Long Durations of Immobilization in the Rat Result in Enhanced Mechanical Properties of the Healing Supraspinatus Tendon Insertion Site

2006 ◽  
Vol 129 (3) ◽  
pp. 400-404 ◽  
Author(s):  
J. A. Gimbel ◽  
J. P. Van Kleunen ◽  
G. R. Williams ◽  
S. Thomopoulos ◽  
L. J. Soslowsky
Keyword(s):  
Mechanical Properties ◽  
Rotator Cuff ◽  
Bone Healing ◽  
Insertion Site ◽  
Supraspinatus Tendon ◽  
Shoulder Function ◽  
Activity Level ◽  
Rotator Cuff Tears ◽  
Operative Activity ◽  
Positive Effect

Rotator cuff tears frequently occur and can lead to pain and decreased shoulder function. Repair of the torn tendon back to bone is often successful in relieving pain, but failure of the repair commonly occurs. Post-operative activity level is an important treatment component that has received minimal attention for the shoulder, but may have the potential to enhance tendon to bone healing. The objective of this study was to investigate the effect of short and long durations of various activity levels on the healing supraspinatus tendon to bone insertion site. Rotator cuff tears were surgically created in Sprague–Dawley rats by detaching the supraspinatus tendon from its insertion on the humerus and these tears were immediately repaired back to the insertion site. The post-operative activity level was controlled through shoulder immobilization (IM), cage activity (CA), or moderate exercise (EX) for durations of 4 or 16 weeks. The healing tissue was evaluated utilizing biomechanical testing and a quantitative polarized light microscopy method. We found that activity level had no effect on the elastic properties (stiffness, modulus) of the insertion site at four weeks post injury and repair, and a decreased activity level had a positive effect on these properties at 16 weeks (IM>CA=EX). Furthermore, a decreased activity level had the greatest positive effect on these properties over time (IM>CA=EX). The angular deviation of the collagen, a measure of disorganization, was decreased with a decrease in activity level at 4 weeks (IM<CA=EX), but was similar between groups at 16 weeks (IM=CA=EX). It appears from this study that decreasing the activity level by immobilizing the shoulder improves tendon to bone healing, which progresses by first increasing the organization of the collagen and then increasing the mechanical properties. Future studies in this area will investigate the effect of passive motion and remobilization on both tendon to bone healing and shoulder function.

Biceps Tendon Changes Along Its Length, and With Altered Loading, in the Presence of Rotator Cuff Tears in a Rat Model

2010 ◽  
Author(s):  
Cathryn D. Peltz ◽  
Jason E. Hsu ◽  
David L. Glaser ◽  
Louis J. Soslowsky
Keyword(s):  
Mechanical Properties ◽  
Rotator Cuff ◽  
Shoulder Pain ◽  
Rat Model ◽  
Biceps Tendon ◽  
Insertion Site ◽  
Shoulder Function ◽  
Optimal Treatment ◽  
Rotator Cuff Tears ◽  
Tendon Pathology

Biceps tendon pathology is commonly seen in the presence of rotator cuff tears and is often identified as a source of shoulder pain. However, the contribution of the biceps tendon to shoulder function is controversial and therefore the etiology of this pathology and its optimal treatment are unknown. Degeneration, inflammation and altered loading have all been hypothesized as possible mechanisms for biceps tendon pathologies. A previous study began to investigate the contribution of altered loading to these pathologies and showed that 4 weeks of increased loading resulted in decreased mechanical properties along the entire length of the tendon while decreased loading resulted in increased stiffness at the insertion site but decreased properties elsewhere [1]. Building on this study, the objective of the present study was to determine the effects of a longer period of altered loading along the length of the biceps tendon in order to determine where biceps tendon pathology originates following rotator cuff tears in a rat model. We hypothesized that: 1) increased loading would result in decreased mechanical and histological properties and decreased loading would result in increased mechanical properties and organization and 2) modulus and organization would increase along the length of the biceps tendon.

