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The purpose of the study was to describe the characteristics and demonstrate proof-of-concept and clinical use of a barium sulfate infused polypropylene radiopaque tissue marker for soft tissue localization and in vivo measurement of lengths and areas. Marker mechanical properties were evaluated by tensile tests. Biocompatibility was evaluated following 8–12 weeks' implantation in a pig model. Proof-of-concept of marker application was performed in a human cadaveric shoulder model, and methods for CT imaging and measurement of dimensions were established. Lastly, the method of clinical use of the markers was described in one patient undergoing arthroscopic rotator cuff repair (RCR). The radiopaque markers had a tensile strength of 28 ±4.7 N and were associated with minimal to mild inflammatory tissue reaction similar to polypropylene control. CT-based measurements showed relatively high precisions for lengths (0.66 mm), areas (6.97 mm2), and humeral orientation angles (2.1°) in the cadaveric model, and demonstrated 19 ±3 mm medio-lateral tendon retraction and 227 ±3 mm2 increase in tendon area in the patient during 26 weeks following RCR. No radiographic leaching, calcification or local adverse events were observed. The radiopaque tissue marker was biocompatible and had adequate strength for handling and affixation to soft tissues using standard suturing techniques. The marker could be used with low-dose, sequential CT imaging to quantitatively measure rotator cuff tendon retractions with clinically acceptable accuracy. We envision the radiopaque tissue marker to be useful for soft tissue localization and in vivo measurement of tissue and organ dimensions following surgery. [ABSTRACT FROM AUTHOR]

Background The factors that associate with surgical decisions about repair technique and the number of suture anchors used in rotator cuff repair have not been previously investigated. This study investigated the extent to which patient, surgeon, and surgical factors associate with performing single-row vs. double-row repair technique and ultimately with the number of suture anchors used. Methods Our institution's prospective surgical cohort was queried for patients undergoing suture anchor repair of superior-posterior rotator cuff tendon tears between February 2015 and August 2017. Exclusion criteria were patients with isolated subscapularis tears, tears that were not repaired, repairs without suture anchors, repairs involving graft augmentation, and repairs by surgeons with fewer than 10 cases. Multivariable statistical modeling was used to investigate associations between patient and surgical factors and the choice of repair technique and number of suture anchors used. Results A total of 925 cases performed by 13 surgeons met inclusion criteria. Tear type (full thickness), tear size (medium, large, and massive), a greater number of torn tendons, repair type (arthroscopic), and surgeon were significantly associated with performing a double-row over a single-row repair. Tear size, a greater number of torn tendons, double-row repair technique, and surgeon were significantly associated with a greater number of anchors used for repair. Conclusions Our findings suggest that in the absence of data to conclusively support a clinical benefit of one repair technique over another, surgeons' training, experience, and inherent practice patterns become the primary factors that define their surgical methods. [ABSTRACT FROM AUTHOR]

