Instability: Open vs. Arthroscopic

Abstract

Anterior shoulder instability is common among young and active individuals, and anterior instability is the most common in 80.3% of cases, which may be the result of trauma or laxity. The glenohumeral joint is the most mobile joint of the human body, formed by the humeral head and the glenoid surface of the scapula, and its stability is given by static and dynamic stabilizers. Typically, a detailed interrogation and an accurate physical examination are required to diagnose and determine the source of the instability. Of great importance is the performance of provocative tests within our physical examination. These are done intentionally to reproduce the symptoms of instability. For treatment options, there is no universal standardized criterion; however, there are different tools such as ISIS and patient-dependent factors, which help us to make better decisions and use the best therapeutic tool, always looking at the type of patient we have in front of us. The conclusion is that different open or closed therapeutic techniques can be used for the management of anterior shoulder instability with similar success and recurrence rates.

1. Introduction

Glenohumeral instability is a common problem in young, active individuals with high functional demands on the shoulder. It occurs in a wide range of patients who need different individualized treatment strategies. Anterior instability is the most common at 80.3%, followed by posterior (10.3%) and multidirectional (9.4%). However, many aspects of the management of these injuries are controversial and much of this is due to a lack of strong evidence in guiding treatment [1, 2].

Shoulder instability results from trauma, microtrauma, and a history of joint hypermobility due to laxity. Traumatic anterior instability is associated with some soft tissue injury and the typical Bankart injury with or without capsular laxity. Soft tissue repair has been shown to have high success rates, either open or arthroscopic. In very rare cases, bony injuries are associated with recurrent instability. There is a guideline in the literature regarding the surgical treatment of anterior shoulder instability with significant glenoid bone loss. Options include Latarjet or Bristow procedures and bone graft blocks. Procedures that transfer the coracoid have been shown to carry an increased risk of loss of mobility, development of osteoarthritis, screw fatigue, and resorption or nonunion of the graft [3].

The diagnosis of anterior instability requires clinical evaluation, determining the patient’s risk for recurrent instability, and thus dictating appropriate treatment. Similarly, the choice of imaging studies needed in the study of anterior instability continues to be variable due to the lack of standardized guidelines [1].

The purpose of this chapter is to present a broad overview of the anatomy, biomechanics, pathophysiology, diagnostic process, non-operative management, and surgical management of glenohumeral joint instability.

2. Anatomy

The glenohumeral joint has the greatest mobility of any joint in the human body, as well as the greatest predisposition for dislocation. It is distributed into three joints: glenohumeral, acromioclavicular, and sternoclavicular. These last two, in combination with the spaces between the scapula and the thorax, are known as the scapulothoracic joint. The three diarthrodial joints are constituted with little bony stability and the stability relies on their ligaments and the adjacent muscles of the glenohumeral joint [4].

2.1 Glenohumeral joint

Formed by the head of the humerus and the glenoid surface of the scapula, the long, spherical head articulates against a small glenoid fossa, a relationship comparable to a golf ball in support. Stability of this ball is provided by dynamic and static stabilizers acting across the joint [4].

The humeral head is long, globular, and one-third of the sphere articulates with the glenoid. The head tilts 130 to 150 degrees relative to the diaphysis. The vertical dimension of the articular portion is about 48 mm, with a radius of curvature of 25 mm; the transverse dimension is 45 mm, with a radius of curvature of 22 mm. The bicipital groove is 30 degrees medial to the axis of the humeral diaphysis. The greater tuberosity is part of the lateral wall, and the lesser tuberosity is part of the medial wall of the bicipital groove [4].

The glenoid cavity has the shape of an inverted comma; in the uppermost area is the tail, it is narrow, and the lower portion is wider. The transversal line that divides these two surfaces corresponds to the epiphyseal line of the glenoid cavity. The glenoid has an articular surface covered by hyaline cartilage. In its center is a circular area where the cartilage is thinned. This area, according to DePalma, is related to the region of greatest contact with the humerus [4].

