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1.  Clinical and Radiological Evaluation after Arthroscopic Rotator Cuff Repair Using Suture Bridge Technique 
Clinics in Orthopedic Surgery  2013;5(4):306-313.
Background
We retrospectively assessed the clinical outcomes and investigated risk factors influencing retear after arthroscopic suture bridge repair technique for rotator cuff tear through clinical assessment and magnetic resonance arthrography (MRA).
Methods
Between January 2008 and April 2011, sixty-two cases of full-thickness rotator cuff tear were treated with arthroscopic suture bridge repair technique and follow-up MRA were performed. The mean age was 56.1 years, and mean follow-up period was 27.4 months. Clinical and functional outcomes were assessed using range of motion, Korean shoulder score, Constant score, and UCLA score. Radiological outcome was evaluated with preoperative and follow-up MRA. Potential predictive factors that influenced cuff retear, such as age, gender, geometric patterns of tear, size of cuff tear, acromioplasty, fatty degeneration, atrophy of cuff muscle, retraction of supraspinatus, involved muscles of cuff and osteolysis around the suture anchor were evaluated.
Results
Thirty cases (48.4%) revealed retear on MRA. In univariable analysis, retear was significantly more frequent in over 60 years age group (62.5%) than under 60 years age group (39.5%; p = 0.043), and also in medium to large-sized tear than small-sized tear (p = 0.003). There was significant difference in geometric pattern of tear (p = 0.015). In multivariable analysis, only age (p = 0.036) and size of tear (p = 0.030) revealed a significant difference. The mean active range of motion for forward flexion, abduction, external rotation at the side and internal rotation at the side were significantly improved at follow-up (p < 0.05). The mean Korean shoulder score, Constant score, and UCLA score increased significantly at follow-up (p < 0.01). The range of motion, Korean shoulder score, Constant score, and UCLA score did not differ significantly between the groups with retear and intact repairs (p > 0.05). The locations of retear were insertion site in 10 cases (33.3%) and musculotendinous junction in 20 cases (66.7%; p = 0.006).
Conclusions
Suture bridge repair technique for rotator cuff tear showed improved clinical results. Cuff integrity after repair did not affect clinical results. Age of over 60 years and size of cuff tear larger than 1 cm were factors influencing rotator cuff retear after arthroscopic suture bridge repair technique.
doi:10.4055/cios.2013.5.4.306
PMCID: PMC3858092  PMID: 24340151
Rotator cuff tear; Suture bridge technique; Retear; Magnetic resonance arthrography
2.  Long-term outcome and structural integrity following open repair of massive rotator cuff tears 
Background:
Surgical repair of massive rotator cuff tears is associated with less favorable clinical results and a higher retear rate than repair of smaller tears, which is attributed to irreversible degenerative changes of the musculotendinous unit.
Materials and Methods:
During the study period, 25 consecutive patients with a massive rotator cuff tear were enrolled in the study and the tears were repaired with an open suture anchor repair technique. Preoperative and postoperative clinical assessments were performed with the Constant score, the simple shoulder test (SST) and a pain visual analog scale (VAS). At the final follow-up, rotator cuff strength measurement was evaluated and assessment of tendon integrity, fatty degeneration and muscle atrophy was done using a standardized magnetic resonance imaging protocol.
Results:
The mean follow-up period was 70 months. The mean constant score improved significantly from 42.3 to 73.1 points at the final follow-up. Both the SST and the pain VAS improved significantly from 5.3 to 10.2 points and from 6.3 to 2.1, respectively. The overall retear rate was 44% after 6 years. Patients with an intact repair had better shoulder scores and rotator cuff strength than those with a failed repair, and also the retear group showed a significant clinical improvement (each P<0.05). Rotator cuff strength in all testing positions was significantly reduced for the operated compared to the contralateral shoulder. Muscle atrophy and fatty infiltration of the rotator cuff muscles did not recover in intact repairs, whereas both parameters progressed in retorn cuffs.
Conclusions:
Open repair of massive rotator tears achieved high patient satisfaction and a good clinical outcome at the long-term follow-up despite a high retear rate. Also, shoulders with retorn cuffs were significantly improved by the procedure. Muscle atrophy and fatty muscle degeneration could not be reversed after repair and rotator cuff strength still did not equal that of the contralateral shoulder after 6 years.
Level of evidence:
Level IV
doi:10.4103/0973-6042.94304
PMCID: PMC3326749  PMID: 22518073
Magnetic resonance imaging; massive rotator cuff tear; open rotator cuff repair; rotator cuff strength; subscapularis function
3.  Does an Arthroscopic Suture Bridge Technique Maintain Repair Integrity?: A Serial Evaluation by Ultrasonography 
Biomechanical studies suggest a suture bridge technique enhances rotator cuff tendon footprint contact area, holding strength, and mean contact pressure. Based on these studies, we asked whether (1) the suture bridge technique would provide a high rate of cuff integrity after surgery, (2) the status of the repaired cuff would change with time, (3) preoperative factors could predict postoperative cuff integrity, and (4) patients with retears had less favorable pain, functional scores, range of motion (ROM), and muscle strength compared with those with intact repairs. We prospectively followed 78 patients with arthroscopic repairs in whom we used the suture bridge technique. The integrity of the rotator cuff repair was determined using ultrasonographic evaluation at 4.5 and 12 months after surgery. Ultrasonography revealed intact cuffs in 91% at 4.5 months postoperatively, all of which were maintained at the 12-month followup. Failure rates were 17.6% (three of 17) for massive tears, 11.1% (two of 18) for large tears, 6.3% (two of 32) for medium tears, and no failures for small tears. Preoperative fatty degeneration of the supraspinatus muscle was a strong predictor of cuff integrity. We found no correlation between the integrity and clinical outcomes except for a temporary decrease of abduction strength at 6 months. Arthroscopic repair using suture bridge technique can achieve a low retear rate in shoulders treated for rotator cuff tears, but the occurrence of retear did not influence the outcome.
Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-009-0990-8
PMCID: PMC2865619  PMID: 19629607
4.  Is the Supraspinatus Muscle Atrophy Truly Irreversible after Surgical Repair of Rotator Cuff Tears? 
Clinics in Orthopedic Surgery  2013;5(1):55-65.
Background
Atrophy of rotator cuff muscles has been considered an irreversible phenomenon. The purpose of this study is to evaluate whether atrophy is truly irreversible after rotator cuff repair.
Methods
We measured supraspinatus muscle atrophy of 191 patients with full-thickness rotator cuff tears on preoperative magnetic resonance imaging and postoperative multidetector computed tomography images, taken at least 1 year after operation. The occupation ratio was calculated using Photoshop CS3 software. We compared the change between pre- and postoperative occupation ratios after modifying the preoperative occupation ratio. In addition, possible relationship between various clinical factors and the change of atrophy, and between the change of atrophy and cuff integrity after surgical repair were evaluated.
Results
The mean occupation ratio was significantly increased postoperatively from 0.44 ± 0.17 to 0.52 ± 0.17 (p < 0.001). Among 191 patients, 81 (42.4%) showed improvement of atrophy (more than a 10% increase in occupation ratio) and 33 (17.3%) worsening (more than a 10% decrease). Various clinical factors such as age tear size, or initial degree of atrophy did not affect the change of atrophy. However, the change of atrophy was related to repair integrity: cuff healing failure rate of 48.5% (16 of 33) in worsened atrophy; and 22.2% (18 of 81) in improved atrophy (p = 0.007).
Conclusions
The supraspinatus muscle atrophy as measured by occupation ratio could be improved postoperatively in case of successful cuff repair.
doi:10.4055/cios.2013.5.1.55
PMCID: PMC3582872  PMID: 23467404
Atrophy; Occupation ratio; Postoperative change; Rotator cuff
5.  Advantages of Arthroscopic Transosseous Suture Repair of the Rotator Cuff without the Use of Anchors 
Background
Although arthroscopic anchor suturing is commonly used for rotator cuff repair and achieves good results, certain shortcomings remain, including difficulty with reoperation in cases of retear, anchor dislodgement, knot impingement, and financial cost. In 2005, we developed an anchorless technique for arthroscopic transosseous suture rotator cuff repair.
Description of Technique
After acromioplasty and adequate footprint decortication, three K-wires with perforated tips are inserted through the inferior margin of the greater tuberosity into the medial edge of the footprint using a customized aiming guide. After pulling the rotator cuff stump laterally with a grasper, three K-wires are threaded through the rotator cuff and skin. Thereafter, five Number 2 polyester sutures are passed through three bone tunnels using the perforated tips of the K-wires. The surgery is completed by inserting two pairs of mattress sutures and three bridging sutures.
Methods
We investigated the retear rate (based on MR images at least 1 year after the procedure), total score on the UCLA Shoulder Rating Scale, axillary nerve preservation, and issues concerning bone tunnels with this technique in 384 shoulders in 380 patients (174 women [175 shoulders] and 206 men [209 shoulders]). Minimum followup was 2 years (mean, 3.3 years; range, 2–7 years). Complete followup was achieved by 380 patients (384 of 475 [81%] of the procedures performed during the period in question). The remaining 91 patients (91 shoulders) do not have 1-year postsurgical MR images, 2-year UCLA evaluation or intraoperative tear measurement, or they have previous fracture, retear of the rotator cuff, preoperative cervical radiculopathy or axillary nerve palsy, or were lost to followup.
Results
Retears occurred in 24 patients (24 shoulders) (6%). The mean overall UCLA score improved from a preoperative mean of 19.1 to a score of 32.7 at last followup (maximum possible score 35, higher scores being better). Postoperative EMG and clinical examination showed no axillary nerve palsies. Bone tunnel-related issues were encountered in only one shoulder.
Conclusions
Our technique has the following advantages: (1) reoperation is easy in patients with retears; (2) surgical materials used are inexpensive polyester sutures; and (3) no knots are tied onto the rotator cuff. This low-cost method achieves a low retear rate and few bone tunnel problems, the mean postoperative UCLA score being comparable to that obtained by using an arthroscopic anchor suture technique.
Level of Evidence
Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
Electronic supplementary material
The online version of this article (doi:10.1007/s11999-013-3148-7) contains supplementary material, which is available to authorized users.
doi:10.1007/s11999-013-3148-7
PMCID: PMC3792255  PMID: 23836242
6.  A Radiographic Classification of Massive Rotator Cuff Tear Arthritis 
Background
In 1990, Hamada et al. radiographically classified massive rotator cuff tears into five grades. Walch et al. subsequently subdivided Grade 4 to reflect the presence/absence of subacromial arthritis and emphasize glenohumeral arthritis as a characteristic of Grade 4.
Questions/purposes
We therefore determined (1) whether patient characteristics and MRI findings differed between the grades at initial examination and final followup; (2) which factors affected progression to a higher grade; (3) whether the retear rate of repaired tendons differed among the grades; and (4) whether the radiographic grades at final followup differed from those at initial examination among patients treated operatively.
Patients and Methods
We retrospectively reviewed 75 patients with massive rotator cuff tears. Thirty-four patients were treated nonoperatively and 41 operatively.
