Abstract
Multidirectional shoulder instability is defined as symptomatic instability of the glenohumeral joint, usually associated with joint capsule laxity. Repetitive microtrauma or congenital hyperlaxity can contribute to the development of this condition. History is often vague, and shoulder pain is aggravated by activities of daily living. Physical exam maneuvers can support the diagnosis, but no findings are pathognomonic. Imaging can be helpful to exclude bony abnormalities, labral pathology, and assess for joint capsule volume. The standard treatment starts with physical therapy to strengthen the shoulder stabilizers and correct any abnormal scapular movement. Surgical treatment options include both open capsular shift and arthroscopic capsular plication, which both aim to tighten the joint capsule to alleviate symptoms.
Key Concepts
- •
Classically defined as symptomatic involuntary instability of the glenohumeral joint in two or more directions (anterior and/or posterior, and inferior) with minimal or no causative trauma ( Fig. 28.1 ).
Fig 28.1
Multidirectional instability.
- •
There is no pathognomonic finding indicative of multidirectional instability, and no objective standardized criteria have been established.
- •
The term laxity refers to increased potential of a joint to sublux or dislocate, whereas the term instability refers to laxity that is also symptomatic.
- •
May be classified as congenital, or secondary to a single traumatic event, or recurrent microtrauma.
- •
Congenital cases typically present at an earlier age and are commonly bilateral.
- •
Microtraumatic, overuse injuries are common in the athletic population.
- •
Increased shoulder laxity may be an independent risk factor for instability.
- •
The primary pathologic issue appears to be generalized laxity of the shoulder capsule ( Fig. 28.2 ), characterized by redundant capsular tissue resulting in increased glenohumeral volume.
Fig 28.2
Axial view of shoulder anatomy depicting excessive laxity of posterior capsule.
- •
Other contributing factors include deficient shoulder proprioception, muscle control; biomechanical abnormalities; and irregular bony, labral, or ligamentous anatomy.
- •
It is rare for multidirectional instability to be present in the absence of hyperlaxity; this may be found in an individual with multiple traumatic events leading to instability in multiple directions.
History
- •
The onset of symptoms may or may not be related to an injury or recurrent traumatic events.
- •
Symptoms reported are often vague, including activity-related pain, fatigue, and sense of apprehension. A presenting symptom of actual instability is less common.
- •
Correlation of symptoms with arm position is important to ensure accurate diagnosis. Inferior instability leads to symptoms when carrying objects. Anterior instability symptoms occur with the arm overhead in an abducted and externally rotated position. Posterior instability occurs with the arm in an adducted position and when reaching.
- •
Patients who can voluntarily dislocate can demonstrate instability on their own, in either one or multiple directions; this usually develops before skeletal maturity and is less commonly associated with trauma.
- •
Atraumatic instability may be associated with connective tissue disorders such as Marfan syndrome, osteogenesis imperfecta, benign hypermobility syndrome, or Ehlers-Danlos syndrome.
- •
Symptoms are common in the midportion of shoulder range of motion and may affect activities of daily living. Patients may frequently change their lifestyle by avoiding certain aggravating positions or developing compensatory routines to avoid inciting symptoms.
- •
Associated with repetitive overhead sports, including swimming, gymnastics, and baseball pitching.
- •
Athletes may present with indistinct symptoms leading to decreased performance, lack of confidence in shoulder function, or painful execution of shoulder activity.
Physical Examination
- •
The examination should begin with the contralateral shoulder for comparative laxity and enhanced patient understanding; observe for any asymmetry, abnormal motion, scapular winging, or atrophy.
- •
The presence of multidirectional instability should be evaluated after traumatic dislocation of any nature, when pain has subsided.
- •
Tests for recurrent instability include apprehension and relocation testing (which may be normal or painful; Fig. 28.3A , Video 28.1
), the sulcus sign, the load-and-shift test, the Gagey hyperabduction test (indicative of inferior laxity if passive abduction is >105 degrees or if there is marked >20 degrees difference in hyperabduction of the contralateral shoulder), and the jerk test (a positive test is indicated by sharp pain in the shoulder).
