Chronic anterior shoulder instability with bone loss: a practical approach

Introduction

The shoulder joint is unique because of its large range of motion and anatomical complexity. Its configuration and biomechanics allow for great mobility, but also make it more prone to instability (1). The stability of this joint, considered one of the most mobile joints in the human body, depends on several factors (Figure 1), including:

• Joint congruency, which in the case of the glenohumeral joint is quite limited. Only 25% to 30% of the humeral head is in contact with the glenoid surface, sometimes the position. It is this low congruence, combined with sphericity, that allows for great mobility.
• The capsulolabral structures including the labrum, the capsule, and the capsular reinforcements that are the glenohumeral ligaments.
• The rotator cuff muscles: including the subscapularis muscle, the supraspinatus muscle, the infraspinatus muscle, and the teres minor.
• The intra-articular negative pressure which plays a secondary role.

Figure 1 Factors contributing to glenohumeral stability. (A) Joint congruency. Only 25% to 30% of the humeral head is in contact with the glenoid surface, sometimes the position. (B) The capsulolabral structures including the labrum, the capsule, and the capsular reinforcements that are the glenohumeral ligaments. (C) The rotator cuff muscles: including the subscapularis muscle, the supraspinatus muscle, the infraspinatus muscle, and the teres minor. (D) The intra-articular negative (effect indicated by the red arrows) pressure which plays a secondary role.

The significance of the rotator cuff muscles underscores the critical role of rehabilitation in achieving shoulder stability. However, when it comes to addressing anterior instability, it’s essential to emphasize that in the abduction and external rotation (ABER) position, the subscapularis muscle no longer acts as a significant barrier against the anterior displacement of the humeral head. Instead, the control of anterior instability is primarily reliant on the bony and capsuloligamentous structures.

As a result, the restoration of these two factors becomes paramount, particularly in the context of chronic anterior instability (2).

Anatomic lesions in anterior shoulder instability

Soft tissue injuries (Figure 2)

Figure 2 Soft tissue injuries in anterior shoulder instability (the red arrows indicate the location of the lesion). (A) Bankart lesion, avulsion of the antero-inferior capsulolabral complex with rupture of the periosteal tissue. (B) Perthes lesion is a variant in that the periosteum remains intact. (C) ALPSA lesion is a chronic lesion where the labrum detaches and then heals in a more medial position. (D) HAGL lesion. (E) The capsule itself can be damaged with rupture or progressive distension. ALPSA, anterior labral periosteal sleeve avulsion; HAGL, humeral avulsion glenohumeral ligament.

The classic Bankart lesion is well known (3,4). It is an avulsion of the antero-inferior capsulolabral complex with rupture of the periosteal tissue. The Perthes lesion is a variant in that the periosteum remains intact. The anterior labral periosteal sleeve avulsion (ALPSA) lesion is a chronic lesion where the labrum detaches and then heals in a more medial position. The lesion may be a humeral avulsion glenohumeral ligament (HAGL) lesion. Finally, the capsule itself can be damaged with rupture or progressive distension. This last factor is sometimes difficult to assess but it plays an essential role in instability alongside the other factors.

Bone injuries (Figure 3)

Figure 3 Bone injuries in anterior shoulder instability. (A) Bony Bankart. (B) Hill-Sachs lesion (shown by the white arrow).

It can occur at the glenoid level or on the humeral head.

In Bony Bankart, acute lesion, the capsulolabral complex is avulsed along with a fragment of anterior glenoid rim bone. The bone deficit can be chronic, either after Bony Bankart or after progressive erosion of the anterior rim of the glenoid.

Bone lesions (5) occurring on the humeral head are summarized in the term Hill-Sachs lesion (formerly called Broca and Hartmann lesion or Malgaigne notch). This is a posterior lateral compression fracture on the humeral head which happens during an anterior dislocation when the glenoid anterior rim hits the posterior part of humeral head (6).

