Editorial Commentary: Illuminating the Fragility of Nonsignificant Trials in Sports Medicine

Orthopaedic clinical research findings can be prone to β error (false negative), owing to small sample sizes. Such trials show no difference between groups when, in fact, a difference may exist. The reverse fragility index is defined as the number of "events" that would cause an individual research study's findings to flip from nonsignificant to statistically significant, and this index can help determine the clinical relevance and validity of clinical trials reporting nonsignificant results. Orthopaedic surgeons should critically evaluate clinical research that shows no statistically significant difference between groups to rule out a β error, given that underpowered studies are particularly prone to fragility. If an orthopaedic trial reports statistically insignificant results, this does not mean the results are clinically insignificant.

Counteractive Effects of IL-33 and IL-37 on Inflammation in Osteoarthritis

Osteoarthritis (OA) is a chronic inflammatory disease where pro-inflammatory cytokines, damage-associated molecular patterns (DAMPs), and macrophages play a crucial role. However, the interactive role of these mediators, the exact cause precipitating OA and definitive treatment for OA are not known yet. Moreover, the interactive role of interleukin (IL)-33 and IL-37 with other factors in the pathogenesis of OA has not been discussed elaborately. In this study, we analyzed the expression of IL-33 and IL-37 in human OA knee and hip joint cartilage tissues. The effect of increased DAMPs, IL-33, and IL-37 on IL-6, tumor necrosis factor (TNF)-α, toll-like receptors (TLRs), and matrix metalloproteinases (MMPs) expression was delineated using human normal and osteoarthritic chondrocytes. The effect of anti-inflammatory cytokine IL-37 on various mediators of inflammation in the presence of IL-33, rHMGB-1, and LPS was investigated to delineate the effects of IL-37. Further, the effects of blocking IL-33 downstream signaling and the effects of IL-33 and IL-37 on macrophage polarization were assessed along with examining the macrophage phenotypes in human OA cartilage tissues. The results of this study revealed increased expression of IL-33 in OA cartilage and that IL-33 increases IL-6, TNF-α, TLRs, and MMPs expression and favors phenotypic conversion towards the M1 phenotype, while IL-37 and blocking IL-33 receptor ST2 have opposite effects. Overall, the results suggest that blocking IL-33 and increasing IL-37 act synergistically to attenuate inflammation and might serve as potential therapeutics in OA.

Hybrid interpenetrating hydrogel network favoring the bidirectional migration of tenocytes for rotator cuff tendon regeneration

Replenishment of tenocytes to the injury site is an ideal strategy to improve healing response and accelerate the tendon ECM regeneration. The present study focused on the synthesis and characterization of a hybrid hydrogel scaffold system poly(propylene-fumarate)-alginate-polyvinyl alcohol-acrylic acid (PAPA) using poly(propylene-fumarate) (PPF), alginate, polyvinyl alcohol (PVA) and acrylic acid and the in vitro investigation of bidirectional mobility of swine shoulder tenocytes (SST) for its potential application in rotator-cuff tendon regeneration. IR analysis revealed the presence of alginate, PPF and PVA segments on the surface, SEM and AFM analyses revealed the porous and nano-topographical features of PAPA, respectively, swelling was 712.6 ± 84.21% with the EWC (%) of 87.59 ± 1.26 having the diffusional exponent and swelling constant 0.551 and 1.8, respectively. PAPA was biodegradable, cytocompatible and supported long-term survival of SSTs. SEM imaging revealed the adhesion, colonization, and sheet formation of SSTs within the PAPA hydrogel network. The SSTs seeded on the PAPA scaffolds were peculiar for their bidirectional migration as the anterograde movement was completed in 9 days whereas the retrograde infiltration occurred up to the depth of 198 μm. These findings suggest the promising translational potential of PAPA scaffold system in the management of rotator cuff tendon injury.

Editorial Commentary: Off the Hip or Off the Shelf? An Analysis of Autograft and Allograft as a Graft Source for Shoulder Superior Capsular Reconstruction

Superior capsular reconstruction can effectively relieve pain and improve function in the rotator cuff-deficient shoulder, but the optimal graft has not been determined. Multiple authors have demonstrated the effectiveness of the procedure, but bias and heterogeneity between studies do not allow valid comparative analysis of graft type. Until we can adequately compare outcomes, complications, or survival, graft availability and cost may be the greatest determinants of graft selection.

Matrix regeneration proteins in the hypoxia-triggered exosomes of shoulder tenocytes and adipose-derived mesenchymal stem cells

Regenerative functions of exosomes rely on their contents which are influenced by pathological stimuli, including hypoxia, in rotator cuff tendon injuries (RCTI). The hypoxic environment triggers tenocytes and adjacent adipose-derived mesenchymal stem cells (ADMSCs) to release regenerative mediators to the ECM via the exosomes which elicit autocrine/paracrine responses to protect the tendon matrix from injury. We investigated the exosomal protein contents from tenocytes and subcutaneous ADMSCs from the shoulder of Yucatan microswine cultured under hypoxic conditions (2% O₂). The exosomal proteins were detected using high-resolution mass spectrometry nano-LC-MS/MS Tribrid system and were compiled using 'Scaffold' software. Hypoxic exosomes from tenocytes and ADMSCs carried 199 and 65 proteins, respectively. The key proteins identified by mass spectrometry and associated with ECM homeostasis from hypoxic ADMSCs included MMP2, COL6A, CTSD and TN-C and those from hypoxic tenocytes were THSB1, NSEP1, ITIH4 and TN-C. These findings were confirmed at the mRNA and protein level in the hypoxic ADMSCs and tenocytes. These proteins are involved in multiple signaling pathways of ECM repair/regeneration. This warrants further investigations for their translational significance in the management of RCTI.

