Publications by authors named "Evan L Flatow"

87 Publications

Retrospective review of open and arthroscopic repair of anterosuperior rotator cuff tears with subscapularis involvement: a single surgeon's experience.

J Shoulder Elbow Surg 2020 May 4;29(5):893-897. Epub 2019 Dec 4.

Leni and Peter May Department of Orthopaedic Surgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Background: There have been conflicting results when comparing outcomes of open vs. arthroscopic anterosuperior rotator cuff repairs with subscapularis involvement. The purpose of this study was to evaluate midterm outcome differences and complications following open vs. arthroscopic repair of rotator cuff tears involving the subscapularis by a single surgeon.

Methods: This was a retrospective review of 57 rotator cuff repairs involving the subscapularis performed by a single surgeon over a 10-year period. During this time, the surgeon transitioned from open to arthroscopic repair. Preoperative and postoperative range of motion, lift-off test, belly press test, and American Shoulder and Elbow Surgeons (ASES) Standardized Shoulder Assessment form scores were measured.

Results: Eighteen patients had open procedures and 39 had arthroscopic repair. The mean preoperative ASES score for the open group was 39 and postoperatively was 79. The mean preoperative ASES score for the arthroscopic group was 44 and improved to 80 postoperatively. There was no significant difference in score or change in score between the 2 groups (P > .05). There was only 1 complication. It occurred in the open group and was a superficial wound dehiscence.

Conclusions: This study demonstrated no outcome differences between open and arthroscopic rotator cuff repair involving the subscapularis, even with large subscapularis tears. Both techniques significantly improved shoulder function. Arthroscopic and open rotator cuff repairs including the subscapularis are relatively safe procedures, and either technique is an acceptable option.
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http://dx.doi.org/10.1016/j.jse.2019.09.035DOI Listing
May 2020

Multiscale mechanisms of tendon fatigue damage progression and severity are strain and cycle dependent.

J Biomech 2019 03 19;85:148-156. Epub 2019 Jan 19.

Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA; Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA; Hospital for Special Surgery, New York, NY, USA. Electronic address:

Tendinopathies are common chronic injuries that occur when damage accumulation caused by sub-rupture fatigue loading outpaces repair. Studies have linked fatigue loading with various mechanical, structural, and biological changes associated with pathology. However, the multiscale progression of damage accumulation with respect to area, severity and the distinct contributions of strain level and number of cycles has not been fully elucidated. The objective of this study was to investigate multiscale mechanisms underlying fatigue damage accumulation and their effect on the cellular environment. Using an in situ model in rat tail tendon (RTT), fatigue loading was applied at various strains and cycle numbers to induce fatigue damage. Pre- and post- fatigue diagnostic mechanical testing, second harmonic generation (SHG) imaging, and transmission electron microscope (TEM) imaging were used to investigate extracellular and cellular damage modes at multiple scales. Fatigue loading at strains at or below 1.0% resulted in no significant changes in SHG damage area or severity and no changes in collagen fibril or cell morphology compared with controls. Fatigue loading at strains above 1.5% resulted in greater mechanical changes correlated with increased damage area measured by SHG and collagenous damage observed by TEM. Increased cycles at high strain further altered mechanical properties, increased structural damage severity (but not area), and altered TEM collagen rupture patterns. Cell morphology was similarly progressively affected with increased strain and cycle number. These damage mechanisms that may trigger degenerative changes characteristic of tendinopathy could be targeted as a part of prevention or therapy.
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http://dx.doi.org/10.1016/j.jbiomech.2019.01.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6608713PMC
March 2019

Promoting effective tendon healing and remodeling.

J Orthop Res 2018 12 21;36(12):3115-3124. Epub 2018 Sep 21.

Department of Orthopaedic Surgery, Mount Sinai West, New York, New York.

