DEFINITION

Symptomatic recurrent posterior instability represents up to 12% of all cases of shoulder instability and is subdivided into two discrete entities.32,40

The first, true posterior dislocation is acute in nature and often related to trauma. It is readily managed with shoulder reduction and carries a low recurrence rate if not associated with a large engaging humeral head defect or a primary uncontrolled seizure disorder.

If the primary dislocation is overlooked, this condition can manifest itself as a chronic locked posterior dislocation with its pathognomonic internally rotated position and loss of external rotation on physical examination.

The second entity is recurrent unidirectional posterior subluxation, which often represents the more challenging dilemma confronting the orthopaedic surgeon and will be the principal topic of this chapter.

Whether due to an increase in awareness by physicians or a more active athletic population, recurrent unidirectional posterior instability is being recognized, diagnosed, and treated more frequently.

Patients with recurrent posterior subluxation complain primarily of pain and weakness. As time progresses, symptoms of posterior subluxation become a secondary complaint. Eventually patients often learn the selected muscular contractions, scapular winging, and arm position (forward elevation, adduction, and internal rotation) needed to demonstrate their instability.

See Table 1 for the classification of posterior instability.

 

ANATOMY

 

Posterior instability may be secondary to a tear of the posteroinferior labrum or a patulous posterior capsule.

 

 

Table 1 Classification of Posterior Instability

 

Acute posterior dislocation Without impression defect With impression defect

 

Chronic posterior dislocation

Locked (missed) with impression defect

 

Recurrent posterior subluxation

Voluntary

 

 

Habitual (willful)

Muscular control (not willful) Involuntary

Positional (able to demonstrate) Nonpositional (unable to demonstrate)

 

 

Rarely, it can involve a posterior labrocapsular periosteal sleeve avulsion or an avulsion of the posterior glenohumeral ligaments as they insert on the humerus (posterior humeral avulsion of glenohumeral ligament [HAGL] lesion).

 

Recently, Kim et al24 described a concealed and incomplete avulsion of the posteroinferior labrum (type II marginal crack or Kim lesion).

 

Pathology may also be bony in nature and secondary to posterior glenoid avulsions, erosions, increased glenoid retroversion, or large engaging reverse Hill-Sachs impression defects.

 

PATHOGENESIS

 

A significant percentage of patients (40% to 50%) with recurrent posterior subluxation relate a history of trauma. Usually athletes, these individuals are typically 18 to 30 years of age and are involved in competitive contact sports.

 

Traumatic cases are often associated with an injury where the arm is in a straight and locked position such as in weightlifting or during football while line blocking. A fall or collision with the individual's arm in the at-risk position (forward elevation, adduction, internal rotation) can also be the cause.

 

Frequently, instead of a traumatic event, subluxation episodes with a poorly defined onset are the initial presentation.

 

In many cases, especially with repetitive overhead endeavors such as swimming, gymnastics, baseball, and volleyball, the athlete recalls first the gradual onset of discomfort, with subluxation episodes occurring later. Such an onset is thought to be atraumatic and involves repetitive “microtrauma” with resultant stretching of the capsular restraints.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Whether the patient presents with a clear traumatic episode or a longer atraumatic course, he or she often has a feeling of the shoulder “coming out.” Such instability episodes occur when the arm is in the at-risk position of forward elevation, adduction, and internal rotation.

 

Patients often describe a vague discomfort, pain, or weakness as their principal complaint. This actually may lead to misdiagnosis at first.

 

True apprehension or a feeling of “impending doom” when the extremity is placed in the provocative position is less common but can be present.

 

 

Overhead throwers may complain of a loss of velocity, fatigue, or aching over the posterior shoulder. Usually, there is no obvious asymmetry of the muscles on inspection.

 

P.3605

 

 

 

FIG 1 • Younger patient able to voluntarily demonstrate, with muscular contraction and positioning of the upper extremity, his posterior instability.

 

 

 

Palpation may elicit some tenderness along the posterior glenohumeral joint line. Crepitation or a click along the posterior joint line due to labral pathology may be noted.

 

The range of motion is full, often with a decrease in internal rotation and an excess of external rotation.

 

Often, patients, if voluntary subluxators, can reproduce the subluxation episode on command with arm position and selective muscular contraction (FIG 1).

 

Physical examination should include the following:

 

 

Modified load shift test: documents direction and degree of instability

 

 

 

Supine load shift test (Gerber and Ganz16): documents direction and degree of instability Seated load shift test: documents direction and degree of instability

 

Posterior stress test: documents direction and degree of instability

 

Sulcus sign: evaluates for an inferior component of the posterior instability (bidirectional) or a more global instability (ie, multidirectional instability)

 

Scapular compression test: verifies the importance of scapular winging in the patient's ability to reproduce the instability and proves to the patient the need to strengthen the periscapular musculature to control instability

 

Jerk test: to document instability. A painful jerk test suggests a posteroinferior labral lesion and is a predictor of the success of nonoperative treatment.