Therapeutic potential of exosomes in rotator cuff tendon healing

Rotator cuff tears are common musculoskeletal injuries that can cause significant pain and disability. While the clinical results of rotator cuff repair can be good, failure of tendon healing remains a significant problem. Molecular mechanisms underlying structural failure following surgical repair remain unclear. Histologically, enhanced inflammation, disorganization of the collagen fibers, calcification, apoptosis and tissue necrosis affect the normal healing process. Mesenchymal stem cells (MSCs) have the ability to provide improved healing following rotator cuff repair via the release of mediators from secreted 30-100 nm extracellular vesicles called exosomes. They carry regulatory proteins, mRNA and miRNA and have the ability to increase collagen synthesis and angiogenesis through increased expression of mRNA and release of proangiogenic factors and regulatory proteins that play a major role in proper tissue remodeling and preventing extracellular matrix degradation. Various studies have shown the effect of exosomes on improving outcome of cutaneous wound healing, scar tissue formation, degenerative bone disease and Duchenne Muscular Dystrophy. In this article, we critically reviewed the potential role of exosomes in tendon regeneration and propose the novel use of exosomes alone or seeded onto biomaterial matrices to stimulate secretion of favorable cellular factors in accelerating the healing response following rotator cuff repair.

Do we really need to order magnetic resonance imaging? Shoulder surgeon ultrasound practice patterns and beliefs

Background

Despite significant benefits, many orthopedic surgeons are hesitant to incorporate diagnostic ultrasound into their practice. This may be because of a lack of comfort, knowledge, and/or training. The purpose of this study was to analyze practice patterns regarding the use of shoulder ultrasound by orthopedic surgeons to diagnose rotator cuff tears.

Materials and methods

We conducted a survey of the members of the American Shoulder and Elbow Surgeons (ASES) regarding their use of ultrasound. A systematic review of the literature on the use of ultrasound in the shoulder by orthopedic surgeons was also performed.

Results

Of the members of ASES responding to the survey, 55% are using ultrasound for diagnostic purposes in the shoulder. The leading reason for not using ultrasound as the sole imaging modality prior to performing rotator cuff repair was lack of confidence in the ability to determine the reparability of the tear (83%). Our systematic review showed that for an orthopedic surgeon diagnosing a full-thickness rotator cuff tear, the mean sensitivity was 92% and mean specificity was 89%.

Conclusions

Many ASES surgeons are not using ultrasound in the shoulder despite its many potential benefits over magnetic resonance imaging. This is because of a lack of confidence in the ability to quantify fatty infiltration, muscle atrophy, and the level of retraction medial to the acromion. Our systematic review showed that orthopedic surgeons can be accurate in the diagnosis of full-thickness rotator cuff tears. Future research should focus on defining parameters of shoulder ultrasound associated with rotator cuff tendon reparability. Educating surgeons on ultrasound technique, cost, and evidence may be a promising strategy to enhance the value in musculoskeletal care delivery.

Genes interconnecting AMPK and TREM-1 and associated microRNAs in rotator cuff tendon injury

Fatty infiltration and inflammation delay the healing responses and raise major concerns in the therapeutic management of rotator cuff tendon injuries (RCTI). Our evaluations showed the upregulation of 'metabolic check point' AMPK and inflammatory molecule, TREM-1 from shoulder biceps tendons collected from RCTI subjects. However, the epigenetic regulation of these biomolecules by miRNAs is largely unknown and it is likely that a deeper understanding of the mechanism of action can have therapeutic potential for RCTI. Based on this background, we have evaluated the miRNAs from RCTI patients with fatty infiltration and inflammation (FI group) and compared with RCTI patients without fatty infiltration and inflammation (No-FI group). NetworkAnalyst was employed to evaluate the genes interconnecting AMPK and TREM-1 pathway, using PRKAA1 (AMPK), TREM-1, HIF1α, HMGB1, and AGER as input genes. The most relevant miRNAs were screened by considering the fold change below - 7.5 and the number of target genes 10 and more which showed 13 miRNAs and 216 target genes. The exact role of these miRNAs in the fatty infiltration and inflammation associated with RCTI is still unknown and the understanding of biological activity of these miRNAs can pave ways to develop miRNA-based therapeutics in the management of RCTI.

Epigenetic mechanisms and implications in tendon inflammation (Review)

Cellular inflammation is not just an immediate response following pathogenic infections or resulting from damage due to injury, it is also associated with normal physiological functions, including wound healing and tissue repair. The existence of such a definitive role in normal physiology and in disease pathology indicates the presence of a regulatory mechanism that is tightly controlled in normal cells. A tight control over gene expression is associated with regulatory mechanisms in the cells, which can be either inducible or epigenetic. Among other intracellular mechanisms that contribute to epigenetic gene regulation, DNA methylation has been shown to maintain a tight control over gene expression through the actions of DNA methyltransferases (DNMTs). With a clear role in developmental and tissue‑specific temporal gene regulation, the involvement of DNMTs is evident in normal and pathological conditions. In this review article, inflammation in tendons associated with disease pathology and tissue repair or regeneration at the musculoskeletal joints is critically reviewed. More specifically, the review focuses on known epigenetic mechanisms and their role in the clinical presentation of the disease in human joint disorders associated with tendon inflammation, with an emphasis on the gene regulatory mechanisms that are controlled through DNA methylation, histone deacetylation, and microRNAs.

Amplification of Mitochondrial Activity in the Healing Response Following Rotator Cuff Tendon Injury

Mitochondrial function following rotator cuff tendon injury (RCI) influences the tendon healing. We examined the mitochondrial morphology and function under hypoxia in the shoulder tendon tissue from surgically-induced tenotomy-RCI rat model and cultured swine tenocytes. The tendon tissue was collected post-injury on 3-5 (Group-A), 10-12 (Group-B), and 22-24 (Group-C), days and the corresponding contralateral tendons were used as control for each group. There was higher protein expression of citrate synthase (P < 0.0001) [10.22 MFI (mean fluorescent intensity)] and complex-1 (P = 0.0008) (7.86 MFI) in Group-A and Group-B that decreased in Group-C [(P = 0.0201) (5.78 MFI and (P = 0.7915) (2.32 MFI), respectively] compared to control tendons. The ratio of BAX:Bcl2 (Bcl2 associated x protein:B cell lymphoma 2) in RCI tendons increased by 50.5% (Group-A) and 68.4% (Group-B) and decreased by 25.8% (Group-C) compared to normoxic controls. Hypoxia increased β-tubulin expression (P = 0067) and reduced PGC1-α (P = 0412) expression in the isolated swine tenocytes with no effect on the protein expression of Complex-1 (P = 7409) and citrate synthase (P = 0.3290). Also, the hypoxic tenocytes exhibited about 4-fold increase in mitochondrial superoxide (P < 0.0001), altered morphology and mitochondrial pore integrity, and increase in mitochondrial density compared to normoxic controls. These findings suggest the critical role of mitochondria in the RCI healing response.

