Age / Sex : 56 / M

Chief complaint : Lt. shoulder pain after bicycle accident, 2-month ago

What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : Hye Jung Choo, Inje University Busan Paik Hospital

Discussion

Answer:  Novel lesion of infraspinatus (myotendinous junctional tear of infraspinatus tendon)

Findings: Isolated increased signal intensity at the infraspinatus muscle with discontinuity of the myotendinous junction of the oblique head of infraspinatus tendon and partial tear of the long head of biceps brachii tendon and subscarpularis tendon

Differential Diagnosis:

Discussion: Novel lesion of infraspinatus

• Tear at or adjacent to MT – not tendon insertion


• Edema of the infraspinatus muscle in the initial phase


• Prominent muscle atrophy & fatty degeneration over time


• Indirect trauma (muscle contracture, resistance…)


• Women > Men


• 49 years (younger than isolated injury of SST)


• Common in patients with local cortisol injection/needling


• Difficult to detect on arthroscopy, even if lesion is prospectively identified on MRI

References:

Isolated lesion of the infraspinatus at the myotendinous junction: a new lesion) J Radiol 2006;87:1875-82

A novel lesion of the infraspinatus characterized by musculotendinous disruption, edema, and late fatty infiltration J Shoulder Elbow Surg 2008;17:546-553