DEFINITION

Anterior shoulder instability typically results from an injury to the capsule, ligaments, and labrum that stabilize the glenohumeral joint.

In cases of higher energy trauma or recurrent dislocation, there can be significant bone loss or erosion of the anterior glenoid rim.

The key to correctly treating anterior shoulder instability is to recognize whether the lesion involves injury to only soft tissue structures (capsule, labrum, ligaments) or if it also involves the anteroinferior glenoid bone.

 

 

ANATOMY

 

 

Shoulder stability is provided by both dynamic and static stabilizers (FIG 1). Dynamic stabilizers include the following:

 

 

Rotator cuff Biceps

 

 

Coordinated scapulothoracic motion Proprioception

 

Static stabilizers include the following:

 

 

 

Bony anatomy of the glenoid and humeral head Labrum

 

 

Glenohumeral capsule and ligaments Negative intra-articular pressure

 

 

 

FIG 1 • Shoulder stability depends on the interaction of dynamic and static soft tissue restraints. The bony architecture of the glenoid and humerus also plays a critical role.

 

 

The inferior glenohumeral ligament (IGHL) complex limits anterior translation of the humeral head on the glenoid in abduction. It takes origin from the labrum of the inferior glenoid. The complex consists of an anterior band, posterior band, and intervening pouch. The anterior band is responsible for anterior restraint with the arm in high degrees of abduction with external rotation. The posterior band limits posterior translation in abduction and internal rotation.

 

The humeral head has a surface area approximately 2 to 3 times that of the glenoid, which results in relatively limited bony stability at the shoulder.13

 

Normal glenoid morphology is the shape of a pear. Contact between the glenoid and humeral head is dependent on shoulder position, with contact area ranging from approximately 10% to 67% of the glenoid

surface through the range of motion (see FIG 1).14

 

The synchronized contractions of the rotator cuff and biceps provide a compressive force directing the convex humeral head into the concave glenoid and labrum unit. This is known as concavity compression.9

PATHOGENESIS

 

Anterior shoulder instability may occur following a dislocation event that results from a fall or collision with the arm in external rotation and abduction.

 

An initial dislocation typically requires a closed reduction of the shoulder after muscle relaxation and sedation.

 

Patients

 

with recurrent dislocations can often self-reduce their shoulders with minimal effort.

 

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FIG 2 • Loss of anterior glenoid bone (dashed line) due to erosion or fracture results in loss of glenoid width

(A) and depth (B). The result is an inverted pear morphology that cannot resist displacement of the humeral head anteriorly as effectively as a normal pear-shaped glenoid.

 

 

A rotator cuff tear should be suspected in patients older than 40 years old who suffer a dislocation episode.

 

An injury to the labrum in the anteroinferior quadrant of the glenoid can destabilize the IGHL complex as well as stretch or tear the anteroinferior capsule, resulting in anterior shoulder instability.

 

Recurrent anterior glenohumeral instability can also occur in the setting of anterior glenoid bone loss due to glenoid fracture after a single dislocation event. Instability may also occur from erosion of the glenoid rim as a result of recurrent subluxations or dislocations.

 

Deficiency of the anterior glenoid rim disrupts the normal mechanism of concavity compression as a result of a

decrease in width and depth of the socket (FIG 2).8

 

Anterior glenoid bone loss or fracture should be suspected in cases of recurrent anterior instability or acute dislocations from a high-energy mechanism.

 

In cases of anterior glenoid bony deficiency, patients often report recurrent dislocation in their sleep and with minimal trauma.

 

NATURAL HISTORY

 

In the context of anterior glenoid bone loss, both open and arthroscopic soft tissue management of anterior shoulder instability have demonstrated increased failure rates compared to the results in patients with normal bony glenoid anatomy.1,2

 

Burkhart and DeBeer3 have shown that contact athletes with substantial bony glenoid defects, noted as an “inverted pear” morphology at arthroscopy, had an 87% recurrent instability rate compared to 6.5% in contact athletes with a normal bony glenoid who underwent an arthroscopic capsulolabral repair only.

