Keywords
shoulder joint - arthroscopy - glenoid cavity - rotator cuff injuries - shoulder injuries
- shoulder dislocation
Introduction
Arthroscopy is widely used in the treatment of anterior shoulder instability and has
results comparable to open repair techniques.[1] The progress in understanding the biomechanical repercussions of bipolar lesions
on shoulder stability, as well as in the identification of factors related to the
higher risk of recurrence,[1]
[2 ] have helped us to define more accurately the limits of arthroscopic repair.
The surgeon should reason the data and the patient's expectations, as well as be trained
and comfortable to use the surgical resources and techniques based on the most recent
evidence. Thus, good results can be achieved with arthroscopic treatment, including
in high-demand athletes.[3]
The objective of the present work is to discuss the limits of arthroscopic labrum-ligament
repair in the treatment of anterior shoulder instability.
Surgical anatomy and major lesions found in instability
Surgical anatomy and major lesions found in instability
The shoulder joint has a large range of motion (ROM) at the expense of a shallow glenoid
articulating with an almost spherical humerus head. This inherently unstable configuration
relies on other structures for the prevention of instability, including static stabilizers
(bone architecture, glenoidal labrum, joint capsule, and glenohumeral ligaments).
Additionally, the coordination of dynamic muscle forces generated by the rotator cuff
and adequate control of scapular positioning are fundamental to maintain stability.[4]
The structures most commonly injured in anterior dislocation are: the anterior labrum,
the anterior edge of the glenoid, the joint capsule and the anterior bundle of the
lower glenohumeral ligament, as well as the posterosuperior impaction of the humeral
head, also known as Hill-Sachs lesion (HSL). Occasionally, there may be an associated
lesion of the rotator cuff;[4] as well as chondral detachment on the articular surface of the humerus and glenoid.
Labrum-ligament complex
The glenoidal labrum is the fibrocartilaginous structure where the capsule and the
upper, middle and lower glenohumeral ligaments are inserted medially. In addition,
the labrum increases the surface area and depth of the glenoidal cavity, serving as
a type of anterior bulkhead to the humerus head. The anteroinferior detachment of
the glenoidal labrum was described by Bankart[5] as the essential lesion necessary to cause anterior instability. Bankart lesion,
as it is commonly known, may be just labrum detachment or have a bony avulsion of
the anterior edge of the associated glenoid (commonly called bony Bankart). An isolated
Bankart lesion results in a loss of between 7 and 5% of the contact area of the joint,[6] but isolated labrum detachment may not be sufficient to produce anterior glenohumeral
instability. Biomechanical studies show that stretching of the anterior capsule and
its associated ligaments is necessary to create glenohumeral instability.[7]
In some cases, the labrum-ligament complex may be avulsionated from the anterior edge
of the glenoid along with the periosteum and heal medially in the glenoid neck, which
is known as anterior labrum-ligament periosteal sleeve avulsion (ALPSA) lesion.[8]
[9] This lesion is distinguished from the classical Bankart lesion, as it practically
only occurs in cases of chronic instability. Failure to identify this lesion, to mobilize
and to restore the labrum to its original position is associated with higher recurrence
rates after arthroscopic repair.[9]
[10]
Another lesion of the labrum-ligament complex that is also distinguished from Bankart
lesion is the glenoid labrum articular disruption (GLAD) injury. In this lesion, there
is rupture and detachment of a fragment of articular cartilage of the glenoid near
the labrum, often with elevation of a cartilaginous flap, exposing the subchondral
bone.[8] The GLAD lesion is also associated with a higher rate of recurrence of instability
by modifying the version of the articular surface. The loss of part of the cartilage
in the anterior region of the glenoid, even with intact bone, may generate an anteversion
that would facilitate recurrence.[2]
The anterosuperior quadrant of the glenoid has anatomical variations (sublabral foramen
and Buford complex) prevalent in up to 25% of arthroscopies for instability,[11] being very important to recognize them in order to differentiate them from pathological
changes during joint inspection, thus avoiding inadequate treatment. In the presence