Returning to Overuse Activity Following a Combined Supraspinatus and Infraspinatus Tear Leads to Shoulder Joint Damage

2013 ◽  
Author(s):  
Katherine E. Reuther ◽  
Stephen J. Thomas ◽  
Jennica J. Tucker ◽  
Joseph J. Sarver ◽  
Chancellor F. Gray ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Articular Cartilage ◽  
Rotator Cuff ◽  
Joint Damage ◽  
Shoulder Function ◽  
Force Balance ◽  
Rotator Cuff Tears ◽  
Subscapularis Tendon ◽  
Supraspinatus Tear ◽  
Anterior Posterior

Rotator cuff tendon tears are common conditions which can lead to significant pain and dysfunction. Tears may progress over time from isolated supraspinatus tears to complete ruptures of both the supraspinatus and infraspinatus tendons, disrupting the anterior-posterior force balance provided by the subscapularis anteriorly and infraspinatus posteriorly (commonly referred to as a “force couple”) [1]. This disruption may lead to increased joint instability and result in altered glenohumeral translations which may cause damage to joint structures, such as articular cartilage and adjacent (intact) tendons. This is a particular concern for active individuals who are likely to continue high levels of overuse activity (e.g., laborers, athletes), despite the presence of rotator cuff tears. Previous studies have shown that returning to overuse activity following an isolated supraspinatus tear alters biceps and glenoid articular cartilage properties, but does not alter shoulder function or the adjacent intact subscapularis tendon [2]. However, the consequences associated with disrupting the anterior-posterior force balance (supraspinatus and infraspinatus tears) are not understood. Therefore, the objectives of this study were 1) to investigate the effect of returning to overuse activity following tears of both the supraspinatus and infraspinatus tendons on shoulder function and the remaining intact tendon and glenoid cartilage mechanical properties and 2) to begin to define the biologic mechanisms responsible for these changes. We hypothesized that overuse activity following two-tendon rotator cuff tears would H1) alter shoulder function and H2) lead to damage (indicated by inferior mechanical properties and increased production of degenerative factors, extracellular matrix, and cartilage markers) in the remaining intact tendons (including the biceps and upper and lower subscapularis tendons) and in the anterior-superior region of the glenoid articular cartilage as a result of the excessive joint loading due to overuse following the supraspinatus-infraspinatus tear.

The Effect of Return to Overuse Activity After a Supraspinatus Tear on Joint Function and Biceps Mechanical Properties in a Rat Model

2011 ◽  
Author(s):  
Stephen J. Thomas ◽  
Joseph J. Sarver ◽  
Jennica Tucker ◽  
Katherine Reuther ◽  
Lena Edelstein ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Insertion Site ◽  
Supraspinatus Tendon ◽  
Shoulder Function ◽  
Shoulder Injuries ◽  
Tendon Tear ◽  
Model Studies ◽  
Cuff Tear ◽  
Supraspinatus Tear ◽  
Long Head

Rotator cuff tendon tears are one of the most common shoulder injuries and are most prevalent in populations performing repetitive overhead activities [1]. In addition, long head of the biceps (LHB) tendon injuries occur secondary to cuff tears and may or may not lead to functional deficits [2]. Previous animal model studies have found that in the presence of a cuff tear, the biceps has decreased mechanical properties at 8 weeks [3]. Such studies, however, did not examine the effect of repetitive overhead activity on biceps properties and shoulder function in the presence of a cuff tear. Therefore, the objective of this study was to evaluate the effect of returning to overuse activity after a supraspinatus tendon tear on shoulder function and biceps structural and mechanical properties. We hypothesized that overuse activity following a supraspinatus tendon tear would not alter shoulder function, when compared to cage activity, but would decrease biceps structural and mechanical properties, particularly at the insertion site.

scholarly journals Biceps Detachment Preserves Joint Function in a Chronic Massive Rotator Cuff Tear Rat Model

2018 ◽  
Vol 46 (14) ◽  
pp. 3486-3494 ◽  
Author(s):  
Mengcun Chen ◽  
Snehal S. Shetye ◽  
Julianne Huegel ◽  
Corinne N. Riggin ◽  
Daniel J. Gittings ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Shoulder Joint ◽  
Shoulder Function ◽  
Rotator Cuff Tears ◽  
Subscapularis Tendon ◽  
Joint Function ◽  
Massive Rotator Cuff Tears ◽  
Sham Surgery ◽  
Biceps Tenotomy