The vertical dimension of the glenoid is 35 mm, and the transverse diameter is 25 mm. Saha noted that the glenoid position can be retroverted or anteverted with respect to the plane of the scapula. Approximately 75% of the shoulders studied had retroversion of 7.4 degrees and the remaining 25% had an anteversion of 2 to 10 degrees. The superior portion of a line drawn from superior to inferior is angled on average about 15 degrees medial to the scapular plane. Based on the contact surface, Saha et al. originally classified the glenohumeral joint into three types. In type A, the humeral surface has a smaller radius of coverage than the glenoid. In type B, the humerus and glenoid have similar areas of coverage and a larger area of contact. In type C, the humeral surface has a larger radius of curvature than the glenoid, and the contact between these two surfaces is limited to the periphery. However, Soslowsky found that the humeral head-to-glenoid ratio is 3.12:1 and 2.0:1 for males and females, respectively [4].

Thus, these authors attributed the relative instability of the shoulder not to shape or incongruity, but to the small surface area of the glenoid compared to the humerus [4].

2.2 Glenohumeral ligaments

The glenohumeral ligaments are reinforcements of the joint capsule. Their functions depend on the integrity of the collagen, their insertion site, and the position of the arm in space [4].

2.2.1 Superior glenohumeral ligament

A constant structure is present in 97% of the shoulders examined in DePalma’s classic study of anatomy. Three anatomical variants can be found at its glenoid insertion:

1. It may initiate from a common origin with the biceps tendon.

2. It may originate from the labrum.

3. It may originate with the medial glenohumeral ligament.

Its insertion is at the fovea capitis and lies just superior to the lesser tuberosity. The size and integrity of the ligament is variable. Biomechanical studies this ligament contributing very little to the static stability of the glenohumeral joint. Its relative contribution is contingent on the integrity and thickness of the collagen fibers [4].

2.2.2 Middle glenohumeral ligament

It is the ligament with the greatest variation in size of all glenohumeral ligaments. It has been shown in different studies to be absent in 27% of specimen studies [4].

When present, it originates from the labrum below the superior glenohumeral ligament or from the glenoid neck. It inserts into the humerus medial to the lesser tuberosity, behind the tendon of the subscapularis muscle to which it is attached [5]. Another variation, the tendon is attached to the anterior portion of the capsule. When it is thick enough, it provides anterior restriction to humeral translation [4].

2.2.3 Inferior glenohumeral ligament

This ligament is a structural complex, which is the main static stabilizer at shoulder abduction. It is a hammock-like structure that originates from the glenoid and inserts into the anatomical neck of the humerus, and consists of an anterior band, a posterior band, and an axillary recess, which lies between the two [4].

The origins of the anterior and posterior bands on the glenoid are in terms of the face of a clock. The anterior band originated from between the 2 o’clock and 4 o’clock positions and the posterior band from between the 7 o’clock and 9 o’clock positions. On the humeral head side, it inserts in an approximately 90-degree arc just below the articular margin of the humeral head [4].

Considering that this ligament has a hammock function to support the humeral head provides the basis for explaining how damage to one of its portions can affect the opposite side. This concept has clinical significance for the treatment of instability [4].

3. Clinical history

Clinicians evaluating patients with acute and chronic instability should obtain a detailed clinical history documented in detail to recognize a patient with a first-time dislocation or a chronic dislocator [3]. This includes the following elements:

3.1 First occasion dislocated patients

• After an acute event, they will typically report a history of recent high-energy trauma that is the cause of the dislocation.

• Clinicians should of the following aspects: degree of trauma (high or low energy), degree of athletic activity and position and discern between true dislocation events [3].

3.2 In patients with chronic dislocation

This typically occurs after decreased range of motion with significant impact on activities of daily living.

• The initial injury is overlooked, and the patient develops chronic and recurrent instability.

• Clinical suspicion is warranted in the presence of the following: a history of epilepsy or electric shock and polytrauma, where instability may have gone unnoticed [3].

