From the Guidelines
Unidirectional instability is the most common type of shoulder instability, accounting for approximately 95% of cases, and typically occurs in the anterior direction, whereas multidirectional instability involves instability in two or more directions and is often associated with generalized ligamentous laxity or repetitive microtrauma. When evaluating shoulder instability, it is crucial to assess both osseous and labroligamentous pathology, as coexisting humeral avulsion of the glenohumeral ligament and significant glenoid bone loss can be found in up to 10% of patients with recurrent shoulder instability 1. Key factors to consider in the diagnosis and treatment of shoulder instability include:
- The direction of joint displacement, with unidirectional instability typically occurring in the anterior direction
- The presence of labroligamentous injury or rotator cuff tears, which are more common in younger and older patients, respectively 1
- Glenoid morphology and bone loss, which can play a significant factor in recurrent shoulder dislocations and may require bone grafting to restore stability 1 Treatment approaches for unidirectional and multidirectional instability differ significantly, with unidirectional instability often responding well to targeted physical therapy or surgical repair of specific structures, and multidirectional instability typically requiring a longer course of rehabilitation emphasizing rotator cuff and periscapular strengthening. The distinction between unidirectional and multidirectional instability is important, as applying a unidirectional treatment approach to multidirectional instability can lead to poor outcomes and potential worsening of symptoms. In clinical practice, a thorough evaluation of the patient's condition, including imaging studies and physical examination, is necessary to determine the type and severity of shoulder instability and to develop an effective treatment plan.
From the Research
Unidirectional vs Multidirectional Instability
- Unidirectional instability refers to the dislocation of the shoulder in one direction, often caused by a traumatic incident 2.
- Multidirectional instability (MDI) is a condition where the dislocation occurs in more than one direction with minimal or no causative trauma, characterized by a redundant capsule and increased glenohumeral joint volume 3.
Key Differences
- Unidirectional instability is often treated with surgical interventions such as open Bankart repair, which has lower rates of recurrence and reoperation compared to arthroscopic repair 2.
- Multidirectional instability, on the other hand, is typically treated with conservative management, focusing on physical therapy to restore strength and balance of the dynamic stabilizers of the shoulder 4, 5, 6.
- Surgical intervention, such as open inferior capsular shift or arthroscopic pancapsulolabral plication, is considered for MDI patients who do not respond to conservative treatment 4, 5.
Treatment Approaches
- Conservative management for MDI includes physical therapy, which aims to restore pain-free mobility, strength, and functioning, as well as improve proprioceptive control and scapular kinematics 6.
- Surgical treatment options for MDI, such as open capsular shift and arthroscopic capsular plication, have similar outcomes and are considered when conservative treatment fails 5.
- Recent research suggests exploring alternative treatment options, including methods to improve cross-linking of native collagen tissue, electric muscle stimulation, and coracohumeral ligament reconstruction 4.