Results
Patients with Grade 3, 4, or 5 tears had a higher incidence of fatty muscle degeneration of the subscapularis muscle than patients with Grade 1 or 2 tears. In 26 patients with Grade 1 or 2 tears at initial examination, duration of followup was longer in patients who remained at Grade 1 or 2 than in those who progressed to Grade 3, 4, or 5 at final followup. The retear rate of repaired supraspinatus tendon was more frequent in Grade 2 than Grade 1 tears. In operated cases, radiographic grades at final followup did not develop to Grades 3 to 5.
Conclusions
We believe cuff repair should be performed before acromiohumeral interval narrowing. Our observations are consistent with the temporal concepts of massive cuff tear pathomechanics proposed by Burkhart and Hansen et al.
Level of Evidence
Level III, Therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-011-1896-9
PMCID: PMC3148384  PMID: 21503787
7.  Rotator Cuff Integrity Correlates With Clinical and Functional Results at a Minimum 16 Years After Open Repair 
Background
Recurrent or persistent defects in the rotator cuff after its repair are common. Short- and medium-term surveys have revealed, after open repair, patients with an intact rotator cuff have increased function and ROM. However, no long-term studies have verified cuff integrity on MR arthrography or correlated it with clinical and functional outcomes.
Questions/purposes
We evaluated long-term cuff integrity and fatty infiltration after open repair using MR arthrography and determined whether these findings correlated with clinical and functional results.
Methods
Using MR arthrography, we retrospectively evaluated 67 patients (48 men, 19 women) who underwent open rotator cuff repair between 1980 and 1989. Their mean age at surgery was 52 years. Minimum followup was 16 years (mean, 20 years; range, 16–25 years).
Results
The retear rate was 94%, and mean size of rerupture was 3.5 × 3.6 cm (ranges, 0.5–5.0 cm × 0.5–5.2 cm; median, 4 × 4 cm). The remaining four patients had a partial supraspinatus tendon tear. Fatty infiltration was marked in the supraspinatus and infraspinatus tendons. Cuff integrity correlated with clinical results: active external rotation and forward flexion, and flexion, abduction, and external rotation strengths, were better in patients with an intact rotator cuff or a small retear of 4 cm2 or less than in patients with larger tears. Cuff integrity also correlated with functional results.
Conclusions
Rotator cuff integrity was lost in 94% of patients after a minimum followup of 16 years. Cuff integrity correlates well with clinical and functional results even several years postoperatively. A large retear seems to be the most important factor in deteriorating long-term clinical and functional results after open rotator cuff repair.
Level of Evidence
Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
Electronic supplementary material
The online version of this article (doi:10.1007/s11999-012-2494-1) contains supplementary material, which is available to authorized users.
doi:10.1007/s11999-012-2494-1
PMCID: PMC3549157  PMID: 22895686
8.  Does Open Repair of Anterosuperior Rotator Cuff Tear Prevent Muscular Atrophy and Fatty Infiltration? 
Background
Repair of cuff tears involving rotator interval reportedly improves function. However, it is unclear whether successful repair prevents shoulder degenerative changes.
Questions/purposes
Therefore, we (1) documented the minimal 4-year function of patients who underwent open surgical repair for rotator interval tears; (2) evaluated repaired tendon healing with postoperative MRI; and (3) sought to determine the influence of tendon healing on muscular and glenohumeral joint changes.
Methods
We retrospectively analyzed 22 patients (23 shoulders) treated by open transosseous reinsertion of supraspinatus and subscapularis tendons. The mean age of the patients was 53 years (range, 37–64 years). The tear was traumatic in four cases. Repair healing and muscular changes were assessed using MRI. The minimum followup was 46 months (mean, 75 months; range, 46–103 months).
Results
We observed an improvement in the absolute Constant-Murley score from 63 points preoperatively to 76 points postoperatively. With the last followup MRI, the supraspinatus tendon repair had failed in two of the 23 shoulders, whereas the subscapularis tendon repair had healed in all cases. Once healing of the repaired tendon occurred, supraspinatus muscle atrophy never worsened. However, on MRI fatty infiltration of the rotator cuff muscles increased despite successful tendon repair. Glenohumeral arthritis remained stable. Postoperative abduction and internal rotation strengths were better when the standardized supraspinatus muscle area was greater than 0.5 at the final evaluation.
Conclusion
Durable functional improvement and limited degenerative articular and muscular changes can be expected in most patients 4 to 10 years after open repair of anterosuperior cuff tears provided that healing of the cuff is obtained.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-012-2443-z
PMCID: PMC3441980  PMID: 22733186
9.  The Factors Affecting the Clinical Outcome and Integrity of Arthroscopically Repaired Rotator Cuff Tears of the Shoulder 
Clinics in Orthopedic Surgery  2009;1(2):96-104.
Background
The purpose of this study was to evaluate the functional and anatomic results of arthroscopic rotator cuff repair, and to analyze the factors affecting the integrity of arthroscopically repaired rotator cuff tears of the shoulder.
Methods
One hundred sixty-nine consecutive shoulders that underwent arthroscopic rotator cuff repair, had a postoperative MRI evaluation and were followed for at least two years were enrolled in this study. The mean age was 57.6 years (range, 38 to 74 years) and the mean follow-up period was 39 months (range, 24 to 83 months).
