Arthroscopic Bone Block and Arthroscopic Latarjet for Anterior Shoulder Dislocation—Technical Note with Tricks and Tips for Conversion and Successful Surgery

Abstract

Background: The treatment of patients affected by recurrent anterior shoulder instability has received more attention in the last ten years, focusing on the management of bone loss, which is crucial in predicting postoperative recurrence risk. Recently, various bone grafting techniques and different fixation methods have been developed to preserve native anatomy and reduce complications. Nowadays, glenoid bone reconstruction is usually carried out via the Latarjet procedure or free bone block technique. While the Latarjet procedure has traditionally been considered the best option, the bone block has been demonstrated to be a successful procedure. Even though the indication to perform a free bone block or a Latarjet procedure may be given preoperatively, in cases where the choice between the two procedures is unclear, the decision can be made intraoperatively, given the possibility to switch from one to another. This technical note aims to outline our techniques for the arthroscopic Latarjet procedure and the arthroscopic free bone block, as well as discuss the indications, benefits and downsides of each procedure. Technical tips and tricks are provided. Methods: A step-by-step thorough description of bone block and Latarjet procedures is provided, as well as a comparison of advantages and disadvantages of each technique and tips to avoid complications. Respective indications are discussed. Results: Both the procedures have benefits and downsides. The arthroscopic Latarjet procedure is the most effective in addressing anterior shoulder instability, but is more elaborate, has a shallow learning curve and can have a high complication rate. The bone block technique is an anatomic procedure with a shorter learning curve but has fewer indications. Conclusion: The Latarjet is currently considered the gold standard for glenoid bone grafting. The bone block technique can allegedly be seen as being “in the middle” of the soft tissue repair and Latarjet procedures. Many factors should be considered when choosing the right surgical technique, and treatment plans must be customized for each patient. More studies with long-term follow-up are needed to evaluate the efficacy of arthroscopic bone grafting procedures in various subtypes of patients based on bipolar bone loss assessment and individual risk factors.

1. Introduction

In the United States (Minnesota state), the incidence of primary shoulder anterior dislocations has been estimated to be 0.08 per 1000 person-years in the general population [1]. In Europe (Denmark), it was found to be 0.12 per 1000 person-years [2]. According to a recent study, 374 high school rugby players had a 14.8% prevalence of a history of shoulder dislocation [3]. Estimated at 1.69 per 1000 person-years, the incidence among military corps is significantly higher than that of the general population and contact athletes. Certain high-risk young men even show incidence rates of up to 3% per year [3,4].

The surgical hospitalization rate for this pathology has increased over the last years, accompanied by a decrease in the hospitalization rate for non-surgical treatment [5].

Males aged 15 to 64 years of age showed the highest hospitalization rate for shoulder instability [5], with ages 15 to 29 making up the majority of cases; 72% of those under 22 and 27% over 30 experience recurring episodes. In addition, young athletes playing contact sports have low return to sport rates and are more likely to experience recurrent instability if treated without surgery [6].

Numerous risk variables, including male gender, age less than 28, bone loss, hyperlaxity, and involvement in contact or overhead sports, have been identified as associated with prolonged symptomatic instability and recurrence postoperatively [7,8,9]. Yet, the two main factors influencing the chance of recurrent instability are the age of the patient and the extent of glenoid and humeral bone loss [10].

In the past decade, there has been more focus on treating patients with recurrent anterior shoulder instability, particularly looking at the position and extent of bone loss [11]. Furthermore, the impact of bipolar defects—which involve both the glenoid and humeral head—has been extensively studied [6,11]. Bipolar bone loss has been found a contributing factor in recurrent shoulder dislocations and worse functional results after soft tissue repairs for glenohumeral instability [12].

It has been observed that 90% to 95% of shoulders with recurrent instability have glenoid and/or humeral bone lesions; recurrently dislocated shoulders had the highest frequency of these lesions [6,13]. In the mid-range of movement, the shoulder capsule is lax, and stability derives largely from the glenoid bone with the concavity–compression effect. For this reason, glenoid bone loss alone can produce mid-range instability. End-range instability, instead, depends not only on glenoid bone loss, but also on humeral bone loss. Depending on the entity of the glenoid bone loss and location of the humeral bone loss, the Hill–Sachs lesion may engage with the anterior glenoid rim at the end-range of movement, producing instability. The combination of these factors is critical in determining the recurrence of anterior shoulder instability, which is why the term bipolar bone loss was introduced [14]. As shown by biomechanical studies, combined defects more effectively increase the instability risk than isolated defects [15,16].

There are currently several methods and treatment plans to address bone loss, taking into account the degree of glenoid bone loss (GBL), the existence of concomitant humeral head bone loss (bipolar defects), the patient’s commitment to sports and/or practiced sport, and the glenoid track concept [6,17]. The ISI score and the GTIM score, a modification of the ISI score incorporating the glenoid track concept, are instruments that can be used to orientate therapeutic choices [18,19].

It is crucial to evaluate the bipolar bone loss before recommending patients for arthroscopic Bankart repair. It is best suited for low-demand patients experiencing first-time shoulder instability, as postoperative instability rates are low, whilst it has a high failure rate in patients experiencing preoperative recurrent instability [20]. When conducted in non-specific patient groups and when patients are monitored for over two years, the failure rate of the arthroscopic Bankart repair goes from 15 to 30% [13].