Background: Glenoid morphology and rotator cuff muscle quality are important anatomic factors that can impact longevity of the glenoid component following total shoulder arthroplasty (TSA). We hypothesized that rotator cuff muscle fatty infiltration is associated with increased pathologic glenoid bone loss in glenohumeral osteoarthritis (OA).Methods: We retrospectively reviewed 190 preoperative computed tomography (CT) scans of 175 patients (mean age, 66 years; range, 44 to 90 years) who underwent TSA for the treatment of primary glenohumeral OA. Two-dimensional orthogonal CT images were reformatted in the plane of the scapula from 3-dimensional images. Pathologic joint-line medialization was defined with use of the glenoid vault model. Pathologic glenoid version was measured directly. Glenoid morphology was graded according to a modified Walch classification (subtypes A1, A2, B1, B2, B3, C1, and C2). Rotator cuff muscle fatty infiltration was assessed and assigned a Goutallier score on the sagittal CT slice just medial to the spinoglenoid notch for each muscle.Results: There was a significant difference in the Goutallier score for the supraspinatus, infraspinatus, and teres minor muscles between Walch subtypes (p ≤ 0.05). High-grade posterior rotator cuff muscle fatty infiltration was present in 55% (21) of 38 B3 glenoids compared with 8% (3) of 39 A1 glenoids. Increasing joint-line medialization was associated with increasing fatty infiltration of all rotator cuff muscles (p ≤ 0.05). Higher fatty infiltration of the infraspinatus, teres minor, and combined posterior rotator cuff muscles was associated with increasing glenoid retroversion (p ≤ 0.05). After controlling for joint-line medialization and retroversion, B3 glenoids were more likely to have fatty infiltration of the supraspinatus and infraspinatus muscles than B2 glenoids were.Conclusions: High-grade rotator cuff muscle fatty infiltration is associated with B3 glenoids, increased pathologic glenoid retroversion, and increased joint-line medialization. Additional studies are needed to determine the causal relationship between these muscle changes and glenoid wear, whether these muscle changes independently affect clinical and radiographic outcomes in anatomic TSA, and whether fatty infiltration can improve postoperatively with correction of pathologic version and/or joint-line restoration.Clinical Relevance: This study investigates the association between different patterns of glenoid bone loss and rotator cuff muscle fatty infiltration. Both factors have been shown to affect clinical outcome following TSA. [ABSTRACT FROM AUTHOR]

Background Minimal information is currently available on the outcome of rotator cuff repair reinforced with an extracellular matrix (ECM) graft. Therefore, the purpose of this study was to determine the clinical and radiographic outcome of repair of large rotator cuff tears with ECM graft reinforcement. Methods This was a prospective study of 61 shoulders with large repairable rotator cuff tears (3 to 5 cm). The rotator cuff tears were surgically repaired and reinforced with a xenograft ECM graft. The average patient age was 56 years (range, 40-69 years). The average tear size was 3.8 cm. Results Follow-up was obtained at 6, 12, and 24 months in 58, 54, and 50 of the 61 patients, respectively. Functional outcome scores, isometric muscle strength, and active range of motion were significantly improved compared with baseline. Magnetic resonance imaging at 12 months showed retorn rotator cuff repairs in 33.9% of shoulders, using the criteria of a tear of at least 1 cm, and tears in 14.5% of the shoulders using the criteria of retear >80% of the original tear size. Three patients underwent surgical revision. Complications included 1 deep infection. Conclusions Repair of large rotator cuff tears structurally reinforced with xenograft ECM resulted in improved functional outcomes scores and strength. Adverse events were uncommon, and the rate of revision surgery was low. [ABSTRACT FROM AUTHOR]

Each year, 250,000 rotator cuff repairs are performed in the United States at a cost of $3 billion. Despite advancements in repair techniques and rehabilitation, 20%-70% of repairs continue to undergo structural failure; however, there is a poor correlation between clinical and structural outcomes, both before and after surgery. "Failure in continuity", or retraction of the repair site without a structural defect, is likely a common phenomenon after rotator cuff repair, and this retraction of the myotendinous unit and interposing scar tissue may be one explanation for the discordance between clinical and structural outcomes. Scaffolds, both synthetic and biologic, have shown promise in both augmentation of repairs and interposition of irreparable tears, but most studies are small retrospective case series without control groups. Future efforts will need to determine the ideal indications for use, methods of application, and comparative effectiveness between the devices. Platelet-rich plasma also has potential to improve rotator cuff healing, but current limitations include the significant variation in preparation methods, biologic makeup, and application methods. Future work may help us understand whether application of platelet-rich plasma and its growth factors should be done at the time of surgery or later during a more advanced stage of healing. Regardless of the device or technique, mechanical and/or biologic augmentation of rotator cuff repairs requires the surgeon to be technically proficient in its use and aware of its associated increased operative time and cost. In order to justify the use of these technologies and their associated incremental cost, we must demonstrate efficacy in improving both clinical and structural outcomes. [ABSTRACT FROM AUTHOR]

