Robert A. Arciero, Augustus D. Mazzocca, and Jeffrey T. Spang
DEFINITION
Glenohumeral stability depends on static and dynamic restraints to ensure stable yet unconstrained range of motion.
Laxity is a physiologic term used to describe the passive translation of the humeral head on the glenoid.
Instability is a pathologic state characterized by abnormal translation of the humeral head on or over the glenoid, leading to frank dislocation, functional impairments, or pain.
The most common direction of glenohumeral instability is anteroinferior.
Anterior instability may be traumatic (occurring with the arm in abduction and external rotation), acquired (subtle instability associated with repeated microtrauma), or atraumatic (multidirectional with underlying anatomic contributions).
ANATOMY
The normal glenoid is broader inferiorly then superiorly (pear-shaped).
The articulating surface of the humeral head is about three times the size of the corresponding glenoid cavity.30
Static and dynamic stability must be provided by a complex interaction between the capsuloligamentous structures, the rotator cuff, the scapular stabilizers, and the biceps muscle.6
The shallow bony glenoid is deepened by thicker articular cartilage on the periphery and the presence of the ringlike labrum.
The fibrocartilaginous labrum increases the depth of the socket and prevents the head from rolling anteriorly over the glenoid. The superior labrum provides an attachment for the biceps, whereas the inferior labrum serves as an attachment for the glenohumeral ligaments.7
The capsule and ligaments are intimately related and different geographic areas contribute to stability based on the anatomic position of the arm.
The inferior glenohumeral ligament complex is the primary static restraint against instability from abduction angles of 45 to 90 degrees. The anterior band is the most important static restraint against anterior instability in the most common position of injury, the abducted and externally rotated arm (FIG 1).
The superior and middle glenohumeral ligaments limit inferior translation and anteroposterior translation with the arm in adduction.
The rotator cuff muscles and the long head of the biceps brachii provide critical dynamic stability by increasing joint compression.
Less important contributors to joint stability include negative intra-articular joint pressure, articular version, and adhesion-cohesion forces.
PATHOGENESIS
Trauma, especially athletic trauma, plays a significant role in recurrent anterior instability.
Overhead athletes can present with more subtle instability.
Repetitive microtrauma contributes to the development of pathologic subluxation.
Injury may result in subluxation and dislocation with spontaneous reduction or dislocation requiring reduction maneuvers.
Traumatic anterior instability is most common in the young, athletic population.
In the 21to 30-year-old age group the male/female incidence was reported as 9:1.11
The Bankart lesion (detachment of the anterior inferior labrum and capsule) is considered the fundamental pathoanatomic lesion associated with anteroinferior instability. It may be present in about 90% of all traumatic glenohumeral dislocations (FIG 2).
Recurrent dislocations lead to plastic deformation of the middle and inferior glenohumeral ligaments, contributing to laxity in the “sling” that is designed to restrict translation of the humeral head in abduction.
Bone injuries to the humerus (such as the Hill-Sachs lesion) and the glenoid (bony Bankart or glenoid erosion) are known to contribute to increased glenohumeral translation, resulting in recurrent instability.
Extensive soft tissue damage is rare but can include the humeral avulsion of the glenohumeral ligaments or a capsular tear.24 In addition, the injured labral tissue may heal medially on the glenoid neck (the so-called anterior labroligamentous periosteal sleeve avulsion [ALPSA lesion]) leading to insufficiency of the inferior glenohumeral ligament and labral complex.25
In the older patient with a traumatic dislocation, rotator cuff pathology must be ruled out. A thorough strength examination coupled with appropriate use of soft tissue imaging should alert the examiner to concomitant rotator cuff pathology.
Other soft tissue injuries (capsular tear and neurovascular injury) as well as glenoid and humeral head defects can occur in this age group.
FIG 1 • Cadaveric image of the inferior glenoid humeral ligament and anteroinferior labral complex.
FIG 2 • Arthroscopic view of a Bankart lesion, left shoulder, sitting position, viewed from posteriorly.