In the past, numerous authors have suggested bone grafting operations when the GBL reaches 20–25% (critical bone loss). This threshold has, nevertheless, progressively gotten lower. A bone graft operation is necessary to treat subcritical glenoid bone loss, which accounts for 15% to 20% of bone loss, because a reduction in quality of life would present if Bankart repair were performed. This is especially true for high-risk patients [17,21,22]. Even a 10% to 15% loss of glenoid width would be better suited for bone grafting operations, as recommended in recent studies on combined defects [23].

These days, Bankart repair is often advised when GBL is inferior to 15%, while glenoid bone grafting is typically indicated with GBL ≥ 15% [17]. Nevertheless, it is important to keep in mind that additional risk factors, including humeral bone loss [24], patient age [25], hyperlaxity, sport (contact versus non-contact), and activity level (competitive versus non-competitive), should also be considered when choosing the right technique for each patient [18].

In the context of an off-track Hill–Sachs lesion, bone treatments are recommended, given the high failure rate of a Bankart repair [26]. In any case, an on-track Hill–Sachs lesion needs to be carefully assessed, as those that are nearly off-track are linked to worse results [17].

Another indication for glenoid bone reconstruction procedures—which are usually carried out via coracoid process transfer (Latarjet) or free bone graft transfer (bone block)—is failed soft tissue repair.

Due to its extensive history of documented clinical success, the open Latarjet procedure is often considered the gold standard for glenoid bone grafting [6]. The glenoid surface augmentation and the conjoined tendon’s function, which produces a sling and a hammock effect, are stabilizing mechanisms that contribute to the Latarjet procedure’s success. When Bankart repair is combined to coracoid transfer, the result is an additional stabilizing action that allows for a triple-blocking effect [13]. This technique is successful even in contact and collision sports athlete and revision surgery; however, it may disturb the subscapularis function and lead to a reduction in proprioception and athletic performance [27]. Also, it has been linked in certain studies to a high complication rate of about 30%, and the process of revising a failed Latarjet is difficult and produces worse outcomes [28]. Anyway, in recent years, arthroscopic Latarjet procedures have been introduced to reduce soft tissue iatrogenic injury, lower the complication rate associated with the open technique, and simultaneously treat several joint structures [29,30].

The open or arthroscopic bone block procedure is an alternative technique easier to perform that allows to preserve shoulder anatomy, reduce the complication rate, and save the Latarjet procedure for revision cases [17,31]. The procedure combines the soft tissue repair with the implant of a bone graft, which is introduced through a small tunnel and secured on the anterior glenoid neck. The graft may be an allograft, xenograft, or autograft harvested from the iliac crest, and serves to increase the glenoid surface and recreate the glenoid concavity with the labrum reinsertion, which, together with the anterior inferior shift of the capsule and anterior inferior glenohumeral ligament, contribute to the success of the technique.

Bone block techniques have demonstrated excellent clinical results and a minimal incidence of subsequent arthritis [32,33]. Even so, aside from posing the problem of donor site morbidity or allograft cost, these procedures require soft tissue repair in order to make the graft extraarticular and strengthen the repair; thus, they cannot be performed in case of substantial capsular–ligamentous injury [31,34]. When there is irreversible soft tissue damage, a Latarjet operation must be carried out [31], wherein the conjoined tendon’s strong supporting action makes soft tissue healing unnecessary [13] (Table 1).

While there may be reasons to prefer an arthroscopic free bone block over arthroscopic Latarjet based on preoperative factors, in dubious cases, the final treatment decision can be determined during the surgery itself. This allows for a simple transition between the two surgical techniques after arthroscopic assessment of soft tissue, since joint preparation and glenoid drilling are common to both methods [31].

This technical note aims to outline our approaches for the arthroscopic Latarjet procedure and the arthroscopic free bone block, as well as discuss the indications and relative benefits and downsides of each procedure.

2. Surgical Technique of the Arthroscopic Free Bone Block

2.1. Positioning of the Patient, Joint Inspection, and Preparation

The procedure is performed in a semi-seated position with general anesthesia. The backrest is at a 45° angle, for a better exposure of the iliac crest. After the harvest of the iliac crest graft, the procedure continues with an angle of 30–45°. With a bolster, the scapula may be externally rotated for better anterior glenoid neck exposure. A conventional posterior portal is made to insert the arthroscope. The anterior and posterior anatomy is examined to evaluate capsular or labral insufficiency, SLAP lesions, anterior bone loss, and Hill–Sachs lesions. A full arthroscopic exploration is carried out.

The arthroscopic examination assesses the condition of the capsuloligamentous tissues. When these soft tissues detached from the glenoid neck show insufficient shift (inadequate elasticity) or poor quality and consistency (tears or deforms while pulling towards the glenoid), the bone block procedure is converted to a Latarjet procedure. In the case of adequate soft tissue quality, a bone block is performed.

The anterosuperior and mid-glenoid portals are created while viewing from the posterior portal. Two 5.5 mm cannulas are positioned in the rotator interval. First, the labrum is separated from the glenoid rim with a soft-tissue shaver. Then, viewing from the anterosuperior portal, the anterior glenoid neck is exposed and abraded using a burr to obtain a regularized flat surface that fits the graft (Figure 1).

A needle is introduced posteriorly, aligned with the glenoid surface, and centered on the anterior glenoid bone defect. The glenoid guide is then positioned through a more posteromedial portal.

2.2. Glenoid Drilling

The glenoid guide’s hook end is positioned posteriorly with the aid of a half-cannula to protect the articular surface, is aligned to the glenoid surface, and is placed centrally on the glenoid defect, engaging the anterior border typically between the three and four o’clock positions in the right shoulder (Figure 2). The guide has to be lined up with the anterior and posterior borders (Table 1).