Background: Lesions of the long head of the biceps tendon are often associated with massive rotator cuff tears (MRCTs), and biceps tenotomy is frequently performed for pain relief and functional reservation. However, the efficacy and safety of biceps tenotomy regarding the effects on the surrounding tissues in chronic MRCT are unclear. Hypothesis: Biceps tenotomy would result in improved mechanical and histological properties of the intact subscapularis tendon and improved in vivo shoulder function while not compromising glenoid cartilage properties. Study Design: Controlled laboratory study. Methods: Right supraspinatus and infraspinatus tendons were detached in 25 male Sprague-Dawley rats, followed by 4 weeks of cage activity to create a chronic MRCT condition. Animals were randomly divided into 2 groups and received either biceps tenotomy (n = 11) or sham surgery (n = 14) and were sacrificed 4 weeks thereafter. Forelimb gait and ground-reaction forces were recorded 1 day before the tendon detachment (baseline), 1 day before the surgical intervention (biceps tenotomy or sham), and 3, 7, 10, 14, 21, and 28 days after the intervention to assess in vivo shoulder joint function. The subscapularis tendon and glenoid cartilage were randomly allocated for mechanical testing or histologic assessment after the sacrifice. Results: Compared with sham surgery, biceps tenotomy partially restored the in vivo shoulder joint function, with several gait and ground-reaction force parameters returning closer to preinjury baseline values at 4 weeks. With biceps tenotomy, mechanical properties of the subscapularis tendons were improved, while mechanical properties and histological Mankin scores of the glenoid cartilage were not diminished when compared with the sham group. Conclusion: Biceps tenotomy in the presence of chronic MRCT partially preserves overall shoulder function and potentially restores subscapularis tendon health without causing detrimental effects to joint cartilage. This laboratory study adds to the growing literature regarding the protective effects of biceps tenotomy on the shoulder joint in a chronic MRCT model. Clinical Relevance: This study provides important basic science evidence supporting the use of biceps tenotomy in patients with massive rotator cuff tears.

Evaluating the Outcomes of Rotator Cuff Repairs With Polytetrafluoroethylene Patches for Massive and Irreparable Rotator Cuff Tears With a Minimum 2-Year Follow-up

2018 ◽  
Vol 46 (13) ◽  
pp. 3155-3164 ◽  
Author(s):  
Vasanth Seker ◽  
Lisa Hackett ◽  
Patrick H. Lam ◽  
George A.C. Murrell
Keyword(s):  
Rotator Cuff ◽  
Range Of Motion ◽  
External Rotation ◽  
Case Series ◽  
Shoulder Function ◽  
Rotator Cuff Tears ◽  
Level Of Evidence ◽  
Irreparable Tear ◽  
Pain At Rest

Background: Massive and irreparable rotator cuff tears are difficult to manage surgically. One technique is to use a synthetic polytetrafluoroethylene (PTFE) patch to bridge the tear. However, there is little information regarding the outcomes of this procedure. Purpose: To determine the ≥2-year outcomes of patients for whom synthetic patches were used as tendon substitutes to bridge irreparable rotator cuff defects. Study Design: Case series; Level of evidence, 4. Methods: This retrospective cohort study used prospectively collected data. Patients included those with a synthetic patch inserted as an interposition graft for large and/or irreparable rotator cuff tears with a minimum 2-year follow-up. Standardized assessment of shoulder pain, function, range of motion, and strength was performed preoperatively, at 6 and 12 weeks, and at 6 months and ≥2 years. Radiograph and ultrasound were performed preoperatively, at 6 months, and ≥2 years. Results: At a mean of 36 months, 58 of 68 eligible patients were followed up, and 53 of 58 (90%) patches remained in situ. Three patches failed at the patch-tendon interface, while 1 patient (2 shoulders/patches) went on to have reverse total shoulder replacements. Patient-ranked shoulder stiffness ( P < .001), frequency of pain with activity and sleep ( P < .0001), level of pain at rest and overhead ( P < .0001), and overall shoulder function improved from bad to very good ( P < .0001) by 6 months. Supraspinatus (mean ± SEM: 29 ± 16 N to 42 ± 13 N) and external rotation (39 ± 13 N to 59 ± 15 N) strength were the most notable increases at the ≥2-year follow-up ( P < .0001). Passive range of motion also improved by 49% to 67%; forward flexion, from 131° to 171°; abduction, from 117° to 161°; external rotation, from 38° to 55°; and internal rotation, from L3 to T10 ( P < .0001) preoperatively to ≥2 years. The most improvement in passive range of motion occurred between 12 months and ≥2 years. The mean (SD) Constant-Murley score was 90 (12), while the American Shoulder and Elbow Surgeons score was 95 (8). Conclusion: At 36 months postoperatively, patients who had synthetic patches used as tendon substitutes to bridge irreparable rotator cuff defects reported less pain and greater overall shoulder function as compared with preoperative assessments. They demonstrated improved range of passive motion and improved strength. The data support the hypothesis that the technique of using a synthetic PTFE patch to bridge a large and/or irreparable tear has good construct integrity and improves patient and clinical outcomes.