Results
The rotator cuff was completely healed in 131 (77.5%) out of 169 shoulders and recurrent tears occurred in 38 shoulders (22.5%). At the last follow-up visit, the mean score for pain during motion was 1.53 (range, 0 to 4) in the completely healed group and 1.59 (range, 0 to 4) in the group with recurrent tears (p = 0.092). The average elevation strength was 7.87 kg (range, 4.96 to 11.62 kg) and 5.25 kg (range, 4.15 to 8.13 kg) and the mean University of California at Los Angeles score was 30.96 (range, 26 to 35) and 30.64 (range, 23 to 34), respectively (p < 0.001, p = 0.798). The complete healing rate was 87.8% in the group less than 50 years of age (49 shoulders), 79.4% in the group over 51 years but less than 60 years of age (68 shoulders), and 65.4% in the group over 61 years of age (52 shoulders, p = 0.049); it was 96.7% in the group with small-sized tears (30 shoulders), 87.3% in the group with medium-sized tears (71 shoulders), and 58.8% in the group with large-sized or massive tears (68 shoulders, p = 0.009). All of the rotator cuffs with a global fatty degeneration index of greater than two preoperatively had recurrent tears.
Conclusions
Arthroscopic repair of full-thickness rotator cuff tears led to a relatively high rate of recurrent defects. However, the minimum two-year follow up demonstrated excellent pain relief and improvement in the ability to perform the activities of daily living, despite the structural failures. The factors affecting tendon healing were the patient's age, the size and extent of the tear, and the presence of fatty degeneration in the rotator cuff muscle.
doi:10.4055/cios.2009.1.2.96
PMCID: PMC2766755  PMID: 19885061
Shoulder; Rotator cuff tear; Arthroscopic repair; Repair integrity; Retear
10.  Arthroscopic Suture Bridge Repair Technique for Full Thickness Rotator Cuff Tear 
Clinics in Orthopedic Surgery  2010;2(2):105-111.
Background
The purpose of our study is to evaluate the clinical results of arthroscopic suture bridge repair for patients with rotator cuff tears.
Methods
Between January 2007 and July 2007, fifty-one shoulders underwent arthroscopic suture bridge repair for full thickness rotator cuff tears. The average age at the time of surgery was 57.1 years old, and the mean follow-up period was 15.4 months.
Results
At the last follow-up, the pain at rest improved from 2.2 preoperatively to 0.23 postoperatively and the pain during motion improved from 6.3 preoperatively to 1.8 postoperatively (p < 0.001 and p < 0.001, respectively). The range of active forward flexion improved from 138.4° to 154.6°, and the muscle power improved from 4.9 kg to 6.0 kg (p = 0.04 and 0.019, respectively). The clinical results showed no significant difference according to the preoperative tear size and the extent of fatty degeneration, but imaging study showed a statistical relation between retear and fatty degeneration. The average Constant score improved from 73.2 to 83.79, and the average University of California at Los Angeles score changed from 18.2 to 29.6 with 7 excellent, 41 good and 3 poor results (p < 0.001 and p = 0.003, respectively).
Conclusions
The arthroscopic suture bridge repair technique for rotator cuff tears may be an operative method for which a patient can expect to achieve clinical improvement regardless of the preoperative tear size and the extent of fatty degeneration.
doi:10.4055/cios.2010.2.2.105
PMCID: PMC2867195  PMID: 20514268
Shoulder; Arthroscopy; Rotator cuff; Suture bridge repair technique
11.  Evaluation of cartilage degeneration in a rat model of rotator cuff tear arthropathy 
Introduction
Rotator cuff tears are the most common injury seen by shoulder surgeons. Many late stage rotator cuff tear patients develop glenohumeral osteoarthritis as a result of torn cuff tendons, termed cuff tear arthropathy. However, the mechanisms of cuff tear arthropathy have not been fully established. It has been hypothesized that a combination of synovial and mechanical factors contribute equally to the development of cuff tear arthropathy. The goal of this study was to assess the utility of this model in investigating cuff-tear arthropathy.
Methods
We utilized a rat model which accurately reflects rotator cuff muscle degradation after massive rotator cuff tears through either infraspinatus and supraspinatus tenotomy or suprascapular nerve transection. Using a Modified-Mankin Scoring System (MMS), we found significant glenohumeral cartilage damage following both rotator cuff tenotomy and suprascapular nerve transection after only 12 weeks.
Results
Cartilage degeneration was similar between groups, and was present on both the humeral head and the glenoid. Denervation of the supraspinatus and infraspinatus muscles without opening the joint capsule caused cartilage degeneration similar to that found in the tendon transection group.
Conclusions
These results suggest that altered mechanical loading after rotator cuff tears is the primary factor in cartilage degeneration after rotator cuff tears. Clinically, understanding the process of cartilage degeneration after rotator cuff injury will help guide treatment decisions in the setting of rotator cuff tears.
Level of evidence
Basic Science Study, Animal Model
doi:10.1016/j.jse.2013.03.014
PMCID: PMC3806888  PMID: 23664745
massive rotator cuff tear; arthropathy; osteoarthritis; histology; articular cartilage
12.  Aging-associated exacerbation in fatty degeneration and infiltration following rotator cuff tear 
Background
Rotator cuff tears are one of the most common musculoskeletal complaints and a substantial source of morbidity in elderly patients. Chronic cuff tears are associated with muscle atrophy and an infiltration of fat to the area, a condition known as “fatty degeneration.” To improve the treatment of cuff tears in elderly patients, a greater understanding of the changes in the contractile properties of muscle fibers and the molecular regulation of fatty degeneration is essential.
Methods
Using a full-thickness, massive supraspinatus and infraspinatus tear model in elderly rats, we measured fiber contractility and determined changes in fiber type distribution that develop 30 days after tear. We also measured the expression of mRNA and miRNA transcripts involved in muscle atrophy, lipid accumulation, and matrix synthesis. We hypothesized that a decrease in specific force of muscle fibers, an accumulation of type IIb fibers, and an upregulation in atrophic, fibrogenic, and inflammatory gene expression would occur in torn cuff muscles.