 

Given the high-failure rate in patients with significant anterior glenoid bone loss, a comprehensive evaluation of the glenoid bony anatomy is imperative before treating recurrent anterior shoulder instability with a capsulolabral reconstruction alone.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

A complete examination of the shoulder should also include an evaluation for concomitant injuries, and other etiologies of shoulder pain must be ruled out. A thorough examination includes, but is not limited to, the following:

 

 

Apprehension test: Apprehension, not simply pain, is required for a positive apprehension test.

 

Relocation test: Relief of apprehension with posterior pressure is necessary for a positive relocation maneuver.

 

Load and shift test: The examiner should note the degree of displacement of the humeral head on the glenoid rim.

 

Belly press: A positive belly press test is when the patient must flex the wrist and extend the arm to maintain the palm of the hand on the abdomen. This indicates insufficiency of the subscapularis muscle.

 

Assessment for generalized ligamentous laxity: Specifically, hyperextension of the elbows and knees as well as the ability to oppose the thumb to the forearm should be noted.

 

Rotator cuff: Manual strength testing of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles must be done. Rotator cuff tears can contribute to instability.

 

Subscapularis insufficiency: Weakness of internal rotation with the shoulder adducted to the side suggests a subscapularis injury but is not specific. Increased external rotation of the injured side with the shoulder adducted compared to the contralateral shoulder, pain with external rotation of the shoulder, a positive belly press sign, or positive lift-off sign should raise suspicion for subscapularis insufficiency.

 

Deltoid motor strength and lateral shoulder sensation: Weakness of the deltoid in conjunction with decreased sensation of the lateral shoulder indicates axillary nerve injury. Atrophy of the deltoid muscle should also be noted.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Plain radiographs are useful to detect Hill-Sachs lesion, glenoid dysplasia, and anterior glenoid fractures or erosion. Standard images should include a true anteroposterior (AP) view of the glenoid, an axillary lateral view, and a Stryker notch view. Fractures and erosions of the glenoid as well as the position of the humerus on the glenoid should be noted.

 

If a significant anterior bony glenoid lesion is suspected owing to plain film findings or a history of recurrent dislocations, a computed tomography (CT) arthrogram should be obtained. This study allows an evaluation of the subscapularis

 

P.3632

tendon, bony architecture of the glenoid, humeral head and tuberosities as well the degree of capsulolabral injury and redundancy.

 

 

 

 

FIG 3 • A 3-D CT reconstruction effectively demonstrates the degree of anterior glenoid bone loss.

 

 

A diagnostic agreement study by Rerko12 comparing the accuracy of x-ray, magnetic resonance imaging (MRI), and CT in quantifying glenoid bone loss in recurrent anterior shoulder instability found that three-dimensional (3-D) CT and CT were the most reliable methods.

 

Both Itoi et al7,8 and Gerber5 have described techniques to quantitatively assess anterior glenoid bone that serve as a guide when bony augmentation is indicated in the treatment of recurrent anterior shoulder instability.

 

Gerber's method5 is easily performed on oblique sagittal or 3-D CT reconstructions of the glenoid surface (FIG 3).

 

 

Cadaveric studies have shown that the force required for anterior dislocation is reduced to 70% of that

required to dislocate an intact glenoid if the length of the glenoid defect measures more than half of the maximal AP diameter of the glenoid fossa.3

 

DIFFERENTIAL DIAGNOSIS

Bankart lesion Multidirectional instability Hill-Sachs lesion Tuberosity fracture

Rotator cuff tear (especially subscapularis)

Scapular winging (especially serratus anterior dysfunction) Axillary nerve injury

 

 

NONOPERATIVE MANAGEMENT

 

Nonoperative treatment for recurrent anterior shoulder dislocation includes strengthening of the rotator cuff musculature as well as the periscapular stabilizers. Deltoid muscle strengthening should be incorporated into a rotator cuff strengthening protocol. Periscapular strengthening should focus on the rhomboids, trapezius, serratus, and latissimus dorsi muscles.