Collagen I: a kingpin for rotator cuff tendon pathology

Derangements in tendon matrisome are pathognomonic for musculoskeletal disorders including rotator cuff tendinopathies (RCT). Collagen type-1 accounts for more than 85% of the dry weight of tendon extracellular matrix (ECM). The understanding of basic tendon physiology, organization of ECM, structure and function of component biomolecules of matrisome and the underlying regulatory mechanisms reveal the pathological events associated with RCT. Histomorphological evidence from RCT patients and animal models illustrate that ECM disorganization is the major hallmark in tendinopathy where a significant decrease in type-1 collagen is prevalent. However, the molecular events and regulatory signals associated with the regulation of collagen organization and its composition switch in response to pathological stimuli are largely unknown. The elucidation of various regulatory signalling pathways associated with collagen type-1 gene expression could benefit to develop novel promising therapeutic approaches to restore the tendon ECM. The major focus of the article is to critically evaluate tendon architecture regarding type-1 collagen, the molecular events associated with gene expression, secretion and maturation, the possible mechanisms of type-1 collagen regulation and its translational significance in RCT management.

Alterations in tendon microenvironment in response to mechanical load: potential molecular targets for treatment strategies

Rotator cuff (RC) tendons could beinflicted in many ways with an eventual outcome of pain, weakness and disability, which represent a large burden on health care cost. However, optimal healing, either conservatively or with surgical intervention, remains an issue that needs further investigation. Disorders of the RC tendons may result from external factors like trauma, or internal factors through physiologic and metabolic derangement. Most RC tendon disorders may be asymptomatic and may result from an over-activity of the inflicted shoulder and its tendons. Such tendon disorders are poorly diagnosed since patients do not seek medical attention until pain or weakness ensue. Immunological and biochemical events in RC disorders due to mechanical intolerance have not been investigated. Generally, the mechanical load drives normal physiological properties of the tendon. But, mechanical overload/burden exerts stress on tenocytes, and disrupts the tendon microenvironment by triggering a multitude of signaling pathways leading to extracellular matrix remodeling, disorganization, alteration in collagen composition and apoptosis. These events result in weak tendon which is highly susceptible to rupture or tear. In this article, we critically reviewed the intrinsic signaling pathways that are excessively triggered by continuous mechanical load and the counteracting physiological responses and associated derangements. The elucidation of the molecular events underlying mechanical stress-induced symptomatic/asymptomatic tendinopathy could provide information on potential target sites for translational application in the management of rotator cuff disorders.

Recent strategies in cartilage repair: A systemic review of the scaffold development and tissue engineering

Osteoarthritis results in irreparable loss of articular cartilage. Due to its avascular nature and low mitotic activity, cartilage has little intrinsic capacity for repair. Cartilage loss leads to pain, physical disability, movement restriction, and morbidity. Various treatment strategies have been proposed for cartilage regeneration, but the optimum treatment is yet to be defined. Tissue engineering with engineered constructs aimed towards developing a suitable substrate may help in cartilage regeneration by providing the mechanical, biological and chemical support to the cells. The use of scaffold as a substrate to support the progenitor cells or autologous chondrocytes has given promising results. Leakage of cells, poor cell survival, poor cell differentiation, inadequate integration into the host tissue, incorrect distribution of cells, and dedifferentiation of the normal cartilage are the common problems in tissue engineering. Current research is focused on improving mechanical and biochemical properties of scaffold to make it more efficient. The aim of this review is to provide a critical discussion on existing challenges, scaffold type and properties, and an update on ongoing recent developments in the architecture and composition of scaffold to enhance the proliferation and viability of mesenchymal stem cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2343-2354, 2017.

Changing Body Movement Patterns in 9-Year-Old Baseball Pitchers: A Pilot Study

Background:

Arm injuries in throwing athletes continue to increase. Injuries may be due to multiple variables, including inefficient body movement patterns, especially in young baseball throwers. It is unclear whether these patterns can be efficiently altered in this population.

Purpose/Hypothesis:

To investigate the effect of a novel 21-day throwing program on body movement patterns in youth baseball players using common practical tools. Our hypothesis was that this program would change body movement patterns over a relatively short period.

Study Design:

Descriptive laboratory study.

Methods:

Ten 9-year-old baseball athletes were asked to participate in a 21–consecutive day throwing program focused on decreasing inefficiencies. All participants underwent video evaluation from 2 vantage points as well as radar evaluation before and after the programs. Throwing arm humerothoracic and antecubital angles as well as pelvic angles in the frontal view were measured at the time of front (directional) leg heel/toe down (late cocking) for each of 3 pitches. Glove-side humerothoracic angles and back leg minimum popliteal angles were measured from behind for each of 3 additional pitches. Velocity was measured using a radar gun. All angular measurements were performed by a physical therapist blinded to the purposes of the program and study as well as to video chronology.

Results:

Throwing arm antecubital angle (P = .01) and humerothoracic angle (P = .03) as well as back leg minimum popliteal angle (P = .03) all decreased, with mean decreases of 35°, 10°, and 8°, respectively. Velocity increased with decreased back leg popliteal angles (P = .019); mean velocity increased 2.6 mph (P = .016).

Conclusion:

Young baseball throwers can quickly retrain their bodies to accomplish different movement patterns.

Clinical Relevance:

This novel throwing program may have implications for injury prevention and treatment as we identify better baseball-throwing movement patterns.

Vitamin D and Its Effects on Articular Cartilage and Osteoarthritis

Background:

Osteoarthritis (OA) currently affects 10% of the American population. There has been a recent push to determine exactly what causes OA and how it can be treated most effectively. Serum vitamin D levels have been associated with OA and may have an effect on articular cartilage remodeling.

Purpose:

To critically review the published research on the effect of vitamin D on articular cartilage and the development of OA as well as on the mechanism behind cartilage regeneration and degeneration.

Study Design:

Review.

Methods:

A systematic search of PubMed and the Web of Science was performed for relevant studies published in the English language through April 30, 2016, using the terms vitamin D, articular cartilage, and osteoarthritis.

Results:

On a molecular level, 1α,25(OH)₂D₃, the activated form of vitamin D, plays a role in articular cartilage degeneration. Vitamin D binds to vitamin D receptors, triggering a signaling cascade that leads to chondrocyte hypertrophy. In clinical trials, vitamin D deficiency poses a risk factor for OA, and those with decreased cartilage thickness are more likely to be vitamin D–insufficient.

