MRI EVALUATION OF TERES MINOR HYPERTROPHY AND FUNCTIONAL STATUS IN

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MRI EVALUATION OF TERES MINOR HYPERTROPHY AND FUNCTIONAL STATUS IN Powered By Docstoc
					       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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