 

Nonoperative treatment of recurrent shoulder dislocation in the setting of a bony glenoid defect, however, is rarely successful.1,2

SURGICAL MANAGEMENT

Preoperative Planning

 

All imaging studies, including plain radiographs (true AP glenoid view, axillary view, Stryker notch view) and CT scan with intra-articular gadolinium, are reviewed. Additional radiographic views can be helpful.

 

The apical oblique can demonstrate anterior glenoid lip defects as well as posterolateral impression fractures of the humeral head. Both the West Point and Bernageau views are useful to note defects of the anteroinferior glenoid rim.

 

The Bernageau view has been shown to have excellent validity and reliability for estimating glenoid bone loss; however, CT with 3-D reconstruction remains the preferred method of quantifying the glenoid defect.10

 

The CT arthrogram is examined for evidence of anterior glenoid bone loss:

 

 

The degree of bone loss is assessed on oblique sagittal reconstruction or a 3-D reconstruction of the glenoid face (FIG 4).

 

The length of the anterior glenoid defect is measured.

 

If the length of the glenoid defect exceeds half of the maximum diameter of the glenoid, an anatomic glenoid reconstruction of the anterior glenoid with autologous iliac crest bone graft is considered.5

 

Often, anterior glenoid erosion is extensive, making it difficult to accurately measure the glenoid diameter. In these instances, the superoinferior axis of the glenoid should be drawn on the glenoid face image and the maximum radius determined from this line to the posterior aspect of the glenoid (see FIG 4).

 

Associated superior labral tears, biceps pathology, rotator cuff tears, and the presence of articular erosion and osteoarthritis should be noted preoperatively and treated appropriately at the index operation.

 

An examination under anesthesia should assess passive range of motion, noting any restrictions as well as excessive motion (in particular excessive external rotation, which may indicate subscapularis insufficiency). In addition, the glenohumeral joint should be assessed for laxity

 

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to ensure there is not a bidirectional or multidirectional component.

 

 

 

 

FIG 4 • Gerber's method for evaluating the degree of glenoid erosion. x is the length of the glenoid defect. Half of the maximum diameter of the glenoid, r, can be measured from a vertical line (blue) connecting the superior glenoid rim to the inferior glenoid rim in cases of significant erosion. If x is greater than r, then the force for dislocation is decreased by 70%.

 

Positioning

 

Although some surgeons choose to use a beanbag, we prefer to use a beach chair with an attachable hydraulic articulated arm holder (Spider Limb Positioner, Tenet Medical Engineering, Calgary, Canada) (FIG 5).

 

The head of the beach chair is elevated 30 to 45 degrees to allow access to the ipsilateral iliac crest.

 

A well-padded bump is placed behind the ipsilateral buttock and hip to ensure that the iliac crest is prominent for ease of dissection.

 

The shoulder and iliac crest are prepared and draped in a standard sterile fashion.

 

Approach

 

Anterior glenoid reconstruction with iliac crest bone graft requires two approaches:

 

 

Deltopectoral approach for glenoid preparation

 

Anterior approach to the iliac crest for tricortical anterior iliac crest bone graft harvesting

 

 

 

 

 

FIG 5 • The patient is secured into a beach chair with an attachable hydraulic articulated arm holder (Spider Limb Positioner). The upper body is positioned at 30 to 45 degrees to allow access to the ipsilateral iliac crest.

TECHNIQUES

• Exposure of Glenoid

   

  A 5- to 7-cm incision is made in the anterior axillary fold beginning at the inferior border of the pectoralis major tendon and extending superiorly to the coracoid.

   

  Once the initial incision is carried through the subcutaneous tissue down to the fascia investing the pectoralis and deltoid muscles, full-thickness skin flaps are sharply developed using a no. 15 blade superiorly to the level of the coracoid. The flaps are extended medially and laterally at least 1 cm to allow identification of the cephalic vein and dissection of the interval between the deltoid and pectoralis major muscles.