Bone injuries epidemiology

Bone lesions are a common occurrence in cases of anterior shoulder instability. On the glenoid side, numerous studies have reported a prevalence ranging from 30% to 80% (4,7-10).

This variability is associated with the sensitivity of the imaging modality employed and the characteristics of the studied population, with particular consideration given to the duration of chronic instability. Research indicates that the prevalence is notably higher in cases of chronic instability compared to instances following the first dislocation, with figures of 86% vs. 41%, as observed in Griffith’s study (10).

Likewise, Hill-Sachs lesions are frequently observed, and their occurrence tends to escalate in cases of chronic shoulder instability (4,11,12), ranging from 45% to 80%.

Consequently, when both types of lesions are considered together, the presence of bone lesions in the context of anterior shoulder instability is highly common. Prevalence figures vary, with rates typically ranging from 40% to 50% in cases of the first episode of anterior dislocation, and increasing to substantial values between 80% and 95% in instances of chronic instability (8).

Assessment of glenoid and humeral bone loss

Initial assessment of bone lesions involves X-ray imaging. Glenoid contour loss, which is visible on the anteroposterior (AP) radiograph, and Hill-Sachs lesions, which are apparent on the AP view with internal rotation, provide an initial indication of the presence or absence of bone loss. For a more precise evaluation, the Bernageau view has been recognized as a reliable and reproducible technique for identifying and quantifying glenoid bone loss. However, it is important to note that this particular view requires meticulous and accurate execution to yield the best results (8,13). The radiographs do not allow for reliable quantification of the osseous lesion when compared with cross-sectional imaging modalities (14).

For a more accurate evaluation of humeral and glenoid bone loss, magnetic resonance imaging (MRI) or computed tomography (CT) scans are preferred (Figure 4). Various techniques have been developed for quantifying glenoid bone loss. Three-dimensional (3D) CT imaging provides a valuable “en face” sagittal view of the glenoid surface, which is particularly useful. Most of the measurement methods for assessing glenoid bone loss employ a width-measurement technique (15) or a “best-fit circle” technique (16).

Figure 4 MRI assessment of glenoid and humeral bone loss. (A) Assessment of glenoid bone loss with the “best-fit circle” technique. The red circle represents the best-fit circle. The green line is reported to the blue line to evaluate the percentage of glenoid bone loss. (B) For assessment of humeral bone loss, a circle in red is drawn to fit the humeral head allowing to measure the depth and width of the Hill-Sachs. MRI, magnetic resonance imaging.

For assessment of humeral bone loss, a circle is drawn to fit the humeral head allowing to measure the depth and width of the Hill-Sachs (17). Both size and location influence the risk of engagement, with larger and medial Hill-Sachs lesions more likely to engage the glenoid.

The “on-track” and “off-track” concept (18) is a calculation method to predict the risk of engagement, particularly in case of bipolar lesions. While this method is elegant and valuable, it relies on a static analysis, essentially treating the glenohumeral joint as a purely spheroid joint. However, clinical experience has shown that in cases of capsulo-ligamentous laxity, significant anterior translation can occur. In practice, all Hill-Sachs lesions are potentially “off-track”, either through a simple rotational movement or in combination with anterior translation. Given that the existence of a Hill-Sachs lesion indicates that engagement has occurred at least once during the history of anterior shoulder instability, this method is not employed in our daily practice.

Bone lesions should be treated

The 1990s witnessed significant advancements in arthroscopic Bankart techniques, which, for a period, were regarded as the gold standard for addressing anterior instability. However, as initial enthusiasm waned, it became increasingly evident that disregarding bone lesions posed a substantial risk of treatment failures. As such, the publication of Burkhart and De Beer is a milestone (19). They analyzed 194 consecutive arthroscopic Bankart repairs by suture anchor technique performed for traumatic anterior-inferior instability. A total of 101 patients were contact athletes. Significant bone deficit was defined either by an “engaging” Hill-Sachs lesion of the humerus or by an “inverted-pear” glenoid. The incidence of recurrence in the group without bone deficit was 4% whereas it was 67% in the group with bone defect. This difference was even greater if the patients participated in contact sports (6.5% vs. 89%).

