Posterior Shoulder Instability

Abstract

Context: Posterior shoulder instability has become more frequently recognized and treated as a unique subset of shoulder instability, especially in the military. Posterior shoulder pathology may be more difficult to accurately diagnose than its anterior counterpart, and commonly, patients present with complaints of pain rather than instability. "Posterior instability" may encompass both dislocation and subluxation, and the most common presentation is recurrent posterior subluxation. Arthroscopic and open treatment techniques have improved as understanding of posterior shoulder instability has evolved.

Evidence acquisition: Electronic databases including PubMed and MEDLINE were queried for articles relating to posterior shoulder instability.

Study design: Clinical review.

Level of evidence: Level 4.

Results: In low-demand patients, nonoperative treatment of posterior shoulder instability should be considered a first line of treatment and is typically successful. Conservative treatment, however, is commonly unsuccessful in active patients, such as military members. Those patients with persistent shoulder pain, instability, or functional limitations after a trial of conservative treatment may be considered surgical candidates. Arthroscopic posterior shoulder stabilization has demonstrated excellent clinical outcomes, high patient satisfaction, and low complication rates. Advanced techniques may be required in select cases to address bone loss, glenoid dysplasia, or revision.

Conclusion: Posterior instability represents about 10% of shoulder instability and has become increasingly recognized and treated in military members. Nonoperative treatment is commonly unsuccessful in active patients, and surgical stabilization can be considered in patients who do not respond. Isolated posterior labral repairs constitute up to 24% of operatively treated labral repairs in a military population. Arthroscopic posterior stabilization is typically considered as first-line surgical treatment, while open techniques may be required in complex or revision settings.

Keywords: instability; posterior stabilization; shoulder arthroscopy.

Figure 1.

Axial radiograph demonstrating a locked posterior glenohumeral dislocation.

Figure 2.

(a) T2-weighted axial magnetic resonance image demonstrating a posterior labral tear. (b) Posterior labral tear with paralabral cyst.

Figure 3.

Three-dimensional computed tomography reconstruction of the glenoid performed with subtraction of the humeral head. Note the significant posterior glenoid bone loss.

Figure 4.

(a) Operative view of beach-chair setup with use of an arm positioner. (b) Posterolateral portal for anchor placement. Portal is placed in line with the posterior border of the distal clavicle. (c) Operative view of anchor placement through the posterolateral portal.

Figure 5.

(a) Arthroscopic view of a posterior labral tear. (b) Liberation of the labrum from the glenoid in preparation for repair. (c) Drilling in preparation for anchor placement through the posterolateral portal. (d) Completed posterior labral repair via knotless technique viewed from the anterosuperior portal.

Figure 6.

(a) Clinical view of distal clavicular autograft harvested and prepared on back table. (b) Posterior bone block augmentation completed through an open posterior incision. (c) Axial computed tomography image demonstrating osteochondral clavicle graft placement.