   

  Typically, there are more crossing vessels emanating from the lateral side of the cephalic vein. Thus, the investing fascia on the medial side of the vein is incised sharply while an assistant places countertraction on the pectoralis major using a two-pronged skin hook. This allows a clean dissection and medially based crossing vessels can be coagulated in a step-by-step fashion. The cephalic vein may then be taken laterally along with the deltoid during retraction.

   

  The deep surfaces of the deltoid and pectoralis are sharply dissected using a no. 15 blade to free up adhesions and broaden the exposure.

   

  A four-quadrant self-retaining retractor is positioned to retract the pectoralis major medially and the deltoid laterally (TECH FIG 1A).

   

  There is often a leash of vessels superficial to the clavipectoral fascia at the level of the coracoid. These vessels should be coagulated if present.

   

  The clavipectoral fascia is sharply incised lateral to the conjoint tendon, making sure to stay lateral to any muscle of the short head of the biceps.

   

  The musculocutaneous nerve can then be palpated on the deep surface of the conjoint tendon. The conjoint tendon is retracted medially, exposing the subscapularis tendon and muscle.

   

   

  The coracoacromial ligament can be released if additional exposure is needed superiorly. The circumflex vessels are then identified and ligated or coagulated (TECH FIG 1B).

   

  The axillary nerve can be palpated as it passes over the inferior portion of the subscapularis and loops under the inferior capsule. A blunt retractor can be placed lateral and deep to the axillary nerve, thus retracting it gently medially away from the subscapularis musculotendinous junction.

   

  The subscapularis tendon is then incised from bone off the lesser tuberosity to avoid disrupting the long head of the biceps tendon in the bicipital groove (TECH FIG 1C).

   

  Through sharp dissection, an interval between the subscapularis tendon and capsule is developed, leaving the capsule intact. It is often easier to start inferiorly and use a blunt elevator to dissect the interval.

   

  The subscapularis tendon and muscle are retracted medially using an anterior glenoid neck retractor.

   

  A blunt retractor is repositioned deep to the axillary nerve to retract away from the capsule, which should be widely exposed at this point.

   

  An inverted L-shaped capsulotomy is then created based on the humeral neck and extending horizontally across the rotator interval region (TECH FIG 1D).

   

  P.3634

   

   

   

  TECH FIG 1 • A. The pectoralis major and deltoid muscles are retracted to reveal a broad exposure of the conjoint tendon (CT) and muscle belly passing over the subscapularis muscle (SS). The coracoacromial ligament (CA) can be released if needed for additional exposure. B. A blunt curved retractor can be placed inferiorly along the subscapularis to protect the axillary nerve. C. The subscapularis is incised from its insertion on the lesser tuberosity and the layer between the deep capsule and the subscapularis muscle and tendon is developed with a blunt elevator. D. An inverted L-shaped capsulotomy based on the humeral neck and extending across the rotator interval region allows access to the glenohumeral joint and leaves tissue for later repair.

• Glenoid Preparation

   

  The anterior glenoid and scapular neck are then exposed (TECH FIG 2).

   

  After the L-shaped capsulotomy, a periosteal elevator is used to strip the periosteal sleeve from the anterior scapular neck.

   

  An anterior glenoid neck retractor is positioned to retract the capsule medially.

   

  A Fukuda retractor or similar blunt retractor is used to retract the humeral head posteriorly, thus exposing

  the face of the glenoid.

   

  The length of the osseous defect is measured and compared to the width of the maximum AP radius of the glenoid. The measured defect length will be the basis for the size of the iliac crest bone graft harvested.

   

  Soft tissue and scar tissue are removed from the anterior glenoid, and this bone and the adjacent scapular neck are roughened with a high-speed burr to create punctate bleeding and a smooth surface for bone grafting.

