Abstract
The current diagnostic and treatment strategies for anterior glenohumeral instability have been refined by high-quality clinical and basic science studies, but many controversies remain. These include the bone loss threshold for arthroscopic Bankart repair and the influence of other clinical factors on this decision, the optimal bracing position following anterior glenohumeral dislocation, and the optimal coracoid graft orientation during the Latarjet procedure. Randomized clinical trials often present conflicting results, and many of these are small-sample and fragile studies. Obtaining an expert consensus on the topic, by means of the Delphi method, is an attractive alternative to such clinical trials. Several studies employing variations of the Delphi method have addressed the diagnosis and treatment of anterior glenohumeral instability. These have stressed the importance of a meticulous technique during arthroscopic Bankart repair and of recognition of glenoid and humeral bone loss and treating this appropriately. These studies have also helped identify areas where consensus is modest or lacking to motivate additional clinical research study.
The evaluation and treatment of traumatic anterior glenohumeral instability has changed dramatically over the past 30 years. Stabilization procedures transitioned from nonanatomic to anatomic Bankart repair and from open to arthroscopic techniques. Suture anchors replaced staples and tacks and arthroscopic suture management techniques evolved to facilitate anatomic labrum repair and to address associated capsular laxity. Glenoid bone loss and its implications were recognized and better appreciated, beginning with the landmark study by Burkhart and De Beer,
1
and this catalyzed the reintroduction of coracoid transfer procedures, such as the Latarjet procedure to successfully treat instability in the setting of glenoid bone loss.2
, 3
, 4
Subsequently, Wolf described remplissage as an adjunct to arthroscopic Bankart repair aimed at addressing the Hill-Sachs lesion.5
The concept of the glenoid track6
was put forth to describe the nuanced interaction of humeral and glenoid bone loss, and a quantitative assessment of on-track/off-track lesions replaced the qualitative description of engaging/nonengaging1
,7
to help guide the selection of the appropriate soft tissue or bony stabilization procedure.8
Despite the refinement of arthroscopic stabilization techniques, some surgeons continue to advocate open Bankart repair in collision athletes, including those with intermediate degrees of bone loss.9
,10
Despite these graduated advancements, several controversies remain that are related to the diagnosis and treatment of anterior glenohumeral instability. The thresholds for subcritical glenoid and humeral bone loss for arthroscopic Bankart repair have been evolving over time, and these thresholds may depend on patient age, activity level, and other factors. For example, the Instability Severity Index Score (ISIS) was developed to identify patients at risk for failure with arthroscopic Bankart repair.
11
However, nearly every high school football player in the United States who sustains a traumatic anterior glenohumeral dislocation merits a score of 5 or greater, thereby exceeding the ISIS threshold for arthroscopic Bankart repair.12
Other controversies relate to various aspects of nonoperative, operative, and postoperative treatment, such as arm position in a brace after closed reduction, the timing of surgery following an in-season anterior glenohumeral dislocation, and the duration of postoperative immobilization.High-quality or Level I evidence in support of various treatments of anterior glenohumeral instability can be obtained from randomized clinical trials, but these are not without their limitations.
13
,14
First, their validity may be limited to the study population and may not generalize to other populations. Second, a practical and readily obtainable outcome measure may be selected, but it may not be the actual outcome of clinical interest. Additionally, randomized clinical trials are very resource-intensive with regard to cost, and with regard to time, when long-term outcomes are of interest.14
Consequently, these studies are often small, and there is risk of study fragility because of inadequate sampling.15
, 16
, 17
To understand the limitations of randomized clinical trials, consider the landmark clinical and basic science studies by Itoi et al. in support of immobilizing the arm in external rotation after reduction of an anterior glenohumeral dislocation.
18
, 19
, 20
The underlying basic science supporting external rotation bracing was intuitive, and the results of the initial randomized clinical trial were compelling because there were no cases of instability following immobilization in external rotation.19
However, larger-scale, randomized clinical trials with longer follow-up have yielded conflicting results, ranging from no benefit of external rotation bracing over traditional sling immobilization21
to modest benefit20
to dramatic benefit.22
As an alternative to clinical studies, consensus-based evidence techniques, such as those employing the Delphi method, may synthesize the collective experience of a group of experts.23
,24
A recent three-part article authored by Hurley et al., employed a modified Delphi method to produce a comprehensive consensus statement on the diagnosis and management of anterior glenohumeral instability.
25
, 26
, 27
The authors addressed various topics and controversies related to the diagnosis of anterior glenohumeral instability, the role of nonoperative treatment, arthroscopic Bankart repair, the role of glenoid and humeral head bone loss in treatment decision-making, and postoperative recovery and return to play.25
, 26
, 27
A principal strength of this study group was its uniquely international composition of 65 surgeon experts from 14 countries on 5 continents.25
, 26
, 27
However, their methodology strayed from the traditional Delphi method because study group participants were divided into 9 subgroups that iterated on the various questions before bringing the questions to a final vote. Additionally, the process was carried out using online surveys rather than in person. Many global thought leaders who have published extensively on anterior glenohumeral instability participated in this study group, but as is often the case, the definition of an expert was somewhat arbitrary.23
The Anterior Shoulder Instability International Consensus Group (ASI-ICG) findings are compelling and help to reaffirm some of the best available evidence from clinical research, including randomized clinical trials. Although influenced to a large degree by the precise wording of the study questions, the overall strength of consensus is remarkable: of the 84 topics addressed across the 3 papers, 72 of 84, or 86%, achieved unanimous consensus or strong consensus exceeding 90%.
