Traumatic Anterior Shoulder Instability - Symptoms and Management

Introduction:

Traumatic anterior shoulder instability is a clinical condition characterized by a weak or dislocated shoulder due to trauma, also known as traumatic unilateral dislocations (TUBS) with bankart lesions requiring surgery. As the name indicates, this injury occurs due to exerting an anterior force on the shoulder. Traumatic anterior shoulder instability is a defect between the glenohumeral joint (shoulder joint) and humerus (bone of the arm), where the glenohumeral joint is seen popping out of the socket without being in contact with the joint fossa. The shoulder is the most unstable part of the body; shoulder instability is a severe condition seen mostly in young adults.

What Is the Occurrence Rate of Traumatic Unilateral Shoulder Instability?

The occurrence of shoulder dislocation is about 1.7 percent in the normal population, in which anterior dislocation due to trauma is the most commonly occurring condition seen in more than 90 percent of the cases, with a recurrence rate of 49 percent. The incidence is seen in young adults between the ages of 18 to 30 years, where their first-time dislocation occurs 72 percent within the age of 22 and only 27 percent from 23 to 30 years. The incidence of ankle instability in males is around 72 percent more than in females.

How Is the Structure of a Shoulder Joint Formed?

A shoulder joint (glenohumeral joint) is a ball and socket joint made up of the scapula (flat shoulder blade) and humerus (bone of the arm). The glenohumeral joint is a very complex movable multidirectional ball and socket joint allowing coordination of movement in all directions with 360-degree hand rotation. Our shoulder joints are sternoclavicular, acromioclavicular, glenohumeral, and scapulothoracic.

How Does Traumatic Anterior Shoulder Instability Occur?

Many factors contribute to shoulder instability; it is very crucial to differentiate laxity from true instability. The incidence of ankle instability occurs as primary dislocations followed by recurrence; however, traumatic shoulder instability is a pathology occurring due to the path of the force exerted on the shoulder anteriorly when the shoulder is closed and rotated externally.

What Are the Clinical Symptoms of Traumatic Anterior Shoulder Instability?

The patient gives a history of repeated traumatic events, shoulder pain, and feeling of unstable shoulder. Loose shoulders with increased arm movements are seen as bankart lesions (an injury occurring after shoulder dislocation). It is then seen as a lesion in the anterior portion of the glenoid labrum (thick cartilage of the shoulder socket), and they are caused by recurrent shoulder luxation (loosening).

What Are the Injuries Associated With Traumatic Anterior Shoulder Instability?

The injuries associated with traumatic shoulder instability are cartilage injuries, bankart lesions, humeral avulsion of the shoulder head, nerve injuries, increased movement of the shoulder joint, and lesions in the labrum of the capsule.

What Are the Factors Causing Traumatic Anterior Shoulder Instability?

The factors causing traumatic shoulder instability are falling with an abducted arm, collisions, and motorcycle accidents. It is commonly seen in sportsmen and in military persons who are involved in strenuous activities.

How Is a Traumatic Anterior Shoulder Instability Evaluated?

Traumatic anterior shoulder instability is evaluated by doing both physical examinations and imaging. The evaluations done are:

1) Physical Examination: The physical examination is performed on the affected individual by the medical professional. It is done in five stages, depending on the load and shoulder shift:

• Grade 0 - This is the normal translation of the humeral head and the glenoid fossa.

• Grade 1 - Humeral head translation up to the rim of glenoid fossa without dislocation.

• Grade 2 - Humeral head translation beyond the glenoid rim with a spontaneous reduction in glenoid dislocation.

• Grade 3 - Humeral head translation beyond the glenoid rim without nonspontaneous glenoid dislocation.

The patient is tested with an arm extended, lying in a supine (flat back facing the bed) position.

2) Imaging Methods:

• Radiographs: X-rays are two-dimensional imaging methods used to evaluate the shoulder and axillary region to detect signs of weakening.

• Computed Tomography (CT): It is a three-dimensional imaging technique to detect dislocation from all possible views.

• Magnetic Resonance Imaging (MRI): It is an imaging method used to detect defects in the tissues attached to the shoulder.

• Magnetic Resonance Arthrogram (MRA): This type of MRI scan is an imaging technique where a fluorescent dye is injected into the system to study the structure of the joints.

How Is Traumatic Anterior Shoulder Instability Managed?

In case of anterior instability occurring for the first time, the condition is treated with a non-surgical procedure where the dislocated joint is repositioned and immobilized. The treatment is given to restore functional movement and muscle strength.

1) Non-surgical Management:

Shoulder instability is treated non-surgically by immediately reducing the dislocation, immobilizing it to the desired location, and managing it with painkillers and physiotherapy. Non-surgical management is done to treat primary dislocations seen in young adults and athletes between 14 to 30 years.

• Reduction: It is done by simple traction and counter-traction methods used to reduce the fracture.

• Immobilization: Immobilization is done to hold the dislocated segment in place to give it some rest from movements, which aids in healing.

• Physical Therapy: Physical therapy or exercises are given to strengthen the shoulder and to prevent recurrence.

2) Surgical Management:

The surgical management of traumatic anterior shoulder instability depends on the number of occurrences. Surgical management is considered during the primary episode, soft tissue reconstruction, and bone or cartilage replacement.

• Arthroscopic Bankart Repair: It is an ideal method of treatment to treat primary dislocations, although it is used for both primary and secondary dislocations. It stabilizes shoulder dislocations with instability in the inferior labrum without bony defects.

• Open Bankart Repair: It is indicated in cases with 20 to 25 percent bone loss. It is also a corrective surgery performed after recurrence following arthroscopic repair. The bankart lesion is fixed using screws or sutures to restore the bone defect.

• Latarjet Or Bristow Procedure: It is one of the most preferred methods to treat shoulder instability. It is commonly used in treating recurrent traumatic instability. In this method, the coracoid process (part of the coracoid bone) is transferred to the glenoid rim to provide additional support to balance the bony defects.

• Autograft: It is also called arthroscopic distal clavicular autograft (DCA). This method is done by placing a graft in the glenoid head taken from the clavicle (chest bone). Also, replacing the bone from the Iliac crest (hip bone) is a preferred option which shows good stability post-surgery.

• Tendon Transfers: Combined transfer of tendon is done and placed near the worn-out glomerulus (bony socket) by minimally invasive arthroscopy procedures.

What Are the Complications of Traumatic Anterior Shoulder Instability?

One of the major complications of traumatic anterior shoulder instability is the avulsion of the anterior portion of the glenoid joint from the glenoid fossa and the recurrence of dislocation. Also, shoulder pain, nerve injuries during trauma, stiffness of the joint, infections, graft rejection or breakdown, and pain due to wear and tear of the cartilage occur.

What Are the Differential Diagnosis of Traumatic Anterior Shoulder Instability?

• Posterior instability.

• A frozen shoulder is one which is stuck and has reduced and limited movements.

• A rotator cuff tear is a tear in the tissue which attaches the muscles to bone.

• Dead arm syndrome is the presence of pain or discomfort on the upper arm experienced during throwing movements.

• Internal impengemnet.

Conclusion:

Anterior shoulder instability due to trauma is a commonly occurring shoulder instability seen in young adults, athletes, or military persons. Although the recurrence rate is still evident, the prognosis of this condition is fair and can improve with appropriate surgical treatment with regular physical exercises and follow-up.