   

  P.3635

   

   

   

  TECH FIG 2 • Glenoid preparation. A. The humeral head (HH) is retracted laterally and posteriorly using a Fukuda retractor or curved blunt retractor. The medial capsule and soft tissue are retracted medially, thus exposing the anterior scapular neck and eroded glenoid (G) surface. B. A malleable ruler is used to measure the length of the anterior glenoid defect.

• Harvesting and Preparing Tricortical Iliac Crest Bone Graft

   

  The iliac crest is harvested as a tricortical bone graft (TECH FIG 3).

   

  A 2- to 3-cm curved incision is made overlying the iliac crest and posterior to the anterosuperior iliac spine.

   

  The incision is carried sharply through subcutaneous tissue down to the periosteum, which is incised sharply and subperiosteally elevated to expose the inner and outer tables of the ilium. Self-retaining retractors are placed between the crest and periosteum along the inner and outer tables.

   

   

   

  TECH FIG 3 • Tricortical iliac crest bone graft. A. Bone graft is harvested from the iliac crest using an oscillating saw and preserving both the inner and outer tables. A high-speed burr is used to contour the graft. B. The size of the graft is typically 3 cm in length and 2 cm in width but should be based on the measured size of the defect.

   

   

  An oscillating saw is used to harvest a tricortical wedge-shaped graft. The graft is typically about 3 cm in length by 2 cm in width, but the size should be based on the measured defect.

   

  A high-speed burr and a small oscillating saw are then used to contour the graft to fit along the anterior glenoid and best reestablish concavity, depth, and length. The inner table serves as the articular portion of the graft and the cancellous surface is opposed to the anterior glenoid defect.

   

  Recent studies have suggested potential alternative donor sites for osteochondral allografts to the glenoid bony defect.

   

  In a controlled laboratory study, DeHaan et al4 found that laterodistal tibial allografts provided an acceptable fit for radius of curvature matching to the glenoid in 94% of their specimens, suggesting that the tibia may be a viable donor site for glenoid reconstruction.

   

  After obtaining initial biomechanical pilot data showing excellent conformity of the distal tibia to the

  glenoid, Provencher and colleagues11 successfully implanted distal tibial allograft in three patients with significant instability and 25% to 35% glenoid bone loss.

   

  Pending further studies and long-term patient follow-up, the iliac crest remains the donor site of choice.

   

   

  P.3636

• Fixation of Tricortical Graft to Glenoid

   

  The tricortical iliac crest graft is secured to the glenoid (TECH FIG 4).

   

  The contoured graft is then positioned onto the anterior glenoid with the inner table of the iliac crest facing laterally and serving as the articular surface.

   

  Proper positioning of the graft is critical. Glenoid concavity should be established but impingement or articular step-off should be avoided. Avoiding too vertical or too horizontal of an angle between the graft and glenoid can prevent these pitfalls.

   

  Too vertical of an angle may result in humeral impingement.

   

  Too horizontal of an angle may yield a failure to reestablish appropriate glenoid concavity.

   

   

   

  TECH FIG 4 • Fixation of graft to the glenoid. A. The graft is positioned to establish concavity to the glenoid as well as a smooth transition between the graft and native glenoid to avoid an articular step-off.

  B. A no. 2 braided polyethylene suture is placed around each 4.0-mm screw before it is fully tightened to assist in later capsular repair. C. Once the graft is secured with screws, the glenohumeral retractor is removed and the position of the humeral head (HH) on the glenoid is noted.

   

   

  Once the graft is correctly positioned, it can be temporarily secured to the anterior glenoid using two or three terminally threaded Kirschner wires from the stainless steel AO 4.0-mm cannulated screw set (AO, Synthes, Paoli, PA).

   

  Two or three partially threaded 4.0-mm cannulated screws are then placed over the Kirschner wires to secure the graft.

   

  A no. 2 braided polyethylene suture is placed around the shaft of each screw before the screw is fully seated and compressing the graft. These sutures may be used for later capsular repair.

