Miyamoto H1,2, Iida N1, Taniguchi T1, Fujimiya M3, Watanabe K4
1Sapporo Medical University, Graduate School of Health Science, Sapporo, Japan, 2Sukegawa Orthopaedic Clinic, Department of Rehabilitation, Sapporo, Japan, 3Sapporo Medical University, Department of Anatomy Ⅱ, Sapporo, Japan, 4Sapporo Medical University, Department of Physical Therapy II, Sapporo, Japan
Background: There are numerous treatment strategies and opinions regarding physical therapy for shoulder joint dysfunction. A thorough understanding of anatomy and biomechanical characteristics of this complex joint is necessary for safe and effective shoulder physical therapy. We quantitatively reproduced the isometric contraction of the supraspinatus, and found that the strain measured of supraspinatus tendon surface layer increases significantly with decreasing scapular elevation angle. However, there are no reports on strain of the deep layer of the supraspinatus tendon as related to scapular plane elevation.
Purpose: To specifically measured the strain of the supraspinatus tendon deep layer during tensile forces applied to the supraspinatus tendon.
Methods: Seven fresh-frozen shoulder specimens from seven cadavers were utilized. The shoulder was fixed at each angle ranging from -10 to 30 degrees on the scapular plane, and tensile load on the shoulder joint was increased from 0 to 120N. Strain of the deep layer of the supraspinatus tendon and tensile force of the supraspinatus tendon were measured.
Results: Significant increases in the strain measured of the deep layer of the supraspinatus tendon were observed with increases in the tensile force on the supraspinatus tendon (p 0.05) for isometric elevation of 30 and 20 degrees. However the strain was substainally less for angles of 10° or less of gleno-humeral elevation (p 0.03).
Conclusion(s): We report that the strain measured on the surface of the supraspinatus tendon positioned in scapular plane elevation from -10 to 0 degrees was significantly larger than that measured from 10 to 30 degrees, based on measurements made using a strain gauge. However when measuring deep layer strain, we observed the strain of the supraspinatus tendon in scapular plane elevation from 30 to 20 degrees was significantly larger than that from 10 to -10 degrees. We also observed that strain of the deep layer of the supraspinatus tendon was less than that of the surface layer at all angles.
Implications: Our data from this research demonstrated that isometric contraction of the supraspinatus during elevation results in strain of the deep layer of the supraspinatus tendon. The deep layer of the supraspinatus tendon is more elongated during elevation from 30 and 20 degrees, but at 10 degrees or less of scapular plane elevation elongation was reduced. During isometric elevation at 30 and 20 degrees, there may be an increased risk of overstress particularily in those cases where degeneration is present.. Regarding isometric exercise, it may be necessary to carefully consider the loads applied to the rotator cuff considering implications that strains of the surface and deep layer differ both in magnitude as well as for scapular positioning.
Keywords: Supraspinatus tendon, tendon strain, cadaver
Funding acknowledgements: The authors thank Fujimiya M.
Purpose: To specifically measured the strain of the supraspinatus tendon deep layer during tensile forces applied to the supraspinatus tendon.
Methods: Seven fresh-frozen shoulder specimens from seven cadavers were utilized. The shoulder was fixed at each angle ranging from -10 to 30 degrees on the scapular plane, and tensile load on the shoulder joint was increased from 0 to 120N. Strain of the deep layer of the supraspinatus tendon and tensile force of the supraspinatus tendon were measured.
Results: Significant increases in the strain measured of the deep layer of the supraspinatus tendon were observed with increases in the tensile force on the supraspinatus tendon (p 0.05) for isometric elevation of 30 and 20 degrees. However the strain was substainally less for angles of 10° or less of gleno-humeral elevation (p 0.03).
Conclusion(s): We report that the strain measured on the surface of the supraspinatus tendon positioned in scapular plane elevation from -10 to 0 degrees was significantly larger than that measured from 10 to 30 degrees, based on measurements made using a strain gauge. However when measuring deep layer strain, we observed the strain of the supraspinatus tendon in scapular plane elevation from 30 to 20 degrees was significantly larger than that from 10 to -10 degrees. We also observed that strain of the deep layer of the supraspinatus tendon was less than that of the surface layer at all angles.
Implications: Our data from this research demonstrated that isometric contraction of the supraspinatus during elevation results in strain of the deep layer of the supraspinatus tendon. The deep layer of the supraspinatus tendon is more elongated during elevation from 30 and 20 degrees, but at 10 degrees or less of scapular plane elevation elongation was reduced. During isometric elevation at 30 and 20 degrees, there may be an increased risk of overstress particularily in those cases where degeneration is present.. Regarding isometric exercise, it may be necessary to carefully consider the loads applied to the rotator cuff considering implications that strains of the surface and deep layer differ both in magnitude as well as for scapular positioning.
Keywords: Supraspinatus tendon, tendon strain, cadaver
Funding acknowledgements: The authors thank Fujimiya M.
Topic: Musculoskeletal: upper limb; Musculoskeletal; Orthopaedics
Ethics approval required: Yes
Institution: Sapporo Medical University
Ethics committee: the institutional research ethics committee
Ethics number: 29-2-30
All authors, affiliations and abstracts have been published as submitted.
