The timing of retears after arthroscopic rotator cuff repair Chona, Deepak V.; Lakomkin, Nikita; Lott, Ariana ...
Journal of shoulder and elbow surgery,
November 2017, 2017-Nov, 2017-11-00, 20171101, Letnik:
26, Številka:
11
Journal Article
Recenzirano
Little is known about the time dependence of the failure rate of surgically repaired rotator cuffs. Retears are significant, as they are common and may lead to less satisfactory outcomes and ...additional operations. Their timing is critical foundational information for understanding failure mechanisms. However, this remains unclear. Currently, there exist a number of studies that have reported retear rates at specific time points. Combining data from these publications can reveal when cuffs retear, which will help inform expectations and guidelines for progression of activity after surgery.
PubMed, Medline, and Embase were searched for studies relating to rotator cuff repair. Abstracts and articles were evaluated on the basis of predefined inclusion and exclusion criteria. Data were extracted from those publications that satisfied all requirements, and regression analysis was performed.
Thirteen articles were included in the final meta-analysis. Retear rates for medium tears increased for approximately 15 months and leveled off at approximately 20%. Retear rates for large tears progressed steadily for about 12 months and approached an upper limit of approximately 40%. Retear rates for massive tears ranged from 20% to 60%, but the distribution of retear rate over time for these cuff tears is not clear from these data.
Retear rates for medium and large tears generally increase until at least 10-15 months after surgery, after which they are likely to level off. Retear rates for massive tears are variable and may follow a time course different from that of other tear sizes. Retear rates depend on size of the original tear.
Adequate glenoid baseplate fixation in reverse total shoulder arthroplasty (rTSA) is important to achieve, but may prove challenging in the context of glenoid bone loss or osteopenia. Current rTSA ...testing standards rely upon synthetic bone surrogates, but it is unclear if these models accurately recapitulate the mechanics of osteoporotic bone. Additionally, it also unknown if the use of a central screw effectively provides resistance to micromotion in the milieu of poor quality bone. The purpose of this experiment was to create a novel cyclic load test protocol that elicited clinically relevant failures, so that comparisons of relative motion between baseplates and bones could be made with: (1) synthetic bones and poor quality cadaveric bones, and (2) the use or omission of a central screw. rTSA components were implanted into cadaveric and synthetic bones with and without a central screw. To model a range of loads that may be experienced during abduction, increasing cyclic loads were applied to shoulder joints in 30° of humeral abduction. Cycles and loads prior to permanent deformation exceeding 150 µm, 1 mm, and joint failure were determined using measurements from the test frame and from 3-D motion analysis. Synthetic bones demonstrated significantly more resistance to micromotion in comparison to cadaveric bones. Use of the central screw improved resistance to dislodgement, which was only observed in the cadaveric specimens. This study highlights the need for biomechanical testing with cadaveric specimens, especially when assessing osteopenic or osteoporotic populations.
While the role of hedgehog (Hh) signaling in promoting zonal fibrocartilage production during development is well-established, whether this pathway can be leveraged to improve tendon-to-bone repair ...in adults is unknown. Our objective was to genetically and pharmacologically stimulate the Hh pathway in cells that give rise to zonal fibrocartilaginous attachments to promote tendon-to-bone integration.
Hh signaling was stimulated genetically via constitutive Smo (SmoM2 construct) activation of bone marrow stromal cells or pharmacologically via systemic agonist delivery to mice following anterior cruciate ligament reconstruction (ACLR). To assess tunnel integration, we measured mineralized fibrocartilage (MFC) formation in these mice 28 days post-surgery and performed tunnel pullout testing.
Hh pathway-related genes increased in cells forming the zonal attachments in wild-type mice. Both genetic and pharmacologic stimulation of the Hh pathway increased MFC formation and integration strength 28 days post-surgery. We next conducted studies to define the role of Hh in specific stages of the tunnel integration process. We found Hh agonist treatment increased the proliferation of the progenitor pool in the first week post-surgery. Additionally, genetic stimulation led to continued MFC production in the later stages of the integration process. These results indicate that Hh signaling plays an important biphasic role in cell proliferation and differentiation towards fibrochondrocytes following ACLR.
This study reveals a biphasic role for Hh signaling during the tendon-to-bone integration process after ACLR. In addition, the Hh pathway is a promising therapeutic target to improve tendon-to-bone repair outcomes.