• Low energy, recurrent subluxation cases: Episodes of shoulder instability during sleep should indicate a more complex instability, which means bone loss [3].

4. Physical examination

Because of the complex, multifaceted role of the shoulder, it is an important and common source of pathology, as we have seen especially in athletes. As with any examination, a detailed questioning can be of great help. To locate shoulder pathology, the interview should begin by identifying the possible causes of the symptomatology. In case of trauma, the location of the trauma (anterior or posterior) should be questioned, and any functional restriction should be identified. The patient’s age should be of importance; certain pathologies, such as rotator cuff injuries and impingement syndrome, should sometimes be ruled out because of the patient’s age. A history of previous trauma should be suspected of instability, and the presence of neurological disorders may increase the risk of various pathologies [6].

Examination should follow a pattern and begins with inspection, and proceeds with palpation, active and passive ranges of motion, strength, and neurological examination. A very important component of the physical examination is the ranges of motion; normal includes elevation 150 to 180 degrees, extension 40 to 60 degrees, abduction 150 to 180 degrees, external rotation 60 to 90 degrees, and internal rotation 50 to 70 degrees [6].

Particularly in athletes, where overhead throwing or overhead activities are performed, such as baseball pitchers, evaluation of the glenohumeral labrum is essential. The speed test can help identify anterior shoulder pathology, as well as injury to the insertion of the long head of the biceps. The most sensitive and specific test for labral pathology is the O’Brien test, which is performed by passively flexing the patient’s arm to 90 degrees and adducting it 10 degrees. The forearm with the hand is brought into pronation, and the arm is internally rotated until the thumb points toward the floor. This position is held against resistance, positive with pain or weakness. For the second part of this test, the arm is externally rotated, or the forearm is supinated so that the thumb is directed upward, and again forced downward against patient resistance [7]. Reduced discomfort on change of thumb position suggests a labral lesion [6].

Examination of instability should begin with a purposeful search for ligament laxity of the patient. Joint laxity, or a Beighton score, should be taken when evaluating ligament instability [6].

4.1 Provocation maneuvers

4.1.1 Anterior apprehension test

This maneuver is performed by lying the patient supine on the examination table. Place the shoulder at 90 degrees of abduction and 90 degrees of external rotation while applying an anterior force to the proximal humerus. The test is positive if it reproduces the symptoms of the anterior instability [3].

The apprehension test in low degrees of abduction may suggest glenoid bone loss. The clinician can determine if the apprehension position triggers the patient’s feelings of anterior instability [3].

4.1.2 Jobe repositioning test

It is used with a prior apprehension maneuver. Once the patient reports subjective feeling, the examiner applies force posteriorly directly while holding the shoulder in the same apprehension position. A resolution or improvement of symptoms indicates a positive test [3].

4.1.3 Load and shift test

The examiner uses one hand to apply axial load through the elbow toward the center of the humeral head and pressing on the glenoid. Direct forces are applied anteriorly or posteriorly to or –46 degrees and 90 degrees of shoulder abduction. An increase in translation with increasing degrees of abduction implies inferior glenohumeral ligament involvement [3].

It can be graded as follows:

• Grade 1: Increased translation compared to the normal shoulder.

• Grade 2: Increased translation of the humeral head, but no more, to the glenoid rim.

• Grade 3: Indicates a translation of the humeral head over the glenoid rim.

5. Treatment options

Dislocation rate is 0.08 per 1000 people annually, and anterior dislocation accounts for 80%. In younger patients under 25 the risk of recurrence is high as 95% as reported by Rowe.

Boileau and Balg, ISIS score may be a guidance to bony augmentation beyond a soft tissue alone procedure utilizing the threshold of 6 to do a Latarjet, and other authors have suggested lowering it [8, 9, 10, 11, 12, 13].

