Joint Reduction, Shoulder Dislocation, Inferior 

The muscular, ligamentous, and bony anatomy of the shoulder (glenohumeral joint) gives it the most extensive range of motion of any joint in the human body. This anatomy also makes the glenohumeral joint the most unstable, and consequently, the most commonly dislocated joint in the body.

Most glenohumeral dislocations (90-95%) occur anteriorly (where the humeral head is displaced anteriorly in relation to the glenoid), as the muscular and ligamentous support is least robust anterior to the humeral head. Posterior dislocations occur far less commonly because of the significant muscular and bony support afforded by the rotator cuff and scapula.

Inferior glenohumeral dislocations, also known as luxatio erecta, are extremely uncommon, accounting for less than 1% of all shoulder dislocations.^{[1, 2]} Most inferior dislocations result from forceful hyperabduction of the shoulder. Hyperabduction of the glenohumeral joint initially results in impingement of the humeral head against the acromion. The leverage caused by this impingement in the setting of forceful hyperabduction ultimately drives the humeral head downward, causing it to disrupt the inferior portion of the glenohumeral capsule and dislocate. Forceful, direct axial loading of an abducted shoulder can also result in luxatio erecta.^{[3, 4]}

Clinical features

Patients with inferior glenohumeral dislocations present with the affected arm "locked" in abduction of varying degrees.^[5] Classically, the affected arm is hyperabducted, with the elbow flexed and forearm resting on top of or behind the head (see image below).

Often, the dislocated humeral head is palpable along the lateral border of the chest wall. The patient is generally in a substantial amount of pain, particularly when attempts are made to move the injured extremity.

Radiographic features

Anteroposterior and trans-scapular lateral or "Y" views of the shoulder should be obtained to ensure a multiplanar view of the glenohumeral joint. These radiographs should be taken both before and after reduction. In inferior humeral head dislocations, the humeral shaft is parallel to the spine of the scapula, with the humeral head lying inferior to the glenoid (without making contact with the glenoid).^[6]

• Orthopedic consultation should be obtained, if immediately available, prior to attempted reduction of inferior glenohumeral dislocations.
• The presence of brachial plexus injury necessitates prompt, atraumatic reduction, with the goal being smooth, uncomplicated, successful reduction on the first attempt.

• Standard closed reduction of an inferior glenohumeral dislocation is contraindicated in the setting of humeral neck or shaft fractures or in the setting of suspected major vascular injury. The presence of these associated injuries necessitates surgical intervention/open reduction.
• Though not a contraindication, per se, a "buttonhole deformity" (where the humeral head becomes trapped in a tear of the inferior capsule) often precludes successful closed reduction, necessitating open reduction.

• The key to successful reduction is adequate analgesia and amelioration of muscle spasm. Glenohumeral joint injection, which is a useful anesthetic technique in the setting of most humeral head dislocations, can be difficult, if not impossible, in the setting of inferior dislocations, where hyperabduction of the arm alters the position of landmarks used to target needle placement. The use of systemic analgesics, muscle relaxants, or procedural sedation is often necessary to facilitate reduction of inferior dislocations.
• The degree of anesthesia should be determined on a case-by-case basis, taking into account patient-related factors (eg, age, level of anxiety and cooperation, time since injury, history of previous shoulder dislocations, history of adverse reactions to systemic analgesics/muscle relaxants/sedatives). In general, younger and more anxious patients, those with no previous history of shoulder dislocations, and those whose injury occurred a significant amount of time prior to presentation are more likely to require more significant degrees of analgesia, muscle relaxation, or procedural sedation. Other factors (eg, operator comfort and experience with the reduction technique, availability of resources, time, ancillary support) should also be taken into consideration when choosing an anesthesia method.

For axial traction-countertraction

• One assistant
• A lengthwise-folded or rolled-up bed sheet

• The patient should be placed supine on a sturdy immobile surface (eg, a wheel-locked gurney).

Neurovascular examination

• A neurovascular examination should be performed prior to attempted reduction to screen for the presence of nerve or vascular injury, and it should be repeated after reduction to document any change. Injuries to the brachial plexus are common in the setting of inferior glenohumeral dislocations.