Daily activities subject our tendons to accumulation of sub-rupture fatigue injury which can lead to tendon rupture. Consequently, tendinopathies account for over 30% of musculoskeletal consultations. We adopted a multidisciplinary approach to determine the role of the extracellular matrix (ECM) in the pathogenesis of tendinopathy and impaired healing of ruptured tendons. We have been investigating three main areas: (i) the pathogenesis of tendon degeneration; (ii) approaches to promoting remodeling of sub-rupture fatigue injuries; and the (iii) role of the ECM in promoting scarless tendon healing. In this Kappa Delta Young Investigator award paper, we describe the key discoveries made in each of our three research areas of focus. Briefly, we discovered that sub-rupture fatigue damage can accumulate from just one bout of fatigue loading. Furthermore, any attempt to repair the fatigue damage diminishes as the severity of induced damage increases. We have utilized exercise to develop animal models of exercise-led degeneration and exercise-led repair of sub-rupture fatigue damage injuries, wherein underlying mechanisms can be uncovered, thereby overcoming a major hurdle to development of therapeutics. Since damage accumulation ultimately leads to rupture that is characterized by formation of a mechanically inferior scar, we have used the MRL/MpJ mouse to evaluate the role of the systemic environment and the local tendon environment in driving regeneration to identify new therapeutic pathways to promote scarless healing. Our data suggests that the therapeutic potential of the MRL/MpJ provisional ECM should be further explored as it may harness biological and structural mechanisms to promote scarless healing. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3115-3124, 2018.
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http://dx.doi.org/10.1002/jor.24133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6608714PMC
December 2018

A potential new role for myofibroblasts in remodeling of sub-rupture fatigue tendon injuries by exercise.

Sci Rep 2018 06 12;8(1):8933. Epub 2018 Jun 12.

Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA.

Tendons are ineffective at repairing sub-rupture fatigue injuries. Accordingly, we evaluated whether an exercise protocol that we have previously found to decrease structural damage kinks in fatigue damaged tendons, leads to improvement in mechanical properties. We hypothesized that exercise that promotes repair of fatigue damage will decrease apoptosis and increase the population of myofibroblasts. Rat patellar tendons underwent in vivo fatigue loading for 500 or 7200 cycles. Animals resumed cage activity for 2-weeks, then either remained cage active or began treadmill running until sacrifice at 4- or 10-weeks post-fatigue loading. Exercise following fatigue damage increased the stiffness back towards naïve levels, decreased apoptosis and increased the population of myofibroblasts. Next, proteins associated with inhibition of apoptosis (Collagen VI) or activation of myofibroblast (pSmad 2/3, fibrillin, integrin subunits αV and α5) were evaluated. Data suggests that collagen VI may not be integral to inhibition of apoptosis in this context. Exercise increased pSmad 2/3 and fibrillin in the insertion region for the 7200-cycles group. In addition, exercise decreased integrin αV and increased integrin α5 in fatigue damaged tendons. Data suggests that a decrease in apoptosis and an increase in population of myofibroblasts may be integral to remodeling of fatigue damaged tendons.
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http://dx.doi.org/10.1038/s41598-018-27196-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5997675PMC
June 2018

Editorial Commentary: Can We Do Better While Spending Less: How Many Shoulder Rotator Cuff Anchors Are Enough?

Authors:
Evan L Flatow

Arthroscopy 2018 05;34(5):1401-1402

Icahn School of Medicine at Mount Sinai.

We have published that shoulder rotator cuff tear is a highly cost-effective procedure, and to continue to improve value, a goal is to contain cost while maintaining or improving outcome. To bend the cost curve, reduction in direct costs (number of suture anchors used) could be a goal, and because rotator cuff repair failures are as much biologic as they are mechanical, the effect of adding anchors to improve outcomes has an obvious limit.
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http://dx.doi.org/10.1016/j.arthro.2018.01.003DOI Listing
May 2018

Anatomic landmarks for arthroscopic suprapectoral biceps tenodesis: a cadaveric study.

J Shoulder Elbow Surg 2018 Jul 27;27(7):1172-1177. Epub 2018 Feb 27.

Department of Orthopaedic Surgery, Icahn School of Medicine at Mount Sinai Health System, New York, NY, USA.

Background: Biceps tenodesis reduces the incidence of Popeye deformity occurring with tenotomy, but pain may occur with tenodesis superior to or within the bicipital groove. Arthroscopic suprapectoral tenodesis is an attractive alternative. The purpose of this study was to establish landmarks for arthroscopic suprapectoral tenodesis and determine the appropriate fixation point to optimize muscle tension.

