Effect of anterior supraspinatus tendon partial-thickness tears on infraspinatus tendon strain through a range of joint rotation angles

Supraspinatus tendon tears are common and often propagate into larger tears that include the infraspinatus tendon, resulting in loss of function and increased pain. Previously, we showed that the supraspinatus and infraspinatus tendons mechanically interact through a range of rotation angles, potentially shielding the torn supraspinatus tendon from further injury while subjecting the infraspinatus tendon to increased risk of injury. Surgical repair of torn supraspinatus tendons is common, yet the effect of the repair on the infraspinatus tendon is unknown. Since we have established a relationship between strain in the supraspinatus and infraspinatus tendons the success of a supraspinatus tendon repair depends on its effect on the loading environment in the infraspinatus tendon. More specifically, the effect of transosseous supraspinatus tendon repair in comparison to one that utilizes suture anchors, as is commonly done with arthroscopic repairs, on this interaction through these joint positions will be evaluated. We hypothesize that at all joint positions evaluated, both repairs will restore the interaction between the two tendons. For both repairs, (1) increasing supraspinatus tendon load will increase infraspinatus tendon strain and (2) altering the rotation angle from internal to external will increase strain in the infraspinatus tendon. Strains were measured in the infraspinatus tendon insertion through a range of joint rotation angles and supraspinatus tendon loads, for the intact, transosseous, and suture anchor repaired supraspinatus tendons. Images corresponding to specific supraspinatus tendon loads were isolated for the infraspinatus tendon insertion for analysis. The effect of supraspinatus tendon repair on infraspinatus tendon strain differed with joint position. Altering the joint rotation did not change strain in the infraspinatus tendon for any supraspinatus tendon condition. Finally, increasing supraspinatus tendon load resulted in an increase in average maximum and decrease in average minimum principal strain in the infraspinatus tendon. There is a significant difference in infraspinatus tendon strain between the intact and arthroscopically (but not transosseous) repaired supraspinatus tendons that increases with greater loads. Results suggest that at low loads neither supraspinatus tendon repair technique subjects the infraspinatus tendon to potentially detrimental loads; however, at high loads, transosseous repairs may be more advantageous over arthroscopic repairs for the health of the infraspinatus tendon. Results emphasize the importance of limiting loading of the repaired supraspinatus tendon and that at low loads, both repair techniques restore the interaction to the intact supraspinatus tendon case.

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Impact of partial-thickness tears on supraspinatus tendon strain based on a finite element analysis

Computer Methods in Biomechanics & Biomedical Engineering ◽

10.1080/10255842.2014.931514 ◽

2014 ◽

Vol 17 (sup1) ◽

pp. 118-119 ◽

Cited By ~ 4

Author(s):

C. Engelhardt ◽

A. Farron ◽

F. Becce ◽

D. Pioletti ◽

A. Terrier

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Supraspinatus Tendon ◽

Element Analysis ◽

Partial Thickness ◽

Tendon Strain

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The Influence of Partial and Full Thickness Tears on Infraspinatus Tendon Strain Patterns

Journal of Biomechanical Engineering ◽

10.1115/1.4026643 ◽

2014 ◽

Vol 136 (5) ◽

Cited By ~ 9

Author(s):

Kayt E. Frisch ◽

David Marcu ◽

Geoffrey S. Baer ◽

Darryl G. Thelen ◽

Ray Vanderby

Keyword(s):

Rotator Cuff ◽

Axial Loading ◽

Surface Markers ◽

Full Thickness ◽

Strain Measurements ◽

Tissue Strain ◽

Partial Thickness ◽

Strain Change ◽

Tendon Strain ◽

Infraspinatus Tendon

Tears on the bursal and articular sides of the rotator cuff tendons are known to behave differently and strain is thought to play a role in this difference. This study investigates the effect of tear location on the changes in three strain measurements (grip-to-grip, insertion, and mid-substance tissue) in a sheep infraspinatus tendon model during axial loading. We introduced a 14 mm wide defect near the insertion from either the articular or bursal side of the tendon to three depths (3 mm, 7 mm & full) progressively. For each condition, tendons were sinusoidally stretched (4% at 0.5 Hz) while insertion and mid-substance strains were tracked with surface markers. For a fixed load, grip-to-grip strain increased significantly compared to intact for both cuts. Insertion strain increased significantly for the bursal-side defect immediately but not for the articular-side until the 66% cut. Mid-substance tissue strain showed no significant change for partial thickness articular-side defects and a significant decrease for bursal-side defects after the 66% cut. All full thickness cuts exhibited negligible mid-substance tissue strain change. Our results suggest that the tendon strain patterns are more sensitive to defects on the bursal side, and that partial thickness tears tend to induce localized strain concentrations in regions adjacent to the damaged tissue.

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Interaction between the Supraspinatus and Infraspinatus Tendons: Effect of Anterior Supraspinatus Tendon Full-Thickness Tears on Infraspinatus Tendon Strain

The American Journal of Sports Medicine ◽

10.1177/0363546509334222 ◽

2009 ◽

Vol 37 (9) ◽

pp. 1831-1839 ◽

Cited By ~ 23

Author(s):

Nelly Andarawis-Puri ◽

Eric T. Ricchetti ◽

Louis J. Soslowsky

Keyword(s):

Glenohumeral Joint ◽

Supraspinatus Tendon ◽

Principal Strain ◽

Rotator Cuff Tears ◽

Full Thickness ◽

Tendon Tear ◽

Load Bearing ◽

Tendon Strain ◽

Tear Size ◽

Infraspinatus Tendon

Background Rotator cuff tears are common and not well-understood shoulder problems. Structural and mechanical inhomogeneity of the supraspinatus tendon complicates accurate prediction of risk of tear propagation and may affect appropriate clinical treatment. Hypothesis We propose that interactions between the supraspinatus and infraspinatus tendons are critical to load bearing at the glenohumeral joint and warrant investigation. Study Design Controlled laboratory study. Methods Principal strains in the infraspinatus tendon of cadaveric human shoulders were evaluated with increasing anterior full-thickness supraspinatus tendon tear sizes and loading to evaluate whether a mechanical interaction between the supraspinatus and infraspinatus tendons exists. A constant nominal load was attached to the infraspinatus throughout all experimental conditions. Results Increasing supraspinatus tendon tear width from intact and 33% to 66% and increasing supraspinatus tendon load caused an increase in maximum and a decrease in minimum principal strain in the infraspinatus tendon. Increasing the supraspinatus tendon tear size from intact to 33% of the width had no significant effect on infraspinatus tendon strain. Conclusion Supraspinatus and infraspinatus tendons mechanically interact. The observed significant increase in maximum and decrease in minimum principal strain was concurrent in both the infraspinatus and supraspinatus tendons. Clinical Relevance Changes in infraspinatus tendon strain associated with increases in supraspinatus tendon tear size and loading may shield a torn supraspinatus tendon from further injury or may have an effect on the load-bearing capacity of the infraspinatus tendon. Results also imply that the effect of a small tear that does not compromise the confluent region between the supraspinatus and infraspinatus tendon may be localized, eliminating its effect on infraspinatus tendon strain.

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