Background: Scaffold devices are used to augment rotator cuff repairs in humans. While the strength of a novel poly-L-lactic acid-reinforced (human) fascia patch has been documented, it is unclear whether such patches will enhance the strength or likelihood of healing of rotator cuff repairs. Questions/purposes: In a canine shoulder model, we asked: Do tendon repairs augmented with a reinforced fascia patch have (1) increased biomechanical properties at Time 0 and (2) less tendon retraction and increased cross-sectional area and biomechanical properties after 12 weeks of healing compared to repairs without augmentation? (3) Do the biomechanical properties of tendon repairs reach normal values by 12 weeks of healing? And (4) is the host response associated with use of the reinforced fascia patch biocompatible? Methods: Eleven dogs underwent bilateral shoulder surgery with partial release and acute repair of the infraspinatus tendon, one shoulder with augmentation and one without augmentation. Repair retraction, cross-sectional area, biomechanical properties, and biocompatibility were assessed at 12 weeks. Results: At Time 0, the mean ± SD ultimate load of augmented repairs was 296 ± 130 N (46% ± 25%) more than nonaugmented repairs, with no difference in stiffness between groups. At 12 weeks, the ultimate load of augmented repairs averaged 192 ± 213 N (15% ± 16%) less than nonaugmented repairs, with no difference in stiffness between groups. At the tendon repair site at 12 weeks, the fascia patch showed a biocompatible host tissue response. Conclusions: The biomechanical properties of repairs augmented with a reinforced fascia patch demonstrated greater ultimate load at Time 0 than nonaugmented repairs but remained essentially unchanged after 12 weeks of healing, despite improvements in the ultimate load of nonaugmented controls in the same time frame. Clinical Relevance: Together with our previous work, these findings support the possibility that reinforced fascia patches would incorporate and provide (at least early) mechanical augmentation to rotator cuff repair in human patients. [ABSTRACT FROM AUTHOR]

Background: Scaffolds continue to be developed and used for rotator cuff repair augmentation; however, the appropriate scaffold material properties and/or surgical application techniques for achieving optimal biomechanical performance remains unknown. The objectives of the study were to simulate a previously validated spring-network model for clinically relevant scenarios to predict: (1) the manner in which changes to components of the repair influence the biomechanical performance of the repair and (2) the percent load carried by the scaffold augmentation component. Materials and methods: The models were parametrically varied to simulate clinically relevant scenarios, namely, changes in tendon quality, altered surgical technique(s), and different scaffold designs. The biomechanical performance of the repair constructs and the percent load carried by the scaffold component were evaluated for each of the simulated scenarios. Results: The model predicts that the biomechanical performance of a rotator cuff repair can be modestly increased by augmenting the repair with a scaffold that has tendon-like properties. However, engineering a scaffold with supraphysiologic stiffness may not translate into yet stiffer or stronger repairs. Importantly, the mechanical properties of a repair construct appear to be most influenced by the properties of the tendon-to-bone repair. The model suggests that in the clinical setting of a weak tendon-to-bone repair, scaffold augmentation may significantly off-load the repair and largely mitigate the poor construct properties. Conclusions: The model suggests that future efforts in the field of rotator cuff repair augmentation may be directed toward strategies that strengthen the tendon-to-bone repair and/or toward engineering scaffolds with tendon-like mechanical properties. [ABSTRACT FROM AUTHOR]

Background: Non-cross-linked xenogeneic extracellular matrix graft materials have typically elicited a hypersensitivity reaction when implanted into humans or other primates. The purpose of this study was to examine the histologic and immune response to a non-cross-linked porcine-derived dermal extracellular matrix graft processed to remove the α-gal epitope. Materials and methods: Eight African green monkeys were implanted with porcine acellular dermal matrix (Conexa Reconstructive Tissue Matrix; Tornier Inc, Edina, MN, USA) to repair and augment a partial excision defect of the supraspinatus tendon of the rotator cuff. Four animals each were sacrificed at 3 months and 6 months, and histologic samples were compared with tissues harvested from unoperated shoulders. Results: Gross examination of grafted Conexa showed the appearance of integration proximally with tendon and distally with bone in each operated rotator cuff complex. Histologically, Conexa appeared to have remodeled to tendon-like architecture, with homogeneous distribution of fibroblast cells and parallel alignment of collagen fibers, with the direction of force evident by 3 months after implantation. Abundant vasculature observed at 3 months, which diminished to native tendon levels by 6 months, also indicated this to be a period of significant remodeling with an absence of significant inflammation, as evidenced by immunochemical methods and serum analysis. Conclusion: Conexa porcine acellular dermal matrix allows for incorporation of host tendon tissue without a hypersensitivity reaction in a primate model and should be a safe material for augmentation of human rotator cuff repair. [ABSTRACT FROM AUTHOR]