It was described by Sugaya et al. that the dislocation in anterior direction of the humeral head accompanied the lesion presenting an avulsion of the inferior glenohumeral ligament in 97%, bony lesion and/or HAGL in 50 and 9%, respectively, like the example in Figure 1 [8, 10].

Figure 1.

MRI T2 axial view showing a bony Bankart lesion.

In first-time dislocators, the treatment of choice could be conservative depending on ISIS and other specific related patient factors, and on the other hand in recurrence >2 dislocations, the gold standard of treatment could be an arthroscopic Bankart; this technique was first described by Arthur Sidney Blundell Bankart in 1923, at that time, other techniques were used, the Clairmont and Ehrlich, Nicola, and the Handerson sling operations. The original technique was published in the British Medical Journal, an open technique with wide exposure of the anterior glenoid rim and utilizing a coracoid osteotomy and subscapularis tenotomy, then suturing the capsule-labral injury. In contrast, the modern arthroscopic Bankart described by Dr. Peter Millett is accomplished with the knowledge of other concomitant pathologies that can be treated at the same time but with the same principles using 3 to 4 portals.

So we need to think about the pitfalls of the technique for doing only a Bankart repair like in the present case in Figure 1, considering the extent of the glenoid bone loss, visualizing associated ALPS, HAGL, the use of less than three suture anchors, inadequate mobilization of the capsule-labral tissues, inadequate plication, and placement of the anchors to medial of the glenoid. With this in mind, we can say that Bankart repair is still the treatment of choice being the arthroscopic technique with its variations the gold standard [8, 14].

Glenoid bone loss increases the contact pressure by 300% in defects of more than 30%, and this was described as “inverted pear” shape of the glenoid, which has been considered a risk factor for arthroscopic stabilization [8, 13].

Conservative treatment has shown recurrences of 58% with end stage arthritis to 39% in cases of recurrent instability [7, 9, 13, 15].

Losses of less than 20–25% are associated with recurrences as 19% in soft tissue-only techniques in cases where there is more than 25% recurrence up to 67% [8, 9, 16].

Augmentation procedures must be considered in patients like in Figure 2, Latarjet is the gold standard in defined critical GBL of >25%, but as we previously mentioned all associated pathology as Hill-Sachs lesions must be taken into account present in 65–67% of the first event and 84–93% in recurrent cases (Figure 3) [8, 17]. Computed tomography with 3D reconstruction of a patient with critical bone loss.

Figure 2.

MRI T2 axial image of a right shoulder with a Bankart lesion.

Figure 3.

3D CT scan showing critical bone loss of a right shoulder.

We follow the recommendation by Di Giacommo were an “on track” Hill-Sachs lesion with GBL of >20% requiring augmentation procedures such as Bristow, Latarjet, the use of autologous iliac crest, femoral head, distal tibia, and clavicle grafts for augmentation and “off-track” HS with glenoid loss of more than 20%. Are amenable for a Latarjet [9, 10, 13, 18, 19].

Isolated arthroscopic Bankart procedure reports recurrences 28.4% vs. 3% in Latarjet, so there has been an interest in performing this procedure in a primary way for all cases of anterior recurrent pathology with high-risk patients with ISIS >4 and in revision cases.

The complication rates with the gold standard treatment are: 30% being neurovascular injury, 1.8% recurrent instability, and infection in 6%. In cases of failed Latarjet, GBL is difficult to manage with recurrences of up to 12% after an Eden-Hybinette procedure reporting 33% of poor results [5, 11, 15, 20].

Moreover, moderate-to-severe osteoarthritis has been reported in 18% of patients without recurrence and up to 26% in patients treated with Latarjet surgical stabilization [7].

The Eden-Hybinette procedure with autologous iliac crest graft has shown good results with lower recurrent rates of instability, the present indication for this technique includes severe glenoid bone loss of more than 40%, recurrent instability after a Latarjet or distal tibia graft, but the main problem of this technique is the morbidity of the donor site and the accelerated rate for postoperative glenohumeral arthritis in up to 20% [21, 22]. Taverna et al. described an arthroscopic technique in 26 patients, reporting 88.5% satisfaction without recurrent dislocations and graft integration of 92.3% [21].