   

  The Fukuda retractor is gently removed and the position of the humeral head is noted. The glenohumeral joint is ranged and any incongruity or instability noted should prompt a change in graft position.

• Repair of Capsule and Subscapularis

 

The capsulotomy and subscapularis are repaired once the graft is in a satisfactory position and once the shoulder has been ranged (TECH FIG 5).

 

The sutures from the graft fixation screws are passed through the capsule-periosteal sleeve as horizontal mattress stitches and tied.

 

The capsulotomy can be further repaired in one of two ways:

 

If the L-shaped capsulotomy can be repaired primarily, it is reapproximated using no. 2 braided polyethylene suture. Often, though, the graft occupies enough space and the capsule is contracted enough that a primary repair of the capsulotomy is not possible.

 

If the L-shaped capsulotomy cannot be repaired primarily to the neck of the humerus with the arm in at least 30 degrees of external rotation, then the capsule is repaired to the lateral portion of the subscapularis tendon. This will tension the anterior capsule as the subscapularis becomes more taut with external rotation.

 

The lesser tuberosity is gently abraded with a high-speed burr to cause punctate bleeding.

 

The subscapularis is then meticulously repaired to the lesser tuberosity with two or three suture anchors using a modified Mason-Allen stitch.

 

The shoulder incision is closed in layers.

 

 

P.3637

 

 

 

TECH FIG 5 • Repair of capsulotomy and subscapularis. A. The sutures around the screws are secured through the capsule with horizontal mattress stitches. B. If the capsule cannot be repaired back to the humeral neck without being excessively tight and restrictive of external rotation, it is secured to the deep surface of the subscapularis tendon with horizontal mattress sutures. The subscapularis is then repaired to the lesser tuberosity with suture anchors.

 

 

PEARLS AND PITFALLS

Indications ▪ A complete history and physical should be performed.

• Associated pathology must be recognized and addressed:

• The glenohumeral joint must be assessed for osteoarthrosis.

• The humeral head must be assessed for a significant engaging Hill-Sachs lesion. It is rare for the lesion to be engaging after reconstruction of the width of the glenoid.

Tricortical

graft harvest

• Care should be exercised to avoid disrupting the anterior superior iliac spine.

• The lateral femoral cutaneous and ilioinguinal nerves are at risk during dissection of the anterior ilium.

Tricortical

graft placement

• Placement of the graft in too vertical of a position may result in impingement of the

  humeral head and articular erosion.

• Placement of the graft in too horizontal of a position does not recreate concavity of the glenoid.

• There must be a smooth transition between the native glenoid and bone graft. Proper positioning ensures this. A burr can be used to remove any prominences from the graft that remain after fixation.

Stiffness

• Patients should be counseled to expect some limitation of external rotation

  postoperatively.

• The goal is to achieve a stable joint with no more than 20 degrees loss of external rotation to limit the risk of capsulorrhaphy arthropathy. This should be considered during capsular repair.

 

 

POSTOPERATIVE CARE

 

Radiographs are obtained to judge graft placement and screw position. A CT scan is helpful to estimate graft incorporation (FIG 6).

 

 

The shoulder is maintained in a sling immobilizer for 4 weeks. Pendulum exercises are allowed after the first week.

 

At 4 weeks, the sling is removed to allow

 

 

Activities of daily living

 

Passive range of motion, active-assisted range of motion, water therapy

 

At 3 months, strengthening is initiated.

 

Participation in overhead recreational sport (golf, tennis, swimming) is allowed at 4 months.

 

Participation in contact or collision sports is allowed at 6 months.

OUTCOMES

With appropriate preoperative workup, diagnosis, and surgical technique, anatomic reconstruction of the glenoid with tricortical iliac crest bone graft is very effective at treating recurrent dislocations in the setting of a bony glenoid defect.