Results
Thirty days following tear, we observed a reduction in muscle fiber force and an induction of RNA molecules that regulate atrophy, fibrosis, lipid accumulation, inflammation and macrophage recruitment. A marked accumulation of advanced glycation end products, and a significant accretion of macrophages in areas of fat accumulation were observed.
Conclusions
The extent of degenerative changes in old rats was greater than that observed in adults. Additionally, we identified that the ectopic fat accumulation that occurs in chronic cuff tears does not occur by activation of canonical intramyocellular lipid storage and synthesis pathways.
doi:10.1016/j.jse.2013.04.011
PMCID: PMC3785561  PMID: 23790676
fatty degeneration; rotator cuff; sarcopenia; atrophy; lipid droplets; macrophages
13.  THE EFFECT OF TEAR SIZE AND NERVE INJURY ON ROTATOR CUFF MUSCLE FATTY DEGENERATION IN A RODENT ANIMAL MODEL 
Background
Irreversible muscle changes following rotator cuff tears is a well-known negative prognostic factor after shoulder surgery. Currently, little is known about the pathomechanism of fatty degeneration of the rotator cuff muscles after chronic cuff tears.
Hypothesis/Purpose
The purposes of this study were: 1) to develop a rodent animal model of chronic rotator cuff tears that can reproduce fatty degeneration of the cuff muscles seen clinically, 2) to describe the effects of tear size and concomitant nerve injury on muscle degeneration, and 3) to evaluate the changes in gene expression of relevant myogenic and adipogenic factors following rotator cuff tears using the animal model.
Methods
Rotator cuff tears were created in rodents with and without transection of the suprascapular nerve. The supraspinatus and infraspinatus muscles were examined 2, 8, and 16 weeks after injury for histological evidence of fatty degeneration and expression of myogenic and adipogenic genes.
Results
Histological analysis revealed adipocytes, intramuscular fat globules, and intramyocellular fat droplets in the tenotomized and neurotomized supraspinatus and infraspinatus muscles. Changes increased with time and were most severe in the muscles with combined tenotomy and neurotomy. Adipogenic and myogenic transcription factors and markers were upregulated in muscles treated with tenotomy or tenotomy combined with neurotomy compared to normal muscles.
Conclusions
The present study describes a rodent animal model that produces fatty degeneration of the rotator cuff muscles similar to human muscles after chronic cuff tears. The severity of changes was associated with tear size and concomitant nerve injury.
doi:10.1016/j.jse.2011.05.004
PMCID: PMC3217129  PMID: 21831663
adipogenesis; myogenesis; tenotomy; neurotomy; tendon
14.  T lymphocytes are not required for the development of fatty degeneration after rotator cuff tear  
Bone & Joint Research  2014;3(9):262-272.
Objectives
Rotator cuff tears are among the most common and debilitating upper extremity injuries. Chronic cuff tears result in atrophy and an infiltration of fat into the muscle, a condition commonly referred to as ‘fatty degeneration’. While stem cell therapies hold promise for the treatment of cuff tears, a suitable immunodeficient animal model that could be used to study human or other xenograft-based therapies for the treatment of rotator cuff injuries had not previously been identified.
Methods
A full-thickness, massive supraspinatus and infraspinatus tear was induced in adult T-cell deficient rats. We hypothesised that, compared with controls, 28 days after inducing a tear we would observe a decrease in muscle force production, an accumulation of type IIB fibres, and an upregulation in the expression of genes involved with muscle atrophy, fibrosis and inflammation.
Results
Chronic cuff tears in nude rats resulted in a 30% to 40% decrease in muscle mass, a 23% reduction in production of muscle force, and an induction of genes that regulate atrophy, fibrosis, lipid accumulation, inflammation and macrophage recruitment. Marked large lipid droplet accumulation was also present.
Conclusions
The extent of degenerative changes in nude rats was similar to what was observed in T-cell competent rats. T cells may not play an important role in regulating muscle degeneration following chronic muscle unloading. The general similarities between nude and T-cell competent rats suggest the nude rat is likely an appropriate preclinical model for the study of xenografts that have the potential to enhance the treatment of chronically torn rotator cuff muscles.
Cite this article: Bone Joint Res 2014;3:262–72.
doi:10.1302/2046-3758.39.2000294
PMCID: PMC4220170  PMID: 25185444
Rotator cuff; Fatty degeneration; Muscle atrophy; T-lymphocytes; Macrophages
15.  Visual MRI Grading System to Evaluate Atrophy of the Supraspinatus Muscle 
Korean Journal of Radiology  2014;15(4):501-507.
Objective
To investigate the interobserver reproducibility and diagnostic feasibility of a visual grading system for assessing atrophy of the supraspinatus muscle on magnetic resonance imaging (MRI).
Materials and Methods
Three independent radiologists retrospectively evaluated the occupying ratio of the supraspinatus muscle in the supraspinatus fossa on 192 shoulder MRI examinations in 188 patients using a 3-point visual grading system (1, ≥ 60%; 2, 30-59%; 3, < 30%) on oblique sagittal T1-weighted images. The inter-reader agreement and the agreement with the reference standard (3-point grades according to absolute occupying ratio values quantitatively measured by directly contouring the muscles on MRI) were analyzed using weighted kappa. The visual grading was applied by a single reader to a group of 100 consecutive patients who had undergone rotator cuff repair to retrospectively determine the association between the visual grades at preoperative state and postsurgical occurrences of retear.
Results
The inter-reader weighted kappa value for the visual grading was 0.74 when averaged across three reader pairs (0.70-0.77 for individual reader pairs). The weighted kappa value between the visual grading and the reference standard ranged from 0.75 to 0.83. There was a significant difference in retear rates of the rotator cuff between the 3 visual grades of supraspinatus muscle atrophy on MRI in univariable analysis (p < 0.001), but not in multivariable analysis (p = 0.026).