of a sublabral foramen, the labrum is partially inserted into the anterior edge of
the glenoid, while in the Buford complex the anterosuperior labrum is absent. These
changes seem to predispose to the development of a superior labrum anterior and posterior
(SLAP) lesion and the finding of a cord like medium glenohumeral ligament should draw
the attention of the surgeon to these variations.[11]
[12]
More rarely (between 1 and 9% of cases), we may encounter lower humeral avulsion of
the glenohumeral ligament (HAGL). This lesion is often related to high-energy trauma,[13] and it may also be present in cases with large bone losses in the glenoid.[14] The inferior glenohumeral ligament (IGHL) is formed by the anterior and posterior
bundles with the axillary recess between both. The HAGL lesion can then be classified
according to the involvement of the anterior IGHL (AHAGL) or to the posterior IGHL
(PHAGL).[10]
[13] A bipolar lesion may also occur, where a HAGL lesion and an anterior labial lesion
(floating HAGL) coexist.[13]
Glenoid
The glenoid is pear-shaped and measures 5 cm in its craniocaudal dimension and 2.5 cm
in the anteroposterior dimension of its lower half. The glenoid is relatively shallow,
with a concavity measuring 2.5 mm deep; thus, providing a limited restriction to humeral
translation. The anteroinferior edge of the glenoid is very important for anterior
glenohumeral stability and is compromised in 90% of cases of instability.[15] In these situations, there are bone failures that can be caused by an acute fracture
(bony Bankart) or by bone erosion after numerous episodes of dislocation that we consider
as an anterior glenoid bone loss due to erosion (GBLE), or even a combination of GBLE
with partially reabsorbed bone fragment. It is important to highlight the difference
between GBLE and glenoid edge fracture ([Figure 1]). When there is a viable bone fragment, whether acute or chronic, we should not
consider it as a GBLE itself.[16]
[17] Incorporating the bone fragment into arthroscopic labrum repair offers advantages
in the face of an invasive and nonanatomical bone graft procedure[18] ([Figure 2]). Sugaya et al.[16] described good results with arthroscopic repair of bone fragments that had an average
of 24.8% (ranging from 11.4 to 38.6%) of the diameter of the glenoid. Functional results
tend to be satisfactory with the consolidation of the fragment even in cases in which
there is partial resorption in preoperative examinations. Studies have shown a potential
remodeling and recovery of bone structure after repair,[17]
[18] with a tendency to normalize the morphology of the glenoid in the medium and long
term.[18] Jiang et al.[17] demonstrated a low recurrence rate after surgery when preoperative tomographic evaluation
projects the possibility of recovery of at least 80% of the area of the lower circle
of the glenoid after fragment reduction. [Table 1] summarizes conduct guidelines that can be considered based on the type of bone failure
found in the glenoid. Bone losses (GBLE) with erosion of 20% at the anterior edge
of the glenoid can significantly reduce the force required for anterior glenohumeral
translation,[19] as well as produce a loss of ∼ 30% of the joint contact area.[6] In 2000, Burkhart et al.[20] observed a high rate of recurrence of instability (61%) after arthroscopic treatment
in cases with significant GBLE, in which the glenoid seen by the upper portal presented
the aspect of "inverted pear". Based on another study by Bigliani et al.,[21] the authors defined that the critical lesion for arthroscopic treatment would be
the loss of 25% of the anteroposterior diameter.
Fig. 1 Illustration representing the types of glenoid bone failure found in anterior shoulder
instability. (A) Presence of fracture (bony Barkart) with viable bone fragment. (B) Combined, in which there is a partially reabsorbed bone fragment associated with
glenoidal erosion. (C) Glenoid bone loss due to erosion (GBLE).
Fig. 2 Images of 3D tomographic reconstruction, before and after surgery, in cases of bone
failure that were treated arthroscopically. (A) Fracture (bony Bankart) at the anterior edge of the glenoid with viable fragment.
(B) Late postoperative arthroscopic repair of case A. (C) Combined bone failure in which there is erosion of the glenoid with partially reabsorbed
bone fragment. (D) Late postoperative in the case with combined bone failure evidencing remodeling
of the bone structure after repair, with the recovery of much of the lower circle
of the glenoid.