Rotator cuff tears affect 40% or more of those aged older than 60 years, and repair failure rates of 20% to 70% remain a significant clinical challenge. Hence, there is a need for repair strategies that can augment the repair by mechanically reinforcing it, while at the same time biologically enhancing the intrinsic healing potential of the tendon. Tissue engineering strategies to improve rotator cuff repair healing include the use of scaffolds, growth factors, and cell seeding, or a combination of these approaches. Currently, scaffolds derived from mammalian extracellular matrix, synthetic polymers, and a combination thereof, have been cleared by the U.S. Food and Drug Administration and are marketed as medical devices for rotator cuff repair in humans. Despite the growing clinical use of scaffold devices for rotator cuff repair, there are numerous questions related to their indication, surgical application, safety, mechanism of action, and efficacy that remain to be clarified or addressed. This article reviews the current basic science and clinical understanding of commercially available synthetic and extracellular matrix scaffolds for rotator cuff repair. Our review will emphasize the host response and scaffold remodeling, mechanical and suture-retention properties, and preclinical and clinical studies on the use of these scaffolds for rotator cuff repair. We will discuss the implications of these data on the future directions for use of these scaffolds in tendon repair procedures. [Copyright &y& Elsevier]

Hypothesis: Rotator cuff repair failure rates range from 20% to 90%, and failure is believed to occur most commonly by sutures cutting through the tendon due to excessive tension at the repair site. This study was designed to determine whether application of a woven poly-L-lactic acid device (X-Repair; Synthasome, San Diego, CA) would improve the mechanical properties of rotator cuff repair in vitro. Materials and methods: Eight pairs of human cadaveric shoulders were used to test augmented and non-augmented rotator cuff repairs. Initial stiffness, yield load, ultimate load, and failure mode were compared. Results: Yield load was 56% to 92% higher and ultimate load was 56% to 76% higher in augmented repairs. No increase in initial stiffness was found. Failure by sutures cutting through the tendon was reduced, occurring in 17 of 20 non-augmented repairs but only 7 of 20 augmented repairs. Conclusions: Our data show that application of the X-Repair device significantly increased the yield load and ultimate load of rotator cuff repairs in a human cadaveric model and altered the failure mode but did not affect initial repair stiffness. [Copyright &y& Elsevier]

Even though several studies have revealed excellent clinical results with arthroscopic repair of rotator cuff tendons, poor healing of the repair and retearing of the tendon occur in many cases. Patterns of outcome correlating functional capacity and anatomic integrity of the repaired rotator cuff are not well defined. The goal of this prospective study was to determine the pattern of anatomic and functional outcomes among patients undergoing single-row arthroscopic rotator cuff repair. This study confirmed that single-row arthroscopic repair of small- and medium-sized supraspinatus tendon tears significantly improves rotator cuff integrity and functional outcomes. A completely healed tendon was observed in 60% of the cases. Age is a predictor of cuff integrity after the operation. Functional improvement was greater and significant in patients with complete healing at follow-up; however, a recurrent tear did not preclude positive functional results. [Copyright &y& Elsevier]