NATURAL HISTORY
Glenohumeral dislocation affects approximately 2% of the general population.11
Few natural history studies exist with long-term follow-up.
A 10-year review of dislocation treated nonoperatively revealed a redislocation rate of about 66% for patients presenting under age 22.12
Other recent studies put the redislocation rate at 64% in those under 20.34 The same author has recently reported a 25-year follow-up of patients under the age of 40 with an overall recurrence rate of 50%. Again patients under 20 years of age had recurrence rates of higher than 60%.13 Another researcher examined a group of patients to determine if the need for surgery could be predicted after an initial dislocation. They reported a 55% recurrence rate but noted that younger patients, especially those involved in overhead or contact sports, were at increased risk.29
Older studies23,27 report redislocation rates as high as 80% to 90% in patients under age 20.
Older patients have much lower redislocation rates (14%).28
Age is the most important predictor of recurrence rates after an initial dislocation. Activity level, especially collision or contact sports, may also increase recurrence rates but has not been definitively proven.
Multiple authors have reported that early surgical reconstruction for primary dislocation decreases the risk of recurrence.1,19,20,35 Further primary arthroscopic stabilization was observed to improve the quality of life, provide better outcome, and reduce recurrence rates.26
PATIENT HISTORY AND PHYSICAL FINDINGS
The patient's age and activity level are critical to decision making. Prior surgical procedures should be reviewed in detail.
There are five important questions in the history of instability:
Did the initial instability episode require a reduction?
What was the arm position for the first dislocation? The last dislocation?
What was the disability after the initial incident?
How many episodes of instability have occurred since the initial event? Were they dislocation or subluxation episodes?
What was the magnitude of the trauma associated with the initial event? Have subsequent events required similar force, or have they occurred with less provocation?
The physical examination should begin with inspection from posterior to assess any muscular atrophy of the trapezius, supraspinatus, and infraspinatus and teres minor. Muscle atrophy may point out nerve injury.
Generalized ligamentous laxity should be examined by testing a thumb hyperextension sign and elbow extension.
Active and passive range of motion in all scapular planes should be recorded and compared with the contralateral shoulder.
Strength testing should include all important shoulder musculature, with a focus on pain as limiting factor.
The contralateral side is examined when doing the load and shift examination; positive findings indicate lax anterior stabilizers.
It is critical to separate feelings of pain from instability relieved with Jobe relocation. A positive relocation maneuver may spotlight subtle instability.
Axillary nerve function should be assessed by carefully testing motor function of the deltoid and examining sensory distribution.
A positive posterior jerk test with pain and or crepitus illicited with posterior translation of the humeral head over the glenoid rim indicates posteroinferior capsular or labral pathology.
When examining for the sulcus sign, the clinician should compare the result with the contralateral side. Failure of external rotation to eliminate the sulcus sign may indicate multidirectional instability or global laxity.
Provocative maneuvers should be employed to evaluate shoulder stability.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Radiographs
Standard AP views of the arm with the arm in slight internal rotation: may show greater tuberosity fracture
AP views of the glenohumeral joint (FIG 3A)
West Point axillary view: may be used to assess bony avulsions of the inferior glenohumeral ligament, bony Bankart lesions, or anteroinferior glenoid deficiency14
Stryker notch view: may be used to examine and quantify a Hill-Sachs lesion
Computed tomography
Bone defects are an important cause of failure for instability surgery.2,32
Three-dimensional reconstructions have been especially useful to quantify bone loss (FIG 3B).
Indications
Instability episodes while asleep
Instability episodes with minimal trauma after a primary instability episode that required manual reduction
Instability episodes at low degrees of humeral abduction
Failure of any prior instability procedure
Apprehension on examination at low degrees of humeral abduction
Remarkable laxity on load and shift test
Any bony lesion on radiographic evaluation
When bony deficiencies are identified, operative approaches must be adjusted accordingly. Careful consideration must be given to open instability procedures with bony augmentation in cases of bone involvement (Table 1).
