Deciphering acute shoulder trauma with normal initial X-ray: Contributions of ultrasonography and MRI.

INTRODUCTION: Shoulder trauma with normal radiographs is a frequent emergency presentation. The predominance of pain makes clinical examination unreliable, and complementary imaging is often needed for diagnosis. The aim of the present study was to assess the contribution of ultrasonography (US) and magnetic resonance imaging (MRI) in deciphering such trauma. The study hypothesis was that MRI can confirm most diagnoses and reveal occult lesions.

METHODS: 48 patients with a median age of 33 years (IQR, 22-48.75), admitted to the Emergency Department between February and September 2016, were prospectively included. All had normal X-ray and underwent emergency and deferred emergency (D+7-10) clinical examination, and US and MRI at D+7-14. The same examinations were repeated to establish diagnosis and initiate treatment. MRI was considered as gold-standard for definite diagnosis.

RESULTS: Diagnoses comprised: 14 shoulder contusions; 13 rotator cuff tears; 8 acromioclavicular sprains; 6 fractures: 3 greater tuberosity, 2 humeral head, 1 lateral quarter of the clavicle; 3 subluxations or anterior dislocations with spontaneous reduction; 1 posterior dislocation with spontaneous reduction; 1 case of resorption of calcification in the pectoralis major tendon; 1 case of coracobrachialis strain; and 1 partial pectoralis major detachment. Concordance with final diagnosis was 42% (20/48) on initial clinical examination and 52% (25/48) on reassessment. On US, concordance was 71% (34/48), with 82% positive predictive value for cuff tear and 0% for instability. MRI was contributive in all cases, revealing 48 abnormal signals in 41 patients, thus establishing 48 diagnoses.

CONCLUSION: Except in precise diagnostic situations such as rotator cuff tear, US is not a contributive examination, completely overlooking shoulder instability and bone contusion. MRI should play an increasing role in deciphering these traumas.

LEVEL OF EVIDENCE: II; prospective cohort study.