CHAPTER 15 Revision Instability Surgery
Arthroscopic techniques to repair the unstable shoulder continue to evolve. Shoulder surgeons have embraced modern techniques to evaluate and anatomically repair the glenohumeral joint with minimally invasive procedures, reducing complications and stiffness. Historically, the absence of recurring dislocation has been equated with a successful outcome, but currently athletes and physically active individuals consider the return to their activity as the true measure of success.1–5 Return to sport and work following arthroscopic stabilization has been achieved based on a successful preservation of external rotation, improved outcomes in overhead athletes, and the avoidance of division of the subscapularis.6–9 Despite an emphasis on anatomic repairs, recurrence of instability is the most common complication of arthroscopic stabilization. To minimize the risk of recurrence, surgeons need to choose the best surgical approach when treating patients with failed shoulder instability surgery. The options for active individuals include arthroscopic stabilization, open stabilization, and possible augmentation with bone or soft tissue in complex revision situations.
Revision surgery is not as unusual as was once thought. Athletes and workers are likely to return to the activity that precipitated the initial injury.10,11 Surgeons continue to make surgical approach decisions based on anatomic lesions and anticipated activity demands.12 Surgical complications that have been reported include recurrence of instability, stiffness, joint pain, and hardware complications; the treatment goal is to return to physical activities and delay or prevent the onset of degenerative joint disease. The arthroscopic approach has met with success in secondary repairs and is an option for properly selected patients undergoing revision surgery.
Revision surgery adds challenges that are not always present when performing initial repairs. Additional trauma and soft tissue and bone changes following surgery can promote degenerative findings.13 Retained hardware, osteolytic changes secondary to implant choice, loss of tissue compliance, and incremental associated pathology can also further complicate treatment choices. As a result, revision surgical outcomes are not as promising as the results of the index surgery.14,15 The more anatomic the original repair, the easier to identify the causes of failure that need to be addressed.
ANATOMY AND PATHOANATOMY
The shoulder is comprised of static and dynamic stabilizers that allow maximal rotation with stability. Although surgery is directed at the static stabilizers, returning an athlete back to his or her sport requires a combined muscular rehabilitation program with repair of the essential lesions. Critical structures include the articular surface of the glenohumeral articulation, labrum, and capsular ligaments. Most experts have agreed that detachment of the labrum along with the capsular ligaments is the most common presentation following a glenohumeral dislocation.16,17 The inferior glenohumeral ligament combined with the superior labrum play a significant role in limiting anterior translation.18–20
Early surgical repair of recurrent instability has become popular as a result of improved outcomes. A progression of soft tissue and bone failure can follow multiple instability events.21 These changes may be permanent and affect the options that treating physicians need to consider. Although it remains controversial whether athletes should be repaired after a single dislocation, most would agree that surgery should be performed after recurrent subluxation or disability caused by apprehension is confirmed.
Following surgical repair, athletes often return to activities that place the shoulder at risk. After additional trauma and disruption of the failed surgical repair, there is often an acceleration of damage to the static stabilizers.22 Minor bone losses can become larger, further reducing the amount of contact and containment of the humeral head. Soft tissue changes in quality and mobility may become a challenge to the reconstructive surgeon.
The most common findings following failure of previous stabilization is the re-creation of a capsule and labrum detachment, capsular pouch, glenoid rim erosion or fracture, and articular changes to the humeral head (Fig. 15-1).16,22,23 Other findings may include extension of injury into the rotator interval or superior labrum, loose bodies, and articular tears of the rotator cuff. These findings often occur in combination, and each of these features needs to be considered when deciding on the best approach to the damaged shoulder.
A concern for arthroscopic treatment of the unstable shoulder is the decision of whether a soft tissue procedure can compensate for bone loss. There have been reports of increased failure rates when anterior and inferior glenoid bone loss exceeds 25% to 30%.24,25 Internationally, the treatment has been to consider bone grafting through open or arthroscopic techniques.26–28 Most surgeons agree that bone loss needs to be considered during primary and revision surgery, and that anatomic repair of the detached labrum may be insufficient to return an athlete back to sport. Experts have not agreed on the amount of bone loss that becomes critical to consider a grafting procedure, but laboratory experiments can demonstrate measurable loss of stability when a glenoid rim deficiency exceeds 20%.29–31 It can be a challenge to quantitate bone loss, although a number of radiologic techniques have been proposed.25,30–33 Operative evaluation may be necessary to appreciate the combined impact of glenoid rim and humeral head deficiency.34
Displaced glenoid rim fractures can be problematic when considering revision surgery. These fractures are often medialized with the displaced labrum in a position that does not contribute to limiting anteroinferior translation.35,36 Some fractures may present as nonunions or fibrous unions; others may actually heal to the glenoid neck in a medial position (Fig. 15-2).37
The anterior dislocated shoulder will also demonstrate a humeral head impression defect that is created in the dislocated position as a result of impaction against the anterior glenoid rim. Duration and frequency of dislocations, combined with muscular force resisting reduction, play a role in the size and shape of the defect. This value needs to be considered in combination with glenoid deficiency when considering the sum effect of this pathologic condition (Fig. 15-3). The position of the shoulder when dislocation occurs will dictate the orientation of the Hill-Sachs lesion. As the lesion becomes more vertical, engagement can occur with less shoulder elevation. This may increase the likelihood of recurrence and potentially complicate activities of daily living.