Conclusion:

The role of vitamin D supplementation in the treatment or prevention of OA remains uncertain. More research is needed to reconcile these conflicting findings.

MicroRNAs associated with inflammation in shoulder tendinopathy and glenohumeral arthritis

Inflammation is associated with glenohumeral arthritis and rotator cuff tendon tears. Epigenetically, miRNAs tightly regulate various genes involved in the inflammatory response. Alterations in the expression profile of miRNAs and the elucidation of their target genes with respect to the pathophysiology could improve the understanding of their regulatory role and therapeutic potential. Here, we screened key miRNAs that mediate inflammation and linked with JAK2/STAT3 pathway with respect to the coincidence of glenohumeral arthritis in patients suffering from rotator cuff injury (RCI). Human resected long head of the biceps tendons were examined for miRNA profile from two groups of patients: Group 1 included the patients with glenohumeral arthritis and massive rotator cuff tears and the Group 2 patients did not have arthritis or rotator cuff tears. The miRNA profiling revealed that 235 miRNAs were highly altered (fold change less than -3 and greater than +2 were considered). Data from the NetworkAnalyst program revealed the involvement and interaction between 3,430 different genes associated with inflammation out of which 284 genes were associated with JAK2/STAT3 pathway and interconnect 120 different pathways of inflammation. Around 1,500 miRNAs were found to play regulatory role associated with these genes of inflammatory responses and 77 miRNAs were found to regulate more than 10 genes. Among them, 25 genes with less than tenfold change were taken to consideration which altogether constitute for the regulation of 102 genes. Targeting these miRNAs and the underlying regulatory mechanisms may advance our knowledge to develop promising therapies in the management of shoulder tendon pathology.

Pain and the pathogenesis of biceps tendinopathy

Biceps tendinopathy is a relatively common ailment that typically presents as pain, tenderness, and weakness in the tendon of the long head of the biceps brachii. Though it is often associated with degenerative processes of the rotator cuff and the joint, this is not always the case, thus, the etiology remains considerably unknown. There has been recent interest in elucidating the pathogenesis of tendinopathy, since it can be an agent of chronic pain, and is difficult to manage. The purpose of this article is to critically evaluate relevant published research that reflects the current understanding of pain and how it relates to biceps tendinopathy. A review of the literature was conducted to create an organized picture of how pain arises and manifests itself, and how the mechanism behind biceps tendinopathy possibly results in pain. Chronic pain is thought to arise from neurogenic inflammation, central pain sensitization, excitatory nerve augmentation, inhibitory nerve loss, and/or dysregulation of supraspinal structures; thus, the connections of these theories to the ones regarding the generation of biceps tendinopathy, particularly the neural theory, are discussed. Pain mediators such as tachykinins, CGRP, and alarmins, in addition to nervous system ion channels, are highlighted as possible avenues for research in tendinopathy pain. Recognition of the nociceptive mechanisms and molecular of biceps tendinopathy might aid in the development of novel treatment strategies for managing anterior shoulder pain due to a symptomatic biceps tendon.

Increased expression of damage-associated molecular patterns (DAMPs) in osteoarthritis of human knee joint compared to hip joint

Osteoarthritis (OA) is a degenerative disease characterized by the destruction of cartilage. The greatest risk factors for the development of OA include age and obesity. Recent studies suggest the role of inflammation in the pathogenesis of OA. The two most common locations for OA to occur are in the knee and hip joints. The knee joint experiences more mechanical stress, cartilage degeneration, and inflammation than the hip joint. This could contribute to the increased incidence of OA in the knee joint. Damage-associated molecular patterns (DAMPs), including high-mobility group box-1, receptor for advanced glycation end products, and alarmins (S100A8 and S100A9), are released in the joint in response to stress-mediated chondrocyte and cartilage damage. This facilitates increased cartilage degradation and inflammation in the joint. Studies have documented the role of DAMPs in the pathogenesis of OA; however, the comparison of DAMPs and its influence on OA has not been discussed. In this study, we compared the DAMPs between OA knee and hip joints and found a significant difference in the levels of DAMPs expressed in the knee joint compared to the hip joint. The increased levels of DAMPs suggest a difference in the underlying pathogenesis of OA in the knee and the hip and highlights DAMPs as potential therapeutic targets for OA in the future.

Damage-associated molecular patterns in the pathogenesis of osteoarthritis: potentially novel therapeutic targets

Osteoarthritis (OA) is a chronic disease that degrades the joints and is often associated with increasing age and obesity. The two most common sites of OA in adults are the knee and hip joints. Increased mechanical stress on the joint from obesity can cause the articular cartilage to degrade and release damage-associated molecular patterns (DAMPs). These DAMPs are involved in various molecular pathways that interact with nuclear factor-kappa B and result in the transcription of inflammatory cytokines and activation of matrix metalloproteinases that progressively destroy cartilage. This review focuses on the interactions and contribution to the pathogenesis and progression of OA through the DAMPs: high-mobility group box 1 (HMGB-1), the receptor for advanced glycation end-products (RAGE), the alarmin proteins S100A8 and S100A9, and heparan sulfate. HMGB-1 is released from damaged or necrotic cells and interacts with toll-like receptors (TLRs) and RAGE to induce inflammatory signals, as well as behave as an inflammatory cytokine to activate innate immune cells. RAGE interacts with HMGB-1, advanced glycation end-products, and innate immune cells to increase local inflammation. The alarmin proteins are released following cell damage and interact through TLRs to increase local inflammation and cartilage degradation. Heparan sulfate has been shown to facilitate the binding of HMGB-1 to RAGE and could play a role in the progression of OA. Targeting these DAMPs may be the potential therapeutic strategies for the treatment of OA.

