The subacromial bursa modulates tendon healing after rotator cuff injury in rats

Rotator cuff injuries result in more than 500,000 surgeries annually in the United States, many of which fail. These surgeries typically involve repair of the injured tendon and removal of the subacromial bursa, a synovial-like tissue that sits between the rotator cuff and the acromion. The subacromial bursa has been implicated in rotator cuff pathogenesis and healing. Using proteomic profiling of bursa samples from nine patients with rotator cuff injury, we show that the bursa responds to injury in the underlying tendon. In a rat model of supraspinatus tenotomy, we evaluated the bursa's effect on the injured supraspinatus tendon, the uninjured infraspinatus tendon, and the underlying humeral head. The bursa protected the intact infraspinatus tendon adjacent to the injured supraspinatus tendon by maintaining its mechanical properties and protected the underlying humeral head by maintaining bone morphometry. The bursa promoted an inflammatory response in injured rat tendon, initiating expression of genes associated with wound healing, including Cox2 and Il6. These results were confirmed in rat bursa organ cultures. To evaluate the potential of the bursa as a therapeutic target, polymer microspheres loaded with dexamethasone were delivered to the intact bursae of rats after tenotomy. Dexamethasone released from the bursa reduced Il1b expression in injured rat supraspinatus tendon, suggesting that the bursa could be used for drug delivery to reduce inflammation in the healing tendon. Our findings indicate that the subacromial bursa contributes to healing in underlying tissues of the shoulder joint, suggesting that its removal during rotator cuff surgery should be reconsidered.

The subacromial bursa is a key regulator of the rotator cuff and a new therapeutic target for improving repair

Rotator cuff injuries result in over 500,000 surgeries performed annually, an alarmingly high number of which fail. These procedures typically involve repair of the injured tendon and removal of the subacromial bursa. However, recent identification of a resident population of mesenchymal stem cells and inflammatory responsiveness of the bursa to tendinopathy indicate an unexplored biological role of the bursa in the context of rotator cuff disease. Therefore, we aimed to understand the clinical relevance of bursa-tendon crosstalk, characterize the biologic role of the bursa within the shoulder, and test the therapeutic potential for targeting the bursa. Proteomic profiling of patient bursa and tendon samples demonstrated that the bursa is activated by tendon injury. Using a rat to model rotator cuff injury and repair, tenotomy-activated bursa protected the intact tendon adjacent to the injured tendon and maintained the morphology of the underlying bone. The bursa also promoted an early inflammatory response in the injured tendon, initiating key players in wound healing. In vivo results were supported by targeted organ culture studies of the bursa. To examine the potential to therapeutically target the bursa, dexamethasone was delivered to the bursa, prompting a shift in cellular signaling towards resolution of inflammation in the healing tendon. In conclusion, contrary to current clinical practice, the bursa should be retained to the greatest extent possible and provides a new therapeutically target for improving tendon healing outcomes.

One Sentence Summary

The subacromial bursa is activated by rotator cuff injury and regulates the paracrine environment of the shoulder to maintain the properties of the underlying tendon and bone.

Transient neonatal shoulder paralysis causes early osteoarthritis in a mouse model

Neonatal brachial plexus palsy (NBPP) occurs in approximately 1.5 of every 1,000 live births. The majority of children with NBPP recover function of the shoulder. However, the long-term risk of osteoarthritis (OA) in this population is unknown. The purpose of this study was to investigate the development of OA in a mouse model of transient neonatal shoulder paralysis. Neonatal mice were injected twice per week for 4 weeks with saline in the right supraspinatus muscle (Saline, control) and botulinum toxin A (BtxA, transient paralysis) in the left supraspinatus muscle, and then allowed to recover for 20 or 36 weeks. Control mice received no injections, and all mice were sacrificed at 24 or 40 weeks. BtxA mice exhibited abnormalities in gait compared to controls through 10 weeks of age, but these differences did not persist into adulthood. BtxA shoulders had decreased bone volume (-9%) and abnormal trabecular microstructure compared to controls. Histomorphometry analysis demonstrated that BtxA shoulders had higher murine shoulder arthritis scale scores (+30%), and therefore more shoulder OA compared to controls. Articular cartilage of BtxA shoulders demonstrated stiffening of the tissue. Compared with controls, articular cartilage from BtxA shoulders had 2-fold and 10-fold decreases in Dkk1 and BMP2 expression, respectively, and 3-fold and 14-fold increases in Col10A1 and BGLAP expression, respectively, consistent with established models of OA. In summary, a brief period of paralysis of the neonatal mouse shoulder was sufficient to generate early signs of OA in adult cartilage and bone.