Soft tissue changes following failed stabilization include synovitis, labral detachment and involution, soft tissue stiffness, and adhesions to neighboring structures (i.e., the subscapularis). Tissue mobility is a critical step in repositioning the labrum and inferior ligaments onto the glenoid. To re-create the compression concavity of the normal articulation, the soft tissue bumper needs to be able to be repositioned on top of the glenoid rim. Following surgical failure, there is often additional scarring to the medial glenoid neck and subscapularis. This has been called an ALPSA (anterior labral periosteal sleeve avulsion) lesion.38 Careful mobilization and repositioning of this tissue is required if an anatomic repair is being considered (Fig. 15-4).
A recurrent labral detachment may resemble the original Bankart lesion or can extend beyond the previous limits. The detachment may extend posteriorly along the inferior aspect of the glenoid and superiorly to the base of the biceps. Additional trauma combined with tissue stiffness can be partially responsible for the enlarged defect. It is essential for the surgeon to visualize the boundaries of the lesion and to assess the degree of damage to the capsule, labrum, and bony structures so that specific treatment can be applied. The rotator interval is the region between the superior border of the middle glenohumeral ligament and superior glenohumeral ligament. Although normal intervals have not been defined, most surgeons agree that closure or reduction of the interval should be considered in revision surgery. This is accomplished in an inferior to superior fashion to augment the anterior repair and reduce translation.39 Tightening this interval may be a concern in overhead throwing athletes, and absorbable versus permanent sutures may be considered. The superior labral attachments and rotator interval play a role in limiting anterior translation and assist the function of the inferior glenohumeral ligament.20,40
Foreign bodies may play a role in developing a painful shoulder following prior surgical stabilization. Metallic and nonmetallic anchors may have become displaced during the traumatic event. Exposed hardware is harmful to the articulation and needs to be removed as soon as the diagnosis is confirmed to limit articular cartilage injury.41,42 Permanent suture material can be embedded in the articular cartilage, creating painful impingement and a sense of subluxation. Removal of foreign matter is an important part of joint débridement prior to considering further repair.
The rotator cuff and biceps may exhibit pathologic changes. Although this was thought to occur in patients older than 40 years, these injuries can be found in younger patients. Rotator cuff tears vary from partial-thickness tears in young athletes to full-thickness tears in adults.43 In addition, subscapularis avulsions may be an important discovery in patients who have undergone prior open surgery.44 Review of previous operative reports is important when considering tissue failure and possible revision surgery.
HISTORY AND PHYSICAL EXAMINATION
The event that created recurrent instability should be reviewed when obtaining a history:
Special tests for shoulder instability include translation tests, apprehension tests, relocation tests, and the superior labral and biceps test, most commonly performed in the seated and supine patient. Translation tests include a load and shift test, which begins with the examiner centering the humerus and stabilizing the scapula. Translation is tested anteriorly, inferiorly, and posteriorly and compared with the other extremity. The arm is initially examined in the neutral position with 20 degrees abduction and retested in a position that would normally tension the involved ligaments (i.e., 45-degree abduction and 45-degree external rotation; Fig. 15-5). Evaluate patients in these positions for pain or apprehension. Apprehension may be demonstrated by verbal concern, visual awareness, or reflexive muscle contracture to try to avoid this position. A supine relocation maneuver can be performed with direct pressure added in the opposite direction, relieving apprehension and pain. Additional shoulder rotation is often demonstrated with this additional step. The superior labrum is evaluated by a combination of translation test and biceps traction tests in the seated patient. This can be accomplished by resisting forward flexion with the palm up, the O’Brien test with the thumb down, and resistance to elbow flexion. Localized tenderness along the biceps groove can lead to suspicion of additional pathology to the biceps, superior labrum, and rotator interval.
