroscopic Bankart Repair: Shoulder Stabilization Surgery Is a Game of Millimeters

      Abstract

      The technical nuances of arthroscopic Bankart repair cannot be overstated. Previous literature has identified a number of risk factors for failure of arthroscopic stabilization procedures, and the implications of glenoid bone loss is widely recognized as a critical driver of postoperative outcomes. However, other technical considerations (inadequate number of suture anchors, improper position of suture anchors) have been acknowledged as risk factors for the failure of arthroscopic stabilization procedures. More recently, concerns have been raised regarding the observed rates of glenoid bone resorption following arthroscopic Bankart repair, which theoretically may predispose higher rates of clinical failure. Furthermore, certain techniques for placing anchors on the glenoid during arthroscopic Bankart repair may accelerate these resorptive changes. Precise measures of poststabilization surgery glenoid resorption coupled with comprehensive assessments of clinical outcomes are required to determine the optimal technique for anchor insertion during arthroscopic Bankart repair.
      “Football is a game of inches, and inches make the champion.”—Vince Lombardi
      We’re not playing football, and we usually use the metric system when discussing units of measure. But I’ll take inspiration from Coach Lombardi in saying that shoulder stabilization surgery truly is a game of millimeters. We measure glenoid and humeral-sided bone loss in millimeters, we choose one anchor over another based upon a millimeter’s difference in implant diameter, we place anchors within millimeters of one another, not too close to compromise adjacent fixation or risk the dreaded “postage stamp fracture”, not too far to result in an insecure capsulolabral repair.
      • Woolnough T.
      • Shah A.
      • Sheean A.J.
      • Lesniak B.P.
      • Wong I.
      • de SA D.
      "Postage stamp" fractures: A systematic review of patient and suture anchor profiles causing anterior glenoid rim fractures after bankart repair.
      We perform arthroscopic shoulder stabilization surgery perform on a thin margin, which is measured in millimeters. The current study by Hirose, Nakagawa, Uchida, Yokoi, Ohori, Tanaka, Sahara, and Mae entitled “On-the-Edge Anchor Placement May Be Protective Against Glenoid Rim Erosion After Arthroscopic Bankart Repair Compared to On-the Face Anchor Placement”
      • Hirose T.
      • Nakagawa S.
      • Uchida R.
      • et al.
      On-the-edge anchor placement may be protective against glenoid rim erosion after arthroscopic Bankart repair compared to on-the-face anchor placement.
      reminds us of this fact and compels us to undertake these procedures with the utmost skill and precision.
      This article is a mostly radiographic analysis of a single surgeon’s arthroscopic Bankart repairs (ABR) performed from 2013 to 2020 using all-suture, soft anchors. The purpose of the study was to assess the radiographic outcomes associated with two different approaches to placing anchors into the glenoid during ABR: 1. “on-the-face” anchoring, which the authors describe as “removal of sufficient cartilage along the anterior edge of the glenoid” (3-4 mm) and subsequent anchor insertion immediately posterior to the area of exposed, subchondral bone, and 2. “on-the-edge” anchoring, which involved inserting anchors directly into the anterior edge of a the glenoid. Given previous concerns for erosive changes observed following ABR, which the authors posit may be a consequence of stress-shielding related to “on-the-face” anchoring, it was hypothesized that less erosive changes would be observed in the group of patients treated with “on-the-edge” anchoring.
      • Hirose T.
      • Nakagawa S.
      • Iuchi R.
      • Mae T.
      • Hayashida K.
      Progression of erosive changes of glenoid rim after arthroscopic Bankart repair.
      There were 225 shoulders (214 patients) with preoperative and at least one postoperative computerized tomography (CT) scan included in the final analysis. Two independent reviewers performed all CT-based measurements, and high levels of interobserver reliability between measurements were identified. Overall, the authors observed significantly greater magnitudes of postoperative glenoid erosion in the “on-the-face” anchoring group compared to the “on-the-edge” anchoring group across the cohort. Interestingly, however, the authors did not observe this finding in shoulders without preoperative glenoid bone loss (GBL) Among shoulders with a bony Bankart lesion, significantly higher rates of fragment union were observed in the “on-the-edge” anchoring group compared to the “on the face” anchoring group, which the authors suggest may be a consequence of a more precise reduction of the fragment with the former technique. Of note, the authors did not report on the absolute value of GBL across the cohort, so it is impossible to know whether higher magnitudes of preoperative GBL were more likely to undergo more advanced levels of erosive changes postoperatively. It is also worth noting that, here, were no differences in rates of postoperative recurrence, defined as dislocation or subluxation within at least two years’ follow-up, between the “on-the-face” and “on-the-edge” anchoring groups. Furthermore, the authors did not report any other functional outcomes associated with either anchoring technique.
      Given these results and the fact that the main distinction between the two different anchoring techniques compared in this article amounts to the difference of anchor position on the glenoid of 3-4 mm, one can’t help but appreciate the extent to which the technical nuances in ABR really do matter. Yes, I acknowledge that there were no differences in rates of recurrence between groups. But I’m inclined to consider this point less a matter of what we commonly acknowledge as the regrettable discrepancy between statistical and clinical significance and more so a general flaw (but not of the fatal variety, in my view) of the authors’ method of assessing clinical outcomes. One can certainly argue that the difference between a successful and failed ABR is more nuanced than simply, did the patient have a recurrent instability event?
      • Kennedy M.I.
      • Murphy C.
      • Dornan G.J.
      • et al.
      Variability of reporting recurrence after arthroscopic Bankart repair: A call for a standardized study design.
      Was the patient apprehensive on physical examination? Were there significant differences in Western Ontario Shoulder Instability scores in the absence of overt postoperative instability events, as has been previously reported (and frequently cited) by Shaha et al.?
      • Shaha J.S.
      • Cook J.B.
      • Song D.J.
      • et al.
      Redefining "critical" bone loss in shoulder instability: Functional outcomes worsen with "subcritical" bone loss.
      Without the answers to these questions, it is not so much that the observed differences in glenoid erosion failed to produce a clinically significant result, as it is that we can’t know for sure what the clinical implications of these findings truly are given the information that we are presented.
      In my estimation, what this study lacks in terms of a precise measurement of clinical outcomes, it makes up for with an exacting and reliable measurement of postoperative GBL in a cohort large enough to detect meaningful differences between groups. Ultimately, we’re left to rely on what we know for sure: GBL matters in isolation, and it almost assuredly matters more in the setting of a larger cohort of subjects, and more likely to engage Hill-Sachs lesions. The results of the current study would suggest that subtle differences in technique—a few millimeters here versus a few millimeters there—have a substantial effect on a parameter that we have long recognized to be of paramount importance as to whether a stabilization surgery is successful or not. Through their focus on resorptive glenoid changes following ABR, Hirose et al.
      • Hirose T.
      • Nakagawa S.
      • Uchida R.
      • et al.
      On-the-edge anchor placement may be protective against glenoid rim erosion after arthroscopic Bankart repair compared to on-the-face anchor placement.
      remind us of just how much millimeters can matter in arthroscopic shoulder stabilization surgery.

      Supplementary Data

      References

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