Subspecialty Selection Impacts Research Productivity and Faculty Rank of Academic Orthopaedic Surgeons

BACKGROUND

Faculty promotion and research productivity are important for the overall career trajectory of academic orthopaedic surgeons. The purpose of this study was to investigate the role that subspecialty and demographic factors play in research productivity and academic advancement among orthopaedic surgeons.

METHODS

We conducted a retrospective cross-sectional analysis of academic rank among orthopaedic surgeons in 2018. We identified academic orthopaedic programs in the United States from the Fellowship and Residency Electronic Interactive Database (FREIDA) and collected publicly available data for surgeons, including fellowship training, gender, faculty rank, geographic region, and years since residency, from institutional websites. Research productivity was defined with the Hirsch index (h-index) from Scopus, and the m-index was calculated from the surgeon's h-index and the date of the first publication. Multivariate regression analyses were performed to determine the variables that are associated with associate professorship, full professorship, and the h-index.

RESULTS

In this study, we identified and included 2,879 academic orthopaedic surgeons. Completion of a fellowship in foot and ankle (odds ratio [95% confidence interval]: 2.45 [1.17 to 5.15]), sports medicine (2.15 [1.12 to 4.15]), trauma (2.83 [1.42 to 5.66]), hand and upper extremity (2.20 [1.13 to 4.28]), musculoskeletal oncology (3.28 [1.49 to 7.21]), or upper-extremity reconstruction (3.20 [1.31 to 7.81]) was associated with associate professorship. Completion of a trauma fellowship was associated with full professorship (2.93 [1.27 to 6.77]). Completion of a fellowship in adult reconstruction (difference in least-squares means [95% confidence interval]: 5.01 [1.22 to 8.81]), sports medicine (4.52 [1.00 to 8.04]), spine (5.40 [1.63 to 9.18]), or upper-extremity reconstruction (10.64 [6.15 to 15.12]) or the completion of multiple fellowships (5.12 [1.27 to 8.94]) were independently associated with a higher h-index. Women had significantly lower h-indices than men at the assistant (median [interquartile range]: 3 [1 to 6] versus 4 [2 to 8]) and full professor (17 [12 to 26] versus 22 [13 to 34]) levels. There were no differences in the m-index between men and women at any academic rank.

CONCLUSIONS

Orthopaedic subspecialty selection is independently associated with research productivity and academic rank. The differences in research productivity may be important to consider when evaluating orthopaedic surgeons for promotion. While female surgeons had lower h-indices than their male counterparts, this difference was not seen when using the m-index.

Statistical fragility of randomized clinical trials in shoulder arthroplasty

BACKGROUND

The P value is a statistical tool used to assess the statistical significance of clinical trial outcomes in orthopedic surgery. However, the P value does not evaluate research quality or clinical significance. The Fragility Index (FI) is an alternative statistical method that can be used to assess the quality and significance of clinical research and is defined as the number of patients in a study intervention group necessary to convert an outcome from statistically significant to statistically insignificant or vice versa. The primary purpose of this study was to evaluate the statistical robustness of clinical trials regarding shoulder arthroplasty using the FI. The secondary goal was to identify trial characteristics associated greater statistical fragility.

METHODS

A systematic review of randomized clinical trials in shoulder arthroplasty was performed. The FI was calculated for all dichotomous, categorical study outcomes discussed in the identified studies. Descriptive statistics and the Pearson correlation coefficient were used to evaluate all studies and characterize associations between study variables.

RESULTS

A total of 13 randomized controlled trials were identified and evaluated; these trials had a median sample size of 47 patients (mean, 54 patients; range, 26-102 patients) and a median of 7 patients (mean, 5.8 patients; range, 0-14 patients) lost to follow-up. The median FI was 6 (mean, 5; range, 1-11), a higher FI than what has been observed in other orthopedic subspecialties. However, the majority of outcomes (74.4%) had an FI that was less than the number of patients lost to follow-up, and most outcomes (89.7%) were statistically insignificant.

CONCLUSION

Randomized controlled trials in shoulder arthroplasty have comparable statistical robustness to the literature in other orthopedic surgical subspecialties. We believe that the inclusion of the FI in future comparative studies in the shoulder arthroplasty literature will allow surgeons to better assess the statistical robustness of future research.