MicroRNAs Associated with Shoulder Tendon Matrisome Disorganization in Glenohumeral Arthritis

The extracellular matrix (ECM) provides core support which is essential for the cell and tissue architectural development. The role of ECM in many pathological conditions has been well established and ECM-related abnormalities leading to serious consequences have been identified. Though much has been explored in regards to the role of ECM in soft tissue associated pathologies, very little is known about its role in inflammatory disorders in tendon. In this study, we performed microRNA (miRNA) expression analysis in the long head of the human shoulder biceps tendon to identify key genes whose expression was altered during inflammation in patients with glenohumeral arthritis. We identified differential regulation of matrix metalloproteinases (MMPs) that could be critical in collagen type replacement during tendinopathy. The miRNA profiling showed consistent results between the groups and revealed significant changes in the expression of seven different miRNAs in the inflamed tendons. Interestingly, all of these seven miRNAs were previously reported to have either a direct or indirect role in regulating the ECM organization in other pathological disorders. In addition, these miRNAs were also found to alter the expression levels of MMPs, which are the key matrix degrading enzymes associated with ECM-related abnormalities and pathologies. To our knowledge, this is the first report which identifies specific miRNAs associated with inflammation and the matrix reorganization in the tendons. Furthermore, the findings also support the potential role of these miRNAs in altering the collagen type ratio in the tendons during inflammation which is accompanied with differential expression of MMPs.

Triggering receptor expressed on myeloid cells and 5'adenosine monophosphate-activated protein kinase in the inflammatory response: a potential therapeutic target

INTRODUCTION

The events in the cellular and molecular signaling triggered during inflammation mitigate tissue healing. The metabolic check-point control mediated by 5'-adenosine monophosphate-activated protein kinase (AMPK) is crucial for switching the cells into an activated state capable of mediating inflammatory events. The cell metabolism involved in the inflammatory response represents a potential therapeutic target for the pharmacologic management of inflammation. Areas covered: In this article, a critical review is presented on triggering receptor expressed on myeloid cell (TREM) receptors and their role in the inflammatory responses, as well as homeostasis between different TREM molecules and their regulation. Additionally, we discussed the relationship between TREM and AMPK to identify novel targets to limit the inflammatory response. Literature search was carried out from the National Library of Medicine's Medline database (using PubMed as the search engine) and Google Scholar and identified relevant studies up to 30 March 2016 using inflammation, TREM, AMPK, as the key words. Expert commentary: The prevention of phenotype switching of immune cells during inflammation by targeting AMPK and TREM-1 could be beneficial for developing novel management strategies for inflammation and associated complications.

Vitamin D attenuates inflammation, fatty infiltration, and cartilage loss in the knee of hyperlipidemic microswine

Background

Osteoarthritis (OA) of the knee joint is a degenerative process resulting in cartilage loss. Recent evidence suggests that OA is not merely a disease of cartilage but a disease of the entire knee joint and that inflammation may play an important role. OA has been associated with vitamin D deficiency. Vitamin D as an immunomodulator and anti-inflammatory agent may attenuate inflammation in the knee. The aim of this study was to assess the anti-inflammatory effect of vitamin D on inflammation in the knee.

Methods

This study was conducted with 13 microswine on a high cholesterol diet categorized into three groups of vitamin D-deficient, vitamin D-sufficient, and vitamin D supplementation. After 1 year, microswine were killed, and their knee joint tissues were harvested. Histological and immunofluorescence studies were carried out on the tissue specimens to evaluate the effect of vitamin D status.

Results

Histological and immunofluorescence studies of the knee joint tissues showed (1) increased inflammation in the knee joint tissues, (2) fatty infiltration in quadriceps muscle, patellar tendon, and collateral ligaments, and (3) chondrocyte clustering in the vitamin D-deficient and vitamin D-sufficient groups compared with the vitamin D supplementation group. Architectural distortion of the quadriceps muscle, patellar tendon, and collateral ligaments was also seen in the areas of inflammatory foci and fatty infiltration in the vitamin D-deficient group.

Conclusions

Decreased inflammation and fatty infiltration in the vitamin D supplementation group suggest the potential role of vitamin D in attenuating inflammation and fatty infiltration as well as in protecting the architecture of the tissue in the knee joint.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1099-6) contains supplementary material, which is available to authorized users.

Accuracy of the Subchondral Smile and Surface Referencing Techniques in Reverse Shoulder Arthroplasty

Inferior glenoid baseplate tilt relative to the coronal axis of the scapular body has been associated with improved results and fewer postoperative complications in reverse shoulder arthroplasty. However, the native glenoid surface is not always a reliable reference for the true scapular axis. Digital preoperative planning software and advanced imaging now allow surgeons to more precisely determine optimal glenoid placement. The purpose of this study was to evaluate the accuracy of the subchondral smile and cannulated surface guide techniques in achieving inferior glenoid baseplate tilt by using 3-dimensional preoperative planning software. Virtual glenoid baseplate preparation and implantation was performed using computed tomography scans of 16 shoulders with rotator cuff deficiency. Two techniques were used: a subchondral smile technique that preferentially reams the interior glenoid, resulting in the appearance of a smile, and a cannulated surface guide technique that references the native glenoid face to place the baseplate in 10° of inferior tilt. Using the subchondral smile technique, the glenoid baseplate was implanted at a mean of 8.9° of superior tilt relative to the transverse scapular axis. Using the surface guide technique, the glenoid baseplate was implanted at a mean of 2.8° of superior tilt. Neither the subchondral smile technique nor the 10° cannulated surface guide technique is a reliable method to produce inferior glenoid tilt relative to the transverse axis of the scapula. Three-dimensional preoperative planning software is a useful tool when attempting to achieve optimal glenoid baseplate positioning in reverse shoulder arthroplasty. [Orthopedics. 2016; 39(4):e615-e620.].

Vitamin D and the immunomodulation of rotator cuff injury

Tendon-to-bone healing after rotator cuff repair surgery has a failure rate of 20%–94%. There has been a recent interest to determine the factors that act as determinants between successful and unsuccessful rotator cuff repair. Vitamin D level in patients is one of the factors that have been linked to bone and muscle proliferation and healing, and it may have an effect on tendon-to-bone healing. The purpose of this article is to critically review relevant published research that relates to the effect of vitamin D on rotator cuff tears and subsequent healing. A review of the literature was conducted to identify all studies that investigate the relationship between vitamin D and tendon healing, in addition to its mechanism of action. The data were then analyzed in order to summarize what is currently known about vitamin D, rotator cuff pathology, and tendon-to-bone healing. The activated metabolite of vitamin D, 1α,25-dihydroxyvitamin D₃, affects osteoblast proliferation and differentiation. Likewise, vitamin D plays a significant role in the tendon-to-bone healing process by increasing the bone mineral density and strengthening the skeletal muscles. The 1α,25-dihydroxyvitamin D₃ binds to vitamin D receptors on myocytes to stimulate growth and proliferation. The form of vitamin D produced by the liver, calcifediol, is a key initiator of the myocyte healing process by moving phosphate into myocytes, which improves function and metabolism. Investigation into the effect of vitamin D on tendons has been sparse, but limited studies have been promising. Matrix metalloproteinases play an active role in remodeling the extracellular matrix (ECM) of tendons, particularly deleterious remodeling of the collagen fibers. Also, the levels of transforming growth factor-β3 positively influence the success of the surgery for rotator cuff repair. In the tendon-to-bone healing process, vitamin D has been shown to successfully influence bone and muscle healing, but more research is needed to delve into the mechanisms of vitamin D as a factor in skeletal tendon health and healing.