Magnetic resonance imaging
Contrast enhancement improves the ability to detect labral injury, rotator cuff tears, and articular cartilage lesions.
FIG 3 • A. AP radiograph showing defect in the humeral head. B. CT scan reconstruction showing erosion of the anteroinferior glenoid. C. MRI example of humeral avulsion of glenohumeral ligament lesion.
It may identify humeral avulsion of the glenohumeral ligament lesions and capsular tears, allowing recognition of these infrequent but critical injuries (FIG 3C).
DIFFERENTIAL DIAGNOSIS
Osseous lesions, including clavicle fractures, proximal humerus fractures, and scapular and glenoid fractures
Soft tissue lesions, including deltoid contusions, acromioclavicular joint sprains, and rotator cuff injuries (more common in patients older than 40 years)
Nerve lesions, including injuries to the axillary nerve, suprascapular nerve, and long thoracic nerve
NONOPERATIVE MANAGEMENT
Nonoperative management has traditionally consisted of a period of immobilization followed by intensive physical therapy to improve proprioception and muscular balance around the shoulder girdle. A recent review noted that recommendations for positioning, length of immobilization, and outcomes are inconsistent at best.3
Recent work by Itoi14 suggested that immobilization in external rotation will reduce recurrence rates after magnetic resonance imaging demonstrates coaptation of the Bankart lesion with the arm in external rotation.17 This same author reported a clinical series comparing immobilization in internal rotation versus external rotation after primary dislocation. Immobilization in external rotation reduced the risk of recurrence by 46%.15
Failure of nonoperative management may be manifested in recurrent symptoms of instability (dislocations, subluxations, or pain) despite adequate nonoperative management and activity modification where appropriate.
Table 1
Arthroscopic Versus Open Treatment of Anterior Instability
Arthroscopic
Minimal to no bone defects—small, nonengaging Hill-Sachs, no glenoid
bone loss
Unidirectional dislocators
Bankart or anterior labroligamentous periosteal sleeve avulsion (ALPSA lesion)
Proper surgeon experience
Open
Bone defects—large Hill-Sachs lesions (>25% articular surface), glenoid deficiencies >20%; “inverted pear” large “HAGL” (humeral avulsion of glenohumeral ligament); capsular deficiency or loss (thermal ablation)
Controversial patient populations
Patients with multidirectional instability or hyperlaxity
High-demand collision athletes
SURGICAL MANAGEMENT
The guiding basis for the described arthroscopic technique is that restoration of the normal glenoid labrum anatomy and retensioning of the inferior glenohumeral ligament can be accomplished in a manner that mirrors the open method (FIG 4).
FIG 4 • Illustration of a surgical reconstruction with a 180-degree arthroscopic repair with three inferior plication sutures, three anchors repairing the labrum, and a rotator interval closure.
FIG 5 • A. Hill-Sachs lesion on glenoid face. B. Hill-Sachs lesion engaged, with humeral head locked over anterior glenoid. C. Arthroscopic view (right shoulder) of inverted pear: camera anterosuperior, showing anterior glenoid bone loss.
In the senior author's experience with traumatic anterior instability, a Bankart lesion will typically extend from the 2 o'clock to the 6 o'clock position. To restore anatomy appropriately, the surgeon should be able to instrument and place suture anchors at the inferior aspect of the joint in the 6 o'clock position.
Arthroscopic knots may be sliding, sliding-locking, or simple. Knot selection is less important than the ability to reproduce the desired knot security and tissue tension consistently.
Preoperative Planning
The indications for arthroscopic stabilization include:
Primary anterior dislocation in young, high-demand patients
Recurrent, traumatic anterior instability without bone loss
Overhead athletes, especially throwing athletes, where preserving motion is important
Contraindications to arthroscopic stabilization include a large Hill-Sachs lesion (the “engaging” Hill-Sachs) and bony deficiencies of the glenoid that represent more than 20% (the “inverted pear”4) (FIG 5).
Arthroscopic stabilization for collision athletes and patients with osseous Bankart lesions is controversial.