Eponyms in Pediatric Sports Medicine: A Historical Review

The use of eponyms in the orthopedics literature has come under scrutiny, and there is a growing body of literature evaluating the utility of these terms in modern healthcare delivery. Although the field of pediatric orthopedic sports medicine is a relatively modern subspecialty, it is built on a foundation of over 100 years of pediatric musculoskeletal medicine. As a result, eponyms account for a significant portion of the vernacular used in the field. The purpose of this review is to summarize and describe the history of common eponyms relevant to pediatric sports pathology, examination maneuvers, classification systems, and surgical procedures. Use of eponyms in medicine is flawed. However, an improved understanding of these terms allows for informed use in future scientific discourse, patient care and medical education and may encourage future innovation and research into understanding pediatric orthopedic pathologies.

Variability in rehabilitation protocols following pediatric anterior cruciate ligament (ACL) reconstruction

Objectives: The objective of this study was to assess the variability of publicly available pediatric anterior cruciate ligament (ACL) reconstruction rehabilitation protocols produced by academic orthopedic surgery departments and children's hospitals.Methods: A web-based search was performed to identify rehabilitation protocols. Protocol and literature review guided the development of a comprehensive scoring rubric that was used to assess protocols for the presence and timing of postoperative adjunctive therapy and physical therapy recommendations.Results: A search of 180 academic orthopedic surgery programs and 250 children's hospitals identified 21 rehabilitation protocols. A majority of these protocols (90%) recommended postoperative adjunctive therapies such as bracing (81%), cryotherapy (43%), electrical muscle stimulation (24%), and/or continuous passive motion (14%). Several protocols (57%) recommended a specific weight-bearing status in the immediate postoperative period, but there was minimal consensus on that status. Conversely, there was more agreement amongst protocols that recommended strength exercises (52%); a majority of protocols suggested quad sets (91%), ankle pumps (73%), leg press (64%), and/or double-leg squats (55%). Ten protocols (48%) recommended initiation of stretches in the first week following surgery, and most commonly suggested patella mobilizations start at an average of 1.9 weeks postop (range 0-8 weeks). Twelve protocols (57%) discussed return to play, with an average recommended return to play at 7.5 months (range 3-11 months) postoperatively. However, few protocols recommended that patients get approval from their surgeon (19%) or pass specific tests (24%) prior to return to play.Conclusion: Few academic departments of orthopedic surgery or children's hospitals publish pediatric ACL reconstruction protocols online. Given the substantial variability observed amongst these protocols and recent findings that patients increasingly turn to the internet for medical information, this study suggests that standardization of pediatric ACL reconstruction rehabilitation has the potential to further optimize patient care.

Perfusion is Not Measurably Decreased in Idiopathic Clubfoot

BACKGROUND

Vascular aberration has been accepted as a potential etiology of clubfoot, and abnormal vasculature has been observed in as high as 85% of children with severe clubfoot. The perfusion index (PI) corresponds to the ratio of pulsatile to nonpulsatile blood flow at a monitoring site and can be used to quantify perfusion of the extremities. The purpose of this study was to use PI to compare the perfusion of clubfeet to controls in order to further assess the role of abnormal vasculature in clubfoot.

METHODS

A Masimo Radical 7 Pulse Oximeter (Masimo Corporation, Irvine, California) was used to measure the PI and oxygen saturation (SpO2) of the feet of children 5 years of age and younger with and without clubfoot. The sensor was placed on the great toe. Patients with clubfoot undergoing non-operative treatment and control patients undergoing treatment in a clinic for orthopedic concerns not involving the foot and with no known vascular issues were assessed. The PI and SpO2 for the following three groups were compared: 1. affected feet of patients with bilateral or unilateral clubfoot, 2. unaffected feet of patients with unilateral clubfoot, and 3. control feet.

RESULTS

One hundred and twenty-eight patients were enrolled, 64 with clubfoot (31 bilateral and 33 unilateral) and 64 controls. No significant differences in PI or SpO2 were found between: 64 clubfeet and 64 feet of controls (PI of 2.9 vs. 2.9, p = 0.984; SpO2 of 97.1 vs. 98.1, p = 0.192); unaffected feet of 30 patients with unilateral clubfoot and 64 controls (PI of 3.0 vs.2.9, p = 0.907; SpO2 of 96.9 vs. 98.1, p = 0.224); and affected and unaffected feet of 30 patients with unilateral clubfoot (PI of 3.3 vs.3.0, p = 0.500; SpO2 of 97.4 vs. 96.9, p = 0.527).

