SHOULDER INSTABILITY AND MAGNETIC RESONANCE IMAGING IN A MILITARY POPULATION

Abstract

Shoulder Instability impacts on the ability of military personnel to fulfil their operational role and maintain sporting competence. Magnetic Resonance Imaging (MRI) and Arthrogram (MRA) are increasingly available as diagnostic adjuncts. We analysed MR reports from personnel undergoing stabilisation, correlating clinical diagnosis with operative findings and reviewed the literature in order to recommend improvements. We report a retrospective, consecutive case note analysis of 106 personnel undergoing open anterior capsulolabral reconstruction (ACLR) by a single surgeon.

Seventy patients had MR (48 MRA, 22 MRI). Commonly reported pathology included Hill Sachs Lesions (41%), Soft tissue (59%) and bony Bankart lesions (16%), capsular laxity (20 %), supraspinatus lesion (20%), ACJ disease (13%) and SLAP tear (12%). The sensitivity of MR for identification of labral lesions was 82% with a specificity of 86%. For bony glenoid lesions, sensitivity was 63% and specificity 94%. Disparity between report and operative findings occurred mainly in standard MRI. Patients with lesions unrelated to instability achieved a pain free functioning shoulder following stabilisation. 100% of patients referred for ACLR with clinical evidence of instability without MR had positive pre-operative and operative correlation with instability. In 5 cases, the original equivocal MRI was repeated by MRA due to clinical suspicion of instability. In all cases the repeat MRA correlated with pre-operative and operative findings of instability. In 5 cases with equivocal clinical findings, MRA provided confirmation of instability. Delay in referral due to scanning and follow up ranged from 0 – 15 weeks.

The diagnosis of those instigating referral is accurate. Reporting of MR is open to variation and has cost implications. MRA performed by a radiologist with a musculoskeletal specialist interest is recommended on an individual basis only and routine use of non-arthrographic studies should be discontinued. This will improve the efficiency of the fast track pathway.