Conclusion
The 3-point visual grading system may be a feasible method to assess the severity of supraspinatus muscle atrophy on MRI and assist in the clinical management of patients with rotator cuff tear.
doi:10.3348/kjr.2014.15.4.501
PMCID: PMC4105814  PMID: 25053911
Rotator cuff tear; Supraspinatus muscle; Muscular atrophy; Magnetic resonance imaging; Occupation ratio
16.  Suprascapular Nerve: Is It Important in Cuff Pathology? 
Advances in Orthopedics  2012;2012:516985.
Suprascapular nerve and rotator cuff function are intimately connected. The incidence of suprascapular neuropathy has been increasing due to improved understanding of the disease entity and detection methods. The nerve dysfunction often results from a traction injury or compression, and a common cause is increased tension on the nerve from retracted rotator cuff tears. Suprascapular neuropathy should be considered as a diagnosis if patients exhibit posterosuperior shoulder pain, atrophy or weakness of supraspinatus and infraspinatus without rotator cuff tear, or massive rotator cuff with retraction. Magnetic resonance imaging and electromyography studies are indicated to evaluate the rotator cuff and function of the nerve. Fluoroscopically guided injections to the suprascapular notch can also be considered as a diagnostic option. Nonoperative treatment of suprascapular neuropathy can be successful, but in the recent decade there is increasing evidence espousing the success of surgical treatment, in particular arthroscopic suprascapular nerve decompression. There is often reliable improvement in shoulder pain, but muscle atrophy recovery is less predictable. More clinical data are needed to determine the role of rotator cuff repair and nerve decompression in the same setting.
doi:10.1155/2012/516985
PMCID: PMC3501891  PMID: 23193484
17.  Expression of Atrophy mRNA Relates to Tendon Tear Size in Supraspinatus Muscle 
Skeletal muscle atrophy and fatty infiltration develop after tendon tearing. The extent of atrophy serves as one prognostic factor for the outcome of surgical repair of rotator cuff tendon tears. We asked whether mRNA of genes involved in regulation of degradative processes leading to muscle atrophy, ie, FOXOs, MSTN, calpains, cathepsins, and transcripts of the ubiquitin-proteasome pathway, are overexpressed in the supraspinatus muscle in patients with and without rotator cuff tears. We evaluated biopsy specimens collected during surgery of 53 consecutive patients with different sizes of rotator cuff tendon tears and six without tears. The levels of corresponding gene transcripts in total RNA extracts were assessed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Supraspinatus muscle atrophy was assessed by MRI. The area of muscle tissue (or atrophy), decreased (increased) with increasing tendon tear size. The transcripts of CAPN1, UBE2B, and UBE3A were upregulated more than twofold in massive rotator cuff tears as opposed to smaller tears or patients without tears. These atrophy gene products may be involved in cellular processes that impair functional recovery of affected muscles after surgical rotator cuff repair. However, the damaging effects of gene products in their respective proteolytic processes on muscle structures and proteins remains to be investigated.
doi:10.1007/s11999-008-0565-0
PMCID: PMC2628494  PMID: 18941855
18.  Natural History of Fatty Infiltration and Atrophy of the Supraspinatus Muscle in Rotator Cuff Tears 
Background
In some patients nonoperative treatment of a rotator cuff tear is sufficient, while in others it is only the first stage of treatment prior to surgery. Fatty infiltration progresses throughout the nonoperative treatment although it is not known at what point fatty infiltration contributes to poor functional outcomes, absence of healing, or increased rerupture rates.
Questions/purposes
We therefore identified factors related to the appearance of supraspinatus muscle fatty infiltration, determined the speed of appearance and progression of this phenomenon, and correlated fatty infiltration with muscular atrophy.
Methods
We retrospectively reviewed 1688 patients with rotator cuff tears and recorded the following: number of tendons torn, etiology of the tear, time between onset of shoulder symptoms and diagnosis of rotator cuff tear. Fatty infiltration of the supraspinatus was graded using either CT or MRI classification. Muscular atrophy was measured indirectly using the tangent sign.
Results
Moderate supraspinatus fatty infiltration appeared an average of 3 years after onset of symptoms and severe fatty infiltration at an average of 5 years after the onset of symptoms. A positive tangent sign appeared at an average of 4.5 years after the onset of symptoms.
Conclusions
Our results suggest that rotator cuff repair should be performed before the appearance of fatty infiltration (Stage 2) and atrophy (positive tangent sign)—especially when the tear involves multiple tendons.
Level of Evidence
Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-009-1207-x
PMCID: PMC2865597  PMID: 20094853
19.  Restoration of Anterior-Posterior Rotator Cuff Force Balance Improves Shoulder Function in a Rat Model of Chronic Massive Tears 
The rotator cuff musculature imparts dynamic stability to the glenohumeral joint. In particular, the balance between the subscapularis anteriorly and the infraspinatus posteriorly, often referred to as the rotator cuff “force couple,” is critical for concavity compression and concentric rotation of the humeral head. Restoration of this anterior-posterior force balance after chronic, massive rotator cuff tears may allow for deltoid compensation, but no in vivo studies have quantitatively demonstrated an improvement in shoulder function. Our goal was to determine if restoring this balance of forces improves shoulder function after two-tendon rotator cuff tears in a rat model. Forty-eight rats underwent detachment of the supraspinatus and infraspinatus. After four weeks, rats were randomly assigned to three groups: no repair, infraspinatus repair, and two-tendon repair. Quantitative ambulatory measures including medial/lateral forces, braking, propulsion, and step width were significantly different between the infraspinatus and no repair group and similar between the infraspinatus and two-tendon repair groups at almost all time points. These results suggest that repairing the infraspinatus back to its insertion site without repair of the supraspinatus can improve shoulder function to a level similar to repairing both the infraspinatus and supraspinatus tendons. Clinically, a partial repair of the posterior cuff after a two tendon tear may be sufficient to restore adequate function. An in vivo model system for two-tendon repair of massive rotator cuff tears is presented.