  • The sensory function of the axillary nerve can be tested by assessing pinprick sensation over the "regimental patch" area of the affected arm (see image below). The "regimental badge" area. Examine pin-prick sensation to this area to assess axillary nerve sensory function.
  • Radial nerve motor function of the affected arm can be assessed by examining the strength of wrist extension.
  • Distal pulses and capillary refill should also be examined before and after reduction.

Reduction methods

Two commonly used methods exist to reduce the inferiorly dislocated humeral head: the traditional axial (inline) traction method and a more recently described two-step reduction method.

• Axial (inline) traction method

  • To perform the axial traction reduction method, the operator stands on the affected side at the head of the patient, who is in a supine position.^[7]
  • Apply axial traction inline with the abducted arm. To facilitate this technique, an assistant can apply parallel countertraction by using a sheet wrapped diagonally over the affected shoulder. While applying axial traction, increasing the degree of abduction (if possible) and applying cephalad pressure to the displaced humeral head can aid in reduction. See image below. The axial traction/countertraction method. Axial traction is applied to the arm with parallel countertraction using a sheet wrapped over the shoulder. Increasing the degree of abduction (if possible) and applying cephalad pressure to the displaced humeral head (star) can aid in reduction.
  • After successful reduction of the humeral head, the arm should be fully adducted against the chest wall and supinated and immobilized in that position. See image below. After reduction of the inferior dislocation, adduct, supinate, and immobilize the arm for postreduction radiography.
• Two-step reduction method

  • In 2006, Nho and colleagues reported a two-step method for the reduction of luxatio erecta.^[8] In this method, the inferior dislocation is converted to an anterior dislocation (step one), which is subsequently reduced (step two).
  • To perform this technique, the operator again stands on the affected side near the patient's head.
  • Place one hand (the one nearest to the patient) on the lateral aspect of the mid-humerus; place the other on the medial condyle.
  • Step one, part one (see image below): "Push" anteriorly with the hand on the mid-humerus and "pull" posteriorly with the hand on the medial condyle. This motion brings the humeral head to a position anterior to the glenoid (that is, the humeral head is now anteriorly dislocated). Step one, part one. Push anteroinferiorly on the mid humerus with hand A while "pulling" posteriorly on the medial condyle with hand B.
  • Step one, part two (see image below): Adduct the arm, and move the hand on the medial condyle to grasp the wrist. Step one, part two. After conversion of the inferior to an anterior dislocation, adduct the arm and grasp the patient's wrist.
  • Step two (see image below): While holding the arm in adduction against the chest wall, externally rotate the shoulder by "pulling" on the wrist. Step two. Hand A holds the patient's arm in abduction while hand B externally rotates the arm to reduce the now anteriorly dislocated humeral head.
  • After successful reduction, the arm, again, should be adducted, supinated, and immobilized.

• The key to successful reduction is adequate pain control and amelioration of muscle spasm. The combination of systemic analgesics/muscle relaxants/sedatives and smooth atraumatic technique helps the operator achieve these goals and avoid complications.
• Most neurovascular injuries are caused by the dislocation itself, but they can be induced or exacerbated by attempted reduction. A conscientious neurovascular examination, both before and after reduction, is important to document the presence and alteration of these injuries.

• An estimated 50-60% of patients with luxatio erecta have associated brachial plexus injury.^[9] Assessment and documentation of the presence of neurologic deficits should be made prior to and after reduction.^[10]
• Injury to the axillary artery, including arterial thrombosis, has also been reported.^[11]
• Rotator cuff tears occur very often with inferior dislocations.^{[12, 13]}
• Ligamentous and connective tissue injuries include disruption of the glenohumeral ligament, the inferior glenoid capsule, or both.
• Associated bony injuries include fractures of the glenoid rim, greater tuberosity, acromion, clavicle, and coracoid process.^[14] These injuries can be induced or exacerbated by attempted reduction; however, they more often occur as a result of the dislocation itself.