Methods: Twelve fresh cadaveric shoulders were dissected. Urethane polymer was injected into the axillary artery. The position of the anterior branch of the axillary nerve was marked. The transverse humeral ligament was split, exposing the biceps (long head of the biceps [LHB]) from its origin to the pectoralis major tendon (PMT). The intra-articular portion was released. Measurements were taken from the proximal tendon to described landmarks.

Results: The mean length of the intra-articular LHB was 2.53 cm (range, 1.72-3.55 cm). The mean distance from the LHB origin to the inferior lesser tuberosity (LT) was 5.58 cm (range, 4.02-6.87 cm), and that to the superior border of the PMT was 8.46 cm (range, 6.46-10.78 cm). The suprapectoral tenodesis zone (inferior LT to superior PMT) was 2.96 cm (range, 1.54-4.40 cm). In all specimens, a branch of the anterior humeral circumflex arose medial to the LHB and distal to the LT and crossed the suprapectoral zone from medial to lateral at 1.49 ± 0.42 cm proximal to the PMT, approximately at the level of the axillary nerve. The musculocutaneous nerve was on average 3.06 cm (range, 1.86-3.76 cm) from the tenodesis zone.

Conclusion: A branch of the anterior humeral circumflex is a reliable landmark for identifying the mid-suprapectoral zone. The distance from the proximal LHB tendon to this crossing vessel averaged 6.32 cm in female specimens and 8.28 cm in male specimens. These findings allow appropriate tensioning of the LHB during arthroscopic suprapectoral tenodesis.
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http://dx.doi.org/10.1016/j.jse.2018.01.007DOI Listing
July 2018

Editorial Commentary: Slow and Steady or Quick and Slick: What Really Wins the Race Between Operative Time and Shoulder Surgery Complications?

Authors:
Evan L Flatow

Arthroscopy 2018 02;34(2):369-370

Icahn School of Medicine at Mount Sinai.

Studies have shown in many disciplines that longer operative times are correlated with increased complications. Recent research has shown that increased shoulder arthroscopy procedure time is associated with adverse short-term outcomes, especially infections and overnight hospital stay. This may be because longer operating time is a proxy for surgical difficulty or complexity, but it may be that operative time is itself a causative factor. Further study is warranted to see if reducing operative times may not only reduce costs but also improve quality, improving value in both the numerator and denominator.
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http://dx.doi.org/10.1016/j.arthro.2017.09.031DOI Listing
February 2018

Cost-benefit analysis of routine pathology examination in primary shoulder arthroplasty.

J Shoulder Elbow Surg 2017 Apr 26;26(4):674-678. Epub 2016 Oct 26.

Leni & Peter W. May Department of Orthopaedic Surgery, Mount Sinai Health System, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Background: The annual number of shoulder arthroplasty procedures is continuing to increase. Specimens from shoulder arthroplasty cases are routinely sent for pathologic examination. This study sought to evaluate the clinical utility and associated costs of routine pathologic examination of tissue removed during primary shoulder arthroplasty cases and to determine cost-effectiveness of this practice.

Methods: This is a retrospective review of primary shoulder arthroplasty cases. Patients whose humeral head was sent for routine pathologic examination were included. Cases were determined to have concordant, discrepant, or discordant diagnoses based on preoperative/postoperative diagnosis and pathology diagnosis. Costs were estimated in 2015 U.S. dollars, and cost-effectiveness was determined by the cost per discrepant diagnosis and cost per discordant diagnosis.

Results: We identified 714 cases of primary shoulder arthroplasty in 646 patients who met inclusion criteria. The prevalence of concordant diagnoses was 94.1%, the prevalence of discrepant diagnoses was 5.9%, and no cases had discordant diagnoses. There were 172 cases that had biceps tendon specimens sent for pathology examination, and none led to a change in patient care. Total estimated costs were $77,309.34 in 2015 U.S. dollars. Cost per discrepant diagnosis for humeral head specimens was $1424.09, and cost per discordant diagnosis is at least $59,811.78.

Discussion/conclusion: Primary shoulder arthroplasty has a high rate of concordant diagnosis. Discrepant diagnoses were 5.9% in our study, and there were no discordant diagnoses. This study showed limited clinical utility in routinely sending specimens from primary shoulder arthroplasty cases for pathology examination, and calculation using a traditional life-year value of $50,000 showed that the standard for cost-effectiveness is not met.
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http://dx.doi.org/10.1016/j.jse.2016.09.028DOI Listing
April 2017

Midterm Follow-Up of Metal-Backed Glenoid Components in Anatomical Total Shoulder Arthroplasties.