 

 

Kim test: evaluates for the presence of a labral tear posteriorly Pivot shift of the shoulder: documents direction of the instability

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Radiographic evaluation includes a three-view trauma series of the shoulder, including a true anteroposterior (AP) view of the shoulder, a scapular lateral, and, more importantly, an axillary view.

 

 

A Velpeau axillary view can be substituted if the attempted axillary view is impossible because of painful abduction of the shoulder.

 

Axillary radiographs of patients with a voluntary component to their instability can be taken while the patient reproduces and maintains the subluxation episode to document the direction (FIG 2A).

 

 

 

 

FIG 2 • A. Axillary radiograph of patient with voluntary posterior instability, reproducing the instability while taking the radiograph. B. CT scan demonstrating significant posterior glenoid retroversion in a patient with posterior instability.

 

 

A computed tomography (CT) scan can be helpful to evaluate humeral head defects and associated fractures of the tuberosities, humeral shaft, and posterior glenoid rim. Significant posterior glenoid

retroversion can also be demonstrated on CT scanning (FIG 2B).

 

Magnetic resonance imaging (MRI) is the imaging modality of choice after plain radiographs to evaluate the posterior capsule and labrum for tears and associated pathology.

 

In certain situations, an MRI arthrogram can help diagnose a posteroinferior labral tear.

DIFFERENTIAL DIAGNOSIS

Superior labrum anterior to posterior tear (SLAP) Anterior instability

Multidirectional instability Internal impingement Posterior Bennett lesion

 

 

NONOPERATIVE MANAGEMENT

 

Nonsurgical treatment of posterior unidirectional instability is reportedly successful in up to 80% of the patients.11,21

 

The physical therapy program consists of concentric and eccentric resistive band exercises that strengthen the external rotators, the deltoid, and the important periscapular musculature.

 

 

Resistive upright and seated rows, with an emphasis on trying to pinch the medial scapular borders together during the exercise, are key, especially in patients whose scapular winging contributes to their instability.

 

 

P.3606

 

A strengthening program as well as a sport-specific attempt to decrease those activities that place the arm at risk is key.

 

The length of nonoperative treatment must be individualized.

 

 

Patients who have lower physical demands, are younger, and those with an atraumatic history are treated 6 months or more.

 

Higher level athletes or those who have a traumatic cause with an associated labral tear are more likely to require surgical treatment. Despite their associated labral tears, such elite athletes are often treated with an exercise strengthening program for at least 3 months.

 

SURGICAL MANAGEMENT

 

Although open procedures have been the mainstay and gold standard in the treatment of patients with recurrent unidirectional posterior subluxation, arthroscopic treatment has become common.

 

 

As with anterior instability, arthroscopic evaluation in posterior instability patients has led to the diagnosis and treatment of an increasing number of associated soft tissue and articular injuries. Obviously, arthroscopic treatment of posterior capsular avulsions or redundancy in the absence of soft tissue

deficiencies or bony abnormalities can have similar success rates without the morbidity of more extensive open surgery.2,7,24,25,27,38

 

Surgical treatment is considered only after an adequate trial of strengthening has failed and the patient remains significantly symptomatic.

 

The ideal surgical candidates are those with recurrent posterior unidirectional subluxation secondary to a traumatic episode. These patients often have an associated traumatic posterior labral tear, which is optimal for arthroscopic repair.

 

 

Patients with atraumatic subluxation due to capsular redundancy can be managed either through an open procedure or an arthroscopic capsular shift or plication procedure.

 

Patients who have multifactorial causes for their instability or are revision situations may be treated better with an open approach.

 

Preoperative Planning

 

An extensive history and physical examination are key to establishing the direction and degree of the patient's instability.

 

All imaging studies are reviewed. Plain films and MRI studies are reviewed for the presence of old fractures, loose bodies, and hardware from previous procedures. More importantly, the MRI establishes whether the instability is due to an associated traumatic posterior labral tear or capsular redundancy.

 

Associated bony pathology (traumatic glenoid avulsions, glenoid retroversion) and soft tissue deficiencies (from previous procedures) should be addressed concurrently.

 

In rare instances, a sizable reverse Hill-Sachs lesion may exist and can be treated in an arthroscopic or open manner.12

 

 

Examination, this time under anesthesia, should be accomplished before positioning to confirm the direction and degree of the instability.

 

TECHNIQUES

• Arthroscopic Posterior Reconstruction (Authors' Preferred Technique)

Positioning

The patient is positioned in a lateral decubitus position with the operative arm placed in about 40 degrees of abduction and no more than 10 pounds of longitudinal traction.

All pressure points are carefully identified and an axillary roll is placed under the down axilla.

The patient's body is placed close to the operating surgeon and tipped posteriorly 15 to 20 degrees.

We do not employ a double-traction setup as we do in anterior instability because increased adduction tends to close down visualization of the posteroinferior joint line, and we have found optimal visualization with 40 degrees of abduction when viewing from the anterior portal.