However, several recent reports describe favorable results with arthroscopic repair in these groups.3,5,21,22,31
The decision to do arthroscopic versus open repair continues to be debated as arthroscopic results are reported (see Table 1).34
All pertinent radiographic studies should be reviewed to confirm prior hardware, expected soft tissue injuries, and potential bony injuries.
An examination under anesthesia should confirm anteroinferior instability in the operative shoulder and verify range of motion. It is important to note the normal range of motion in the contralateral shoulder before final positioning.
Positioning
Both the beach-chair position and the lateral decubitus position may be used for instability surgery. We prefer the lateral decubitus position to allow greater access to the inferior portions of the joint.
For the lateral decubitus position the patient is stabilized with a beanbag in a 30-degree backward tilt to place the glenoid face parallel to the floor.
A three-point distraction device that applies longitudinal and vertical traction allows distraction of the humerus.
Typically 5 pounds of longitudinal traction is combined with 7 pounds of lateral traction or distraction.
In most cases an interscalene block provides excellent operative and postoperative pain control.
For the beach-chair position, this may be all that is required.
For the lateral decubitus position, it is prudent to add general anesthesia for comfort.
Preoperative antibiotics are administered before the skin incision (FIG 6).
FIG 6 • Setup for the lateral decubitus position with arm traction device.
Approach
A standard posterior portal should be placed in the soft spot at midglenoid level, taking care to be just lateral to the glenoid.
The blunt arthroscopic trocar and sheath are then inserted into the space between the glenoid rim and the humeral head.
Using needle localization, the surgeon places the anterior portals. The anterosuperior portal should be as high as possible while staying just inferior to the biceps tendon.
The anteroinferior portal should enter just above the superior border of the subscapularis.
The needle used for portal placement should first be navigated throughout the joint to ensure that instrumentation with suture shuttling devices and anchor insertion equipment is feasible.
The anterosuperior portal is instrumented with a 7.0-mm cannula and the anteroinferior portal is instrumented with an 8.25-mm cannula (FIG 7A–C).
FIG 7 • A. View of posterior portal position. B. View of anterior portal positions. C. View of dual anterior portals. Note spread between cannulas to allow instrument passage. D. View of rolled blanket “bump” positioned in axilla to improve visualization.
Before beginning the surgical procedure, a through diagnostic arthroscopy is performed.
After diagnostic arthroscopy, the arthroscope is brought to the anterosuperior portal and another 8.25-mm cannula is placed in the posterior portal.
With the arthroscope in the anterosuperior portal, visualization of the inferior glenohumeral ligament and labrum is optimized.
A rolled blanket “bump” placed into the axilla provides further gentle distraction and improves exposure of the inferior aspect of the joint (FIG 7D).
TECHNIQUES
SUTURE FIRST (AUTHORS' PREFERRED TECHNIQUE)
Arthroscopy and Glenoid Preparation
First, the labral and ligamentous complex must be released off the face of the glenoid.
Care should be taken to maintain the tissue as one unit, using elevators to adequately release to at least the 6 o'clock position.
When muscle fibers of the subscapularis are visible, the release is adequate (TECH FIG 1A).
The glenoid neck must be prepared by either a burr or a shaver to decorticate down to bleeding bone. A meniscal rasp can be a helpful adjunct.
The bone preparation must be as inferior as the soft tissue release on the glenoid.
It is critical to begin the repair at the low 6 o'clock position in the capsule.
Various techniques may be used to ensure that the initial shuttling suture can be placed inferior at the 6 o'clock position. Options include:
Arthroscope in anterosuperior portal (our preferred method): suture-passing instrument inserted through posterior cannula (TECH FIG 1B)
Arthroscope in anterosuperior portal: suture-passing instrument inserted through anteroinferior cannula (TECH FIG 1C,D)
Arthroscope in posterior portal: suture-passing instrument inserted through anteroinferior cannula to capture tissue (TECH FIG 1D). Arthroscope in anterosuperior portal with shuttling instrument brought in from anteroinferior portal
“Pinch and Tuck”
Capsular retensioning and labral repair may be accomplished by the “pinch and tuck” method (TECH FIG 2).
