Any dislocation where there was a prior to any reduction attempt
You should order a repeat set of shoulder xrays if someone else has tried and failed a reduction attempt. You always want to make sure to identify any fracture that they might have produced before your attempt. (This goes for any joint dislocation).
The Shoulder Series
What should come in the 3 view shoulder xray series?
AP view
Grashey
Axillary view
Systematic Approach to Reading Shoulder Xrays
Systematic approach to review shoulder xrays, review this section if you haven’t yet:
Look at the whole AP, Grashey, and Axillary images and see what immediately stands out to you
Pull up the Axillary View and check to see if the shoulder is dislocated or not
In each image, review each structure systematically working from proximal to distal
Outline clavicle cortices
AC joint, Acromion
Scapula, coracoid
Glenoid, glenohumeral joint and where the humeral head sits on the glenoid
Outline the humeral head, greater and lesser tuberosity, and humeral shaft
Review all soft tissue from proximal to distal
Axillary
This is the most important view to assess whether a shoulder is dislocated or not.
A scapular-Y view is not sufficient to rule out a dislocation.
This xray is taken with the arm abducted by 20-30 degrees and the beam aimed at the armpit
Use the coracoid (Outlined in red) to orient yourself to what is anterior. In all shoulder images from xrays to MRIs, the coracoid is the most easily found anterior structure in the shoulder
Notice how the humeral head is centered on the glenoid (termed the glenohumeral joint), like a golf ball (humerual head) on a golf tee (glenoid). This means the shoulder is reduced (where it should be).
What if the shoulder doesn’t stay reduced on your reduction attempt? Sometimes you have to hold it reduced while you obtain to the axillary view to prove it can be reduced. (If there is a major cuff tear or severe bankart/bony bankart, the shoulder may not stay reduced in any position)
Great for scapula series and assessing angle of scapular wing, coracoid and base of acromion fractures.
You can see dislocations on this view, but it can be difficult to rule out dislocations. It is not as sensitive as an axillary view to rule out dislocations
Light Bulb Sign
Light bulb sign = Posterior shoulder dislocation
Posterior dislocations are easily missed because they can look like they are not dislocated on the AP view. This is what a posterior dislocation looks like on the AP view, hence the term, “light bulb sign”.
Neers Classification for Proximal Humerus Fractures
This classification is useful for thinking about and making plans for treating proximal humerus fractures
Always differentiate high vs. low energy injuries in your mind, as well as the functionality and activity level of your patient
Know what attaches to each part of the fracture and what motion is the result
Humeral head articular segment is not reduced with glenoid
Can include two part, three part or four part fractures
Sometimes fracture dislocations can just look like a simple shoulder dislocation, you must look for nondisplaced fracture lines prior to any reduction attempts. You can make the problem worse if the fractures become displaced after the reduction attempt.
Fracture dislocation example (can’t tell how many “parts” without the other views, this is at least a 2-part, shaft and separate proximal humerus piece likely separated at the surgical neck):
Surgical Indications for Proximal Humerus Fractures
Greater tuberosity displaced >5mm
2, 3, and 4-part fractures in younger patients (higher energy fracture mechanism)
Head-splitting fractures in younger patients
Fracture dislocation
Open fractures
Reverse total shoulders are used when there is a high risk for AVN in more comminution such as 3 to 4 part fractures in the elderly. Reverse total shoulders can function without an intact rotator cuff (relies on a functional deltoid) where shoulder hemi-arthroplasties need an intact rotator cuff.