CONCLUSIONS

No difference was observed in the PI or SpO2 when comparing affected clubfoot limbs with unaffected limbs, suggesting that vascular anomalies cannot fully explain the development of clubfoot.

New Brain Tumor Entities Emerge from Molecular Classification of CNS-PNETs

Primitive neuroectodermal tumors of the central nervous system (CNS-PNETs) are highly aggressive, poorly differentiated embryonal tumors occurring predominantly in young children but also affecting adolescents and adults. Herein, we demonstrate that a significant proportion of institutionally diagnosed CNS-PNETs display molecular profiles indistinguishable from those of various other well-defined CNS tumor entities, facilitating diagnosis and appropriate therapy for patients with these tumors. From the remaining fraction of CNS-PNETs, we identify four new CNS tumor entities, each associated with a recurrent genetic alteration and distinct histopathological and clinical features. These new molecular entities, designated "CNS neuroblastoma with FOXR2 activation (CNS NB-FOXR2)," "CNS Ewing sarcoma family tumor with CIC alteration (CNS EFT-CIC)," "CNS high-grade neuroepithelial tumor with MN1 alteration (CNS HGNET-MN1)," and "CNS high-grade neuroepithelial tumor with BCOR alteration (CNS HGNET-BCOR)," will enable meaningful clinical trials and the development of therapeutic strategies for patients affected by poorly differentiated CNS tumors.

Abstract 11: Advancing methylation profiling in neuropathology: Diagnosis and clinical management

Introduction: Although molecular profiling is increasingly being applied to improve subgroup classification and to provide novel prognostic and predictive biomarkers, clinical neuropathology practice is largely based on morphology and immunohistochemistry. Current molecular methods play only a small role in determining the diagnosis itself.

Methods: For molecular subclassification of tumors at NYU neuropathology and to improve diagnostic accuracy, we introduced genome-wide methylation profiling through Illumina Infinium HumanMethylation 450k array that can detect methylation marks from the DNA extracted from formalin-fixed paraffin embedded tissues. To this effort, an in-house pipeline was established in-house pipeline, which includes morphologic review, sample preparation, molecular profiling and bioinformatics analysis. We compared the methylation profiles to a reference cohort of 2150 cases from 77 tumor entities previously profiled and analyzed at German Cancer Research Center using a random forest algorithm and customized bioinformatics packages, which were shared between our institutions. Selected copy number variants (CNV) and mutations were confirmed by Fluorescence in situ Hybridization (FISH) or sequencing, and mutation specific immunohistochemistry, respectively.

Results: We profiled 60 difficult in-house or consult adult and pediatric brain tumors where diagnosis, grade and/or molecular subtype were not conclusive by morphology, immunohistochemistry or standard molecular studies alone. There was 100% concordance with concurrently performed molecular tests such as 1p/19q, EGFR/BRAF CNV, MGMT promoter methylation or IDH1 status testing when these tests were performed for clinical care. Methylation profiling provided additional, relevant information in 30 of 60 (50%) cases, leading to a change of diagnosis in 9 (15%), clarification of the diagnosis in 7 (12%) cases, and further molecular subgroup refinement in 14 (23%) of cases, helping to direct further molecular testing and clinical management.

Conclusion: The 450k methylation array platform represents a cost-efficient method to obtain molecular profiles of brain tumors to identify biologically relevant diagnostic subgroups, thereby improving diagnostic accuracy, and helping inform appropriate clinical management decisions.

Citation Format: Kasthuri S. Kannan, Aristotelis Tsirigos, Jonathan Serrano, Lynn Ann Forrester, Arline Faustin, Cheddhi Thomas, David Capper, Volker Hovestadt, Stefan M. Pfister, David T. W Jones, Martin Sill, Daniel Schrimpf, Andreas von Deimling, Adriana Heguy, Sharon L. Gardner, Jeffrey Allen, Cyrus Hedvat, David Zagzag, Matija Snuderl, Matthias A. Karajannis. Advancing methylation profiling in neuropathology: Diagnosis and clinical management. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Integrating Clinical Genomics and Cancer Therapy; Jun 13-16, 2015; Salt Lake City, UT. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(1_Suppl):Abstract nr 11.

