Test Your X-Ray IQ: Deep Posterior Shoulder Pain

This is a 30-year-old male with deep posterior shoulder pain, stiffness, and limited ROM following a football injury six months earlier. There are no signs of instability. The patient had limited response to conservative management.

What are the arrows pointing to? From a clinical exam point of view, why are the yellow arrows important?

  • Noted here are a SLAP tear (red arrow) and a large paralabral cyst (yellow arrows)

Dx: Paralabral Cyst

Paralabral Cyst

  • Approximately 5% of the population.
  • Men>Female; 30-40 years old.
  • Believed to be formed following trauma to the capsulolabral complex causing extravasation of synovial fluid.
  • Best identified with MRI.
  • Although sometimes regarded as incidental findings, they are commonly associated nearby labral tear (posterior tears/SLAP are most common) that may not always be seen on MRI.
  • The cysts may cause a neuropathy via mass effect based off location: suprascapular notch (suprascapular and/or infrascapular nerve), spinoglenoid notch (infrascapular nerve), inferior paralabral cysts (axillary nerve).


Suprascapular Nerve

  • Innervates the supraspinatus and infraspinatus muscles
  • Originates from roots C4, C5, C6

Upper Subscapular Nerve

  • Innervates solely the subscapularis muscle
  • Originates from roots C5, C6, C7
  • Subscapularis muscle is tested with the teres major as a group

Lower Subscapular Nerve

  • Innervates the subscapularis and teres major muscles
  • Originates from roots C5, C6, C7
  • Subscapularis and teres major are tested as a group

Putting it together, you can use muscle testing to help figure out where a paralabral cyst might be based on what is weak and what isn’t.


Paralabal Cyst Management

Treatment has traditionally been performed by open surgery.

  • However, more recently, success has been made with arthroscopic cyst excision.
    • 0-8% recurrence rate.
    • 89-100% return to sport.

Plain film radiography can still be a helpful tool in evaluating for suspected soft tissue injuries (such as ACL tears) if you know what you’re looking for. Of course MRI is a much better modality, but x-ray can help guide you with your clinical evaluation.

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