Late Partial Dissociation of a Humeral Head Morse Taper Associated with Periprosthetic Proximal Humeral Fracture: A Case Report

CASE

A fifty-two-year-old man who had undergone total shoulder arthroplasty ten years previously presented following a mechanical fall onto his operatively treated shoulder, resulting in a periprosthetic humeral fracture and partial dissociation of the humeral head from the stem.

CONCLUSION

Shoulder surgeons should consider late disengagement of the Morse taper as a potential cause of surgical failure. Partial late dissociation of the humeral head from the stem after shoulder arthroplasty is possible and can be associated with a fracture. The shoulder surgeon should be aware of this potential complication when evaluating periprosthetic proximal humeral fractures, emphasizing the importance of attention to detail when evaluating patients.

Immunobiological factors aggravating the fatty infiltration on tendons and muscles in rotator cuff lesions

Rotator cuff lesions (RCLs) are a common cause of shoulder pain and dysfunction. The rotator cuff tendons can degenerate and/or tear from the greater tuberosity of the humerus, which is associated with several anatomical, physiological, biochemical, and molecular changes in tendon and muscle. In this article, these pathways are critically reviewed and discussed with various management strategies of RCLs. The article also highlights the immunobiological responses following the RCL and the inherent repair mechanisms elicited by the body. The greatest difficulty in treating this pathology is that the muscle can undergo irreversible fatty infiltration in the setting of chronic tears that is associated with poor surgical outcomes. The article also investigates the key molecular pathways of the muscle homeostasis (mTOR, Rho kinase, AMPK, and Ca(2+)) with the energy metabolism to propose a possible mechanism for fatty infiltration. Future research is warranted to target the key players of these pathways in the management of fatty infiltration and thus RCL.

Intramedullary nailing of the proximal humerus: evolution, technique, and results

Proximal humerus fractures are the third most common fracture in the elderly. Although most fractures can be treated conservatively with acceptable outcomes, certain fracture patterns are at high risk for progression to humeral malunions, nonunions, stiffness, and post-traumatic arthrosis. The goal of antegrade humeral nailing of proximal humerus fractures is to provide stability to a reduced fracture that allows early motion to optimize patient outcomes. Certain technical pearls are pivotal in managing these difficult fractures with nails; these include rotator cuff management, respect of the soft tissues, anatomic tuberosity position, blood supply maintenance, knowledge of the deforming forces on the proximal humerus, fracture reduction, and rehabilitation strategies. Modern proximal humeral nail designs and techniques assist the surgeon in adhering to these principles and have demonstrated promising outcomes. Humeral nail designs have undergone significant innovation during the past 40 years and now can provide stable fixation in the humeral shaft distally as well as improved stability in the head and tuberosity fragments, which were the common site of fixation failure with earlier generation implants. Compared with other fixation strategies, such as locking plate fixation, no compelling evidence exists to suggest one technique over another. The purpose of this review is to describe the history, results, new designs, and techniques that make modern intramedullary nailing of proximal humerus fractures a viable treatment option.

The association of incomplete glenoid component seating and periprosthetic glenoid radiolucencies after total shoulder arthroplasty

BACKGROUND

Radiolucent lines surrounding prosthetic glenoid components are commonly seen after unconstrained total shoulder arthroplasty and can be a harbinger of subsequent glenoid component failure. Whether less than 100% glenoid seating is associated with the development of radiolucent lines around glenoid prostheses is unknown. This study investigated the association between incomplete glenoid component seating and periprosthetic glenoid radiolucencies.

METHODS

Thirty-six unconstrained total shoulder arthroplasties were performed in 29 patients for primary glenohumeral osteoarthritis with a minimum 2-year follow-up. All were implanted with a partially cemented all-polyethylene glenoid prosthesis. Patients were evaluated with standardized plain films preoperatively and postoperatively and with thin-cut computed tomography (CT) scans at the latest follow-up. The Lazarus and Yian classifications were used to assess radiolucency and seating on radiographs and CT scans. Ratings were calculated for intraobserver and interobserver reliability and given κ, the Kendall coefficient, and interclass correlation coefficient values.

RESULTS

At a mean of 43 months (range 24-26 months) after surgery, neither Lazarus plain film radiolucency scores (P = .78) nor Yian CT radiolucency scores (P = .68) were associated with Lazarus plain film seating scores. Neither Lazarus plain film radiolucency scores (P = .25) nor Yian CT radiolucency scores (P = .91) were associated with modified Lazarus CT scan seating scores. CT allowed for better intraobserver and interobserver reliability in all categories.

CONCLUSION

Radiolucencies around a partially cemented glenoid component were not associated with the degree of component seating. Complete seating of the glenoid component is not necessary to achieve radiographic implant stability at a mean follow-up of 43 months.

Conversion to Reverse Shoulder Arthroplasty: Humeral Stem Retention Versus Revision

As the volume of shoulder arthroplasty procedures performed in the United States continues to increase, the predicted number of revision shoulder arthroplasties grows even higher. Conversion of failed shoulder arthroplasty to reverse total shoulder arthroplasty has become common. Many commercially available shoulder arthroplasty systems now offer a platform humeral stem that is used for both anatomic shoulder arthroplasty and reverse total shoulder arthroplasty. This study investigated whether retaining the humeral stem offers advantages over revising the humeral stem in conversion of failed shoulder arthroplasty to reverse total shoulder arthroplasty. The study included 26 patients (mean age, 68.46 years) with failed shoulder arthroplasty who underwent conversion to reverse total shoulder arthroplasty with a minimum 2-year follow-up (mean, 34.38 months). Patients who had retention of the humeral stem were compared with those who had stem revision. Humeral stem retention was associated with a significantly shorter operative time (178.92 vs 237 minutes, P=.02). Decreases in blood loss, complications, and length of hospitalization were observed, but the differences were not statistically significant. Minimal differences were observed for patient-reported outcomes. Of patients undergoing humeral stem removal, 21.4% had an intraoperative humeral shaft or tuberosity fracture compared with none in the stem retention group. Humeral stem retention was associated with decreased operative time compared with humeral stem revision in the conversion of failed shoulder arthroplasty to reverse total shoulder arthroplasty. The use of a platform shoulder arthroplasty system may benefit patients with failed shoulder arthroplasty undergoing conversion to reverse total shoulder arthroplasty by avoiding humeral stem revision.