scholarly journals Icariin Promotes Tendon-Bone Healing during Repair of Rotator Cuff Tears: A Biomechanical and Histological Study

2016 ◽  
Vol 17 (11) ◽  
pp. 1780 ◽  
Author(s):  
Chenyi Ye ◽  
Wei Zhang ◽  
Shengdong Wang ◽  
Shuai Jiang ◽  
Yuanbin Yu ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Bone Healing ◽  
Histological Study ◽  
Rotator Cuff Tears

Freeze-dried chitosan-platelet-rich plasma implants improve supraspinatus tendon attachment in a transosseous rotator cuff repair model in the rabbit

2018 ◽  
Vol 33 (6) ◽  
pp. 792-807 ◽  
Author(s):  
Gabrielle Deprés-Tremblay ◽  
Anik Chevrier ◽  
Martyn Snow ◽  
Scott Rodeo ◽  
Michael D Buschmann
Keyword(s):  
Rotator Cuff ◽  
Rotator Cuff Repair ◽  
Platelet Rich Plasma ◽  
Rabbit Model ◽  
Supraspinatus Tendon ◽  
Rotator Cuff Tears ◽  
Polymorphonuclear Cells ◽  
Post Surgery ◽  
Freeze Dried ◽  
Cuff Repair

Rotator cuff tears result in shoulder pain, stiffness, weakness and loss of motion. After surgical repair, high failure rates have been reported based on objective imaging and it is recognized that current surgical treatments need improvement. The aim of the study was to assess whether implants composed of freeze-dried chitosan (CS) solubilized in autologous platelet-rich plasma (PRP) can improve rotator cuff repair in a rabbit model. Complete tears were created bilaterally in the supraspinatus tendon of New Zealand White rabbits ( n = 4 in a pilot feasibility study followed by n = 13 in a larger efficacy study), which were repaired using transosseous suturing. On the treated side, CS-PRP implants were injected into the transosseous tunnels and the tendon itself, and healing was assessed histologically at time points ranging from one day to two months post-surgery. CS-PRP implants were resident within transosseous tunnels and adhered to tendon surfaces at one day post-surgery and induced recruitment of polymorphonuclear cells from 1 to 14 days. CS-PRP implants improved attachment of the supraspinatus tendon to the humeral head through increased bone remodelling at the greater tuberosity and also inhibited heterotopic ossification of the supraspinatus tendon at two months. In addition, the implants did not induce any detectable deleterious effects. This preliminary study provides the first evidence that CS-PRP implants could be effective in improving rotator cuff tendon attachment in a small animal model.

scholarly journals Supraspinatus-to-Glenoid Contact Occurs During Standardized Overhead Reaching Motion

2021 ◽  
Vol 9 (10) ◽  
pp. 232596712110369
Author(s):  
Gaura Saini ◽  
Rebekah L. Lawrence ◽  
Justin L. Staker ◽  
Jonathan P. Braman ◽  
Paula M. Ludewig
Keyword(s):  
Rotator Cuff ◽  
Pearson Correlation ◽  
Supraspinatus Tendon ◽  
Contact Angles ◽  
Magnetic Resonance Images ◽  
Rotator Cuff Tears ◽  
Internal Impingement ◽  
Glenoid Morphology ◽  
Minimum Distances ◽  
The Relationship