P.3638

 

FIG 6 • Postoperative imaging of glenoid reconstruction with tricortical iliac crest bone graft. A. Axillary lateral. B. Anterior view of 3-D CT reconstruction demonstrating position and incorporation of graft. C. Posterior view of 3-D CT reconstruction demonstrating restored glenoid width, depth, and concavity.

 

Hutchinson and colleagues6 demonstrated no recurrent dislocations after tricortical iliac crest bone grafting in a population of epileptics who continued to have seizures postoperatively.

Warner and associates15 reported no recurrent dislocations or subluxations after anterior glenoid bone grafting in a population of athletes with traumatic recurrent anterior instability. There was a mean loss of external rotation in abduction of 14 degrees.

 

 

 

COMPLICATIONS

Subscapularis insufficiency Hardware failure and migration Nonunion or graft reabsorption Stiffness

Brachial plexus injury

 

 

REFERENCES

1. Balg F, Boileau P. The instability severity index score. A simple preoperative score to select patients for arthroscopic or open shoulder stabilisation. J Bone Joint Surg Br 2007:89:1470-1477.

    

    

2. Bigliani LU, Newton PM, Steinmann SP, et al. Glenoid rim lesions associated with recurrent anterior dislocation of the shoulder. Am J Sports Med 1998;26:41-45.

    

    

3. Burkhart SS, DeBeer JF. Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs: significance of the inverted-pear glenoid and the humeral engaging Hill-Sachs lesion. Arthroscopy 2000;16:677-694.

    

    

4. Dehaan A, Munch J, Durkan M, et al. Reconstruction of a bony bankart lesion: best fit based on radius of curvature. Am J Sports Med 2013;41:1140-1145.

    

    

5. Gerber C, Nyffeler RW. Classification of glenohumeral joint instability. Clin Orthop Relat Res 2002;400:65-76.

    

    

6. Hutchinson JW, Neumann L, Wallace WA. Bone buttress operation for recurrent anterior shoulder dislocation in epilepsy. J Bone Joint Surg Br 1995;77B:928-932.

    

    

7. Itoi E, Lee SB, Amrami KK, et al. Quantitative assessment of classic anteroinferior bony Bankart lesions by radiography and computed tomography. Am J Sports Med 2003;31:112-118.

    

    

8. Itoi E, Lee SB, Berglund LJ, et al. The effect of glenoid defect on anteroinferior stability of the shoulder after Bankart repair: a cadaver study. J Bone Joint Surg Am 2000;82A:35-46.

    

    

9. Lippitt SB, Vanderhooft JE, Harris SL, et al. Glenohumeral stability from concavity-compression: a quantitative analysis. J Shoulder Elbow Surg 1993;2:27-35.

    

    

10. Pansard E, Klouche S, Billot N, et al. Reliability and validity assessment of a glenoid bone loss measurement using the Bernageau profile view in chronic anterior shoulder instability. J Shoulder Elbow Surg 2013;22:1193-1198.

     

     

11. Provencher MT, Ghodadra N, LeClere L, et al. Anatomic osteochondral glenoid reconstruction for recurrent glenohumeral instability with glenoid deficiency using a distal tibia allograft. Arthroscopy 2009;25:446-52.

     

     

12. Rerko MA, Pan X, Donaldson C, et al. Comparison of various imaging techniques to quantify glenoid bone loss in shoulder instability. J Shoulder Elbow Surg 2013;22:528-534.

     

     

13. Soslowsky LJ, Flatow EL, Bigliani LU, et al. Articular geometry of the glenohumeral joint. Clin Orthop Relat Res 1992;285:181-190.

     

     

14. Warner JJ, Bowen MK, Deng XH, et al. Articular contact patterns of the normal glenohumeral joint. J Shoulder Elbow Surg 1998;4: 381-388.

     

     

15. Warner JP, Gill TJ, O'Hollerhan JD, et al. Anatomical glenoid reconstruction for recurrent anterior glenohumeral instability with glenoid deficiency using an autogenous tricortical iliac crest bone graft. Am J

Sports Med 2006;34:205-212.