MRI Clinical Value Of Subacromial Impingement Syndrome

Objectives1. To analyze the difference about the imaging criteria(MRI) between Subacromial Impingement Syndrome(SAIS) and asymptomatic shoulder.2. To analyze the imaging features about the SAIS.3. To explore the correlation bewween clinical symptoms and imaging criteria (MRI) in patients with SAIS.Materials and Methods Collected28patients with SAIS in our hospital who underwent MRI from July2011and March2013,including15male patients and13female patients, average age of52years(35-68years).16patients accept arthroscopic examination or treatment. Other12patients who accept injection in subacromial bursa or physiotherapy were discharged with a better health condition. Collected30healthy subjects with gender and age groups statistically no difference, including16male patients and14female patients, average age of48years(25-66years). All of them was underwent MRI. Acromial shape was evaluated on oblique sagittal T1-weighted MRIs; AHD (acromio-humeral distance) was evaluated on oblique coronal T1-weighted MRIs. The Constant score was determined in28patients of SAIS before receiving the treatment.To analyse:①Statistically significant difference in acromial shape and AHD between the case group and control group.②The imaging features about the28patients with SAIS.③Makes a correlation analysis on the Constant score, acromial shape and AHD in case group.Results1. Comparison between case group and control group:①There were statistically significant difference in AHD between the case group [(5.7±1.6) mm]and control group [(8.5±0.9) mm](P＜0.05).②There were type I acromion9cases, type II acromion15cases and type Ⅲ acromion4cases in case group. There are type Ⅰ acromion7cases, type Ⅱ acromion18cases and type Ⅲ acromion5cases in case group. There were no statistical differences between case group and control group about acromial shape(P＞0.05).③Results about MRI:6cases of partial tears,2cases diagnosis of calcified supraspinatus tendonitis(eight of them were confirmed by arthroscopy).1case diagnosis of full-thickness tear(were not confirmed by arthroscopy). Supraspinatus tendonitis had an irregular shape and heterogeneous signal11case.Results about the16arthroscopic:9cases of supraspinatus tendon partial tears,2cases of calcified supraspinatus tendonitis.2. Analysis about the case group:①Patients with an AHD≤7mm [(4.12±1.26)mm]on MRI scored significantly lower than those with an AHD＞7[(9.26±1.36)mm](mean difference=15.5; P＜0.05).②The Constant score was moderately correlated with AHD (r=0.489, P＜0.05) but not with acromial shape.③Acromial shape on MRI and Constant score were not correlated in case group(r=-0.17, P>0.05).④Acromial shape on MRI and AHD were not correlated in case group (r=-0.001, P＞0.05).Conclusions①AHD is a better descriptor of subacromial space narrowing.②Acromial shape is not a good descriptor of subacromial space narrowing.③Acromial shape can be determined using a combination of2oblique sagittal slice positions:directly lateral to the acromioclavicular joint and4mm medial of the lateral acromial edge.④Shoulder MRI is multi-sequence, multi-faceted advantages,with a higher accuracy of the diagnosis of SAIS,which is the preferred method for diagnosis of SAIS.⑤AHD seems to better reflect the clinical status of patients with subacromial impingement than acromial shape.