Shoulder Anatomy

The shoulder is a ball (humeral head) and socket (glenoid) joint. It is a large, round ball and a shallow, small socket. It resembles a golf ball on a tee. There are a number of structures that keep the ball centered on the socket while still allowing the tremendous range of motion that the shoulder enjoys.

Static stabilizers of the shoulder include the labrum and the capsule (lining) of the joint.

Dynamic stabilizers of the shoulder include the rotator cuff and periscapular muscles.

Top Down View of the Shoulder

Dislocating Shoulder Pathology

To allow increased range of motion of the shoulder, the ball and socket cannot have inherent bony stability.  The absence of inherent bony stability means that that the ball is at risk of coming out of the socket. The ball can slip out the front of the socket (an anterior shoulder dislocation) or it can slip out the back of the socket (a posterior shoulder dislocation). The vast majority of shoulder dislocations are anterior. They are often the result of trauma; falls, accidents, and sporting injuries.

An isolated shoulder dislocations puts a patient at risk of having recurrent shoulder instability.  Recurrent shoulder instability can mean anything from feeling that the shoulder is loose to feeling the shoulder dislocate without significant trauma. The younger the patient is who sustains a dislocation, the higher the risk of recurrent instability. This recurrent instability is because of the damage that happens to the important stabilizing structures of the shoulder.

Top Down View of a Dislocated Shoulder

Dislocating Shoulder Treatment

Treatment options for shoulder instability depend on multiple factors including the patients age and activity level, number of dislocation events and patient limitations. There are surgical and nonsurgical options available. Call Dr. Gibbs today for an appointment in Salt Lake City, Park City or Tooele to find out your options for shoulder instability.


Shoulder Dislocation Information FAQs

What structures are injured when a shoulder dislocates?

  • The typical shoulder dislocation is a traumatic anterior dislocation.  When the shoulder dislocates, the anterior inferior labrum often tears. This is referred to a Bankart lesion. The labrum is a cartilaginous gasket that goes around the bony socket. It’s main job is to deepen the socket and stabilize the shoulder
  • Other injuries include:
    • Hill-Sach Lesion: bony indentation on the humeral head
    • HAGL Lesion: humeral avulsion of the glenohumeral ligament/ligament tear
    • Bony Bankhart: avulsion fracture of the glenoid

Do I need surgery after a shoulder dislocation?

  • This is a complex questions with multiple factors involved.  The answer requires a discussion with your orthopaedic surgeon about the risks, benefits and alternatives to surgery.  A younger age predicts a higher recurrence risk. Contact athletes have a higher recurrence risk.  More severe bony and cartilaginous damage predicts a higher recurrence risk.