The literature then largely confirmed this notion of bone lesions as a risk factor for failure after Bankart procedure (20).

Traditionally, the critical bone loss (greater than 20–25%) is considered a contraindication for soft tissue procedures alone due to high clinical failure (19). Recent research has identified the concept of “subcritical” bone loss suggesting that bone augmentation may result in better outcomes for patients with this subcritical bone loss between 13.5% and 17.3% (21,22). Further research will shed light on whether it is necessary to address all bone lesions, regardless of their size. In our clinical practice, we do not differentiate between the concept of critical or subcritical bone loss; instead, we advocate treating any bone lesion that is identified.

Current techniques for the surgical treatment of anterior shoulder instability

Numerous interventions are available for addressing shoulder instability (20). We will only discuss those routinely performed in everyday clinical practice. The Bankart procedure entails the reattachment of the labrum using sutures and anchors. This procedure is typically performed arthroscopically (Figure 5).

Figure 5 Bankart procedure. The current Bankart procedure entails the reattachment of the labrum using sutures and anchors.

Repairing a HAGL can be performed using a similar technique at the humeral level.

These procedures are often complemented by capsular retention. However, there are ongoing debates regarding the effectiveness of capsular plasty in treating anterior instability. Excessive capsular plasty can lead to restricted joint motion. On the other hand, if the capsular tissue’s quality is poor, the capsular plasty may not be effective. While capsular retention is a fundamental component of the Bankart procedure, we find it unrealistic to attempt to address joint hyperlaxity solely through arthroscopic capsular plasty.

The Remplissage consists in making the Hill-Sachs lesion extra-articular by fixing the posterior capsule in the lesion (Figure 6) (23,24).

Figure 6 Remplissage procedure. The Remplissage consists in making the Hill-Sachs lesion extra-articular by fixing the posterior capsule in the lesion.

The Eden-Hybinette procedure involves grafting an iliac bone fragment onto the anterior glenoid rim to restore the AP surface of the glenoid (Figure 7) (25,26). The distal clavicle has been used for reconstruction of the anterior glenoid rim (27). Bone allografts (iliac crest, distal tibial, and xenograft) are now regularly used and the term bone-block is frequently used for these modifications of the Eden-Hybinette procedure (28).

Figure 7 Eden-Hybinette. The Eden-Hybinette procedure involves grafting an iliac bone fragment onto the anterior glenoid rim to restore the AP surface of the glenoid. AP, anteroposterior.

The Latarjet procedure is a transfer of the coracoid process with the attached conjoined tendon to the anteroinferior aspect of the glenoid rim (29). It combines bone grafting, capsular repair, and tendon plasty which create the “triple locking effect”: bone effect, Bankart effect, and sling effect (Figure 8) (30). The sling effect is particularly important in ABER position, moving the inferior part of the subscapularis muscle distally to control the anterior humeral translation. The Latarjet procedure have the lowest rate of dislocation recurrence and do not seem to increase the risk of osteoarthritis if the bone block is not lateralized (20).

Figure 8 Latarjet procedure with the “triple locking effect”: sling effect ①, Bankart effect ②, and bone effect ③.

Personalized treatment approach: tailoring interventions to lesion, capsulo-ligamentous status, and patient profile

Chronic anterior shoulder instability is predominantly associated with anatomical abnormalities. It is essential to consider the loss of integrity of the capsule attachment, including lesions like the Bankart or ALPSA lesions on the labrum and HAGL on the humerus, along with bone loss such as glenoid bone loss and Hill-Sachs lesions. Equally significant are the considerations of the joint capsule and its supporting structures, particularly the glenohumeral ligaments (3). Indeed, this capsule can be damaged following episodes of dislocations with progressive distension but it can also be lax by constitution. This capsular laxity is clinically assessed with the Gagey test (31), the importance of external rotation and the assessment of constitutional laxity (Beighton score) (32). It is known that the age of the patient also influences the degree of capsular laxity (9). In parallel, extrinsic dynamic factors can lead to a risk of capsular distension and repeated damage to the repair. Some sport activities lead to capsuloligamentary constraints. The type of sports activity (contact and collision) as well as the level of competition must be taken into account in the overall evaluation (33). At an end stage, epilepsy represents a major extrinsic risk factor for the capsulo-ligamentous structures (34).