A bullet is inserted into the inferior hole of the guide and advanced through a tiny skin incision until it makes firm contact with the glenoid neck posteriorly. The screws next to the guide handle should line up with the bullet’s ratchet teeth. The superior bullet goes through the same procedure again. Two 2.8 mm sleeved drills are inserted in the bullets and brought forward to emerge from the anterior glenoid.

The drills are positioned 10 mm apart, parallel to one another, with a 6 mm offset from the anterior glenoid border (Table 1). The sleeves remain after the inner drills are taken out. Fluid emerging posteriorly validates intra-articular positioning. The bullets are then extracted posteriorly, disengaging the ratchet teeth; then, the guide is removed. Attention is required to make sure the outer sleeves remain in place.

On the anterior glenoid rim, suture anchors are now positioned to allow for Bankart repair, which will be performed afterwards (Figure 3).

Next, one looped guidewire is inserted into each sleeve to enter the joint. A forceps inserted in the rotator interval is used to retrieve each guidewire. Once this is complete, the sleeves are removed (Figure 4).

2.3. Graft Preparation

The ipsilateral anterior iliac crest is incised. Dissection of muscles from the bone is performed. While keeping at least 4 cm from the anterior superior iliac spine, a 20 × 8 × 8 mm tricortical bone graft is usually harvested with an osteotome or a power saw or drill guides, preserving the medial cortex. Two holes with a diameter of 2.8 mm, spaced 10 mm and centered concerning the edges, are drilled on the graft with a specific grasping drill guide, entering through the cortex and exiting through the cancellous bone.

2.4. Graft Positioning and Tensioning with Anterior and Posterior Double Round Endobuttons (Smith and Nephew)

Attention must be taken to ensure the looped guidewires are not twisted inside the joint before loading the graft onto the guidewires. The bone block is loaded on looped guidewires, which enter on the cancellous side and emerge on the cortical side. Two Endobutton sutures are passed through each looped guidewire and are loaded on the graft. A slip knot is performed. The graft is advanced to the end of the Endobutton sutures to seat the two round Endobuttons.

By pulling the guidewires posteriorly, the Endobutton sutures exit the skin posteriorly, and the bone graft is seated flush on the anterior glenoid neck with two round Endobuttons lying flat on the anterior side (Figure 5). The bone block is tilted before being put into the 10 mm cannula. Throughout this process, the sutures should be kept slightly taut.

A suture retriever is inserted in each eyelet of the posterior Endobuttons to allow for loading of the posterior implants on the Endobutton sutures. With a knot pusher, the Endobuttons are slid and seated on the posterior glenoid neck. At this point, a Nice knot is performed with the two sutures exiting from an Endobutton. One of the two sutures is cut, obtaining two suture tails to be used as a post for the knot. Before pulling the post, the knot must be entirely taut.

The same steps are performed for the other Endobutton.

We now use a suture tensioner to compress the bone block to the glenoid firmly. After the implant tensioning, half-hitches are performed to lock the posterior knots, and a blind knot cutter is used to cut the remaining sutures.

2.5. Bankart Repair

With a typical arthroscopic Bankart repair procedure, the anterior soft tissues are reattached to the glenoid border (Figure 6).

3. Surgical Technique of the Arthroscopic Latarjet Procedure

3.1. Positioning of the Patient, Joint Inspection, and Preparation

The procedure is performed in a semi-seated position with general anesthesia A bolster can help externally rotate the scapula. In this procedure, six arthroscopic portals are used: superior to the coracoid (C), axillary (AX), posterior (P), anterosuperior (AS), anterolateral (AL), and anteroinferior (AI) (Figure 7).

A conventional posterior portal is made to insert the arthroscope and examine the joint. The anterosuperior portal is created and used to resect the anteroinferior labrum, the middle glenohumeral ligament, and a portion of the inferior glenohumeral ligament. The lateral aspect of the coracoid is seen with the opening of the rotator interval, and the coracoacromial ligament can then be released.

After inserting a needle aligned with the top edge of the subscapularis directed to the coracoid base, the anterolateral portal is created (Figure 8).

Viewing from the anterolateral portal, the anterior glenoid neck is exposed and decorticated using a burr inserted in the anterosuperior portal (Figure 9).

A spinal needle is inserted in the posterior portal and centered on the anterior glenoid defect. The parallelism of the needle and the glenoid surface is checked. If the needle is not aligned to the glenoid, another portal is made to position the glenoid drilling guide properly.

3.2. Glenoid Drilling

This phase is identical to the two techniques. While viewing from the anterolateral portal, with the aid of a half-cannula, the hook of the posterior double tunnel glenoid guide is aligned to the glenoid surface and positioned centrally on the anterior glenoid bone loss, engaging the anterior glenoid border, typically at the four o’clock position (right shoulder) (Figure 10) (Table 1).

Thereafter, a bullet is inserted into the guide’s inferior hole. The bullet is advanced through a tiny skin incision until it makes firm contact with the posterior portion of the glenoid neck. The same step is repeated for the superior bullet (Figure 11).

Two 2.8 mm sleeved drills are inserted in the bullets and brought forward to emerge from the anterior glenoid.

The drills are positioned 10 mm apart, parallel to one another, with a 6 mm offset from the anterior glenoid border (Table 1). The sleeves remain after the inner drills are taken out. Fluid emerging posteriorly validates intra-articular positioning.

The bullets are extracted posteriorly, then the guide is taken out. Attention is required to make sure the outer sleeves remain in place (Figure 12).

3.3. Subscapularis Split

The anteroinferior portal allows for easily visualizing the inside and the outside of the joint. With the aid of a switching stick inserted in the posterior portal, the location of the subscapularis split is determined. Using the radiofrequency probe inserted in the axillary portal, the split is carried out viewing from the anteroinferior portal (Figure 13 and Figure 14).

