Camilo Enrique Jaimes MD, Abstract Co-Author: Nothing to Disclose

Rafael Mauricio Jimenez MD, Abstract Co-Author: Nothing to Disclose

Grant Garcia, Presenter: Nothing to Disclose

Min Jung Park MD, Abstract Co-Author: Nothing to Disclose

Laura Wiegand MD, Abstract Co-Author: Nothing to Disclose

Russell Huffman MD, MPH, Abstract Co-Author: Nothing to Disclose

Nancy Marie Major MD, Abstract Co-Author: Nothing to Disclose

To determine if a measureable difference in posterior shoulder capsule (PSC) thickness is present on MRI in patients with and without GIRD.

A case control study was conducted. A priori power analysis with an alpha of 0.05 for samples with unequal variance revealed power of 0.81. Cases were overhead athletes with GIRD (20 degree loss of internal rotation compared to the non-throwing arm). For every case we included 2 controls, which were gender, age (within 5 years), and dominant extremity matched. 8 cases (median age: 20.6; range:16.8-50.7 yrs) and 16 controls (Median age:24; range: 18.9-49.8yrs) with MRI were used. Relevant clinical and demographic data were also assessed. Two MSK trained radiologists blinded to these data reviewed the MRIs on two separate occasions. The capsule was measured on axial images near to its insertion in the glenoid labrum, at the 7-8 o'clock position. A single measurement (mm) was taken at the point where each reader thought it was thickest. Foci of abnormal signal intensity in the articular surface were excluded as they could represent synovitis or debris. Mann-Whitney median testing was used to determine differences between cases and controls and interclass correlation coefficients were calculated for inter- and intra-observer reliability

The cases (7 male, 1 female) were actively engaged in sports as follows: baseball/softball (n=4), tennis (n=2) hockey (n=1) and swimming (n=1). The controls (14 males , 2 females) had arthroscopically confirmed SLAP tears and no GIRD in their dominant shoulder. The computed median PSC thickness was 2.3 (range: 2.0-3.3) in GIRD subjects and 1.4 (range: 1.0-2.7) in controls. The PSC was consistently thicker in subjects with GIRD than in controls, and the difference was significant for the computed (p<.01) and individual measurements (p<.04). Agreement between observers was excellent (ICC=0.78). Intra-observer variability was also high (reader1: ICC=0.87 and reader 2: 0.58).

In patients with GIRD the posterior inferior capsule is significantly thicker using standardized MRI measurements than in similar patients without GIRD. This may aid in identification and treatment of these athletes.

Glenohumeral internal rotation deficit (GIRD) is related to glenoid labrum tears and altered shoulder kinematics in overhead throwing. MRI criteria for the diagnosis of GIRD remain unclear.

Jaimes, C, Jimenez, R, Garcia, G, Park, M, Wiegand, L, Huffman, R, Major, N, MR Assessment of the Posterior Shoulder Capsule in Patients with GIRD: Comparison to Controls.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11016315.html