Background: Rotator cuff tears may result from repeated mechanical deformation of the cuff tendons, and internal impingement of the supraspinatus tendon against the glenoid is one such proposed mechanism of deformation. Purpose: To (1) describe the changing proximity of the supraspinatus tendon to the glenoid during a simulated overhead reaching task and (2) determine the relationship between scapular morphology and this proximity. Additionally, the patterns of supraspinatus-to-glenoid proximity were compared with previously described patterns of supraspinatus-to-coracoacromial arch proximity. Study Design: Descriptive laboratory study. Methods: Shoulder models were created from magnetic resonance images of 20 participants. Standardized kinematics were imposed on the models to simulate functional reaching, and the minimum distances between the supraspinatus tendon and the glenoid and the supraspinatus footprint and the glenoid were calculated every 5° between 0° and 150° of humerothoracic elevation. The angle at which contact between the supraspinatus and the glenoid occurred was documented. Additionally, the relationship between glenoid morphology (version and inclination) and the contact angle was evaluated. Descriptive statistics were calculated for the minimum distances, and glenoid morphology was assessed using Pearson correlation coefficients and simple linear regressions. Results: The minimum distances between the tendon and the glenoid and between the footprint and the glenoid decreased as elevation increased. Contact between the tendon and the glenoid occurred in all participant models at a mean elevation of 123° ± 10°. Contact between the footprint and the glenoid occurred in 13 of 20 models at a mean of 139° ± 10°. Less glenoid retroversion was associated with lower tendon-to-glenoid contact angles ( r = –0.76; R 2 = 0.58; P < .01). Conclusion: This study found that the supraspinatus tendon progressively approximated the glenoid during simulated overhead reaching. Additionally, all participant models eventually made contact with the glenoid by 150° of humerothoracic elevation, although anatomic factors influenced the precise angle at which contact occurred. Clinical Relevance: Contact between the supraspinatus and the glenoid may occur frequently within the range of elevation required for overhead activities. Therefore, internal impingement may be a prevalent mechanism for rotator cuff deformation that could contribute to cuff pathology.

scholarly journals Pregnancy and Lactation Impair Subchondral Bone Leading to Reduced Rat Supraspinatus Tendon-to-Bone Insertion Site Failure Properties

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Ashley K. Fung ◽  
Snehal S. Shetye ◽  
Yihan Li ◽  
Yilu Zhou ◽  
X. Sherry Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bone Loss ◽  
Subchondral Bone ◽  
Bone Mineralization ◽  
Insertion Site ◽  
Supraspinatus Tendon ◽  
Bone Microstructure ◽  
Female Rats ◽  
Pregnancy And Lactation ◽  
Failure Properties

Abstract Pregnant women experience weight gain, gait changes, and biochemical fluctuations that impair joint function and alter the maternal skeleton. Hormonal changes increase pelvic ligament laxity in preparation for childbirth and affect peripheral joint laxity. Calcium demands also rise during pregnancy and lactation, resulting in reduced bone mineral density (BMD) and maternal bone loss. Altered tendon properties and bone loss during pregnancy and lactation may impact tendon insertion sites, such as rotator cuff tendons where insertion site ruptures are common. However, the effects of pregnancy and lactation at the tendon-to-bone interface have not been investigated. Therefore, the objective of this study was to evaluate supraspinatus tendon mechanical properties and insertion site microstructure during pregnancy, lactation, and postweaning recovery in female rats. We hypothesized that pregnancy and lactation would compromise supraspinatus tendon mechanical properties and subchondral bone microstructure. Female rats were divided into virgin, pregnancy, lactation, and recovery groups, and supraspinatus tendons were mechanically evaluated. Surprisingly, tendon mechanics was unaffected by pregnancy and lactation. However, tendon modulus decreased two-weeks postweaning. Additionally, tendons failed by bony avulsion at the insertion site, and the lactation group exhibited reduced failure properties corresponding to decreased subchondral bone mineralization. Lactation also resulted in dramatic bone loss at the epiphysis, but trabecular bone microarchitecture recovered postweaning. In conclusion, lactation following pregnancy impaired trabecular bone microstructure and subchondral bone mineralization, leading to reduced supraspinatus tendon-to-bone insertion site failure properties. These findings will contribute toward understanding the pathogenesis of tendon-to-bone disorders.

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