Acute Versus Delayed Magnetic Resonance Imaging and Associated Abnormalities in Traumatic Anterior Shoulder...

The delayed management of patients with shoulder instability may increase the prevalence and severity of concomitant intra-articular shoulder injuries resulting from persistent subluxations and dislocations.

Patients with a longer delay from the initial dislocation event to undergoing magnetic resonance imaging (MRI) or magnetic resonance arthrography will demonstrate more subluxations or dislocations and a greater amount of intra-articular shoulder damage.

Cohort study; Level of evidence, 3.

We performed a retrospective review of 89 patients from a single institution with clinically and radiographically confirmed primary traumatic anterior shoulder dislocations. Patients were divided into 2 groups: those undergoing MRI less than 6 months (n = 44; LT6) or greater than 6 months (n = 45; GT6) from the initial dislocation event. The MRI assessment included evaluation of soft tissue injuries, including the labrum, capsule, rotator cuff, and cartilage damage severity along with bone loss.

The delayed MRI group (GT6) demonstrated a greater degree of intra-articular abnormalities compared to the early MRI group (LT6). A greater percentage of superior labral anterior-posterior (SLAP) tears (58% vs 34%, respectively) and cartilage damage (73% vs 27%, respectively) was present in the GT6 group compared to the LT6 group. Cartilage damage was 18% mild, 7% moderate, and 2% severe for the LT6 group as compared to 38% mild, 31% moderate, and 4% severe for the GT6 group. Additionally, more recurrent shoulder dislocations were seen in the GT6 group (n = 6) compared to the LT6 group (n = 2). In the LT6 group, there were more rotator cuff tears (50% vs 24%, respectively) and capsular tears (25% vs 9%, respectively) than the GT6 group. There was no difference in anterior glenoid bone loss, glenoid version, or humeral head subluxation between the 2 groups.

Patients who undergo MRI greater than 6 months from the time of primary or initial shoulder dislocation had significantly more recurrent shoulder instability events and demonstrated a greater incidence and severity of intra-articular abnormalities, including SLAP tears, posterior labral tears, and anterior glenoid cartilage damage.