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MRI EVALUATION OF TERES MINOR HYPERTROPHY AND FUNCTIONAL STATUS IN PATIENTS WITH MASSIVE ROTATOR CUFF TEARS Ryan Cassilly BSE*, Anuli Mkparu BS‡, Lauren Fabian MD*, Katherine Vadasdi MD*, Thomas Gardner MCE*, Christopher Ahmad MD*, William N. Levine MD* * Center for Shoulder, Elbow, and Sports Medicine ‡ Duke University School of Medicine Department of Orthopaedic Surgery Durham, NC Columbia University, NY, NY BACKGROUND METHODS (continued) RESULTS (continued) Rotator cuff tears (RCT) are one of the most common conditions • Patient Data Collected • Exclusion Criteria affecting the shoulder, but the decline in shoulder function in patients – Active Range of Motion – Acute/Traumatic RCT with RCT is variable and not well understood. While some patients – Simple Shoulder Test (SST) – Teres Minor Tears with massive RCT present with inability to raise the arm, others – Standard Shoulder MRI – Subscapularis Insufficiency maintain mobility. Preservation of teres minor volume has been reported in the literature in the setting of massive RCT (1-4). One Computer Modeling – Rotator Cuff Analysis (Figures 3 & 4) theory that accounts for maintaining active motion is related to axial • Sagittal shoulder MRI “Y view” (6) - Using Mimics Software, plane balance of the anterior (subscapularis) and posterior measured the cross-sectional area (CSA) of Teres Minor, (infraspinatus, teres minor) rotator cuff musculature (Figure 1) (5). Supraspinatus, Infraspinatus, Subscapularis muscles • Calculated ratio of mean CSA of Teres Minor : Subscapularis Figure 5: Difference in forward elevation Figure 6: Results of Simple Shoulder Test between the three experimental groups patient questionnaire and Teres Minor : Total Rotator Cuff Statistical Analysis: 1-way ANOVA with Student-Newman-Keuls multiple comparisons test Supraspinatus Infraspinatus Figure 1: Shoulder joint indicating axial plane balance of forces (red arrows) of anterior and posterior Figure 7: Teres minor CSA as percentage of total Figure 8: Teres minor CSA as percentage of cuff musculature. (Dotted line on Anterior View represents axial cut for Superior View) rotator cuff CSA subscapularis CSA HYPOTHESIS CONCLUSIONS In the setting of massive RCT, preservation of axial plane balance Subscapularis •In patients with massive RCT, relative teres minor hypertrophy helps maintain Teres Minor active range of motion for forward elevation and external rotation. requires maintenance or hypertrophy of the teres minor muscle. Figure 3: Proton-density MRI of the parasagittal Figure 4: Rotator cuff muscles highlighted on Y view of the rotator cuff muscles on scapular Y View. view with Mimics software to calculate CSA •Patients with preservation or relative hypertrophy of teres minor have a better METHODS subjective assessment of function than those without as measured by the SST. RESULTS Retrospective Chart Review: Patients separated into three groups: •The current study provides a better understanding of cuff musculature and axial •Patients in the Tear-FE group maintained active range of motion plane balance, and may lead to improved therapeutic interventions and pre- 1)Patients with RCT on MRI able to forward (forward elevation, internal rotation, external rotation) similar to operative planning in patients with massive rotator cuff tears. elevate (Tear – FE; N=20) the No Tear group, and were significantly better when compared to the Tear-Poor FE group (Figure 5). •A prospective study that includes 3D computer reconstruction of cuff musculature, 2)Patients with RCT on MRI unable to Isoforce strength testing and ASES scores to further quantify the relationship forward elevate (Tear – Poor FE; N=20) •Simple Shoulder Test scores (higher score indicates better between teres minor hypertrophy and overall function is currently underway. subjective function) for patients in the Tear-FE group were similar 3)Control patients without MRI evidence to patients with No Tear, and higher than patients with Tear-Poor REFERENCES of RCT (No Tear; N=20) (Figure 2) 180 FE (Figure 6). 1.Goutallier, D., J. M. Postel, et al. (1994), Clin Orthop Relat Res(304): 78-83. 2.Walch, G., A. Boulahia, et al. (1998). J Bone Joint Surg Br 80(4): 624-8. Figure 2: 180º of Active Forward Elevation •Patients with in the Tear-FE group had a higher teres minor/total 3.Sato, T., E. Itoi, et al. (1996), J Shoulder Elbow Surg 5: 127. 4.Shimizu, T., E. Itoi, et al. (2000), J Shoulder Elbow Surg 9: 459. rotator cuff CSA ratio and a higher teres minor/subscapularis 5.Newman, Kinesiology of the Musculoskeletal System, 2002. CSA ratio than both other groups (Figures 7 & 8). 6.Lehtinen, J. T., et al. (2003), Acta Orthop Scand 74(6): 722-9.
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