3.4. Coracoid Graft Harvesting

With the arthroscope in the anteroinferior portal, the pectoralis minor tendon is released, and the lower face of the coracoid process is smoothed off using a rasp to obtain a regularized surface. To insert the 6 mm offset coracoid drill guide, a coracoid portal is created. After inserting two K wires through the coracoid, spaced 10 mm from each other, the guide is taken out. Two tunnels with a 2.7 mm diameter are drilled over the K wires, which are then removed (Figure 15).

3.5. Anterior Endobutton (Smith and Nephew) Insertion

A suture retriever loaded with high-resistance sutures is inserted posteriorly through each sleeve of the glenoid. After that, sutures are retrieved with forceps (located in the axillary portal) and brought through the split. A suture retriever is inserted in each coracoid hole. Each suture is passed in the respective suture retriever, and, therefore, the sutures are brought through the coracoid holes.

The drill sleeves are removed. The introduction sutures are tied to the loop and button sutures and are pulled from the posterior. Two anterior Endobuttons are pushed and properly seated on the coracoid (Figure 16).

3.6. Coracoid Osteotomy

With the arthroscope in the anteroinferior portal, the oscillating saw is put inside the anterolateral portal to carry out the coracoid osteotomy (Figure 17).

3.7. Coracoid Transfer

Viewing from the anteroinferior portal, the graft is passed in the split by taking back the sutures. Two switching sticks inserted in the posterior and axillary portals can facilitate this passage by opening the split. The coracoid position is adjusted with bone forceps so that the graft surface becomes flush with the anterior surface of the glenoid (Figure 18). The posterior sutures must slide into the glenoid and coracoid.

3.8. Posterior Endobutton Positioning

A suture retriever is inserted in each eyelet of the posterior Endobuttons to allow for loading of the posterior implants on the Endobutton sutures. With a knot pusher, the Endobuttons are slid and seated on the posterior glenoid neck. At this point, a Nice knot is performed with the two loop sutures exiting from each Endobutton. One of the two loop sutures is cut, obtaining two suture tails that will be used as a post for the knot. Before pulling the post, the knot must be entirely taut.

The same steps are performed for the other Endobutton.

A suture tensioner is used to compress the graft to the glenoid with a strength of 100 N. The correct graft position is confirmed from the posterior and anteroinferior portals. After the implant tensioning, half-hitches are performed to lock the first knots, and a blind knot cutter is used to cut the remaining sutures.

Table 1. Tips to avoid pitfalls of the arthroscopic bone block and arthroscopic Latarjet with Endobutton fixation.

Table 1 Tips to avoid pitfalls of arthroscopic Bone block and arthroscopic Latarjet procedures with endobutton fixation
Pitfall	Tip
The glenoid guide introduced through the posterior portal may not be parallel to the glenoid surface	Create a more posteromedial portal to achieve correct alignment of the glenoid guide with the articular surface
The two glenoid tunnels may have different offset, causing an unwanted tilt of the graft	Carefully check the position of the drills emerging from the anterior glenoid. In case of unequal offset between the tunnels, remove the drills, rotate the guide as requested and make new tunnels with the same offset. Hold the guide with both hands while drilling for better precision
In case of different offset between glenoid and graft tunnels, graft overhang may produce	The prominent portion of the graft must be accurately rimmed to achieve flush positioning of the graft
A graft too small causes higher risk of fracture	Aim for at least 2 cm of graft length
Certain off-track Hill-Sachs lesions (gap between Hill-Sachs interval and glenoid track width > 7.45 mm) may remain off-track after the Latarjet procedure	In case of relatively low size of the coracoid or excessive glenoid bone loss, perform a bone block technique
In case of substantial capsular-ligamentous injury a stable repair is not achieved with the bone block technique	Convert to the Latarjet procedure

Table 1. Tips to avoid pitfalls of the arthroscopic bone block and arthroscopic Latarjet with Endobutton fixation.

Table 1 Tips to avoid pitfalls of arthroscopic Bone block and arthroscopic Latarjet procedures with endobutton fixation
Pitfall	Tip
The glenoid guide introduced through the posterior portal may not be parallel to the glenoid surface	Create a more posteromedial portal to achieve correct alignment of the glenoid guide with the articular surface
The two glenoid tunnels may have different offset, causing an unwanted tilt of the graft	Carefully check the position of the drills emerging from the anterior glenoid. In case of unequal offset between the tunnels, remove the drills, rotate the guide as requested and make new tunnels with the same offset. Hold the guide with both hands while drilling for better precision
In case of different offset between glenoid and graft tunnels, graft overhang may produce	The prominent portion of the graft must be accurately rimmed to achieve flush positioning of the graft
A graft too small causes higher risk of fracture	Aim for at least 2 cm of graft length
Certain off-track Hill-Sachs lesions (gap between Hill-Sachs interval and glenoid track width > 7.45 mm) may remain off-track after the Latarjet procedure	In case of relatively low size of the coracoid or excessive glenoid bone loss, perform a bone block technique
In case of substantial capsular-ligamentous injury a stable repair is not achieved with the bone block technique	Convert to the Latarjet procedure

4. Discussion

Anteroinferior shoulder instability has been treated with various stabilization procedures in recent years, the outcome of which is primarily dependent on bipolar bone loss. Soft tissue procedures are associated with failure if severe bone loss is present [13]. There has been growing interest in using arthroscopic methods to perform bone grafts on the glenoid to treat anterior shoulder instability, as the amount of bone loss on the glenoid deemed acceptable has gradually decreased. Restoring glenohumeral stability and lowering the complication rate of open procedures are common goals of the arthroscopic Latarjet and arthroscopic bone block techniques. Performing these procedures arthroscopically also has several advantages. The arthroscopic approach makes it possible to reduce soft tissue iatrogenic damage and treat posterior or superior labral tears and Hill–Sachs lesions [29].