In the Eden-Hybinette procedure, 17.6% of complications have been described, compared to 17.2% in arthroscopic Latarjet and Bristow-Latarjet in 15% [20].

Last but not least, a novel technique based on the transfer of the long head of the biceps called “dynamic anterior stabilization” must be discussed since, although in general, arthroscopic Bankart continues to be the gold standard, the variety and severity of the lesions shared in the pathology of anterior instability, be it bone loss, Hill-Sachs, hyperlaxity, quality of the tissue, and so this being the case when the treatment becomes more complex, the choice of the gestures coupled with the repair becomes confusing.

In addition to the concern for reducing the rate of complications to which the gold standard of instability with subcritical bone loss has led, the Latarjet compared to the Bankart plus remplissage has shown improvement in the reduction of recurrence of 7% vs. 9.8% but with an increase in complications of 9% vs. 1%, respectively [23].

The oldest antecedent of this procedure dates from a labrumplasty described in 1967 called the Vainstein procedure, but in 2018 Collin and Ladermann describe the transposition of the head of the long head of the biceps through the subscapularis and to the anterior glenoid rim by tunneling it for what is considered an inlay technique performing fixation with an interference screw and subsequently with a suspension system. Immediately afterward in 2019 [24], Toussaint describes a modification of the technique to an onlay in which they performed an augmentation of the labrum by inserting the tendon into the glenoid rim.

In both techniques, the long head tendon is prepared outside, so it is not a totally arthroscopic technique [24, 25].

In 2021, results were published in 22 patients with a subcritical bone loss of <20% in which they had a 13.6% recurrence rate which happened in the first patients and could be related to the learning curve [26].

In the same year, Campos and Angelo describe their onlay arthroscopic technique in which they perform a double-row all-suture anchor fixation to the anterior glenoid rim using only three portals. They presented 18 patients with bone loss of less than 20% and follow-up of 48 months; without recurrences in the subgroup analysis of patients without hyperlaxity, WOSI and Rowe scales improved significantly and without complications [27, 28].

Regarding the biomechanics of DAAS, various studies have been carried out, which demonstrate the sling and hammock effect, with decreases of anterior translation, and without a decrease in external rotation compared to Bankart repair in bone losses of 10–20%; additionally in losses of less than 13% it is significantly stronger than the Bankart at 16.3 and 16.6% against the conjoint tendon.

To mention other advantages, it is possible to manage the SLAP lesion in the same procedure, hardware is not handled, and as previously mentioned, neurovascular complications are reduced, the disadvantage would be returning to sports at 6 months compared to 3 months for the Latarjet [28, 29, 30].

6. Open vs. arthroscopic treatment

Recurrent shoulder instability results in decreased performance in sports and certain demanding military activities. Bankart’s lesion is present in 85–90% of cases of traumatic shoulder dislocations. The age and activity level of the patient who suffers an acute dislocation best correlates with the risk of recurrence after medical treatment [31].

The open Bankart repair allows the ability to perform open capsular plication. The use of arthroscopic stabilization in chronic anterior instability was initially reported to have a lower success rate than open surgery (Figure 4). However, with advances in arthroscopic instrumentation and techniques, results continue to improve [31]. Numerous studies with 2-year follow-up have demonstrated comparable efficacy between open and arthroscopic techniques [32, 33].

Figure 4.

Arthroscopic indications.