Portal Placement

Most posterior reconstructions are performed using only two portals.

The posterior portal is established just lateral to the posterior lateral corner of the acromion.

This differs from the traditional posterior viewing portal, which is 1 cm medial and 2 cm inferior from the posterior lateral corner of the acromion.

Lateralization of this portal and moving it somewhat superiorly provides an optimal angle of attack to the posterior and inferior portion of the posterior glenoid.

 

The anterior portal is established in the rotator interval under direct visualization using needle localization.

 

A 6.5-mm cannula is established to allow insertion of the arthroscope and an 8-mm cannula is placed in the posterior portal to allow the passage of the Spectrum crescent suture-passing devices (ConMed Linvatec, Largo, FL).

Site Preparation

 

Repair is begun by assessing the posterior labral construct for the presence of labral displacement and tearing (TECH FIG 1A).

 

A grasper is used to capture the posterior band of the inferior glenohumeral ligament (IGHL), attempting to mobilize it superiorly to determine the amount of capsular laxity and ultimate position for repair.

 

If a posterior Bankart lesion is identified, a Liberator knife (ConMed Linvatec) is used to mobilize the labrum (TECH FIG 1B), and a burr is used to débride the posterior face of the glenoid in preparation for anchor placement (TECH FIG 1C).

 

This is a critical step so that a freely mobile labrum can be placed up on the glenoid, thereby restoring its bumper effect. Anchor placement begins at the most inferior aspect of the glenoid, usually the 5:30 or 6:30 position, depending on the side involved (TECH FIG 1D).

 

P.3607

 

 

 

TECH FIG 1 • A. Probe entering the posterior cannula is demonstrating mobility of posterior Bankart lesion with evidence of granulation tissue in the defect. B. After the lesion is defined, a Liberator knife is introduced to take down the fibrous interface in the posterior Bankart lesion. C. After preparation using a high-speed burr, the posterior inferior aspect of the glenoid is lightly decorticated in preparation for anchor placement. D. Initial anchor placement begins at the inferior extent of the glenoid with the use of a guide. E. First anchor in place 2 mm up on the articular surface.

 

 

This position allows secure placement of an anchor while allowing optimal inferior capsular plication. Bioabsorbable anchors are employed for this reconstruction (TECH FIG 1E).

Suturing

 

A Spectrum 45-degree-offset suture passer, preloaded with a no. 0 polydioxanone (PDS) monofilament suture (Ethicon, Somerville, NJ), is passed through the posterior cannula, capturing the inferior capsule in the area of the posterior band of the IGHL (TECH FIG 2A).

 

This tissue is brought superiorly and the second pass comes deep, exiting at the posterior labral defect.

 

 

 

TECH FIG 2 • A. The Spectrum suture passer is used to capture inferior capsular tissue and the posterior band of the IGHL. B. After anchor placement, stability is assessed with gentle traction on the anchor sutures and a monofilament suture is passed through the suture passer. (continued)

 

 

The PDS suture is reeled into the joint through the passer and retrieved in the posterior cannula using a ring grasper (TECH FIG 2B,C).

 

The deep limb of the PDS is tied to one limb of the anchor suture, and using a pulling technique, the PDS is drawn in a retrograde fashion, with the anchor suture attached, through the capsule and labral tissue, thereby creating a simple stitch (TECH FIG 2D).

 

This allows the inferior capsule to be drawn superiorly and medially while at the same time closing the posterior Bankart lesion.

 

P.3608

 

 

 

TECH FIG 2 • (continued) C. The monofilament suture, having been passed through a capsule inferiorly, is drawn up to assess capsular mobility and determine the amount of translation. D. One limb of the anchor suture is tied to the monofilament suture, which is then drawn back out the posterior cannula, thus creating a simple stitch. E. Having tied the suture on the first anchor, a drill hole is created 7 to 8 mm superiorly for the second anchor. F. A second anchor suture has been passed, demonstrating the purchase of additional posterior capsule. G. With the final superior anchor in position, the suture passer is directed superiorly to capture additional posteromedial capsule and superior labrum. H. Final anchor sutures are tied, demonstrating excellent reconstruction of the posterolabral defect, recreating the posterior labrum bumper effect.

 

 

A second suture is placed after tying the first suture in a similar fashion, again incorporating the capsule as well as labrum (TECH FIG 2E,F).

 

This process is repeated as many times as is necessary, moving superiorly at 6- to 8-mm increments, thereby obliterating any labral defect and capsular redundancy (TECH FIG 2G,H).

Capsular Plication

 

Alternatively, if no labral detachment is identified and only excessive capsular redundancy exists, a posterior superior capsular shift without anchors is performed.

 

The posterior capsule is lightly abraded with a synovial shaver or rasp to promote healing.

 

A Spectrum suture passer is used again to pierce the capsule 1 cm lateral to the labrum at the 6:30 position on the glenoid.