Following anterior cruciate ligament (ACL) reconstruction surgery, a staged repair response occurs where cells from outside the tendon graft participate in tunnel integration. The mechanisms that ...regulate this process, including the specific cellular origin, are poorly understood. Embryonic cells expressing growth and differentiation factor 5 (GDF5) give rise to several mesenchymal tissues in the joint and epiphyses. We hypothesized that cells from a GDF5 origin, even in the adult tissue, would give rise to cells that contribute to the stages of repair. ACLs were reconstructed in Gdf5‐Cre;R26R‐tdTomato lineage tracing mice to monitor the contribution of Gdf5‐Cre;tdTom+ cells to the tunnel integration process. Anterior−posterior drawer tests demonstrated 58% restoration in anterior−posterior stability. Gdf5‐Cre;tdTom+ cells within the epiphyseal bone marrow adjacent to tunnels expanded in response to the injury by 135‐fold compared with intact controls to initiate tendon‐to‐bone attachments. They continued to mature the attachments yielding zonal insertion sites at 4 weeks with collagen fibers spanning across unmineralized and mineralized fibrocartilage and anchored to the adjacent bone. The zonal attachments possessed tidemarks with concentrated alkaline phosphatase activity similar to native entheses. This study established that mesenchymal cells from a GDF5 origin can contribute to zonal tendon‐to‐bone attachments within bone tunnels following ACL reconstruction.
The objective of our study was to use Gdf5‐Cre transgenic mice to trace the origin of cells that revitalize the tendon graft following ACL reconstruction in a mouse model and to examine the extent to which these cells can create mineralized attachments within bone tunnels.
Many drug delivery systems rely on degradation or dissolution of the carrier material to regulate release. In cases where mechanical support is required during regeneration, this necessitates ...composite systems in which the mechanics of the implant are decoupled from the drug release profile. To address this need, we developed a system in which microspheres (MS) were sequestered in a defined location between two nanofibrous layers. This bilayer delivery system (BiLDS) enables simultaneous structural support and decoupled release profiles. To test this new system, PLGA (poly-lactide-co-glycolic acid) microspheres were prepared using a water-in-oil-in-water (w/o/w) emulsion technique and incorporated Alexa Fluor-tagged bovine serum albumin (BSA) and basic fibroblast growth factor (bFGF). These MS were secured in a defined pocket between two polycaprolactone (PCL) nanofibrous scaffolds, where the layered scaffolds provide a template for new tissue formation while enabling independent and local release from the co-delivered MS. Scanning electron microscopy (SEM) images showed that the assembled BiLDS could localize and retain MS in the central pocket that was surrounded by a continuous seal formed along the margin. Cell viability and proliferation assays showed enhanced cell activity when exposed to BiLDS containing Alexa Fluor-BSA/bFGF-loaded MS, both in vitro and in vivo. MS delivered via the BiLDS system persisted in a localized area after subcutaneous implantation for at least 4 weeks, and bFGF release increased colonization of the implant. These data establish the BiLDS technology as a sustained in vivo drug delivery platform that can localize protein and other growth factor release to a surgical site while providing a structural template for new tissue formation.
Localized and controlled delivery systems for the sustained release of drugs are essential. Many strategies have been developed for this purpose, but most rely on degradation (and loss of material properties) for delivery. Here, we developed a bilayer delivery system (BiLDS) that decouples the physical properties of a scaffold from its delivery kinetics. For this, biodegradable PLGA microspheres were sequestered within a central pocket of a slowly degrading nanofibrous bilayer. Using this device, we show enhanced cell activity with FGF delivery from the BiLDS both in vitro and in vivo. These data support that BiLDS can localize sustained protein and biofactor delivery to a surgical site while also serving as a mechanical scaffold for tissue repair and regeneration.