Recently, modifications have been made to the arthroscopic bone block technique, and graft fixation utilizing specially developed double-round Endobuttons has been introduced [31]. Soon after, the arthroscopic Latarjet procedure was also performed with this fixation technique [35]. Compared to the screw fixation utilized in open procedures, Endobutton fixation provides several advantages.

4.1. Arthroscopic Bone Grafting with Double Endobutton Fixation

When paired with round Endobutton fixation, the glenoid guide offers additional intraoperative benefits and may enhance the graft’s bone integration compared screws fixation used in an anterior approach [31]. Two precisely parallel tunnels that are perpendicular to the anterior glenoid neck can be created using the posterior guide designed for bone block procedures. For bone integration, the bony tunnels’ proper orientation is unquestionably crucial, and it is difficult to achieve with screws [31].

These tunnels are perfect for precisely placing either the free bone graft or the coracoid in cases of arthroscopic Latarjet procedures [31]. This allows for conversion from the bone block to Latarjet technique anytime during the procedure, depending on the doctor’s decision and the specific patient anatomy, which may have been variably damaged by the recurrent instability events, especially the capsular tissue.

Further benefits come from fixation using Endobuttons and a tensioner device. The ideal tension is developed between the anterior and posterior devices. Furthermore, bone marrow is transferred from the glenoid tunnel to the graft because of the narrow bony tunnels and the lack of screws. This should increase the likelihood that the graft will integrate into the bone. This may justify the modest graft changes seen at 1-year follow-up as opposite to other procedures [31].

Prevention of potential issues with screws that can occur early or late after surgery is another benefit of using round Endobuttons: Endobutton fixation eliminates the possibility of screw head impact with the humeral head during movements, screw breakage or loosening, and suprascapular nerve injuries (that can occur with inadequate screw dimension or positioning) [31]. Screw fixation may cause discomfort, pain, or snapping during external rotation, making screw removal necessary. Because the round buttons are flush with the coracoid and smaller than screws, they do not irritate soft tissues.

The fact that smaller holes must be drilled in the coracoid is another benefit of utilizing buttons over screws. Bigger holes increase the chance of graft fracture. No changes in the maximal load-to-failure rate and a reduced chance of graft breakage were found using single Endobutton fixation in the Latarjet procedure instead of screw fixation, according to a study evaluating the biomechanical properties of the two methods. Each fixation method had a different failure mechanism: screw fixation failed because of graft fractures through the drill holes, while Endobutton fixation failed because of fractures of the glenoid bone [35].

Arthroscopic bone block and Latarjet procedures with Endobutton fixation proved to be effective [29,31], but which is the right procedure for each patient is still a topic of debate. The pros and cons of the two techniques are discussed hereafter.

4.2. Bone Block

Bone block techniques can also be used in cases of subcritical or severe glenoid bone loss as an alternative to coracoid graft, and they bring a lower risk of complications and are easier to perform than Latarjet, beside preserving the subscapularis tendon function [13,17,29]. Regarding biomechanics, free bone grafts might be less effective than the Latarjet procedure because they lack the stabilizing function provided by the conjoined tendon [36]. However, a remplissage can be performed together with a bone block in off-track lesions, restoring stiffness closer to that of a healthy shoulder than using a bone block or Latarjet alone [37].

The aim of this technique is to restore the unstable shoulder’s native anatomy [13]. The wider glenoid socket at 1-year follow-up points to a rise in the stability angle, and the graft also functions as a structural support to soft tissue integrity [31,38].

The graft can be harvested considering the size of the missing bone on the glenoid (Table 2). However, in case of major bone loss, concern may arise due to increased stress on the repaired soft tissue. Indeed, Taverna et al. used arthroscopic bone block surgery on patients with glenoid bone loss ranging from 10% to 20%, one prior dislocation episode within the past 3 years, or a history of up to five total dislocation episodes [31].

There are some theoretical advantages of the arthroscopic bone block over the arthroscopic Latarjet. First off, eliminating coracoid osteotomy and subscapularis split usually shortens surgery times, lowers the risk of intraoperative and postoperative bleeding, and preserves the anatomy of the shoulder [29]. Free bone block procedures preserve the shoulder anatomy more than Latarjet surgery since the subscapularis tendon does not need to be split because the graft and fixation devices are inserted through a small tunnel passing through the rotator interval [31] and the muscles of the pectoralis minor and the short head of the biceps remain intact, resulting in a shortened period for functional recovery (three to four weeks) [27] (Table 2).

Furthermore, it is easier to correctly position the bone graft because the conjoint tendon is not attached to the graft. Theoretically, these factors might shorten the learning curve and promote widespread adoption of the surgical technique. Moga et al. reported that surgeons were able to master the arthroscopic bone block procedure more quickly and achieve better placement of the bone graft when compared to the arthroscopic Latarjet [29] (Table 2).

Additionally, the bone block technique does not put the neurovascular structures medial to the coracoid at risk and does not need the creation of unsafe portals [31] (Table 2).

The range of motion can be maintained by aligning the bone block with the joint surface and repairing soft tissues in their natural location. The procedure’s small range of motion loss allows for most patients to return to their pre-injury sporting level. Even elite athletes see a high success rate in returning to pre-injury performance (67%), likely because the procedure restores stability and range of motion [31].