25
, 26
, 27
Importantly, the study group obtained unanimous consensus that arthroscopic Bankart repair should be performed with suture anchors spaced 5-8 mm apart,25
which is equivalent to stating that surgeons should prioritize fastidiousness over expediency by using a minimum of 3 to 4 anchors to shift the capsule and reduce the labrum onto the glenoid face. Unanimous consensus was also achieved on other disparate topics ranging from the various prognostic factors that should be considered in patients undergoing a glenoid bone-grafting procedure to the primary indications for revision surgery. For some topics in which consensus was reached, follow-up questions remain unanswered. For example, there was consensus (87%) that the Latarjet procedure should be performed using the classic rather than the congruent arc technique,26
,28
but it is unclear whether most experts favored the classic technique because of superior clinical results or because of greater familiarity and technical proficiency with that technique.More importantly, this effort has also identified gaps in our knowledge and persistent areas of controversy. For example, there was unanimous consensus that the role of capsular repair during glenoid bone grafting procedures remains unclear.
26
In this case the study group has acknowledged that they know what they do not know. This is an important first step that needs to be followed by well-designed clinical trials. Additionally, no consensus was achieved regarding the optimal position of shoulder immobilization for patients treated nonoperatively after anterior glenohumeral dislocation. However, it is unclear if the disparate opinions relate to conflicting scientific evidence on the benefit of external rotation bracing, to different interpretations of that evidence, or to practical considerations, such as patient noncompliance29
and the pressures of early return to sport, as well as the cost and logistical issues associated with widespread adoption of immediate external rotation bracing after closed reduction.Other study groups have employed Delphi methods differently to study the diagnosis and treatment of anterior glenohumeral instability. Tokish et al.
30
reported on the results of a Delphi approach, employed by 72 members of the Neer Circle of the American Shoulder and Elbow Surgeons, aimed at understanding the treatment decision following a first-time anterior glenohumeral dislocation. As in the study by Hurley et al.,25
consensus was sought by means of several surveys, but with different formats. An initial survey identified patient-related features that influence treatment decisions following first-time anterior glenohumeral dislocation. A second survey ranked each feature’s impact on treatment decisions, and a third survey used highly impactful features to construct 162 clinical scenarios. Experts were instructed to recommend surgery or not for each clinical scenario and to note the strength of their recommendation. The data were analyzed to identify clinical scenarios achieving strong consensus for recommending treatment. Only 8 of 162 (5%) of these scenarios achieved strong consensus for recommending surgery, and all 8 related to the treatment of athletes with meaningful bone loss at the end of their season.30
Rossi et al. also explored the diagnosis and treatment of anterior glenohumeral instability with associated bone loss using a more traditional Delphi method.
31
Twenty-two shoulder instability experts from 5 continents participated in 3 rounds of surveys to establish consensus, defined as 70% of greater agreement and less than 10% disagreement, on 31 statements. According to their study, 86% of experts agreed that a history of multiple dislocations and failed soft-tissue surgery should arouse suspicion about an associated bone deficit. There was strong consensus that Hill-Sachs lesions are poorly quantified and classified by current imaging systems and that glenoid bone graft reconstruction should be performed with any of the available options for cases with greater than 20% glenoid bone loss. In their study, experts were unable to reach consensus on the management of Hill-Sachs injuries or on postoperative rehabilitation.31
Importantly, all three studies took different paths to reach the same conclusion that glenoid bone loss exceeding 15-20% warrants a glenoid bone graft procedure, including arthroscopic or open Latarjet. To varying degrees, all three studies suggest that quantifying the Hill-Sachs lesion and understanding its role in clinical decision making remain incompletely understood, despite the recent flurry of basic science and clinical research study. However, unlike the other studies, Hurley and colleagues did not limit their scope to anterior instability with bone loss.
25
,26
Rather, the ASI-ICG tackled all aspects of diagnosis and management of traumatic anterior shoulder instability include duration of postoperative follow-up and criteria for return to play. Strong or unanimous consensus was achieved for many of the questions posed, which helps provide a meaningful and global benchmark or standard for treating patients with traumatic anterior glenohumeral instability. More importantly, the study group also identified controversies that warrant further careful study, such as the role of external rotation bracing in the acute nonoperative treatment of patients following anterior glenohumeral dislocation and the role of adjunctive capsular repair during glenoid bone grafting. Hopefully, this will motivate better large-scale randomized clinical trials to put these controversies to rest.Supplementary Data
- ICMJE author disclosure forms
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Article info
Footnotes
See related articles pages 214, 224, and 234
The author reports no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
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