Background: We are not aware of any in vitro study comparing the biomechanical, biochemical, and cellular properties of commercial extracellular matrix materials marketed for rotator cuff tendon repair. In this study, the properties of GraftJacket, TissueMend, Restore, and CuffPatch were quantified and compared with each other. The elastic moduli were also compared with that of normal canine infraspinatus tendon. Methods: Samples were tested from different manufacturing lots of four materials: GraftJacket (ten lots), Tissue-Mend (six), Restore (ten), and CuffPatch (six). The Kruskal-Wallis test was used to compare thickness, stiffness, and modulus as well as hydroxyproline, chondroitin/dermatan sulfate glycosaminoglycan, hyaluronan, and DNA contents among these matrices. The moduli of the extracellular matrices were also compared with those of normal canine infraspinatus tendon. Results: All four extracellular matrices required 10% to 30% stretch before they began to carry substantial load. Their maximum moduli were realized in their linear region at 30% to 80% strain. The elastic moduli of all four commercial matrices were an order of magnitude lower than that of canine infraspinatus tendon. TissueMend had significantly higher DNA content than the other three matrices (p < 0.0001), although both Restore and GraftJacket also had measurable amounts of DNA. Conclusions: Our data demonstrate chemical and mechanical differences among the four commercial extracellular matrices that we evaluated. Probably, the source (dermis or small intestine submucosa), species (human, porcine, or bovine), age of the donor (fetal or adult), and processing of these matrices all contribute to the unique biophysical properties of the delivered product. The biochemical composition of commercial extracellular matrices is similar to that of tendon. However, the elastic moduli of these materials are an order of magnitude lower than that of tendon, suggesting a limited mechanical role in augmentation of tendon repair. Clinical Relevance: These data will help inform and guide the clinical community with regard to the appropriate use of commercially available extracellular matrix products for augmentation of rotator cuff tendon repair. Knowledge of the biophysical properties of these materials is fundamental to making an educated decision about whether a given matrix might provide mechanical augmentation and/or enhance the biology of tendon-to-bone healing. [ABSTRACT FROM AUTHOR]

Background: Long-standing tears of the rotator cuff can lead to substantial and perhaps irreversible changes in the affected rotator cuff muscles. We developed a chronic rotator cuff tear in a canine model to investigate and quantify the time-related changes in passive mechanics, volume, and fat of the infraspinatus muscle. We hypothesized that infraspinatus muscle stiffness would increase, volume would decrease, and fat content would increase at twelve weeks following tendon detachment. Methods: The right infraspinatus tendon of eight adult mongrel dogs were surgically detached from the proximal part of the humerus. The uninvolved left shoulder served as a control. Muscle volume changes were quantified with use of magnetic resonance imaging. At twelve weeks, the passive mechanical properties of the chronically detached and control muscles were determined intraoperatively with use of a custom-designed device. Intramuscular fat was evaluated histologically at the time that the animals were killed. Results: After twelve weeks of detachment, the stiffness was significantly increased in the detached infraspinatus muscles relative to that in the controls (p < 0.0001). Magnetic resonance image analysis demonstrated that the detached muscle volumes decreased by an average of 32% in the first six weeks and remained constant thereafter. Intramuscular fat increased significantly in the detached muscles and to a greater extent in the lateral regions (p < 0.05). Conclusions: The chronically detached muscle is not merely a smaller version of the original muscle but, rather, a different muscle. The detached muscle becomes stiffer, and the passive loads required to repair it can become excessive. A significant reduction in muscle volume occurs within days to weeks following tendon detachment (p < 0.0001). The nonuniformity of changes in muscle fat suggests that fat content should be used cautiously as an indicator of muscle quality. Clinical Relevance: Clinically, chronic large rotator cuff tears are observed to have a qualitatively shorter and stiffer muscle-tendon unit than normal. We developed a chronic rotator cuff model to quantitatively investigate changes in the detached infraspinatus muscle. The passive mechanical properties of a chronically torn rotator cuff muscle-tendon unit may be a useful predictor of repairability and clinical outcome. [ABSTRACT FROM AUTHOR]