 

The capsule is then advanced superiorly and medially, with the suture passer reentering the joint at the junction between the intact labrum and the glenoid rim articular cartilage.

 

This is repeated at least two or three times, depending on amount of laxity.

 

With each suture, the capsule is advanced about one hour's position on the glenoid face (ie, 6:30 capsular stitch to the 7:30 labral position, 7:30 to 8:30, and so on).

Rotator Interval Plication

 

In individuals with a significant component of ligamentous laxity, additional closure of the rotator interval is accomplished by moving the arthroscope back to the posterior portal.

 

Through the anterior portal, a no. 0 PDS suture is passed through the upper border of the middle glenohumeral ligament, capturing the superior glenohumeral ligament and rotator interval capsule.

 

This suture is used as a pulling stitch for a no. 2 braided polyester fiber (TI•CRON) suture (Tyco, United States Surgical, Norwalk, CT).

 

This is repeated again and sutures are tied just outside the capsule.

 

 

P.3609

• Open Posterior Humeral-Based Capsular Shift

Positioning

 

Under general anesthesia, the patient is positioned in the lateral decubitus position using a full-length beanbag.

 

 

A large axillary roll is placed under the down nonsurgical axilla. The operative arm and shoulder are draped free.

Incision and Dissection

 

A longitudinal incision in the posterior axillary fold is made beginning at a point 2 cm medial to the posterolateral corner of the acromion and extending distally, following the posterior axillary line (TECH FIG 3).

 

The underlying deltoid muscle is split along its fibers bluntly, and a self-retaining retractor is placed.39

 

Caution should be exercised as to not split the deltoid distally greater than 4 to 5 cm to avoid injuring the axillary nerve.10,39

 

If the individual is larger and more exposure is needed, the deltoid can be detached from its scapular origin for a short distance, leaving a small tendinous attachment to repair later.

 

Repair of the deltoid origin can also be accomplished by placing drill holes along the scapular spine for suture passage.

 

The underlying infraspinatus is identified by its bipennate nature, a central fatty raphe dividing the muscle, and the fiber direction change compared with the teres minor inferiorly.

 

 

 

TECH FIG 3 • The posterior longitudinal incision begins about 2 cm medial to the posterolateral corner of the acromion and extends into the axillary crease.

 

 

 

TECH FIG 4 • With the deltoid fibers bluntly split, a vertical incision is made directly through the infraspinatus while keeping a small stump of infraspinatus tendon attached laterally for reattachment later.

 

 

The infraspinatus can be handled in three ways:

 

 

It can be split horizontally to expose the underlying capsule.37 Care is taken with this technique not to extend the split farther than 1.5 to 2 cm medial to the glenoid rim as the infraspinatus branches of the suprascapular nerve are coursing along the inferior fascia of the infraspinatus directly on the scapular surface. Extension of the split into the branches or elevation of the fascia off the scapula will injure a number of, if not all, the branches to the infraspinatus.

 

The second method is to identify the interval between the infraspinatus and teres minor. This interval is developed with the muscle being worked superiorly, thereby exposing underlying capsule.

 

Third, the infraspinatus may be completely detached, leaving a 2-cm remnant of the tendon still attached for later repair (TECH FIG 4). It is tagged and carefully released from the underlying thin capsule.

Capsulotomy

 

A vertical capsulotomy is made on the humeral side with the arm in neutral rotation (TECH FIG 5A).

 

A small amount of capsule, 3 to 4 mm, can be left on its humeral attachment to aid in repair of the capsular flaps laterally during the shift.

 

Care is taken to protect the axillary nerve inferiorly from retractors as it is traversing from anterior to posterior to exit in the quadrangular space inferiorly.

 

P.3610

 

 

 

TECH FIG 5 • A. The infraspinatus is elevated as a single layer, exposing the underlying posterior capsule. A vertical capsulotomy is then made based on the humeral side from the 12 o'clock to the 6 o'clock position. B. Traction stitches are then placed as the medial capsule is divided horizontally, between the sutures, toward but not through the glenoid labrum.

 

 

With the vertical capsulotomy completed, two traction stitches are placed at the midposition and the capsule is horizontally divided, between the stitches, toward the middle of the glenoid rim, stopping 1 to 2 mm from the posterior glenoid labrum (TECH FIG 5B).

T Capsulorrhaphy

 

Although both medial and lateral capsular shifts have been described, we prefer a humeral-based T capsulorrhaphy because we believe tensioning of the capsular flaps is easier to control and a larger volume reduction can be achieved, if desired.

 

Those who prefer a glenoid-based T-capsular shift cite advantages of a muscle-splitting approach and ease of repair if an associated reverse Bankart lesion is encountered.

 

If a glenoid-based shift is selected, most authors position the arm in 20 degrees of abduction and neutral to 20 degrees of external rotation while doing the capsular repair.

Posterior Inferior Capsular Shift

 

The posterior glenoid labrum is inspected and if there is a small detachment, it is repaired before

completing the capsular shift procedure.