Bottoni et al. found a long-term failure rate of 14.3% for arthroscopic surgeries and 12.5% for open surgeries. Subjective outcome tests between the two treatment groups were similar at 32-month follow-up and 15-year follow-up. The value on the UCLA marker postoperatively was 31.4 at 12 months and 28.6 at 15 years. There was no statistically significant difference between treatments in all functional tests measured at 15-year postoperative follow-up (p > 0.05) [31]. Long-term follow-up results agree that there is no difference in failure rates between arthroscopic and open techniques [18]. Burkhart and De Beer reported inferior results with an arthroscopic technique in the context of Hill-Sachs hooking lesions and suggested reconstruction with an alternative technique, especially if associated with critical glenoid bone loss [19]. However, in this study there were only three patients with this type of defect and follow-up was limited to 27 months. In conclusions, open or arthroscopic Bankart repairs are safe and reproducible in returning most patients to their pre-injury activity status. In the context of an off-track injury, there are higher failure rates regardless of the technique used [31].

In terms of Latarjet surgery it is a procedure that regardless of whether the arthroscopic or open technique is used has reported high success rates (Figure 5). The Laterjet procedure is a well-established treatment option with favorable long-term results. Re-luxation rates following this procedure are estimated to be around 4-5% [34].

Figure 5.

Latarjet procedure, open technique.

Lafosse et al. proposed that the arthroscopic technique offers advantages of more accurate graft placement, faster recovery, decreased stiffness, and cosmetic benefits [35]. While minimal cases of recurrence have been reported with both techniques, the theoretical disadvantages of the arthroscopic Latarjet are costly, have longer operative time, and have increased difficulty in graft positioning [36, 37]. Several studies explain a greater and more complex learning curve for the arthroscopic Latarjet [37].

Patients treated with arthroscopic Latarjet have less pain in the first 2 weeks postoperatively, but at 1 month they are comparable to the pain experienced by those undergoing open Latarjet. The average time has been reported to be longer for the arthroscopic technique compared to the open technique; however, it has not been determined if this is significant. For screw position and bone locking, there is no improvement with arthroscopic Latarjet according to Horner et al. Only 1% in their study was converted from an arthroscopic to an open procedure due to technical difficulties [38]. One study suggests that conversion rates are quite low once the surgeon has performed a sufficient number of arthroscopic Latarjet procedures [39].

For glenohumeral joint instability, to provide optimal treatment, good preoperative imaging is critical, and based on the degree of one loss and patient expectations White et al. recommend a treatment algorithm (Figure 6).

Figure 6.

Treatment algorithm [40].

In conclusion, both techniques can be used to successfully treat anterior shoulder instability with similarly low rates of complications, recurrence, and need for revision [34, 41].

7. Rehabilitation and return to physical activity

Rehabilitation and time to return to sport after glenohumeral joint stabilization surgery is one of the most important factors to consider. This includes consideration of psychological, physiological readiness and resilience factors; these are highly linked to the ability to return to sport and the prognosis of the surgery [42, 43].

Weekes et al. showed that 51% of patients treated with arthroscopic stabilization had symptoms of depression on postoperative screening, while these improved by 24% postoperatively; patients who experienced signs of depression at 1 year had lower scores on the WOSI test. Tjong identified several psychological factors that prevent patients from returning to sport. These include re-injury, mood, and self-motivation [42, 43]. Most surgeons base their criteria on time, but Junior et al. found that athletes who underwent objective criteria for return to sport were shown to have lower recurrence rates after arthroscopic stabilization than those who used a decision based on time after surgery [44]. Those undergoing the Latarjet procedure should be followed up with periodic radiographs. Most surgeons obtain radiographs at the first postoperative visit to ensure proper positioning of the graft and fixation device, and at 3 months to evaluate graft union before allowing the patient to undergo specific training [45].

8. Conclusions

As can be seen, different issues are involved in the diagnosis and treatment of anterior shoulder instability. A detailed clinical examination allows us to identify the probable cause of the instability and to select the imaging studies and type of procedure to be performed.

Both arthroscopic and open stabilization techniques are reproducible and have similar recurrence and complication rates. Dynamic stabilization is a useful technique for reducing neurovascular complications. It avoids the decrease in external rotation of the shoulder seen in the Latarjet and allows SLAP type lesions to be managed in the same procedure. However, there are still no studies comparing this technique with the Bankart and Latarjet repair procedures.