Research Article: Is MRA an unnecessary expense in the management of a clinically unstable shoulder?

Date Published: June 4, 2012

Publisher: Informa Healthcare

Author(s): Sam C Jonas, Michael J Walton, Partha P Sarangi.

http://doi.org/10.3109/17453674.2012.672090

Abstract

In detection of glenoid labrum pathology, MR arthrography (MRA) has shown sensitivities of 88-100% and specificities of 89-93%. However, our practice suggested that there may be a higher frequency of falsely negative reports. We assessed the accuracy of this costly modality in practice.

We retrospectively reviewed MRA reports of 90 consecutive patients with clinical shoulder instability who had undergone shoulder arthroscopy. All had a history of traumatic anterior shoulder dislocation and had positive anterior apprehension tests. All underwent arthroscopy and stabilization during the same procedure. We compared the findings, using arthroscopic findings as the gold standard in the identification of glenoid labrum pathology.

83 of the 90 patients had glenoid labrum tears at arthroscopy. Only 54 were correctly identified at MRA. All normal glenoid labra were identified at MRA. This gave a sensitivity of 65% and a specificity of 100% in identification of all types of glenoid labrum tear. 74 patients had anterior glenoid labral tears that were detected at an even lower rate of sensitivity (58%).

The sensitivity of MRA in this series was substantially lower than previously published, suggesting that MRA may not be as reliable a diagnostic imaging modality in glenohumeral instability as previously thought. Our findings highlight the importance of an accurate history and clinical examination in the management of glenohumeral instability. The need for MRA may not be as high as is currently believed.

Partial Text

90 consecutive patients (78 men) undergoing arthroscopic anterior stabilization surgery were identified over a 3-year period. Mean age was 27 (15–53) years. All patients had a history of traumatic anterior shoulder dislocation with persistent symptoms of instability. 41 had dislocated twice or less, 47 had dislocated more than twice, and 2 had a history of persistent subluxation. At clinical examination, all patients had a positive anterior apprehension test. They all had a preoperative MRA; this was thought to help in surgical planning.

83 of the 90 patients had a glenoid labrum tear identified at arthroscopy. These were all described as having substantial labral damage, 74 with avulsion of the anteroinferior labrum consistent with a Bankart lesion, 4 with avulsion of the posterior labrum, and 7 with avulsion of the superior anterior to posterior labrum consistent with a SLAP lesion. Of the remaining 7 cases, 2 were described as having a mobile labrum with a degree of anterior capsular laxity but no labral detachment, 3 were described as cases of medial subluxation, and 2 were described as having an essentially normal but anteriorly scuffed labrum. All patients underwent arthroscopic stabilization of the shoulder.

Although several studies have examined the sensitivity of the MR arthrogram in detecting glenoid labral lesions, the majority had small sample size and identified the patient group at the time of arthroscopy—retrospectively evaluating those with proven labral lesions rather than prospectively including all clinically unstable shoulders that were indicated for surgery (Chandnani et al. 1993, Palmer et al. 1994, Waldt et al. 2005).

 

Source:

http://doi.org/10.3109/17453674.2012.672090