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Arthroscopic techniques to manage multidirectional instability of the shoulder


OVERVIEW

Chapter synopsis

Multidirectional instability (MDI) is a complex condition that involves symptomatic subluxations or dislocations of the glenohumeral joint in two or more directions. A thorough clinical history and detailed physical examination are necessary for proper diagnosis, while a comprehensive understanding of the glenohumeral anatomy and joint biomechanics is critical for successful management. Magnetic resonance imaging (MRI) is the gold standard imaging modality when it comes to the diagnosis of MDI. Conservative treatment is typically attempted for at least 3 to 6 months in the absence of traumatic injury or labral tear. The preferred arthroscopic surgical option is an anchor-based pancapsular plication, with or without labral repair. Patients are typically immobilized in a neutral gunslinger position for 4–6 weeks following surgery, with return to unrestricted activities and sports at 6 months. Recent studies have reported limited postoperative instability recurrence, significant improvement in patient reported outcomes, and low rates of perioperative complications.

Important points

Patient characteristics

  • Patients with MDI can present with a variety of symptoms, such as pain, instability, or decreased strength

  • Typically MDI presents in the second or third decade of life

  • Patients may or may not have a history of trauma

  • It is important to identify patients with underlying collagen disorders or generalized hyperlaxity

  • Physical exam maneuvers will elicit instability, but it is important to observe scapular motion, evaluate for generalized laxity, and perform a proper neurovascular exam

  • Glenoid hypoplasia and increased retroversion are risk factors for MDI

Diagnostic work-up

  • MDI is largely a clinical diagnosis□Imaging will allow for evaluation of concomitant pathologies, identify anatomic variants, and is important for preoperative planning

  • MRI, with or without intra-articular contrast, is the gold standard imaging modality

  • It can be argued that MRI with intra-articular contrast increases the sensitivity and specificity of the exam

Surgical technique highlights

  • Perform supine examination under anesthesia with side-to-side comparison, preferably with stabilization of the scapula, followed by placing the patient in a lateral decubitus position

  • A posterior portal, anterior-inferior portal, a anterior-superior portal, and 7 o’clock portal are routinely used

  • The labrum may be débrided and mobilized or left in situ, and the capsule and underlying glenoid are rasped to create a bleeding bed at the repair site

  • Capsulolabral repair or pancapsular plication is performed by placing anchors from inferior to superior, first posteriorly, then anteriorly, and superiorly as indicated

  • Double-loaded anchors can be placed at 5- to 10-mm increments around the glenoid, ensuring adequate fixation in healthy subchondral bone

  • In rare circumstances, the rotator interval may be closed

Clinical and surgical pearls and pitfalls

  • It is paramount to identify patients with collagen disorders during initial evaluation because these patients have been shown to have poorer outcomes following surgical stabilization

  • Conservative treatment is typically attempted for at least 3–6 months in the absence of a labral injury

  • Knotless anchors are preferred above the level of the equator to minimize contact with the humeral head, mitigating risk of abrasion and iatrogenic chondral damage

  • Passive range of motion of the shoulder is not initiated until 6 weeks

  • Concomitant pathologies, such as that involving the long head of the biceps or rotator cuff, should be addressed

Clinical outcomes

  • Arthroscopic and open capsular plication provide similar, favorable results, with respect to rates of reoperation, range of motion, and recurrence of instability

  • At least one study has demonstrated that arthroscopic capsular plication is associated with less loss of external rotation than open capsular shift

  • MDI caused by trauma was associated with superior postoperative American Shoulder and Elbow Surgeons (ASES) scores, return to sport rate, and satisfaction score compared with atraumatic causes of MDI

Introduction

Multidirectional instability (MDI) of the shoulder is a condition defined by symptomatic subluxation or dislocation of the glenohumeral joint that occurs in greater than one direction. Contrary to what was previously reported, MDI is not an uncommon shoulder pathology; However, it remains difficult to diagnose. Conservative treatment, including patient education, changing of one’s lifestyle and work pattern, and muscle-strengthening exercises can lead to symptomatic improvement in most atraumatic cases. When conservative methods fail, surgical intervention with a glenohumeral capsular shift to tighten the loose capsular structures can provide good-to-excellent results for most patients. However, surgery is technically demanding and requires a thorough knowledge of shoulder anatomy and the native joint biomechanics.

This complex condition was originally described by Neer and Foster in 1980 and has a variety of associated pathologies and multiple potential underlying medical conditions. Although the exact incidence of MDI has yet to be defined in the literature, a 2012 study using the Norwegian database suggested that 7% of shoulder instability procedures were for management of MDI. This condition frequently occurs in association with congenital disorders such as Ehlers-Danlos or Marfan syndrome or in patients with generalized hyperlaxity or benign joint hypermobility syndrome (BJHS). To this end, the reported prevalence of ligamentous laxity for patients with symptomatic MDI ranges from 47% to 76%. ,

The etiology of MDI can be classified into either traumatic or atraumatic mechanisms of injury. Most commonly, MDI occurs without any inciting trauma event but rather occurs in association with repetitive microtrauma from overuse or hyperlaxity about the glenohumeral joint. Specifically, athletes that perform repetitive overhead movements, including swimming, volleyball, weightlifting, and tennis, have an increased prevalence of MDI. Atraumatic MDI most commonly peaks in the second or third decade of life. Conversely, significant trauma to the glenohumeral joint can lead to MDI by extensive injury to the glenoid labrum or rotator cuff, such as with high energy glenohumeral dislocation. Male patients have been reported to be 2.3 times more likely to have a traumatic onset of MDI.

MDI is typically managed nonoperatively for a minimum of 6 months, with formal physical therapy focused on dynamic stabilization and strengthening programs. Surgical options include both arthroscopic and open techniques. The primary aim of this chapter is to provide an in-depth presentation of the preferred arthroscopic management technique and associated outcomes of multidirectional shoulder instability. This chapter also aims to describe the relevant clinical anatomy, typical patient presentation, including past medical history and mechanism of injury, diagnostic modalities, and conservative management strategies for MDI.

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