Clearly, in addition to soft tissue lesions and bone lesions, the ability of the joint capsule to distend to a greater or lesser extent must be evaluated by assessing the intrinsic and extrinsic factors (35).

While the significance of the muscle factor should not be overlooked, it’s important to recognize that surgical interventions do not directly influence it. Rather, it’s the post-operative rehabilitation process that plays a pivotal role in harnessing the full potential of the surgical procedure (36).

In the therapeutic choice of an anterior instability of the shoulder, our approach is summarized in Table 1. The primary author of this article places significant emphasis on the Latarjet procedure, as the literature indicates its lower dislocation recurrence rate and, when executed correctly, minimal risk of osteoarthritis (20). Despite the emergence of new “bone block” techniques derived from Eden-Hybinette’s intervention, it’s crucial to note that they do not possess the same biomechanical equivalence as the Latarjet procedure. The Latarjet procedure, apart from its bone effect, offers the added advantage of capsular plasty through the “sling effect” (28). This provides undeniable benefits in limiting anterior humeral head translation, especially in cases of capsuloligamentary hyperlaxity or participation in contact sports.

Additionally, the Remplissage procedure, involving infraspinatus tendon tenodesis, may yield favorable dynamic effects while making Hill-Sachs lesions extra-articular (24). However, we still lack conclusive evidence to determine the true advantages of Remplissage in comparison to the Latarjet procedure (37).

A treatment algorithm serves as a valuable tool to assist clinicians in determining their treatment approach, but it should not be viewed as inflexible. In our treatment guide, we often present two viable options, as supported by the literature, since both options have demonstrated beneficial outcomes. Moreover, when evaluating the extent of bone loss and discussing treatment options with the patient, it is crucial to engage in a comprehensive dialogue.

Patients should be well-informed about the advantages and potential risks associated with each surgical option, allowing them to actively participate in the decision-making process. Notably, while the Bankart procedure is considered more anatomical than the Latarjet procedure, some patients may choose to assume a higher risk of recurrence in favor of a procedure that preserves the potential for a subsequent Latarjet procedure, particularly if they are young.

The decision regarding whether to opt for the Latarjet procedure or a bone block is similarly based on a similar rationale.

Conclusions

The surgical management of chronic anterior shoulder instability has undergone significant evolution over the last two decades. In cases involving bone lesions, the isolated Bankart procedure has shown a high rate of failure. For us, the Latarjet procedure stands as a benchmark due to its excellent outcomes in both the short- and long-term.

The introduction of techniques like Remplissage for addressing humeral bone loss and bone blocks for glenoid bone lesions has expanded the therapeutic options. However, we require more substantial evidence to precisely define the role of these various procedures within the treatment algorithm. It’s entirely possible that our approach will evolve in the coming years as we gather more knowledge and experience in this field.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editor (Prashant Meshram) for the series “Controversies in Shoulder Surgery and Algorithmic Approach to Decision Making” published in Annals of Joint. The article has undergone external peer review.

