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Arthroscopic Treatment of Anterior Shoulder Instability

Indications

Anterior shoulder instability is a spectrum of injury that ranges from anterior subluxation of the shoulder in provocative positions to traumatic dislocation with a propensity for recurrence. The majority of patients who present with anterior glenohumeral instability will report an initial traumatic episode that caused a shoulder dislocation or subluxation event. Patients may have required an emergent closed reduction, either on the athletic field or in an emergency room environment. Anterior glenohumeral instability is much more common than posterior instability, representing nearly 90% of all patients with pathologic shoulder instability.

Patients are candidates for surgical repair, and more specifically, arthroscopy, when conservative measures such as physical therapy and activity modification have failed to alleviate symptoms. The patient history may include a traumatic (or several traumatic) dislocation, typically with the arm in an abducted and externally rotated position (position of apprehension). With each dislocation, the patient may report a succession of instability episodes with a less traumatic etiology and occasionally progressing to persistent instability with activities of daily living.

Physical examination may demonstrate abnormal load and shift testing, a positive apprehension test, and a positive relocation test. Patients should be evaluated for signs of multi-directional instability (sulcus sign, posterior translation, and joint hypermobility).

Routine radiographs (AP, Y view, axillary lateral) are typically obtained to evaluate the osseous anatomy, confirm anatomic reduction, and rule out any associated fractures. Specialized views can be obtained to evaluate for a Hill Sachs lesion (Stryker notch) or anterior glenoid bone loss (West Point axillary view).

In cases of severe bone loss where an open approach to fixation is being considered, computerized tomography (CT) can be helpful to further quantify the amount of deficiency. Magnetic resonance imaging (MRI) or MR arthrography is usually reviewed to evaluate the anterior inferior glenohumeral ligament and capsule-labral complex (Figure 1).


Figure 1. Axial T2 MRA of the shoulder demonstrating a medially healed Bankart lesion in a patient who sustained multiple dislocations of the shoulder


Arthroscopic reconstruction is indicated in the majority of patients who warrant surgical repair.  Contraindications to arthroscopy may include: significant bone defects (Hill Sachs, glenoid), deficient anterior capsule, humeral avulsion of the inferior glenohumeral ligaments, and revision surgery (although arthroscopic techniques are evolving to include many of these cases as well).

Preoperative Planning

Images are inspected for osseous lesions, loose bodies, and concomitant pathology (SLAP lesions, rotator cuff tears, articular cartilage loss). MRI and MR arthrography are inspected to evaluate the position of the anterior inferior glenohumeral ligament to help plan for surgical repair. Patients with periosteal sleeve avulsions and medially healed Bankart lesions may demonstrate a loss of external rotation with instability, and the surgeon should be prepared for extensive mobilization of the capsule and labrum complex during arthroscopy.

While the patient is under general anesthesia and interscalene nerve block, load and shift testing may demonstrate excessive anterior translation of the humeral head relative to the glenoid fossa. A sulcus sign could also indicate multi-directional instability with incompetence of the rotator interval. Controversy exists as to whether the interval should be routinely closed during anterior shoulder instability surgery.

Positioning

Patients are positioned in the operating room in the lateral decubitus position. A bean bag or sand bag is used to assist with positioning and helps to avoid pressure injury. The affected extremity is typically placed in balanced arm traction at 45 degrees of abduction and slight (20 degrees) forward flexion using 10 to 15 pounds of traction (Figure 2). During surgery, hyperabduction by an assistant can aid with visualization of the anterior and inferior capsule. Alternatively, the beach chair approach can be employed. The surgeon should choose the approach that is most familiar.


Figure 2. Patient undergoing shoulder surgery in the lateral decubitus position

Approach and Technique

We typically use an all arthroscopic approach for this procedure, with the main working portal being the anterior portal. The posterior portal is created first after injection of the glenohumeral joint with 40-60 mL of saline. The posterior portal is the main viewing portal in our technique; however, an accessory rotator interval portal can be created to assist with viewing the anterior glenoid rim and help with mobilization of the labrum. The posterior portal is created in the posterior “soft spot”, approximately 3 cm inferior and 2 cm medial to the lateral border of the acromion.

The main working anterior portal is created just above the subscapularis tendon in the rotator interval through an outside in technique. This portal should be established so that access to the 6 o’ clock position on the glenoid face is easily achieved. The trajectory of this portal is at approximately 45 degrees to the glenoid face. A cannula is placed in the anterior portal to assist with suture management and, as stated previously, an accessory anterior portal can be established higher in the rotator interval if necessary.

A diagnostic arthroscopy is first performed to assess the spectrum of injury. The glenoid and humeral articular surfaces are inspected, as well as the rotator cuff, the labrum, the biceps tendon, and the anchor complex. The size of the Hill Sachs defect, if present, is measured, as well as the degree of glenoid bone loss. If there is insufficient bone loss to warrant an open approach, the surgery is begun with mobilization of the anterior capsule and labrum complex.

Through the anterior portal, a periosteal elevator is first used to elevate the damaged labrum and release scar tissue that may have formed between the labrum and glenoid neck. Visualization of the subscapularis muscle belly helps to confirm that adequate mobilization and release have been performed (Figure 3). A motorized shaver or burr can be used to abrade the glenoid margin. Anchors (ranging in size from 2 mm to 3 mm) are then sequentially placed along the anterior glenoid face from a distal to proximal direction.