Finally, bone grafting of the glenoid may be a great surgical alternative with a low risk of complications and side effects for patients with lower functional requests or those with a higher risk of nerve damage due to previous surgical procedures or long-standing injuries [39]. Due to these advantages, even if the Latarjet method with its “triple blocking effect” continues to be the gold standard [39], the bone block technique could be considered a strong first-line surgical option to treat recurrent anterior instability, having the possibility, in case of recurrence, to perform the Latarjet, which allows for excellent long-term results and a high return to sport rate [40] (Table 2). Some bone block techniques can also be used to revise the failed Latarjet [41]. Larger free bone block procedures capable of restoring the glenoid track (distal tibial allograft, iliac crest bone graft) may be recommended in patients with extensive or medialized Hill–Sachs off-track lesions with severe glenoid bone loss or in cases where the Latarjet procedures fail. However, these procedures are typically carried out in the context of a revision of a glenoid reconstruction.

However, donor site morbidity or allograft cost are potential downsides of the arthroscopic bone block technique that the surgeon should consider [29]. Also, this technique cannot be performed in cases of substantial, irreversible soft tissue damage. In such cases, the Latarjet procedure becomes the necessary option [31] (Table 2).

Nevertheless, the outcomes of this procedure demonstrate that, given the proper indications, stabilization of the joint can be achieved by augmenting the glenoid width with proper graft placement, reattaching the torn labrum, and suitable tightening and shifting of the capsule and ligaments. The function of the conjoint tendon transfer can be overcome by the joint anatomical reconstruction in this technique, probably lowering the likelihood of scapular dyskinesia, which is theoretically possible after the Latarjet procedure [34].

Hovelius et al. [42] emphasized the relevance of the proprioceptive ability of ligaments and capsules. Therefore, it is suggested that these structures be used to recreate joint stability [34]. Beside preserving shoulder proprioception, arthroscopic stabilization with a free bone block maintains the delicate coordination of muscles needed for precise movements. This is particularly important for athletes in sports that require high levels of control and precision, such as gymnastics, figure skating, synchronized swimming, and ballet [27] (Table 2).

4.3. Latarjet Procedure

However, the Latarjet procedure, whether open or arthroscopic, is a dependable treatment with a low recurrence incidence (6.9% for open procedures and 6.7% for arthroscopic procedures) [43]. Due to the transfer of the coracoid bone and the action of the conjoint tendon, it is thought to be the most successful technique to address revisions, significant bone deformities, and situations where the quality of the capsules and ligaments in the anterior portion of the shoulder joint is compromised [44]. In fact, the Latarjet technique becomes necessary when years of repeated shoulder dislocations result in a loss of mechanical properties of labrum, capsule, and ligaments, impeding soft tissue repair [31] (Table 2).

Finding out how surgery affects professional athletes’ rates of return to competition—especially those who play contact sports—is vital. According to Rossi et al., rugby players who underwent the Latarjet treatment and had glenoid bone loss inferior to 20% experienced a 4% recurrence rate and a low 4% reoperation rate [45].

Yang et al. [46] reported that the Latarjet technique had a 0% recurrence rate among athletes participating in collision and contact sports.

In their study, Privitera et al. [47] found that 8% of athletes involved in contact or collision suffered a dislocation following the treatment; 49% went back to their pre-surgery level of sports participation, 14% reduced their level of activity in the same sport, 12% switched sports, and 25% reduced their activity level and either changed sports or quit sports entirely. Individuals with two or more stabilization procedures before the Latarjet surgery showed a decreased probability of returning to their previous sport (p = 0.019).

A study by Rossi et al. examined Latarjet surgery for competitive athletes with minimal glenoid bone loss (under 20%) [48]. It showed promising results: the need for additional surgery was low (1.5%), and the dislocation rate after surgery was just 4.6%; 84% returned to their previous level of play, while 94% were able to resume sports. Importantly, shoulder mobility remained similar before and after surgery, with no significant changes between the initial surgery and any revision procedures. Contact athletes can quickly return to full competition thanks to the Latarjet technique [43]. Some patients even fully returned to competition within four months after the procedure, according to research by Neyton et al. involving professional rugby players. In nearly all cases, the procedure made it possible to resume rugby practice [49].

Even in cases of extensive glenoid bone loss associated with an off-track Hill–Sachs lesion, the Latarjet surgery appears to be able to restore stability [50]. Concerns exist, though, regarding the Latarjet procedure’s ability to turn any off-track Hill–Sachs lesion into an on-track lesion. In case of an off-track Hill–Sachs lesion, it is advised to measure the Hill–Sachs interval and the glenoid track width before surgery, since a gap between them greater than 7.45 mm increases the risk of instability persistence after surgery. The size of the coracoid process should be measured in order to understand if the graft can make up for the calculated gap [36]. If not, larger free bone block procedures capable of restoring the glenoid track (e.g., distal tibial allograft, iliac crest bone graft) may be recommended (Table 1 and Table 2).

However, this technique has certain areas for improvement. Its learning curve is quite shallow. Surgical time and graft position significantly improve with surgical experience, and the fixation and placement of the graft have theoretically improved with minimization of the learning curve, but the current technique is still technically challenging [35,51] (Table 2). That is why surgeons who want to begin to perform the arthroscopic Latarjet should first attend courses and cadaver labs and start performing arthroscopic procedures such as acromioclavicular reconstruction in order to become familiar with the anterior structures of the shoulder prior to start performing this challenging procedure.

Plus, it is not an anatomic procedure and may disturb subscapularis tendon function [52] (Table 2).