Peer Review File: Available at https://aoj.amegroups.com/article/view/10.21037/aoj-23-8/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aoj.amegroups.com/article/view/10.21037/aoj-23-8/coif). The series “Controversies in Shoulder Surgery and Algorithmic Approach to Decision Making” was commissioned by the editorial office without any funding or sponsorship. P.L. receives consulting fees and payment for lectures from Smith & Nephew and Arthrex. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Halder AM, Itoi E, An KN. Anatomy and biomechanics of the shoulder. Orthop Clin North Am 2000;31:159-76. [Crossref] [PubMed]
2. Muench LN, Imhoff AB. The unstable shoulder: what soft tissue, bony anatomy and biomechanics can teach us. Knee Surg Sports Traumatol Arthrosc 2021;29:3899-901. [Crossref] [PubMed]
3. Hantes M, Raoulis V. Arthroscopic Findings in Anterior Shoulder Instability. Open Orthop J 2017;11:119-32. [Crossref] [PubMed]
4. Hintermann B, Gächter A. Arthroscopic findings after shoulder dislocation. Am J Sports Med 1995;23:545-51. [Crossref] [PubMed]
5. Provencher MT, Frank RM, Leclere LE, et al. The Hill-Sachs lesion: diagnosis, classification, and management. J Am Acad Orthop Surg 2012;20:242-52. [Crossref] [PubMed]
6. Hill HA, Sachs MD. The Grooved Defect of the Humeral Head. Radiology 1940;35:690-700. [Crossref]
7. Rowe CR, Patel D, Southmayd WW. The Bankart procedure: a long-term end-result study. J Bone Joint Surg Am 1978;60:1-16. [Crossref] [PubMed]
8. Edwards TB, Boulahia A, Walch G. Radiographic analysis of bone defects in chronic anterior shoulder instability. Arthroscopy 2003;19:732-9. [Crossref] [PubMed]
9. Boileau P, Villalba M, Héry JY, et al. Risk factors for recurrence of shoulder instability after arthroscopic Bankart repair. J Bone Joint Surg Am 2006;88:1755-63. [Crossref] [PubMed]
10. Griffith JF, Antonio GE, Yung PS, et al. Prevalence, pattern, and spectrum of glenoid bone loss in anterior shoulder dislocation: CT analysis of 218 patients. AJR Am J Roentgenol 2008;190:1247-54. [Crossref] [PubMed]
11. Owens BD, Dickens JF, Kilcoyne KG, et al. Management of mid-season traumatic anterior shoulder instability in athletes. J Am Acad Orthop Surg 2012;20:518-26. [Crossref] [PubMed]
12. Taylor DC, Krasinski KL. Adolescent shoulder injuries: consensus and controversies. Instr Course Lect 2009;58:281-92. [PubMed]
13. Murachovsky J, Bueno RS, Nascimento LG, et al. Calculating anterior glenoid bone loss using the Bernageau profile view. Skeletal Radiol 2012;41:1231-7. [Crossref] [PubMed]
14. Lemmex D, Cárdenas G, Ricks M, et al. Arthroscopic Management of Anterior Glenoid Bone Loss. JBJS Rev 2020;8:e0049. [Crossref] [PubMed]
15. Griffith JF, Antonio GE, Tong CW, et al. Anterior shoulder dislocation: quantification of glenoid bone loss with CT. AJR Am J Roentgenol 2003;180:1423-30. [Crossref] [PubMed]
16. Huysmans PE, Haen PS, Kidd M, et al. The shape of the inferior part of the glenoid: a cadaveric study. J Shoulder Elbow Surg 2006;15:759-63. [Crossref] [PubMed]
17. Cho SH, Cho NS, Rhee YG. Preoperative analysis of the Hill-Sachs lesion in anterior shoulder instability: how to predict engagement of the lesion. Am J Sports Med 2011;39:2389-95. [Crossref] [PubMed]
18. Yamamoto N, Itoi E, Abe H, et al. Contact between the glenoid and the humeral head in abduction, external rotation, and horizontal extension: a new concept of glenoid track. J Shoulder Elbow Surg 2007;16:649-56. [Crossref] [PubMed]