 

The inferior flap of the capsule is carefully mobilized past the 6 o'clock position, inferiorly on the humerus.

 

This step is critical as an inadequate release of the inferior capsule will prevent correction of the posteroinferior capsular redundancy and volume.

 

The nonarticular sulcus, medial to the capsular remnant left behind, is then decorticated with a high-speed burr to facilitate healing (TECH FIG 6A).

 

The inferior capsular flap is brought superiorly and slightly laterally with the arm held in 40 to 45 degrees of abduction and 15 to 20 degrees of external rotation.

 

This inferior flap is sutured in place with multiple figure-eight nonabsorbable sutures.

 

If the capsular remnant stump is of poor quality, suture anchors are used for repair. In a similar fashion, the superior capsular flap is shifted inferiorly down over the inferior flap and sutured (TECH FIG 6B,C).

 

The horizontal portion of the T capsulorrhaphy is then closed and reinforced with nonabsorbable sutures.

 

The degree of closure of this horizontal portion can further tighten the posterior capsule if desired.

 

If the infraspinatus was released with a small remnant left attached to the humeral side, the infraspinatus is sutured back to its tendinous stump anatomically with nonabsorbable suture.

 

If the infraspinatus was split, it is allowed to fall back in position and the fascia is closed with absorbable suture.

 

Routine closure is performed, and the arm is placed into a shoulder orthosis or spica cast depending on patient compliance, incorporating 20 degrees of abduction and 20 degrees of external rotation.

 

P.3611

 

 

 

TECH FIG 6 • A. With the capsular flaps fully developed, the metaphyseal area between the capsular insertion and the articular surface is decorticated using a motorized burr. B,C. The arm is then brought into slight extension and the inferior capsular flap is first shifted superiorly with the arm positioned in about 45 degrees of abduction. The superior capsular flap is subsequently shifted inferiorly.

• Open Posterior Labral Repair (Reverse Bankart Repair)

   

  The patient positioning and surgical exposure are similar down to the infraspinatus musculature.

   

  The infraspinatus can be split, as is our preference, or a horizontal incision can be made 2 cm lateral to the glenoid rim through both the infraspinatus and capsule as one layer.

   

  The posterior capsulolabral tissue is freely mobilized from the glenoid neck.

   

  The scapular neck is then decorticated with a motorized burr to promote healing and the labrum is reattached using the surgeon's preferred commercially available absorbable suture anchors or through transosseous tunnels.

   

  Again, the goal is to roll the labrum up onto the posterior glenoid rim, restoring the capsulolabral bumper effect.

   

  Although this procedure is usually done as a primary procedure, it may be combined with a humeral or glenoid-based posterior inferior T-capsular shift in patients with excessive laxity or instability on clinical examination.

   

  Care must be taken not to overtighten the repair when both procedures are used because postoperative stiffness and loss of motion, especially internal rotation, can occur.

   

  P.3612

• Open Posterior Infraspinatus Capsular Tenodesis (Rare or in Revision Cases)

 

The posterior infraspinatus and capsular tenodesis, as described by Hawkins and Janda,19 is

reproducible and takes advantage of the thick quality of the infraspinatus tendon and underlying capsule layer.5

 

It is extremely useful, in our opinion, as a salvage procedure in situations of poor-quality capsular tissue, because often the posterior capsule is only 1 to 2 mm thick, and in revision cases in which multiple posterior procedures have failed (TECH FIG 7).

Positioning

 

This technique is performed using the same positioning and exposure as described earlier down to the infraspinatus musculature.

 

Preoperatively, the patient can be fitted for an outrigger shoulder spica cast with a fiberglass long-arm component and a detachable spica bar or a shoulder orthosis.

 

Preparation and draping are done with the involved arm free.

Incision and Approach

 

The same posterior axillary incision and split of the underlying deltoid muscle described earlier are used.

 

With the arm in neutral position, the glenoid rim is located under the infraspinatus using a spinal needle, starting medially and walking the needle laterally over the glenoid rim until the exact location of the joint is identified.

 

This position is then marked to confirm the lateral extent of the glenoid rim.

 

This is a crucial step because if the vertical incision to be made through both the infraspinatus and capsule is made too far laterally, severe overtightening will result.

 

 

 

TECH FIG 7 • Anatomic dissection with the posterior rotator cuff musculature reflected, revealing the often thin posterior capsular structures.

 

 

 

TECH FIG 8 • The arm is positioned in neutral rotation and the infraspinatus and underlying posterior capsule are incised together and parallel to the glenoid rim.

Vertical Arthrotomy

 

A single vertical incision is made through the infraspinatus tendon and underlying capsule parallel to and

1.0 to 1.5 cm lateral to the joint line with the arm in neutral rotation (TECH FIG 8).

 

Most of the infraspinatus tendon runs on its inferior surface, with visible overlying muscle. This anatomic situation leads to a feeling of uneasiness as the surgeon begins to incise through the fleshy infraspinatus musculature portion posteriorly.