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Rotator cuff tendon tears and tendinopathies are common injuries affecting a large portion of the population and can result in pain and joint dysfunction. Incidence of rotator cuff tears ...significantly increases with advancing age, and up to 90% of these tears involve the supraspinatus. Previous literature has shown that aging can lead to inferior mechanics, altered composition, and changes in structural properties of the supraspinatus. However, there is little known about changes in supraspinatus mechanical properties in context of other rotator cuff tendons. Alterations in tendon mechanical properties may indicate damage and an increased risk of rupture, and thus, the purpose of this study was to use a rat model to define age-related alterations in rotator cuff tendon mechanics to determine why the supraspinatus is more susceptible to tears due to aging than the infraspinatus, subscapularis, and teres minor. Fatigue, viscoelastic, and quasi-static properties were evaluated in juvenile, adult, aged, and geriatric rats. Aging ubiquitously and adversely affected all rotator cuff tendons tested, particularly leading to increased stiffness, decreased stress relaxation, and decreased fatigue secant and tangent moduli in geriatric animals, suggesting a common intrinsic mechanism due to aging in all rotator cuff tendons. This study demonstrates that aging has a significant effect on rotator cuff tendon mechanical properties, though the supraspinatus was not preferentially affected. Thus, we are unable to attribute the aging-associated increase in supraspinatus tears to its mechanical response alone.
Surgical repairs of torn rotator cuff tendons frequently fail. Immobilization has been shown to improve tissue mechanical properties in an animal model of rotator cuff repair, and passive motion has ...been shown to improve joint mechanics in animal models of flexor tendon repair. Our objective was to determine if daily passive motion would improve joint mechanics in comparison with continuous immobilization in a rat rotator cuff repair model. We hypothesized that daily passive motion would result in improved passive shoulder joint mechanics in comparison with continuous immobilization initially and that there would be no differences in passive joint mechanics or insertion site mechanical properties after four weeks of remobilization.
A supraspinatus injury was created and was surgically repaired in sixty-five Sprague-Dawley rats. Rats were separated into three postoperative groups (continuous immobilization, passive motion protocol 1, and passive motion protocol 2) for two weeks before all underwent a remobilization protocol for four weeks. Serial measurements of passive shoulder mechanics (internal and external range of motion and joint stiffness) were made before surgery and at two and six weeks after surgery. After the animals were killed, collagen organization and mechanical properties of the tendon-to-bone insertion site were determined.
Total range of motion for both passive motion groups (49% and 45% of the pre-injury values) was less than that for the continuous immobilization group (59% of the pre-injury value) at two weeks and remained significantly less following four weeks of remobilization exercise. Joint stiffness at two weeks was increased for both passive motion groups in comparison with the continuous immobilization group. At both two and six weeks after repair, internal range of motion was significantly decreased whereas external range of motion was not. There were no differences between the groups in terms of collagen organization or mechanical properties.
In this model, immediate postoperative passive motion was found to be detrimental to passive shoulder mechanics. We speculate that passive motion results in increased scar formation in the subacromial space, thereby resulting in decreased range of motion and increased joint stiffness. Passive motion had no effect on collagen organization or tendon mechanical properties measured six weeks after surgery.
Rotator cuff repair failure remains common due to poor tendon healing, particularly at the enthesis. We previously showed that pulsed electromagnetic field (PEMF) therapy improved the mechanical ...properties of the rat supraspinatus tendon postoperatively. However, little is known about the mechanisms behind PEMF‐dependent contributions to improved healing in this injury model. The objective of this study was to determine the influence of PEMF treatment on tendon gene expression and cell composition, as well as bone microarchitecture and dynamic bone metabolism during early stages of healing. We hypothesized that PEMF treatment would amplify tendon‐healing related signaling pathways while mitigating inflammation and improve bone metabolism at the repair site. Rats underwent rotator cuff injury and repair followed by assignment to either control (non‐PEMF) or PEMF treatment groups. Gene and protein expression as well as tendon and bone histological assessments were performed 3, 7, 14, 21, and 28 days after injury. Gene expression data demonstrated an upregulation in the bone morphogenetic protein 2 signaling pathway and increases in pro‐osteogenic genes at the insertion, supporting important processes to re‐establish the tendon‐bone interface. PEMF also downregulated genes related to a fibrotic healing response. Anti‐inflammatory effects were demonstrated by both gene expression and macrophage phenotype. PEMF significantly increased the rate of kinetic bone formation directly adjacent to the tendon enthesis as well as the number of cuboidal surface osteoblasts (active osteoblasts) in the humeral head. This study has provided insight into how PEMF affects cellular and molecular processes in the supraspinatus tendon and adjacent bone after injury and repair.
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