The Latarjet procedure has faced criticism for potentially limiting a patient’s rotational movement after surgery, which has led some authors to conclude that throwing athletes should not undergo the procedure [34,53,54]. Moreover, the excision of the coracoid process in patients who had arthroscopic Latarjet surgery resulted in a 14.9% decrease in the strength of the operated limb and a decline in athletic performance (boxers, weightlifters, and martial artists, among others). An 18.7% reduction in the shoulder joint’s proprioceptive function was also discovered, resulting in deficits in fine motor coordination [27] (Table 2).

Table 2. Advantages and disadvantages of arthroscopic bone block and arthroscopic Latarjet with Endobutton fixation.

Table 2 Comparison of Advantages and Disadvantages of arthroscopic Bone block and arthroscopic Latarjet procedures with endobutton fixation
Bone block		Latarjet
Advantages	Disadvantages	Advantages	Disadvantages
The graft can be harvested considering the size of the glenoid bone loss	Donor site morbidity	Most successful technique to address shoulder anterior instability	Neural structures are at risk
Joint anatomy and proprioception are preserved	Allograft cost	Triple-blocking effect with the stabilizing effect of the conjoined tendon	Subscapularis function may be affected
The nerve structures are not endangered	Contraindicated in cases of extensive capsular-ligamentous injury	Effective in the revision setting	Certain off-track Hill-Sachs lesions may remain off-track after the Latarjet procedure
Little loss of ROM		Effective in contact and collision athletes	Reduced athletic performance in some sports
Shorter operative time		Can be performed in cases of extensive capsular-ligamentous injury	Mild osteoarthritis can be developed
Shorter learning curve			Slight internal rotation loss
			Prolonged operative time
			Shallow learning curve

Table 2. Advantages and disadvantages of arthroscopic bone block and arthroscopic Latarjet with Endobutton fixation.

Table 2 Comparison of Advantages and Disadvantages of arthroscopic Bone block and arthroscopic Latarjet procedures with endobutton fixation
Bone block		Latarjet
Advantages	Disadvantages	Advantages	Disadvantages
The graft can be harvested considering the size of the glenoid bone loss	Donor site morbidity	Most successful technique to address shoulder anterior instability	Neural structures are at risk
Joint anatomy and proprioception are preserved	Allograft cost	Triple-blocking effect with the stabilizing effect of the conjoined tendon	Subscapularis function may be affected
The nerve structures are not endangered	Contraindicated in cases of extensive capsular-ligamentous injury	Effective in the revision setting	Certain off-track Hill-Sachs lesions may remain off-track after the Latarjet procedure
Little loss of ROM		Effective in contact and collision athletes	Reduced athletic performance in some sports
Shorter operative time		Can be performed in cases of extensive capsular-ligamentous injury	Mild osteoarthritis can be developed
Shorter learning curve			Slight internal rotation loss
			Prolonged operative time
			Shallow learning curve

4.4. Complications

While the Latarjet procedure excels at restoring anterior stability of the shoulder, it is important to consider potential complications, including musculocutaneous nerve damage, failure of the bone graft to heal properly, misalignment between the graft and the glenoid socket, wound and hardware issues, and postoperative rigidity [39,55]. A systematic review showed a total complication rate of 16.1% in 2560 Latarjet procedures [55]. The arthroscopic Latarjet procedure has also been questioned for its potential complications [35,56]. Research by Athwal et al. suggests a complication rate of approximately 10% at a mean follow-up of 17 months [57]. Both open and arthroscopic Latarjet techniques produced comparable rates of overall recurrence of instability (2.0% vs. 2.4%), total complications (13.8% vs. 11.9%), and additional surgery (2.4% vs. 5.4%), according to a comprehensive analysis of multiple studies including 896 patients [40]. A more recent study by Hurley on short-term complications including 7175 shoulders revealed that the open Latarjet brings an overall complication rate of 6.1%, with 1.9% graft-related, 1.1% hardware-related, 1.1% wound-related, 0.9% neurological complications, and 1.2% other complications, while the arthroscopic Latarjet has an overall complication rate of 6.8%, with 3.2% graft-related, 1.9% hardware-related, 0.5% wound-related, 0.7% neurological complications, and 0.5% other complications [58]. Screw fixation may lead to certain issues. Therefore, the implementation of Endobutton fixation of the coracoid graft could lead to a general acceptance of the arthroscopic Latarjet [35]. A prospective study by Bonnevialle et al. on 88 patients treated with the arthroscopic Latarjet with double-button fixation reported a 3.3% rate of intraoperative complications, which were all observed before the 10th case of the surgeons’ learning curve, and a 6.8% rate of postoperative complications with a mean follow-up of 12 months, not observed beyond the 20th case of the learning curve [51].

In the literature, bone block outcomes have generally been positive. In their meta-analysis, Longo et al. found a 9.8% recurrence rate after open iliac crest bone block [59]. A study by Tahir et al. on 265 individuals who underwent an arthroscopic bone block procedure recorded a mean overall rate of recurrent instability of 6.6% [60].

A thorough meta-analysis by Gilat et al., which reported outcomes on a total of 4540 shoulders, revealed no significant differences between Latarjet surgery and bone block procedures in the incidence of recurrent instability (5% vs. 3%, respectively), other complications (4% vs. 5%, respectively), worsening of osteoarthritis (12% vs. 4%, respectively), or ability to resume sports (73% vs. 88%, respectively). However, a significantly higher increase in the ASES score of patients treated with bone block instead of Latarjet was observed, which may be linked to better preservation of ROM in the bone block technique (32.86 vs. 10.44, p = 0.006) [61].