 

However, one should not worry because the thicker tendinous portion of the infraspinatus will be encountered deeper during the vertical incision.

 

With the capsulotomy complete, a Fukuda retractor is placed in the joint and the posterior labrum is inspected.

Posterior Repair

 

The retractor is then removed, and the arm is externally rotated 20 degrees (TECH FIG 9A).

 

The lateral stump of the infraspinatus and capsule (one layer) is sutured to the intact posterior labrum using nonabsorbable sutures (TECH FIG 9B).

 

The remaining medial portion of the infraspinatus and capsule is then reflected laterally, overlapping the primary repair and sutured again with nonabsorbable sutures (TECH FIG 9C).

 

The deltoid is allowed to fall back together and the fascia is closed. Routine wound closure is performed.

 

 

P.3613

 

 

 

TECH FIG 9 • A. After completing the posterior capsulotomy, the arm is positioned in about 20 degrees of external rotation, and the lateral tendon portion of the infraspinatus and capsule are sutured to the intact posterior labrum. B. The arm is then externally rotated 20 degrees and the lateral flap of infraspinatus and capsule is sutured to the posterior glenoid labrum. C. The medial flap of the infraspinatus is then overlapped and sutured to its lateral tendon.

• Open Posterior Glenoid Osteotomy (Rare or in Revision Cases)

 

Preoperative evaluation will rarely identify a patient who demonstrates glenoid retroversion in excess of 20 degrees.34,36

 

In these situations, the surgeon may need to consider a posterior glenoid osteotomy as the primary procedure or in combination with a posterior capsulorrhaphy or shift.20

 

This procedure is rarely needed, however, and is reserved for those special circumstances. This procedure is technically demanding and should be performed only by a surgeon with previous exposure to the procedure.

Positioning and Approach

 

The initial steps, including preoperative spica application and positioning, are repeated.

 

 

P.3614

 

The standard approach down to the infraspinatus is used, with the infraspinatus released from its lateral insertion.

Vertical Capsulotomy

 

A vertical capsulotomy is made 1 cm lateral to the glenoid rim.

 

The medial capsule is detached sharply from the posterior aspect of the glenoid, with the labrum left attached to the posterior glenoid rim.

 

Caution is again exercised because the suprascapular nerve is running superiorly around the spine of the scapula about 2 to 3 cm from the glenoid rim.

 

The Fukuda retractor is placed into the joint to permit visualization of the glenoid retroversion and orientation of the plane of the glenoid.

Glenoid Osteotomy

 

With the orientation determined and the line of the osteotomy marked, drill holes are made through both anterior and posterior cortices.

 

These holes should be no closer than 1 cm from the glenoid articular surface.

 

The concavity of the glenohumeral joint as well as its superior to inferior and anterior to posterior orientation is kept in mind to avoid accidental intra-articular penetration and fracture.

 

A depth gauge is used to measure each hole to get an idea of the depth of the glenoid neck.

 

 

 

TECH FIG 10 • A. Bicortical drill holes are created about 1 cm medial and parallel to the posterior glenoid rim. An oscillating saw then completes the osteotomy posteriorly. B. A small osteotome is used to gently hinge open the osteotomy site laterally, thus preserving somewhat the integrity of the anterior cortex and its periosteal and soft tissue attachments. (continued)

 

 

The oscillating saw blade is marked just short of this glenoid depth, thus decreasing the potential for traversing both the anterior and posterior cortices with the saw blade, which would result in creation of a free-floating glenoid (TECH FIG 10A).

 

With the osteotomy complete, a 1-inch osteotome is gently tapped into place and the osteotomy is opened by moving the osteotome and glenoid laterally.

 

The partially intact anterior periosteum and cortex maintain the appropriate position of the glenoid fragment.

 

The osteotomy is then opened with a 1-inch osteotome, and a quarter-inch osteotome is placed perpendicular to the osteotomy at either the superior or inferior margin to hold the osteotomy in the open position (TECH FIG 10B).

 

A tricortical graft harvested from the posterior acromion or iliac crest is placed into the osteotomy and its position and stability are checked.

 

Usually, the humeral head against the glenoid will provide an adequate compressive force to close down the osteotomy and stabilize its position without hardware or internal fixation (TECH FIG 10C). If fixation is required, small fascial or hand set plates are ideal.

 

This procedure can be combined, depending on how the infraspinatus is handled, with a humeral-based posteroinferior capsular shift or infraspinatus capsular tenodesis.

 

The arm is placed in a shoulder spica postoperatively and held for 4 to 6 weeks to allow consolidation of the posterior bone graft.

 

P.3615

 

 

 

TECH FIG 10 • (continued) C. A tricortical graft is harvested from the posterior acromion or iliac spine and inserted into the osteotomy site. This procedure can be also combined with a posteroinferior capsular shift or with infraspinatus tenodesis.