Table 1
|
Types of bone failure
|
Failure presentation
|
Conduct
|
|
Bony Bankart/Fracture
|
Viable bone fragment
|
Consider arthroscopic repair, especially if fragment < 25% of the anteroposterior
diameter of the glenoid.
|
|
Combined
|
Erosion + partially reabsorbed fragment
|
Consider arthroscopic repair when there is a possibility of reconstruction of 80%
of the area of the lower circle of the glenoid
|
|
Bone loss (GBLE)
|
Erosion
|
Consider bone graft depending on failure size and demand
|
This cutoff point between 20 and 25% loss of the anteroposterior diameter of the glenoid
has been revised and tends to be reduced. Shaha et al.[22] analyzed a group of patients formed by military personnel with high functional demand
and recommended a review of bone lesions considered "critical" to the level of 13.5%.
Shin et al.,[23] in a case-control study with 169 patients with anterior instability and GBLE, defined
that a loss ≥ 17.3% would lead to a higher recurrence rate after isolated arthroscopic
labrum repair. Other authors have indicated bone block surgeries even for bone lesions
∼ 10%.[24] In general, the current discussion about "critical injury" has revolved around a
limit between 13.5 and 15% of GBLE, which may not be easy to distinguish in daily
practice. For this reason, there is a tendency to establish an integer for "critical
injury" (15% GBLE).[25]
[26]
Humerus head
Postero-supero-lateral impaction of the humerus head against the anterior edge of
the glenoid can lead to bone deformation. Hill-Sachs lesion occurs in between 40 and
90% of anterior shoulder dislocation events, although it is present in 100% of recurrent
cases.[27] This humeral bone failure is important in the recurrence of instability, as it can
fit the anterior edge of the glenoid during abduction movement with lateral rotation
(engaging Hill-Sachs),[20] increasing the risk of recurrence after isolated repair of Bankart lesion.[28]
[29] This risk can be mitigated by associating the remplissage procedure,[28] especially in cases in which there is fit without significant GBLE.[30]
Rotator cuff
The rotator cuff and the long head tendons of the biceps arm muscle play a key role
in dynamic shoulder stability. The incidence of these lesions increases with age and
with the number of episodes, being higher in patients with primodislocation after
the age of 40 years old.[4] Lesions range from partial joint injuries that require only debridement[10] to complete lesions, in which repair is required. Complete rotator cuff lesions
occur more in patients between 40 and 60 years old, are usually posterosuperior, and
are strongly associated with the number of dislocations, especially when there are > 7
episodes.[31]
Bipolar shoulder injury and glenoid track concept
Bipolar shoulder injury and glenoid track concept
The name of bipolar lesion is used for cases of glenohumeral instability with bone
losses both in the anterior rim of the glenoid and in the posterolateral region of
the humeral head (HSL). Its prevalence can vary between 62 and 84% of cases of anterior
recurrent shoulder dislocation[26]
[32] and this percentage increases significantly according to the number of episodes
of dislocation and to the type of sport.[32] Nakagawa et al.[32] observed an average prevalence of bipolar injuries in 33% of cases of primary instability
against 61.8% of cases of instability recurrence. In the same study, the authors found
a prevalence of 58.9% in cases of collision sports, of 53.3% in contact sports, and
of 29.4% in sports that use the arm above the head; the difference between the first
2 groups (collision and contact athletes) and sports with the arm above the head group
is statistically significant.
Currently, the mechanism of the dynamic relationship of these bone losses and their
contribution to the episodes of shoulder dislocation and recurrence of surgical treatment
are recognized as decisive for the choice of surgical technique, and should be routinely
addressed during the treatment of glenohumeral instability.[3]
[25]
[26]
Understanding the role of bone losses in the treatment of anterior shoulder instability
continues to evolve. Historically, emphasis has been placed on bone losses in the
glenoid. Although HSL was also pointed out as a risk factor for recurrence, it was
not evaluated in conjunction with anterior GBLE. Only more recently, through the glenoid
track concept, there has been the development of a better understanding of the role
of humeral bone loss, as well as the way it interacts biomechanically with anterior
bone loss in the glenoid.
The glenoid track concept emphasizes the importance of preoperative evaluation of
bipolar lesions to determine the possibility of fitting the HSL during the shoulder
range of motion and thus try to guide the best approach strategy. It provides us with
a practical form of evaluation and has been validated by clinical and biomechanical
studies as a way to help preventing poor outcomes in the treatment of instability.[1]
[22]
[33]
[34]
[35] Failure to identify the docking mechanism may result in recurrence and eventual
need for surgical revision.