Background: This prospective multi-institutional study was designed to define the accuracy of ultrasonography, when performed in an orthopaedic surgeon's office, for the diagnosis of rotator cuff tears. Methods: An anatomic diagnosis and a treatment plan were made on the basis of office-based shoulder ultrasonography, physical examination, and radiographs for ninety-eight patients (ninety-nine shoulders) with a clinical diagnosis of a rotator-cuff-related problem. The results of the ultrasonographic studies were then compared with the results of magnetic resonance imaging and the operative findings. Results: Office-based ultrasonography led to the correct diagnosis for thirty-seven (88%) of forty-two shoulders with a full-thickness rotator cuff tear or both full and partial-thickness tears, twenty-six (70%) of thirty-seven shoulders with a partial-thickness rotator cuff tear only, and sixteen (80%) of twenty shoulders with normal tendons. In no case was the surgical approach (open or arthroscopic) that had been planned on the basis of the ultrasonography altered by the operative findings, but the operative finding of a full-thickness tear resulted in an arthroscopic cuff repair in four shoulders. Magnetic resonance imaging led to the correct diagnosis for forty (95%) of forty-two shoulders with a full-thickness rotator cuff tear or both full and partial-thickness rotator cuff tears, twenty-seven (73%) of thirty-seven shoulders with only a partial-thickness tear, and fifteen (75%) of twenty shoulders with normal tendons. There were no significant differences between magnetic resonance imaging and ultrasonography with regard to the correct identification of a full-thickness tear or its size. The sensitivity of ultrasonography for detecting tear size in the anteriorposterior dimension was 86% (95% confidence interval, 71% to 95%), and that of magnetic resonance imaging was 93% (95% confidence interval, 81% to 99%) (p = 0.26). The sensitivity of ultrasonography for detecting tear size in the medial-lateral dimension was 83% (95% confidence interval, 69% to 93%), and that of magnetic resonance imaging was 88% (95% confidence interval, 74% to 96%) (p = 0.41). Conclusions: A well-trained office staff and an experienced orthopaedic surgeon can effectively utilize ultrasonography, in conjunction with clinical examination and a review of shoulder radiographs, to accurately diagnose the extent of rotator cuff tears in patients suspected of having such tears. Errors in diagnosis made on the basis of ultrasonography most often consist of an inability to distinguish between partial and full-thickness tears that are approximately 1 cm in size. In this study, such errors did not significantly affect the planned surgical approach. Level of Evidence: Diagnostic Level I. See Instructions to Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Rotator cuff tears, a common source of shoulder pathology, are often the cause of debilitating shoulder pain, reduced shoulder function and compromised joint mechanics. The treatment, evaluation and management of this disease puts an annual financial burden of 3 billion US dollars on the US economy. Despite surgical advances, there is a high rate of recurrent tears ranging (20-70%) after surgical repair, particularly for chronic, large to massive cuff tears. The inability to obtain a high healing rate in these tears has fueled investigation in the use of extracellular matrix (ECM) derived materials as a scaffolds for rotator cuff tendon repair and regeneration. The present paper reviews the current state of knowledge regarding the mechanical and biological characteristics of commercially available ECM materials, delineates indications for their clinical use and suggests future directions in developing ECM scaffolds for rotator cuff repair. [Copyright &y& Elsevier]

Animal shoulder models are used to systematically investigate the factors influencing rotator cuff injury and repair. Each model has advantages and disadvantages that must be considered in the context of the specific research questions being asked. This study evaluated the utility of the canine model for studies of acute, full-thickness rotator cuff tendon injury and repair. We found that time-zero failure load is dependent on the suture type and configuration used for repair. Acute, full-width tendon repairs fail anatomically within the first days after surgery in the canine model, regardless of suture type, suture configuration, or postoperative protocol. Robust scar tissue forms in the gap between the failed tendon end and the humerus, which can be visually, mechanically, and histologically misconstrued as tendon if an objective test of repair connectivity is not performed. We conclude that a full-width injury and repair model in the canine will provide a rigorous test of whether a new repair strategy or postoperative protocol, such as casting or temporary muscle paralysis, can maintain repair integrity in a high-load environment. Alternatively, a partial-width tendon injury model allows loads to be shared between the tendon repair and the remaining intact portion of the infraspinatus tendon and prohibits complete tendon retraction. Thus a partial-width injury in the canine may model the mechanical environment of many single tendon tears in the human injury condition and warrants further investigation. [Copyright &y& Elsevier]