• Open Posterior Bone Block Graft Augmentation (Rare or in Revision Cases)

 

A posterior-placed bone block may be selected as the primary procedure but is usually needed as an additional augmentation procedure to backup a soft tissue procedure in revision situations with inadequate capsular tissue or with posterior glenoid bone deficiencies.

 

This technique has been used only twice in 10 years as an augmentation procedure by the authors.

 

We prefer a bone block placed extra-articularly in those oftendifficult patients with soft tissue deficiencies, such as seen in Ehlers-Danlos syndrome.

 

Using the bone block extra-articularly allows the capsular repair anterior to the graft to act as a soft tissue interposition.

 

The positioning and exposure down to the capsule are as earlier described.

After the posterior capsule has been shifted, a 3- × 2-cm, 8- to 10-mm thick bone graft is obtained either from the posterior acromial spine or iliac crest.

After the glenoid neck is exposed and the glenoid neck decorticated, the cancellous side of the graft is placed posterior and inferior and fixated with two cancellous screws.

The graft is tailored to its final desired shape using a motorized burr.

Care must be used such that the graft is not placed excessively lateral to the glenoid rim with secondary impingement on the humeral head or too medial to the glenoid rim, rendering it ineffective. The goal is to increase the width and depth of the glenoid without contacting the humeral head.

 

 

 

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PEARLS AND PITFALLS
	Indications ▪ Failure to make an accurate diagnosis of the direction or degree of instability A complete history and physical examination is crucial and must be performed. If needed, an examination under anesthesia to rule out a more global instability is useful. Patient selection is key for each planned procedure. Failure to identify the habitual “pathologic” voluntary dislocator33   Soft tissue ▪ Failure to address associated ligamentous laxity management ▪ It is imperative to rule out a more global instability (multidirectional instability). Beware of patients with previous failure from an extensive thermal capsulorrhaphy procedure.42   Bony ▪ Significant glenoid rim deficiencies need to be addressed with reconstruction. deficiency Soft tissue procedures will not be sufficient. management ▪ Rarely, excessive glenoid retroversion needs to be addressed.   Operative ▪ Proficiency in each procedure is key. A suboptimal attempt arthroscopically or technique open procedures will doom the repair to failure. Capsular plication in conjunction with arthroscopic posterior labral repair may be required in patients with more ligamentous laxity. Care must be taken not to close down the rotator cuff interval too much, especially close to the glenoid as a loss of external rotation can occur. It is important to close the interval based on the individual's clinical laxity. During arthroscopic repair, it is crucial to place the suture anchors 1 to 2 mm over the glenoid rim onto the articular surface. This ensures that the capsulolabral tissue will be rolled up and onto the glenoid rim, restoring the bumper effect of the labrum. In patients with large capsular redundancy, inadequate release of the capsule past the 6 o'clock position on the humeral metaphysis while performing a capsular shift will lead to residual inferior symptomatic instability and failure. During the open infraspinatus tenodesis, the step of identifying the exact location of the glenoid rim is critical because a misplaced vertical incision through the infraspinatus and capsule, if done far laterally, will lead to overtightening,

 

	increased loss of internal rotation, and a risk of eventual secondary arthritis. Again, only rarely is glenoid osteotomy needed in those cases of excessive glenoid retroversion. Predrilling to the anterior cortex will decrease the risk of a free-floating glenoid or accidental intra-articular fracture. Postoperative loss of motion and stiffness, especially in open procedures, is often overlooked and most likely underreported. Although loss of internal rotation may be acceptable in revision cases to achieve stability, even insignificant losses of internal rotation and forward elevation in high-performance elite athletes, such as swimmers or overhead throwers, can be devastating. Thus, swimmers and elite overhead athletes are addressed arthroscopically if possible.

 

 

 

POSTOPERATIVE CARE

 

Using these techniques, the procedure can be tailored to meet the patient's clinical instability; however, the rehabilitation is similar in all patients regardless of technique.

 

After completion of the repair, the arm can be removed from traction and posterior translation reassessed.

 

The patient is then placed in a 30-degree external rotation brace and held in this position for 3 to 4 weeks postoperatively

(UltraSling, DonJoy, Carlsbad, CA).

 

At that point, gentle active-assisted range-of-motion exercises are begun, avoiding all internal rotation posterior to the coronal plane for the first 6 weeks.

 

At the 6-week mark postoperatively, a gentle isometric strengthening program is started.

 

Throwing activities are not started until the fourth month, with resumption of athletic endeavors anticipated at 6 months.

 

Although the surgical approach may vary, all posterior reconstructions are treated similarly in their postoperative regimen.

 

COMPLICATIONS

Recurrent or residual instability Postoperative loss of motion or stiffness

Neurovascular injury, especially posterior cord or axillary or suprascapular nerve Anchor pullout or hardware failure

Infection

Postinstability repair arthritis (capsulorrhaphy arthropathy) Chondral injury

Chondrolysis secondary to thermal capsular shrinkage41 Hematoma

Postoperative rotator cuff atrophy or weakness

Subcoracoid impingement (obligate anterior humeral head shift due to posterior capsular tightness or glenoid osteotomy)

 

 

 

OUTCOMES

Posterior instability encompasses a continuum from acute and chronic posterior dislocation to the more frequently encountered recurrent posterior subluxation. Earlier reports in the literature have often involved small patient populations and isolated case reports with minimal follow-up.