Figure 3. Arthroscopic view from the posterior viewing portal. The labrum/capsule complex (L) is being elevated off of the glenoid (G) neck so that the subscapularis muscle belly (SS) is visualized.


We prefer single-loaded suture anchors to avoid knot confusion; however, double-loaded anchors can be employed for added fixation. Care is taken to place the anchors within glenoid bone, leaving adequate spacing between fixation points (typically 3-5 mm apart). The most inferior anchor is typically placed between 5 and 6 o’ clock on the glenoid face, as inferiorly as possible. Studies have shown that placing less than three anchors below the equator of the glenoid has been associated with a higher failure rate, so the goal in almost every instance should be to place three points of fixation below the 3 o’ clock position.

The anterior suture limbs of the anchors are shuttled through the capsule and labrum complex inferior to the fixation point of the anchor. This will allow plication of the inferior capsule while mobilizing the labrum to the glenoid face. We typically use a suture hook loaded with a PDS suture (Ethicon, Somerville, NJ) for this purpose. If additional plication of the capsule is desired, additional passes through the capsule can be taken to titrate the repair to the degree of instability. All sutures are tied with locking and sliding knots with the anterior suture limb serving as the post to prevent intra-articular placement of the suture knot complex (Figures 4-5).


Figure 4. Arthroscopic view from the posterior viewing portal demonstrating an anterior labral repair (H – humeral head; G – glenoid; L – capsule/labrum complex)


Figure 5. Arthroscopic view from the anterior viewing portal demonstrating an anterior labral repair (H – humeral head; G – glenoid; L – capsule/labrum complex)


Once the capsule and labrum have been repaired and adequate tension restored to the inferior glenohumeral ligament complex, the posterior band of the inferior glenohumeral ligament is also inspected and repaired if injured. If necessary, the rotator interval is closed if signs of multi-directional instability or rotator interval laxity were detected on pre-operative physical examination. This can be accomplished with a suture hook and grasping penetrator with the anterior cannula backed out just anterior to the working portal. Closure of the anterior portal/rotator interval completes the repair.

Pearls and Pitfalls

  • The lateral decubitus position with the arm in traction allows for easy access to the inferior and anterior recesses of the glenohumeral joint and may assist the novice arthroscopist.
  • When visualization from the posterior portal is challenging, two working anterior portals can be beneficial and greatly assist in visualizing the anterior glenoid and capsule complex.
  • Three anchors should be placed below the level of the equator to provide adequate fixation and plication of the anterior and inferior capsule.
  • Anchors should be placed on the glenoid face to maximize bone contact and restore the proper length-tension relationship of the glenohumeral ligament complex.
  • Rotator interval closure is performed in patients who demonstrate excessive laxity. Routine closure of the interval remains a controversial topic in shoulder surgery.

Postoperative Care

The patient is placed in an abduction sling while under anesthesia. He/she is allowed to perform passive range-of-motion exercises at home immediately on discharge. We allow 90 degrees of forward elevation and rotation to neutral by 4 weeks post-surgery. After 6 weeks, the sling is discontinued and the patient begins active assisted range-of-motion exercises with slow progression to active range of motion without motion constraints (typically by 10 weeks).

After 4 months, the shoulder is often pain free and near normal range of motion is achieved. Rotator cuff and scapular strengthening are begun at this stage. Beyond 6 months, patients are assessed for return of strength and the ability to begin sport-specific activity. Patients who throw may begin a throwing program at this stage of the rehabilitation process. Competitive throwing is typically not attained until 12 to 18 months post-surgery.

Outcome

Arthroscopic anterior shoulder stabilization, when properly indicated, has achieved excellent outcomes with respect to recurrence and return to sport. Various studies have shown rates of recurrence ranging from 5% to 33%, with return to sport in the majority of patients.

Complications

Complications from surgery may include:

  • Infection
  • Stiffness
  • Osteoarthritis
  • Complex regional pain syndrome
  • Persistent pain
  • Glenoid fracture
  • Chondral injury
  • Recurrence of instability

Axillary nerve and vascular injury are rare complications when an all arthroscopic approach is utilized.

References

1. Castagna A, Markopoulos N, Conti M, et al. Arthroscopoic bankart suture-anchor repair : radiological and clinical outcome at minimum 10 years follow-up. Am J Sports Med 2010;38(10): 2012-2016.
2. Kropf EJ, Tjoumakaris FP, Sekiya JK. Arthroscopic shoulder stabilization: is there ever a need to open? Arthroscopy 2007;23(7): 779-784.
3. Tjoumakaris FP, Bradley JP. The rationale for an arthroscopic approach to shoulder stabilization. Arthroscopy 2011;27(10): 1422-1433.
4. Tjoumakaris FP, Abboud JA, Hassan SA, et al. Arthroscopic and open bankart repairs provide similar outcomes. Clin Orthop Relat Res 2006;446: 227-232.
5. van der Linde JA, van Kampen DA, Terwee CB, et al. Long-term results after arthroscopic shoulder stabilization using suture anchors: an 8 to 10 year follow-up. Am J Sports Med 2011;39(11): 2396-2340.

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