A 23-year-old man comes to the emergency department after injuring his right shoulder during a basketball game. He was trying to block a shot when his abducted and externally rotated arm was forced backward by an opposing player. The patient immediately felt excruciating pain and fell to the ground holding his right arm. He has no other medical conditions and has never had a similar injury. On examination, there is gross asymmetry of the right shoulder compared to the left, and the right arm is held in slight abduction and external rotation. Distal pulses are full. Plain film x-ray of the right shoulder is shown below. If left untreated, which of the following is the most likely complication of this patient's injury?

Question

A 23-year-old man comes to the emergency department after injuring his right shoulder during a basketball game.  He was trying to block a shot when his abducted and externally rotated arm was forced backward by an opposing player.  The patient immediately felt excruciating pain and fell to the ground holding his right arm.  He has no other medical conditions and has never had a similar injury.  On examination, there is gross asymmetry of the right shoulder compared to the left, and the right arm is held in slight abduction and external rotation.  Distal pulses are full.  Plain film x-ray of the right shoulder is shown below.  If left untreated, which of the following is the most likely complication of this patient's injury?

Quizplus · Accepted Answer

11ec25c8_d82c_6e84_bc81_a990bfb4958b_MD0003_00 This patient has an anterior dislocation of the humeral head. The glenohumeral joint is the most commonly dislocated joint in the body due to the shallow articulation between the humeral head and the glenoid fossa of the scapula. The shoulder may dislocate anteriorly, inferiorly, or posteriorly, but anterior dislocations are by far the most common. anterior dislocation Anterior dislocations are typically caused by a blow to an externally rotated and abducted arm. When the head of the humerus is displaced anteriorly, there is flattening of the deltoid prominence, protrusion of the acromion, and anterior axillary fullness (due to the humeral head's displacement into this location); the arm is abducted and externally rotated. flattening of the deltoid prominence The axillary nerve is the nerve most commonly injured by anterior shoulder dislocations. It innervates the teres minor and deltoid (weakened shoulder abduction) muscles. It also provides sensory innervation to the skin overlying the lateral shoulder. Other potential complications of shoulder dislocation include fractures of the proximal humerus, labral injuries, and tears to the rotator cuff system. axillary nerve (Choice A) The extensor muscles of the wrist and digits are primarily innervated by branches of the radial nerve, which also provides sensory innervation to the posterior arm, forearm, and dorsolateral hand. The radial nerve is frequently injured in humeral midshaft fractures and from use of improperly fitted crutches. radial nerve (Choice B) The biceps reflex is mediated by C5 and C6 spinal nerves, with muscular innervation via the musculocutaneous nerve (lateral cord of the brachial plexus). Traumatic injuries to this system are uncommon but can occasionally be seen in high-velocity motor vehicle collisions. musculocutaneous nerve (Choice C) The ulnar nerve may be injured by fracture of the medial epicondyle of the humerus or, more distally, by deep lacerations of the anterior wrist. Symptoms include "claw hand" resulting from paralysis of the intrinsic muscles of the hand as well as sensory loss involving the medial hand. ulnar nerve (Choice E) The long thoracic nerve innervates the serratus anterior muscle. Deep lacerations to the axillary region and axillary lymphadenectomy are common causes of long thoracic nerve injury. Damage causes scapular winging. scapular winging Educational objective: Acute shoulder pain after forceful abduction and external rotation at the glenohumeral joint suggests an anterior shoulder dislocation, which may cause injury to the axillary nerve. The axillary nerve innervates the teres minor and deltoid muscles, and injury can result in weakened shoulder abduction and decreased sensation over the lateral shoulder. References: Axillary nerve injury associated with glenohumeral dislocation (http://www.ncbi.nlm.nih.gov/pubmed/29657847)

A 23-Year-Old Man Comes to the Emergency Department After Injuring