Yamamoto et al.[35] introduced this concept in 2007 and helped to understand the biomechanical interaction
between GBLE and HSL. Their study in cadavers showed that the glenoid track is equivalent
to ∼ 84% of the width of a normal glenoid, discounting 16% equivalent to the space
occupied by the insertion of the rotator cuff when the arm is in 60° abduction, horizontal
extension and maximum lateral rotation, simulating the apprehention test. Thus, the
presence of bone defects in the anterior edge determines a reduction in the anteroposterior
diameter of the glenoid, and consequently a narrower rail for excursion of the humerus
head. On the other hand, the larger and/or more medial the HSL, the more likely it
is to fit into the anterior edge of the glenoid,[19] and, apparently, it is unreliable to only make the isolated repair of Bankart injuries
due to the great risk of continuing to fit the glenoid and, consequently, of recurrence
of instability.
In 2014, in a joint study between Di Giacomo et al.,[30] the concept of glenoid track has become more widely disseminated. The authors evaluated
bilateral computed tomography scans of patients with anterior shoulder instability
and were able to predict which HSL would generate engaging. Thus, the glenoid track
concept can predict a higher risk of dislocation recurrence when HSL fits into the
glenoid, known as off-track injury, and a lower risk when the HSL does not fit the
glenoid, known as on-track injury. In another study, Locher et al.[1] evaluated retrospectively 100 patients and reported that off-track HSL was an important
risk factor for recurrence of instability after arthroscopic repair of Bankart lesions.
Hartzler et al.[36] conducted a biomechanical study evaluating shoulder stability in the repair of Bankart
lesions alone compared with the repair associated with the remplissage procedure.
The results showed that, with the shoulder at 90° of abduction and 90° of lateral
rotation, the isolated labrum repair prevented the fitting of the HSL in all cases
of 15% of GBLE associated with an HSL of 15% (on-track). On the other hand, the isolated
labrum repair did not prevent the fitting of HSL in any of the cases of 15% of GBLE
associated with an off-track HSL. This study corroborates the concept of glenoid track
and the dynamics of the interaction between bone failure at the anterior glenoid edge
and HSL.
As mentioned above, bipolar lesions and the glenoid track concept are well established,
with off-track injuries associated with higher recurrence rates after isolated Bankart
repairs, since this type of ligament repair does not correct bone defects such as
the Latarjet and remplissage procedures.[35] Some authors have developed algorithms to facilitate clinical decision making. In
2014, Di Giacomo et al.[30] established an algorithm for the treatment of bipolar lesions based on the concept
of the glenoid track, using a 25% GBLE limit for arthroscopic labrum repair. In 2019,
this algorithm was reviewed by Gowd et al.,[25] reducing the GBLE limit to 15%. Both studies do not consider risk factors related
to patients (age, activity level, expectations, sports contact/collision and ligament
laxity), nor the possibility of incorporating bone fragments from the glenoid. As
an example of situations not contemplated, we can mention the possibility of arthroscopic
treatment in sedentary and low-demand patients with intermediate bone loss. On the
other hand, in the same category of bone loss (intermediate), we can indicate the
reconstruction of the glenoid with bone graft in patients with high demand and/or
in contact/collision athletes. In 2020, Di Giacomo et al.[26] proposed a new algorithm contemplating these situations, aiming to facilitate clinical
decision-making ([Figure 3]).
Fig. 3 New algorithm proposed by Giacomo et al.[26] considering the possibility of incorporation of the bone fragment and the degree
of patient activity in intermediate bone lesions.