In a similar study by Longo et al. [59], the recurrence rate following the open iliac crest bone block technique was 9.8%, while the recurrence rate of arthroscopic Latarjet was found to be 3.4%. The overall postoperative complication rate of arthroscopic Latarjet was 17.2%. The same investigation found that the development of osteoarthritis following bone block versus Bankart repair did not differ significantly, which could be attributed to the preservation of natural biomechanics [32].

A recent meta-analysis comparing arthroscopic bone block with arthroscopic Latarjet by Cozzolino et al. reported no difference between the two techniques regarding recurrence, reoperation, and complication rates. When comparing screw fixation to flexible fixation, the subgroup analyses revealed that the former was associated to a greater prevalence of hardware-related problems (p = 0.01) [29].

In a study by Moroder et al., open Latarjet was compared to open iliac crest bone graft in a randomized fashion. They found that the only significant difference between the two groups was a slightly reduced range of internal shoulder rotation in the Latarjet group. However, 27% of patients receiving iliac crest bone grafting experienced sensory abnormalities at the donor location [62]. According to Antoni et al., after 12 weeks, patients with the arthroscopic Latarjet treatment had better WOSI and external rotation to internal rotation strength ratio (closer to 1) [63].

While a relevant criticism of the Latarjet procedure has been the development of osteoarthritis after surgery, and reports of a 62% incidence of glenohumeral arthritis have been provided [64], only 30% of the rugby players who underwent the procedure were found to have developed arthritis twelve years after surgery in a study by Neyton et al. [49]. Mild arthritis is common in these patients. Still, it does not affect their shoulder function [64]. The proper placement of the graft, which is supposed to be aligned with the joint surface, has been judged critical to both the long-term effectiveness of these surgeries and the risk of recurrence [59]. If the graft is placed too far to the side and overlaps the joint space, it can lead to the early onset of osteoarthritis; conversely, positioning the graft too far inwards can create unfavorable mechanics in the shoulder joint, increasing the chances of instability returning. A precise alignment between the coracoid and the glenoid rim is necessary for excellent joint stability [13] (Table 1). In fact, failures are consequences of wrong patient selection, technical issues, or adverse events like coracoid fracture or malpositioning (Table 1), but complications are uncommon with a precise surgical technique [65]. Neurological complications, which account for 1–20% of cases, are due to dissection medial to the conjoint tendon, so the surgeon can avoid them staying always lateral to this tendon. The use of self-retractors should also be limited. Partial osteolysis of the coracoid is frequent, but rarely connected to worse outcomes. The graft position has no influence on this complication. It can be limited by preserving part of the coracoid vascularization [66].

5. Future Directions

A pivotal role in determining the surgical approach is played by bipolar bone loss, but there is variability in its measurement method, leading to different results. Furthermore, there are still controversies worldwide on how to manage different degrees of bone loss, especially subcritical bone loss. New surgical techniques and graft alternatives have been developed to address recurrent shoulder anterior instability. Clarification on which graft is better is still needed.

More studies with long-term follow-up are needed to evaluate the efficacy of arthroscopic bone grafting procedures in various subtypes of patients based on bipolar bone loss assessment and individual risk factors.

6. Conclusions

The patient’s history of sports participation, activity level, goals, expectations, amount of time passed since the first dislocation, number of dislocations, age, and soft tissue quality should all be considered when deciding on the best surgical technique for repeated anterior shoulder instability. The latter factor denotes the most relevant difference between the indications for the two procedures.

The gold standard method for treating anterior glenoid bone loss is currently the Latarjet procedure. Because it is a dependable technique with a low chance of instability returning that enables contact athletes to resume sports more quickly than soft tissue repair, some surgeons even perform the Latarjet procedure in patients without glenoid bone loss [43].

Even so, an increasing volume of research supports the application of novel procedures that may more closely replicate the natural anatomy of the shoulder socket and lower the risk of both instability returning and early onset of arthritis in the shoulder joint [12]. High rates of return to sport, especially among competitive athletes, are achieved with the bone block procedure, which is useful in a subset of patients with recurrent anteroinferior shoulder instability. This technique can allegedly be seen as being “in the middle” of the soft tissue repair and Latarjet procedures, used to properly treat patients in whom Bankart repair is not effective but who do not necessitate the Latarjet technique. The arthroscopic evaluation can determine the right procedure to perform, and the surgeon can convert the bone block procedure into a Latarjet procedure at any time.

The arthroscopic Latarjet and the arthroscopic bone block procedures are both secure and successful. Bone block techniques, however, preserve native shoulder anatomy and allow for reserving the Latarjet procedure for revision surgery.

It is important to note that the shoulder joint is of utmost functional significance in certain high-performance sports, including combat sports, team sports like basketball or volleyball, gymnastics, and athletics [27]. Consequently, when choosing which surgical treatment to undertake, the kind of sport practiced and the degree of engagement in sport must be carefully considered.

The Latarjet procedure has been recommended in the treatment of contact and collision athletes and revision surgery, because of its demonstrated low risk of instability recurrence [46], and in team sports where the upper limb is held above the head, thus avoiding a major loss of athletic performance after the procedure [27]. Free bone grafting, on the other hand, is a better option in patients who need to preserve their fine motor coordination, such as gymnasts, and also in power sports, to prevent a decline in muscle strength that would harm competition results [27].

To summarize, we provided some indications about the most typical clinical scenarios involving anterior shoulder instability. However, we must keep in mind that treatment plans must be customized for each patient, as it is challenging to develop a treatment algorithm that is effective in all situations due to the variety of factors that affect management choices.