doi:10.1002/jor.21361
PMCID: PMC3094494  PMID: 21308755
20.  The association between retraction of the torn rotator cuff and increasing expression of hypoxia inducible factor 1α and vascular endothelial growth factor expression: an immunohistological study 
Background
Differing levels of tendon retraction are found in full-thickness rotator cuff tears. The pathophysiology of tendon degeneration and retraction is unclear. Neoangiogenesis in tendon parenchyma indicates degeneration. Hypoxia inducible factor 1α (HIF) and vascular endothelial growth factor (VEGF) are important inducers of neoangiogenesis. Rotator cuff tendons rupture leads to fatty muscle infiltration (FI) and muscle atrophy (MA). The aim of this study is to clarify the relationship between HIF and VEGF expression, neoangiogenesis, FI, and MA in tendon retraction found in full-thickness rotator cuff tears.
Methods
Rotator cuff tendon samples of 33 patients with full-thickness medium-sized rotator cuff tears were harvested during reconstructive surgery. The samples were dehydrated and paraffin embedded. For immunohistological determination of VEGF and HIF expression, sample slices were strained with VEGF and HIF antibody dilution. Vessel density and vessel size were determined after Masson-Goldner staining of sample slices. The extent of tendon retraction was determined intraoperatively according to Patte's classification. Patients were assigned to 4 categories based upon Patte tendon retraction grade, including one control group. FI and MA were measured on standardized preoperative shoulder MRI.
Results
HIF and VEGF expression, FI, and MA were significantly higher in torn cuff samples compared with healthy tissue (p < 0.05). HIF and VEGF expression, and vessel density significantly increased with extent of tendon retraction (p < 0.05). A correlation between HIF/VEGF expression and FI and MA could be found (p < 0.05). There was no significant correlation between HIF/VEGF expression and neovascularity (p > 0.05)
Conclusion
Tendon retraction in full-thickness medium-sized rotator cuff tears is characterized by neovascularity, increased VEGF/HIF expression, FI, and MA. VEGF expression and neovascularity may be effective monitoring tools to assess tendon degeneration.
doi:10.1186/1471-2474-11-230
PMCID: PMC2958987  PMID: 20932296
21.  Variation in External Rotation Moment Arms among Subregions of Supraspinatus, Infraspinatus, and Teres Minor Muscles 
A rotator cuff tear causes morphologic changes in rotator cuff muscles and tendons and reduced shoulder strength. The mechanisms by which these changes affect joint strength are not understood. This study’s purpose was to empirically determine rotation moment arms for subregions of supraspinatus, infraspinatus, and for teres minor, and to test the hypothesis that subregions of the cuff tendons increase their effective moment arms through connections to other subregions. Tendon excursions were measured for full ranges of rotation on 10 independent glenohumeral specimens with the humerus abducted in the scapular plane at 10 and 60°. Supraspinatus and infraspinatus tendons were divided into equal width subregions. Two conditions were tested: tendon divided to the musculotendinous junction, and tendon divided to the insertion on the humerus. Moment arms were determined from tendon excursion via the principle of virtual work. Moment arms for the infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly greater when the tendon was only divided to the musculotendinous junction versus division to the humeral head. Moment arms across subregions of infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly different. A difference in teres minor moment arm was not found for the two cuff tendon conditions. Moment arm differences between muscle subregions and for tendon division conditions have clinical implications. Interaction between cuff regions could explain why some subjects retain strength after a small cuff tear. This finding helps explain why a partial cuff repair may be beneficial when a complete repair is not possible. Data presented here can help differentiate between cuff tear cases that would benefit from cuff repair and cases for which cuff repair might not be as favorable.
doi:10.1002/jor.20188
PMCID: PMC1551907  PMID: 16779813
shoulder; external rotation; moment arm; infraspinatus; teres minor; supraspinatus
22.  Factors related to successful outcome of conservative treatment for rotator cuff tears 
Upsala Journal of Medical Sciences  2010;115(3):193-200.
Background
Much controversy exists as to the management of full-thickness tears of the rotator cuff. Not all patients with rotator cuff tears require surgical treatment. We have little information whether there are factors that are related to successful outcome of conservative treatment.
Aim
The purpose of this study was to determine the factors related to the successful outcome following conservative treatment.
Methods
This study included 123 shoulders in 118 patients with full-thickness tears of the rotator cuff diagnosed by high-resolution magnetic resonance imaging with a microscopy coil. All patients were treated conservatively for at least 3 months. Clinical symptoms improved in 65 shoulders in 62 patients by conservative treatment (conservative group), but remained unchanged or aggravated in 58 shoulders in 56 patients, who eventually underwent surgical repair (surgical group).
Results
The following parameters showed significant differences: 1) integrity of the intramuscular tendon of the supraspinatus (24.1% in the surgical group and 58.4% in the conservative group showed an intact intramuscular tendon); 2) supraspinatus muscle atrophy (occupancy ratio was 69.8% in the surgical group and 78.0% in the conservative group); 3) impingement sign (positive in 79.3% in the surgical group and 30.7% in the conservative group); and 4) external rotation angle (35.0 degrees in the surgical group and 52.2 degrees in the conservative group). The success rate of conservative treatment was 87% in the cases with at least three of these four factors.