Arthroscopic treatment
Arthroscopic shoulder stabilization is widely performed and has the advantage of evaluating
the joint more effectively and reliably, and other lesions that may not be noticed
on preoperative physical examination or that are not documented in imaging associated
with anterior labrum detachment may be diagnosed, documented and treated.[4]
[37] Arthroscopy offers lower morbidity and better cosmetics, besides reducing the chance
of problems in the subscapularis muscle (insufficiency and/or adhesions) because it
is not necessary to highlight or to divide the tendon to expose the joint.[4]
The success of the treatment depends on the selection of patients and details in the
execution of the technique. There are some factors that may be associated with a higher
risk of relapse from instability and that should be thoroughly evaluated by the attending
physician to guide the best surgical indication. The most impacting factors for the
risk of recurrence of anterior instability are bipolar injuries and the level of patient
activity (contact and collision sports).[25]
[26]
[38] Other risk factors are: young patient, male, many previous episodes, ligament hyperlaxity,
HSL, bone failures in the glenoid, ALPSA lesion, and GLAD lesion.[1]
[2]
[26]
[37]
[39]
Following the criteria of indication and selection of patients, as well as performing
the arthroscopic technique based on current evidence, we can obtain good and excellent
results even in collision and/or contact athletes,[3] especially when operated after the first episode.[40] Leroux et al.,[3] in a systematic review, evaluated the results of arthroscopic treatment of anterior
instability in collision and contact athletes. They found an overall failure rate
of ∼ 18%. However, when filtering only the studies that excluded athletes with significant
bone losses, surgery performed in lateral decubitus and using a minimum of 3 anchors,
the failure rate dropped to 8%.[3]
Arthroscopic technique
Some details can make a big difference to improve arthroscopic technique results in
the treatment of anterior shoulder instability. We have summed up some tips ([Table 2]) that we consider important because they can help in daily practice, which will
be addressed below.
Table 2
|
Tips and tricks
|
Possible advantages
|
|
Preference for
lateral decubitus.
|
It allows a better visualization of bone injury as well as of secondary lesions in
the other quadrants of the glenoid and facilitates implant insertion and balanced
capsuloligamentar tensioning.
|
|
Use 3 cannulas.
|
Facilitates switching between portals, decreases tissue infiltration.
|
|
Liberal use of anchors (at least 3 to 4).
|
Decrease the risk of relapse.
|
|
Use delicate suture needles.
|
Prevents tissue straining, decreases surgical time and allows a more accurate stitch
passage.
|
|
Mastering of the technique of using accessory portals (in particular the transubscapular
or 5-hour portal and the accessory rear portal).
|
Allows the positioning of anchors with a better angle of attack.
|
|
In the preparation of the posterior portal, enter the stitch that is 2 cm posterior
and 1 cm medial to the posterolateral angle of the achromial.
|
Thus, it is possible to have a better view of labrum repair, as it allows a broader
view, from lateral to medial.
|
|
Remplissage
|
- Positioning of the anchor in the deep region of the bone defect.
- Pass stitches at the beginning of the procedure when there is still no infiltration
and tie after previous labrum repair
- Be careful not to pass the suture stitched too medially, as this restricts movement.
|
Patient position
Good results can be obtained regardless of positioning, although lateral decubitus
may offer some advantages.[3] The vision through the anterosuperior portal, as well as the easy alternation between
the portals allows simultaneous access to the anterior and posterior part of the shoulder,
facilitating joint inspection, the observation of possible anterior, inferior and
posterior capsular redundancy to evaluate tissue quality, besides facilitating implant
insertion and balanced capsuloligamentar tensioning.
Portals and cannulas
Arthroscopic portals should be established with care as they are of paramount importance
for the success of the procedure. Poorly positioned portals create difficulties such
as cannula conflict and exaggerated infiltration of the shoulder, hindering instrumentation,
bone bed preparation, and the precise passage of suture points, as well as impairing
the angle of attack for anchor placement. The surgeon should be prepared to perform
the most diverse portals, safely accessing all quadrants of the glenoid, since some
lesions of the posterior and superior labrum are only evidenced in the intraoperative
period.[37]
[41]
[42] All these portals can be safely performed in the outside-in shape using a needle
or percutaneous guide.[42] In addition to the posterior, anterior, and anterosuperior portals, we must also
master the execution of the posterior accessory (which provides access to the posteroinferior
quadrant) portal, of the trans-subscapular or 5-hour portal (which provides access
to the anteroinferior quadrant), and to the Wilmington and Rothmann portals (which
provide access to the posterosuperior quadrant).[43]
In 2008, Simmer Filho et al.[44] showed the safety and reproducibility of the routine use of the trans-subscapular
portal (5-hour portal) used in a series of 126 cases of arthroscopic labrum repair,
in which they did not observe any neurovascular alteration.