Using a curved suture-passing device, the capsule is pierced 5 to 10 mm lateral to the labrum.
The device exits the capsule and pierces the capsule again to re-enter at the lateral base of the labral complex and emerge at the articular margin.
A monofilament suture is inserted to be used as a shuttle suture. The shuttling suture or device will eventually be used to shuttle the nonabsorbable suture housed in the anchor. Or it may be used to shuttle a nonabsorbable suture being used purely as a plication suture.
With the introduction of newer ultrastrong suture, subsequent knot tying will combine capsular plication and labral repair.
All shuttling should be done from the articular side of the labrum out to the soft tissue side and through a cannula.
TECH FIG 1 • Right shoulder. A. Elevator releasing labral and capsular tissue off face of glenoid. B. Pinch of capsular and ligamentous tissue with shuttling instrument coming from posterior portal to place at inferior aspect. C. Shuttling instrument brought through anteroinferior portal and taking tuck of inferior capsule. D. After piercing capsule the needle of the shuttling instrument pierces the labrum. E.Camera in posterior portal with suture passer in anteroinferior cannula. F. Camera in anterosuperior portal with suture passer in anteroinferior cannula.
TECH FIG 2 • Camera in anterosuperior portal with suture passer in posterior cannula.
Anchor Placement
The initial suture anchor is placed inferiorly on the glenoid, close to the 6 o'clock position.
Suture anchors should be placed on to the articular face of the glenoid to recreate the “bumper” effect of the normal labrum.
It is critical to place anchors 5 to 10 mm cephalad to the shuttle suture to accomplish the “superior shift” portion of the procedure (TECH FIG 3A). Subsequent knot-tying will combine capsular re-tensioning and labral repair.
If appropriate access for anchor placement cannot be gained from the anteroinferior portal, a percutaneous transsubscapular entry may be used.
In this case, a stab incision is made just inferior to the anteroinferior portal.
Using needle localization the surgeon confirms appropriate access, and a small trocar may be inserted to place the anchor onto the glenoid (TECH FIG 3B,C).
TECH FIG 3 • A. Anchor placed superior to shuttle suture. B. Transsubscapular needle localization for inferior anchor. C. Placement of transsubscapular trocar for inferior anchor.
Capsular Plication
The process of capsular plication and anchoring is repeated, moving in a superior direction to restore labral anatomy and retension the inferior glenohumeral ligament.
Typically at least four anchors are used in the final construct.
It may be necessary to return the arthroscope to the posterior portal for placement of the most cephalad anchor (2 o'clock position for the right shoulder) to avoid anterior instrument crowding. A 7.0-mm cannula may be reinserted in the anterosuperior portal for instrumentation. The final repair should re-establish normal positioning of the glenoid labrum over the glenoid rim and retension the inferior glenohumeral ligament (TECH FIG 4A,B)
TECH FIG 4 • A. Finished repair with labral “bumper” re-established. B. Finished repair with inferior glenohumeral ligament tension re-established.
ANCHOR FIRST
The same general techniques and principles from the suture-first technique apply.
An anchor is inserted onto the face of the glenoid in an appropriate location.
Both limbs of the anchor suture are pulled out of a cannula for suture management.
A tissue penetrator or suture-shuttling device is used to gather the inferior tissue and place a shuttle suture.
The suture is grasped in the joint and pulled out the anterosuperior cannula.
A standard suture-shuttle technique is used to pass the anchor suture.
ADDITIONAL ENHANCING TECHNIQUES
Traction Suture
If access to the inferior capsule and labrum is difficult, a “traction suture” can be used.
The initial stitch can be placed in the inferior capsule and then brought out the anterosuperior portal.
Traction on this stitch may allow a more inferior grasp of tissue in the early stages of a repair.