Past surgical treatment options included a number of nonanatomic reconstruction procedures to indirectly control posterior subluxation or dislocation.

Eventually, a more anatomic approach developed, with procedures designed to openly repair the detached labrum (reverse Bankart repair)3,31 or address the patient's excessive capsular redundancy (posteroinferior capsular shift).6,15,18,23,30

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Preliminary results, published in 1980 by Neer and Foster,31 described a humeral-based posterior and inferior capsular shift for multidirectional instability with early good results. Since then, multiple authors have advocated the use of Neer and Foster's posteroinferior capsular shift with excellent results for posterior instability. Other authors have modified this concept by using a glenoid-based posterior T-

capsular shift to similarly tighten the posterior capsule.28

More recently, Misamore and Facibene29 reported promising results in unidirectional posterior instability patients using an open posterior glenoid-based capsular shift. Excellent results were achieved, with 12 of 14 returning to competitive sports.

Fronek and colleagues,14 using a similar capsular shift, reported on 10 of 11 patients without further episodes of instability and overall good results. However, only three patients were able to return to their preinjury ability level during sports. If the capsular laxity was not eliminated by this medial-based shift, then an additional lateral incision in the capsule and an H-type repair was used.

Osseous reconstructions, including a posterior opening wedge glenoid osteotomy5,9,17,26,37 and posterior bone block procedures,1,13,14,22,30 to augment or address bony deficiencies have been described and,

although rarely used, still have a place under certain circumstances. Hernandez and Drez20 combined glenoplasty with a capsulorrhaphy and infraspinatus advancement.

The posterior infraspinatus tenodesis, as illustrated, remains a valuable procedure, especially in cases of

poor posterior capsular tissue or in revision cases. Hawkins and Janda19 reported an 85% success rate using such a tenodesis as a primary procedure. Even when including revision cases, Pollock and

Bigliani33 reported an 80% success rate using the same technique.

Papendick and Savoie,32 followed by McIntyre and associates,28 were among the first of many to describe their arthroscopic techniques in the treatment of unidirectional posterior subluxation with encouraging results.

Further improvements in arthroscopic suture repair techniques and instruments have led to the effective and reproducible arthroscopic treatment of recurrent posterior subluxation. The most promising arthroscopic repair techniques include posterior labral repair using suture anchor fixation, posterior capsulolabral plication, and the increasing role of rotator interval plication as an augmentation to the primary repair.

 

 

Kim and colleagues23 prospectively reported on 27 a thletes with unidirectional recurrent posterior subluxation due to a distinct traumatic event. All were treated with an arthroscopic posterior Bankart repair and capsular shifting superiorly. Suture anchors were used in all cases and, if an incomplete labral lesion was encountered, it was converted to a complete detachment before repair. At a mean of 39 months postoperatively, patients had improved functional scores and only 1 patient out of 27 (4%) had a recurrence.

 

Bahk and colleagues4 reported on 29 patients with traumatic unidirectional posterior instability who underwent arthroscopic posterior labral reconstruction and anterior balancing capsular plication. Of the study group, 85% of patients returned to sports, 68% to their previous level.

 

Savoie and colleagues,35 using an all-arthroscopic posterior capsulolabral repair, reported 97% success rate in 92 patients at a mean of 28 months postoperatively.

 

Recently, Bradley and colleagues7,8 updated the largest prospective study to date, which reviewed 183 athletes (200 shoulders) with unidirectional, recurrent posterior instability. Three types of capsulolabral repairs were performed based on preoperative clinical examination and arthroscopic findings: capsulolabral plication without suture anchors, capsulolabral plication with suture anchors and additional plication sutures, and capsulolabral plication with suture anchors.

 

The capsulolabral repair without suture anchors was used in cases of significant posterior capsular laxity even though the labrum was not detached. The capsule was advanced superiorly and medially. Patients with acute traumatic injuries with minimal capsular stretching underwent minimal capsular advancement during the repair. Patients with chronic capsular redundancy required more

advancement.7,8

 

The mean follow-up in the study was 36 months. All were involved in athletics, and 58% were involved in contact sports. Of the 200 shoulders, 64% had full-thickness detachment of the posterior labrum, 15% had an incomplete detachment, and 21% had a patulous posterior capsule. Patients who underwent capsulolabral plications with suture anchors showed significantly greater American Shoulder and Elbow Surgeons (ASES) scores and a high return to play when compared with patients with anchorless repairs. Fourteen failures (7%) were due to recurrent instability, pain, or decreased function. Only 10% of the patients in the study group did not return to their sport, 27% returned to a

limited level, and 64% returned at the same level.8

 

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