19. Burkhart SS, De Beer JF. Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs: significance of the inverted-pear glenoid and the humeral engaging Hill-Sachs lesion. Arthroscopy 2000;16:677-94. [Crossref] [PubMed]
20. Bauer S, Collin P, Zumstein MA, et al. Current concepts in chronic traumatic anterior shoulder instability. EFORT Open Rev 2023;8:468-81. [Crossref] [PubMed]
21. Dickens JF, Owens BD, Cameron KL, et al. The Effect of Subcritical Bone Loss and Exposure on Recurrent Instability After Arthroscopic Bankart Repair in Intercollegiate American Football. Am J Sports Med 2017;45:1769-75. [Crossref] [PubMed]
22. Shin SJ, Kim RG, Jeon YS, et al. Critical Value of Anterior Glenoid Bone Loss That Leads to Recurrent Glenohumeral Instability After Arthroscopic Bankart Repair. Am J Sports Med 2017;45:1975-81. [Crossref] [PubMed]
23. Gouveia K, Harbour E, Athwal GS, et al. Return to Sport After Arthroscopic Bankart Repair With Remplissage: A Systematic Review. Arthroscopy 2023;39:1046-1059.e3. [Crossref] [PubMed]
24. Polio W, Brolin TJ. Remplissage for Anterior Shoulder Instability: History, Indications, and Outcomes. Orthop Clin North Am 2022;53:327-38. [Crossref] [PubMed]
25. Eden R. Zur Operation der habituellen Schulterluxation unter Mitteilung eines neuen Verfahrens bei Abriss am inneren Pfannenrande. Deutsche Zeitschrift für Chirurgie 1918;144:269-80. [Crossref]
26. Hybbinette S. De la transplantation d’un fragment osseux pour remédier aux luxations récidivantes de l’épaule: Constatations et résultats opératoires. Acta Chir Scand 1932;71:26.
27. Tokish JM, Fitzpatrick K, Cook JB, et al. Arthroscopic distal clavicular autograft for treating shoulder instability with glenoid bone loss. Arthrosc Tech 2014;3:e475-81. [Crossref] [PubMed]
28. Calvo E, Itoi E, Landreau P, et al. Anterior and posterior glenoid bone augmentation options for shoulder instability: state of the art. J ISAKOS 2021;6:308-17. [Crossref] [PubMed]
29. LATARJET M. Treatment of recurrent dislocation of the shoulder. Lyon Chir 1954;49:994-7. [PubMed]
30. Yamamoto N, Muraki T, An KN, et al. The stabilizing mechanism of the Latarjet procedure: a cadaveric study. J Bone Joint Surg Am 2013;95:1390-7. [Crossref] [PubMed]
31. Gagey OJ, Gagey N. The hyperabduction test. J Bone Joint Surg Br 2001;83:69-74. [Crossref] [PubMed]
32. Beighton P, Solomon L, Soskolne CL. Articular mobility in an African population. Ann Rheum Dis 1973;32:413-8. [Crossref] [PubMed]
33. Alkaduhimi H, van der Linde JA, Willigenburg NW, et al. Redislocation risk after an arthroscopic Bankart procedure in collision athletes: a systematic review. J Shoulder Elbow Surg 2016;25:1549-58. [Crossref] [PubMed]
34. Atwan Y, Wang A, Labrum JT 4th, et al. Management of Shoulder Instability in Patients with Seizure Disorders. Curr Rev Musculoskelet Med 2023;16:201-10. [Crossref] [PubMed]
35. Balg F, Boileau P. The instability severity index score. A simple pre-operative score to select patients for arthroscopic or open shoulder stabilisation. J Bone Joint Surg Br 2007;89:1470-7. [Crossref] [PubMed]
36. Stokes DJ, McCarthy TP, Frank RM. Physical Therapy for the Treatment of Shoulder Instability. Phys Med Rehabil Clin N Am 2023;34:393-408. [Crossref] [PubMed]
37. Horinek JL, Menendez ME, Narbona P, et al. Arthroscopic Bankart Repair With Remplissage as an Alternative to Latarjet for Anterior Glenohumeral Instability With More Than 15% Glenoid Bone Loss. Orthop J Sports Med 2022;10:23259671221142257. [Crossref] [PubMed]