Conclusion
These four factors are useful in selecting patients who will respond well to conservative treatment before initiating the treatment.
doi:10.3109/03009734.2010.493246
PMCID: PMC2939521  PMID: 20636254
Conservative treatment; operative treatment; prognostic factors; rotator cuff tears
23.  Are Platelet-Rich Products Necessary during the Arthroscopic Repair of Full-Thickness Rotator Cuff Tears: A Meta-Analysis 
PLoS ONE  2013;8(7):e69731.
Background
Platelet-rich products (PRP) are widely used for rotator cuff tears. However, whether platelet-rich products produce superior clinical or radiological outcomes is controversial. This study aims to use meta-analysis to compare clinical and radiological outcomes between groups with or without platelet-rich products.
Methods
The Pubmed, Embase, and Cochrane library databases were searched for relevant studies published before April 20, 2013. Studies were selected that clearly reported a comparison between the use or not of platelet-rich products. The Constant, ASES, UCLA, and SST scale systems and the rotator cuff retear rate were evaluated. The weighted mean differences and relative risks were calculated using a fixed-effects model.
Results
Seven studies were enrolled in this meta-analysis. No significant differences were found for the Constant scale (0.73, 95% CI, −1.82 to 3.27, P = 0.58), ASES scale (−2.89, 95% CI, −6.31 to 0.53, P = 0.1), UCLA scale (−0.79, 95% CI, −2.20 to 0.63, P = 0.28), SST scale (0.34, 95% CI, −0.01 to 0.69, P = 0.05), and the overall rotator cuff retear rate (0.71, 95% CI, 0.48 to 1.05, P = 0.08). Subgroup analysis according to the initial tear size showed a lower retear rate in small- and medium-sized tears (0.33, 95% CI, 0.12 to 0.91, P = 0.03) after platelet-rich product application but no difference for large- and massive-sized tears (0.86, 95% CI, 0.60 to 1.23, P = 0.42).
Conclusion
In conclusion, the meta-analysis suggests that the platelet-rich products have no benefits on the overall clinical outcomes and retear rate for the arthroscopic repair of full-thickness rotator cuff tears. However, a decrease occurred in the rate of retears among patients treated with PRP for small- and medium-sized rotator cuff tears but not for large- and massive-sized tears.
Level of Evidence
Level II
doi:10.1371/journal.pone.0069731
PMCID: PMC3709895  PMID: 23874991
24.  Upregulation of transforming growth factor-β signaling in a rat model of rotator cuff tears 
Background
Muscle atrophy, fatty infiltration, and fibrosis of the muscle have been described as important factors governing outcome after rotator cuff injury and repair. Muscle fibrosis is also thought to have a role in determining muscle compliance at the time of surgery. The transforming growth factor-β (TGF-β) pathways are highly conserved pathways that exert a potent level of control over muscle gene expression and are critical regulators of fibrosis in multiple organ systems. It has been shown that TGF-β can regulate important pathways of muscle atrophy, including the Akt/mammalian target of rapamycin pathway. The purpose of this study was to evaluate the expression of TGF-β and its downstream effectors of fibrosis after a massive rotator cuff tear (RCT) in a previously established rat model.
Methods
To simulate a massive RCT, infraspinatus and supraspinatus tenotomy and suprascapular nerve transection were performed on Sprague-Dawley rats with use of a validated model. Two and 6 weeks after surgery, supraspinatus muscles were harvested to study alterations in TGF-β signaling by Western blotting, quantitative polymerase chain reaction, and histologic analysis.
Results
There was a significant increase in fibrosis in the rotator cuff muscle after RCT in our animal model. There was a concomitant increase in TGF-β gene and protein expression at both 2 and 6 weeks after RCT. Evaluation of the TGF-β signaling pathway revealed an increase in SMAD2 activation but not in SMAD3. There was an increase in profibrotic markers collagen I, collagen III, and α-smooth muscle actin.
Conclusions
TGF-β signaling is significantly upregulated in rat supraspinatus muscles after RCTs.
doi:10.1016/j.jse.2014.02.029
PMCID: PMC4198422  PMID: 24875732
Massive rotator cuff tear; transforming growth factor-β; fibrosis
25.  Rotator cuff tear reduces muscle fiber specific force production and induces macrophage accumulation and autophagy 
Summary
Full-thickness tears to the rotator cuff can cause severe pain and disability. Untreated tears progress in size and are associated with muscle atrophy and an infiltration of fat to the area, a condition known as “fatty degeneration.” To improve the treatment of rotator cuff tears, a greater understanding of the changes in the contractile properties of muscle fibers and the molecular regulation of fatty degeneration is essential. Using a rat model of rotator cuff injury, we measured the force generating capacity of individual muscle fibers and determined changes in muscle fiber type distribution that develop after a full thickness rotator cuff tear. We also measured the expression of mRNA and miRNA transcripts involved in muscle atrophy, lipid accumulation, and matrix synthesis. We hypothesized that a decrease in specific force of rotator cuff muscle fibers, an accumulation of type IIb fibers, an upregulation in fibrogenic, adipogenic, and inflammatory gene expression occur in torn rotator cuff muscles. Thirty days following rotator cuff tear, we observed a reduction in muscle fiber force production, an induction of fibrogenic, adipogenic and autophagocytic mRNA and miRNA molecules, and a dramatic accumulation of macrophages in areas of fat accumulation.
doi:10.1002/jor.22168
PMCID: PMC3449033  PMID: 22696414
Rotator cuff; muscle fiber contractility; fatty degeneration; autophagy

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