Traumatic Supraspinatus Tears in Patients Younger Than 25 Years

Traumatic rotator cuff tears in patients younger than 25 years are rare events, with few reports in the literature. When compared with the more mature shoulder, the young, healthy supraspinatus tendon is a robust tendon that is able to absorb a significant amount of energy before tendon failure. Therefore, the diagnosis of a rotator cuff tear can be often overlooked in this population due to the patient's age. This is a report of traumatic supraspinatus repairs in patients younger than 25 years. Nine patients younger than 25 years were identified with a posttraumatic supraspinatus tear as visualized during routine diagnostic shoulder arthroscopy. These 9 patients represented 0.33% of all rotator cuff repairs during a 9-year period. Average patient age was 19.1 years (±3.7 years; range, 13 to 25 years). Magnetic resonance imaging failed to diagnose a rotator cuff tear in 50% of the patients. Mean delay from injury to surgery was 6.6 months. All tears were arthroscopically repaired. Concomitant anterior instability pathology was demonstrated among 66.7% of the patients. No complications were reported. At latest follow-up, all patients reported minimal to no shoulder pain and were tolerating strenuous work, activities, and sports without significant complaints. Even with advanced imaging, the diagnosis of a rotator cuff tear can often be missed in this patient population. Although clinical outcomes can be good, care must be taken to broaden the diagnostic differential in young patients with posttraumatic shoulder pain.

Transparency to Reduce Surgical Implant Waste

BACKGROUND

Rising health care costs and emphasis on value have placed the onus of reducing healthcare costs on the surgeon.

METHODS

Financial data from 3,973 hip, knee, and shoulder arthroplasties performed at a physician owned orthopedic hospital was retrospectively reviewed over a two-year period. A wasted implant financial report was posted starting the second year of the study. Each surgeon's performance could be identified by his peers.

RESULTS

After posting of the financial report, 1.11% of all hip and knee arthroplasty cases had a waste event compared to 1.50% during the control year. Shoulder arthroplasty waste events occurred twice as often than that observed in hip and knee arthroplasty during the study period. A decrease in waste events was observed but was not statistically significant (p = 0.30).

CONCLUSIONS

Posting a non-blinded wasted implant data sheet was associated with a reduction in the number of wasted orthopedic surgical implants in this series, although the reduction was not statistically significant.

Arthroscopic tissue culture for the evaluation of periprosthetic shoulder infection

BACKGROUND

Periprosthetic shoulder infections can be difficult to diagnose. The purpose of this study was to investigate the utility of arthroscopic tissue culture for the diagnosis of infection following shoulder arthroplasty. Our hypothesis was that culture of arthroscopic biopsy tissue is a more reliable method than fluoroscopically guided shoulder aspiration for diagnosing such infection.

METHODS

A retrospective review identified patients who had undergone culture of arthroscopic biopsy tissue during the evaluation of a possible chronic periprosthetic shoulder infection. The culture results of the arthroscopic biopsies were compared with those of fluoroscopically guided glenohumeral aspiration and open tissue biopsy samples obtained at the time of revision surgery.

RESULTS

Nineteen patients had undergone arthroscopic biopsy to evaluate a painful shoulder arthroplasty for infection. All subsequently underwent revision surgery, and 41% of those with culture results at that time had a positive result, which included Propionibacterium acnes in each case. All arthroscopic biopsy culture results were consistent with the culture results obtained during the revision surgery, yielding 100% sensitivity, specificity, positive predictive value, and negative predictive value. In contrast, fluoroscopically guided glenohumeral aspiration yielded a sensitivity of 16.7%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 58.3%.

CONCLUSIONS

Arthroscopic tissue biopsy is a reliable method for diagnosing periprosthetic shoulder infection and identifying the causative organism.

LEVEL OF EVIDENCE

Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Risk factors for manipulation after total knee arthroplasty: a pooled electronic health record database study

A commercially available software platform, Explorys (Explorys, Inc., Cleveland, OH), was used to mine a pooled electronic healthcare database consisting of the medical records of more than 27 million patients. A total of 229,420 patients had undergone a total knee arthroplasty; 3470 (1.51%) patients were identified to have undergone manipulation under anesthesia. Individual risk factors of being female, African American race, age less than 60, BMI >30 and nicotine dependence were determined to have relative risk of 1.25, 2.20, 3.46, 1.33 and 1.32 respectively. Depressive disorder, diabetes mellitus, opioid abuse/dependence and rheumatoid arthritis were not significant risk factors. African Americans under the age of 60 at time of TKA had the greatest incidence of MUA (5.17%) and relative risk of 3.73 (CI: 3.36, 4.13).

Transtendon, double-row, transosseous-equivalent arthroscopic repair of partial-thickness, articular-surface rotator cuff tears

Arthroscopic transtendinous techniques for the arthroscopic repair of partial-thickness, articular-surface rotator cuff tears offer the advantage of minimizing the disruption of the patient's remaining rotator cuff tendon fibers. In addition, double-row fixation of full-thickness rotator cuff tears has shown biomechanical advantages. We present a novel method combining these 2 techniques for transtendon, double-row, transosseous-equivalent arthroscopic repair of partial-thickness, articular-surface rotator cuff tears. Direct visualization of the reduction of the retracted articular tendon layer to its insertion on the greater tuberosity is the key to the procedure. Linking the medial-row anchors and using a double-row construct provide a stable repair that allows early shoulder motion to minimize the risk of postoperative stiffness.