Evaluation of a Clostridium difficile infection management policy with clinical pharmacy and medical microbiology involvement at a major Canadian teaching hospital

WHAT IS KNOWN AND OBJECTIVE

Clostridium difficile infection (CDI) represents a spectrum of disease and is a significant concern for healthcare institutions. Our study objective was to assess whether implementation of a regional CDI management policy with Clinical Pharmacy and Medical Microbiology and Infection Control involvement would lead to an improvement in concordance in prescribing practices to an evidence-based CDI disease severity assessment and pharmacological treatment algorithm.

METHODS

Conducted at a tertiary care teaching hospital, this two-phase quality assurance study consisted of a baseline retrospective healthcare record review of patients with CDI prior to the implementation of a regional CDI management policy followed by a prospective evaluation post-implementation.

RESULTS AND DISCUSSION

One hundred and forty-one CDI episodes in the pre-implementation group were compared to 283 episodes post-implementation. Overall treatment concordance to the CDI treatment algorithm was achieved in 48 of 141 cases (34%) pre-implementation compared with 136 of 283 cases (48·1%) post-implementation (P = 0·01). The median time to treatment with vancomycin was reduced from five days to one day (P < 0·01), with median length of hospital stay decreasing from 30 days to 21 days (P = 0·01) post-implementation. There was no difference in 30-day all-cause mortality.

WHAT IS NEW AND CONCLUSION

A comprehensive approach with appropriate stakeholder involvement in the development of clinical pathways, education to healthcare workers and prospective audit with intervention and feedback can ensure patients diagnosed with CDI are optimally managed and prescribed the most appropriate therapy based on CDI disease severity.

Notch suppresses angiogenesis and progression of hepatic metastases

The Notch pathway plays multiple key roles in tumorigenesis, and its signaling components have therefore aroused great interest as targets for emerging therapies. Here, we show that inhibition of Notch, using a soluble receptor Notch1 decoy, unexpectedly caused a remarkable increase in liver metastases from neuroblastoma and breast cancer cells. Increased liver metastases were also seen after treatment with the γ-secretase inhibitor PF-03084014. Transgenic mice with heterozygous loss of Notch1 demonstrated a marked increase in hepatic metastases, indicating that Notch1 signaling acts as metastatic suppressor in the liver microenvironment. Inhibition of DLL1/4 with ligand-specific Notch1 decoys increased sprouting of sinusoidal endothelial cells into micrometastases, thereby supporting early metastatic angiogenic growth. Inhibition of tumor-derived JAG1 signaling activated hepatic stellate cells, increasing their recruitment to vasculature of micrometastases, thereby supporting progression to macrometastases. These results demonstrate that inhibition of Notch causes pathologic activation of liver stromal cells, promoting angiogenesis and growth of hepatic metastases. Our findings have potentially serious implications for Notch inhibition therapy.

A cross-sectional study of SEN virus in liver transplant recipients

A new DNA virus, referred to as SEN virus (SEN V), has been isolated and is associated with blood-product transfusion and possibly Non A to Non E hepatitis. We performed a cross-sectional analysis of SEN V in liver transplant recipients at our center. Polymerase chain reaction was used to test for 2 genotypes of SEN V (SEN V:C/H and SEN V:D) in 58 unselected patients. Comparisons were made between SEN V--positive and SEN V--negative groups in terms of age, time posttransplantation, indications for transplantation, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and cytomegalovirus and Epstein-Barr virus status. Thirty of 58 transplant recipients (51.7%) were SEN V positive; 15.5% were positive for SEN V:C/H, 24.1% for SEN:D, and 12.1% for both strains. No significant differences were found based on primary indication for transplantation, including hepatitis C virus (HCV). Of the 14 of 21 patients with HCV seropositivity and HCV reinfection, 79% were positive for SEN V (P =.02). There was no difference in the proportion of patients with abnormal serum ALT and/or AST levels. A trend for the SEN V--positive group to have a greater mean ALT level (82 v 41 U/L; P =.067) was attributable to the subgroup with HCV recurrence because there was no difference in mean ALT levels (34.9 v 34.5 U/L; P =.968) in non--HCV-infected transplant recipients. Even in the subgroup (n = 14) with recurrent HCV, there was no statistically significant difference in mean ALT levels (140 v 105 U/L; P =.665). Age and cytomegalovirus or Epstein-Barr virus status were not significantly different between the 2 groups, but a significant difference in posttransplantation time was noted (16.8 v 32 months; P =.021). We conclude that SEN V is common among liver transplant recipients but does not appear to cause graft dysfunction as an isolated agent. There is a suggestion that SEN V may be associated with HCV recurrence, but we did not detect biochemical differences attributable to SEN V.