Mattress Suture
In addition to simple sutures, a mattress suture can be used to position the tissue on the glenoid face.
For a mattress suture, the process of capsular plication with a suture-passing device and subsequent suture shuttling is repeated so that both limbs of the suture exit the tissue on the tissue side.
As the arthroscopic knot is tied, a mattress stitch is created to enhance capsular plication and gather additional capsular tissue on the glenoid rim.
This is particularly useful with a degenerative atrophic labrum or with poor-quality capsular tissue (TECH FIG 5).
Posterior Anchors
Should the Bankart lesion extend posteriorly past the 6 o'clock point, posterior anchors may be required.
A percutaneous technique for anchor insertion can be employed using needle localization and a trocar and anchor guide through a posteroinferior stab incision.
Alternatively, a posteroinferior portal may be established using needle localization and gradually increasing dilators to place an additional cannula for posterior and inferior access.
TECH FIG 5 • A. Mattress posteroinferior plication suture placed in a right shoulder viewed from anterosuperior portal. B. Final mattress stitch with gathered tissue.
TECH FIG 6 • A,B. Needle localization of posterior stab to ensure access to glenoid. C. Protective trocar for anchor inserted for posterior anchor placement.
TECH FIG 7 • Posterior capsular plication.
TECH FIG 8 • A. Suture passer penetrating middle glenohumeral ligament to deliver suture. B. Tissue penetrator piercing superior portion of rotator interval (superior glenohumeral and coracohumeral ligament) and just anterior to biceps tendon to grasp suture. C. Completed stitch.
This accessory posterior portal is typically located more laterally on the shoulder (TECH FIG 6).
Plication Stitches
If the posterior labrum is intact but posterior laxity remains, plication stitches can be placed to better balance the anterior and posterior tension on the inferior glenohumeral ligament.
Using the pinch-tuck technique, the capsule and ligament can be grasped and connected to the labrum (TECH FIG 7).
Closure of Rotator Interval
When additional stability is required, the rotator interval can be closed.
Current recommendations for rotator interval closure include greater then 1+ sulcus sign, laxity with a posterior component, and a collision athlete.9
A stitch is passed through a suture passer placed in the anterosuperior cannula through the superior border of the subscapularis or the middle glenohumeral ligament.
The superior glenohumeral and coracohumeral complex is then pierced with a tissue penetrator to grasp the suture. The suture is then tied and cut with a guillotine knot cutter (TECH FIG 8).
POSTOPERATIVE CARE
Goals of postoperative care include controlled mobilization to allow adequate soft tissue healing, adequate motion (external rotation), and successful return to activities.
Postoperative protocols must respect the biologic repair process.
Our postoperative protocol includes:
Immediate postoperative immobilization in an abduction orthosis
Codman exercises and pendulum exercises immediately with assistance
Active assisted range-of-motion exercises, including external rotation (0 to 30 degrees) and forward elevation (0 to 90 degrees), for 6 weeks
Weeks 6 to 12 include active assisted and active range of motion with the goal of establishing full range of motion.
Strengthening exercises begin only after full motion is restored.
Sports-specific exercises are begun at 16 to 20 weeks.
Final release to full activity is 20 to 24 weeks.
OUTCOMES
Multiple recent studies using a suture anchor technique similar to the open method have documented clinical success, with recurrent instability rates of 4% to 10%.5,8,10,18,34
As arthroscopic techniques and equipment have evolved, the literature indicates decreasing rates of recurrence and results approaching open instability procedures.
Careful patient selection remains critical for arthroscopic instability procedures and may vary with surgeon experience.
COMPLICATIONS
The overall rate of recurrent instability from arthroscopic stabilization can safely be placed at 10% to 15%.
Postoperative glenohumeral noise or squeaking can occur if arthroscopic knots are captured in the glenohumeral joint. This may require later débridement of the knots.
Loss of external rotation from overtightening can occur.
Rupture of the repair can occur with aggressive early activities or rehabilitation.
Injury to the axillary nerve is possible with electrical or mechanical damage.
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