The placement of three cannulas (two anterior through the anterior and anterosuperior
portals and one by the posterior portal) facilitates instrumentation and visualization
changes during surgery, maintains stable serum pressure within the joint, and reduces
tissue infiltration throughout the procedure.
Anchors
For good repair, it is recommended to have an adequate number of anchors available,
since the labral lesion is often more extensive than it appears in imaging.[37] In previous dislocations, it is recommended to use at least three or four anchors
to reduce the chance of recurrence.[45] Preferably, these anchors should be made from a material that integrates into the
bone to avoid future complications.[46] More recently, "knotless" implants have been suggested for use as a way to avoid
chondral lesions caused by suture threads. This seems to be a valid alternative especially
in panlabral lesions in which many implants and upper labrum lesions are used to avoid
the abrasion of the node against the humerus head during abduction and lateral rotation.[47]
After adequate labrum mobilization and opening of the bone bed, the anchors should
be inserted into the articular face of the glenoid.[48] Its medial positioning, towards the glenoid neck, constitutes a technical error
that predisposes the recurrence of instability. When the surgeon deems it necessary,
the 2 lower anchors in the glenoid can be inserted through a percutaneous trans-subcapular
portal (5-hour portal), because a lower position is achieved in the glenoid this way,
with an orthogonal angle of insertion, thus improving the quality of implant fixation
in the bone.[49]
[50] In addition, in cases in which the lesion extends to the lower or to the posteroinferior
region, the positioning of an even lower anchor facilitates labrum-ligament plication
at the level of the axillary recess.
Labral repair and capsular plicature
Labral repair and capsular plicature
The suture points should always be positioned distally to the implants and ∼ 0.5 to
1.0 cm lateral to the labral edge, so that we can perform a capsular tension and plication
with superior traction, thus reducing the anteroinferior capsular volume. In cases
with a multidirectional component, there is a large capsular volume in the axillary
recess and in the posteroinferior region. This volume should be reduced by capsular
plication. In these cases, even if there is no labral lesion, the plication with anchors
presents better biomechanical and clinical results.[51]
[52]
Remplissage
Remplissage is a procedure consisting of capsulomyodesis, using the tendon and infraspinal
muscle to fill the HSL.[28]
[29]
[53] It reduces the anterior translation of the humerus head dynamically by prevent engaging.
It is indicated for the treatment of off-track injuries, with a potential restriction
of lateral rotation with the shoulder in abduction.[54]
In the general population, repair of the anterior labrum associated with remplissage
promotes clinical results similar to Latarjet surgery, but with less chance of complications.
However, when assessing collision and contact athletes more objectively or patients
undergoing revision surgery who have intermediate and large GBLE, Latarjet surgery
seems to offer better results.[26]
[55]
Remplissage can be performed with one or two anchors depending on the size of the
bone failure. The anchors should be inserted early in the surgery and positioned preferably
in the deeper region of the bone defect to improve tissue contact with bone and to
increase the chance of healing.[29]
[55] Also, at the beginning of the procedure, when there is no joint swelling and we
have better vision, the suture points are placed through the capsule and infraspinal.
It is important to keep in mind that if the suture points become medial, it is possible
to restrict the lateral rotation movement of the shoulder in abduction excessively,
causing pain and functional loss.[56]
[57]
Final considerations
Arthroscopy is an important weapon in the treatment of anterior shoulder instability.
The success of the procedure depends on a good indication, on the selection of patients,
and on the appropriate surgical technique. We emphasize the importance of differentiating
GBLE and fractures of the glenoid edge, because the prognosis of treatment differs
between these forms of glenoid bone failure.
Until recently, the choice of surgical method was basically based on the degree of
bone involvement, and bone block was indicated for bone failures in the glenoid above
between 20 and 25% (critical bone loss). With the evolution of knowledge, the biomechanics
of bipolar lesions and the concept of glenoid track, the cut-off point of critical
injury, has been altered with a downward trend (15%). In addition to bone failures
or losses, other variables were added and made the decision more complex, but a little
more objective.
The careful evaluation of the existence or not of bone lesions, as well as their type
and magnitude is paramount, but we should also make use of the current evidence and
include in our decision-making analysis the association of other risk factors for
recurrence, as well as the individual characteristics of each patient. Following these
principles, it is possible to expand the limits of arthroscopic treatment and achieve
better results.