Long head of the biceps tendon allis clamp evaluation technique

Disorders of the long head of the biceps brachii are a common finding in conjunction with other causes of shoulder pathology. Nonoperative means as first-line treatment are often successful; however, surgery can be indicated for refractory tendinopathy. There is debate as to the best surgical treatment of the long head of the biceps tendon (LHBT) with different types of arthroscopic and open techniques. The decision on what treatment option to perform is often made at the time of surgery after arthroscopic evaluation of the LHBT. Certain examples of tendon disease are easily visible intra-articularly; however, a large portion of the tendon is not intra-articular and not readily viewed during routine arthroscopy. This study describes a simple arthroscopic technique for evaluation of an increased portion of the LHBT using an Allis clamp. The clamp is inserted through the anterior portal, placed around the LHBT, and rotated such that the tendon is wrapped around itself, bringing the distal tendon into the joint for arthroscopic viewing. This procedure is a routine part of our assessment of the LHBT during arthroscopy.

Osteonecrosis following short-term, low-dose oral corticosteroids: a population-based study of 24 million patients

Although the association between chronic, high-dose corticosteroid use and osteonecrosis is well known, the incidence of osteonecrosis following short-term, low-dose steroid taper packs has never been reported across a large population. The goal of this study was to report the incidence and risk of osteonecrosis after methylprednisolone taper pack (MTP) prescriptions in a multicenter electronic medical records database. A commercially available software platform was used to evaluate the records of 24,533,880 patients to determine the incidence of osteonecrosis in patients who had received single or multiple MTP over a 12-year period. This was compared with the incidence of osteonecrosis in patients who had never been prescribed an MTP. Patients with a history of osteonecrosis or prior corticosteroid use were excluded from the study. A total of 98,390 patients were identified who had received a single MTP. One hundred thirty (0.132%; 95% confidence interval [CI], 0.176%-0.283%) of these patients were subsequently diagnosed with osteonecrosis. The incidence of osteonecrosis in patients who had been prescribed 2 or more MTPs was 0.230% (95% CI, 0.176%-0.283%). Compared with the 0.083% incidence of osteonecrosis in the control group that had never been prescribed an MTP, the relative risk of osteonecrosis after the prescription of a single MTP or multiple MTPs was 1.591 and 2.763, respectively, with a statistically significant difference between cohorts (P<.001). Short-term, low-dose oral corticosteroid administration may be associated with a low but statistically significant increased incidence of osteonecrosis when compared with patients who have never been prescribed a steroid product.

Postarthroscopic humeral head osteonecrosis treated with reverse total shoulder arthroplasty

Although postarthroscopic glenohumeral chondrolysis has become a well-known disastrous complication of arthroscopic shoulder surgery, little is known about postarthroscopic humeral head osteonecrosis. This article describes 3 patients who were referred to the authors' practice with end-stage osteonecrosis after an arthroscopic rotator cuff repair or debridement.Three patients (average age, 63.3 years) presented to the authors' practice reporting severe shoulder pain after a rotator cuff debridement or repair was performed at an outside facility. After an interval period of mild improvement, all patients experienced progressive pain and loss of shoulder range of motion at a mean of 4.8 months postoperatively. Plain radiographs and magnetic resonance imaging obtained prior to the index operation showed no evidence of osteonecrosis. Postoperatively, progressive clinical and radiographic evidence showed humeral head osteonecrosis and subsequent glenohumeral destruction with cuff tear arthropathy. The authors managed all patients with a reverse total shoulder arthroplasty due to severe glenohumeral arthrosis and massive rotator cuff tears not amendable to repair. Satisfactory results were achieved in all cases.Although many complications of arthroscopic shoulder surgery are documented, little is known about postarthroscopic humeral head osteonecrosis. Shoulder surgeons should be aware of this potential complication when performing arthroscopic rotator cuff surgery and when evaluating painful and stiff postarthroscopic shoulders.

Extended Neviaser portal approach to antegrade humeral nailing

Certain arthropathies can distort the normal acromiohumeral relationship and make traditional anterolateral access to the proximal humerus for nailing difficult or impossible. This article presents a case of bilateral antegrade humeral nailing in which the Neviaser portal approach was used for humeral shaft fractures in a patient with distorted shoulder anatomy secondary to severe cuff tear arthropathy and rheumatoid arthritis. Based on a literature review, extending the traditional superomedial (Neviaser) portal to the shoulder to perform humeral nailing has never been described clinically. An 85-year-old woman with rheumatoid arthritis and bilateral cuff tear arthropathy presented after a mechanical fall from standing height with bilateral acute humeral shaft fractures. Preoperative fluoroscopy confirmed the inability to access the traditional starting point with an anterolateral approach due to a shield acromion resulting from cuff tear arthropathy and rheumatoid arthritis. Bilateral locked antegrade humeral nails were successfully placed through a 3-cm incision just off the medial border of the acromion and directly posterior to the acromioclavicular joint (the extended Neviaser portal approach). Postoperatively, the patient demonstrated early evidence of clinical and radiographic union. She was able to return to her preinjury function level, with an active range of motion comparable with her baseline. The Neviaser portal approach to antegrade humeral nailing is an effective solution to diaphyseal humeral fractures when access to the traditional anterolateral proximal humeral starting port is not possible due to distorted shoulder anatomy.

ECM production of primary human and bovine chondrocytes in hybrid PEG hydrogels containing type I collagen and hyaluronic acid

The development of advanced materials that facilitate hyaline cartilage formation and regeneration in aging populations is imperative. Critical to the success of this endeavor is the optimization of ECM production from clinically relevant cells. However, much of the current literature focuses on the investigation of primary bovine chondrocytes from young calves, which differ significantly than osteoarthritic cells from human sources. This study examines the levels of extracellular matrix (ECM) production using various levels of type I collagen and hyaluronic acid in poly(ethylene glycol) dimethacrylate (PEGDM) hydrogels in total knee arthroplasties, compared with the results from bovine chondrocytes. The addition of type 1 collagen in both the presence and absence of low levels of hyaluronic acid increased ECM production and/or retention in scaffolds containing either bovine or human chondrocytes. These findings are supported consistently with colorimetric quantification, whole mount extracellular matrix staining for both cell types, and histological staining for glycoaminoglycans and collagen of human chondrocyte containing samples. While exhibiting similar trends, the relative ECM productions levels for the primary human chondrocytes are significantly less than the bovine chondrocytes which reinforces the need for additional optimization.