Am J Orthop (Belle Mead NJ) 2015 Sep;44(9):E340-2

Department of Orthopaedic Surgery, Southern Illinois University School of Medicine, Springfield, IL.

Loosening of the glenoid remains one of the most common complications of total shoulder arthroplasty (TSA) and is the most cited reason for performing revision arthroplasty. Ingrowth metal-backed glenoid components offer the theoretical advantage of bone growth directly into the prosthesis with a single host-prosthesis interface. In the study reported here, we retrospectively reviewed the charts of patients who had TSAs performed by 2 fellowship-trained shoulder surgeons using glenoid components with porous tantalum anchors. Standard radiographs were analyzed for lucency surrounding the anchors. Before and after surgery, American Shoulder and Elbow Surgeons (ASES) scores and active forward elevation (AFE) and active external rotation (AER) measurements were recorded. Twelve shoulders (11 patients) were examined. Mean follow-up was 20 months. In all cases, radiographs showed no glenoid lucency. Mean AFE and mean AER both increased significantly (P < .01), as did postoperative ASES scores (P < .01). Porous tantalum ingrowth glenoid components show no radiographic or clinical evidence of loosening at midterm follow-up. Long-term studies are needed to determine if these midterm outcomes are maintained and provide benefit over conventional cemented polyethylene designs.
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September 2015

Percutaneous Fixation of Proximal Humeral Fractures.

JBJS Essent Surg Tech 2015 May 27;5(2):e10. Epub 2015 May 27.

Department of Orthopaedic Surgery, Icahn School of Medicine at Mount Sinai Medical Center, 5 East 98th Street, New York, NY 10029.

Introduction: The percutaneous approach to proximal humeral fixation emphasizes minimum dissection with the goal of preserving vascularity of the articular segments and thereby decreasing the risk of osteonecrosis.

Step 1 Preoperative Planning: Perform preoperative imaging to assess fracture displacement and comminution in order to confirm that percutaneous treatment is appropriate.

Step 2 Closed Fracture Reduction: Attempt closed fracture reduction prior to incision.

Step 3 Surgical Approach For Humeral Head And Shaft Reduction: Obtain anatomic humeral head reduction, insert terminally threaded pins, and check pin placement fluoroscopically.

Step 4 Tuberosity Fracture Reduction And Fixation Of The Tuberosity Fragments: Fix the tuberosity fracture(s).

Step 5 Wound Closure: Cut the pins below the skin and irrigate and close the wounds.

Step 6 Postoperative Rehabilitation: Begin passive shoulder motion after pin removal, and initiate active motion at six weeks after pin removal.

Results: The results of this technique in twenty-seven patients with an average age of 58.8 years (range, forty-two to seventy-six years) at the time of injury were reported previously.IndicationsContraindicationsPitfalls & Challenges.
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http://dx.doi.org/10.2106/JBJS.ST.N.00096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6221428PMC
May 2015

Tendon basic science: Development, repair, regeneration, and healing.

J Orthop Res 2015 Jun 24;33(6):780-4. Epub 2015 Apr 24.

Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1188, New York, New York, 10029.

Tendinopathy and tendon rupture are common and disabling musculoskeletal conditions. Despite the prevalence of these injuries, a limited number of investigators are conducting fundamental, basic science studies focused on understanding processes governing tendinopathies and tendon healing. Development of effective therapeutics is hindered by the lack of fundamental guiding data on the biology of tendon development, signal transduction, mechanotransduction, and basic mechanisms underlying tendon pathogenesis and healing. To propel much needed progress, the New Frontiers in Tendon Research Conference, co-sponsored by NIAMS/NIH, the Orthopaedic Research Society, and the Icahn School of Medicine at Mount Sinai, was held to promote exchange of ideas between tendon researchers and basic science experts from outside the tendon field. Discussed research areas that are underdeveloped and represent major hurdles to the progress of the field will be presented in this review. To address some of these outstanding questions, conference discussions and breakout sessions focused on six topic areas (Cell Biology and Mechanics, Functional Extracellular Matrix, Development, Mechano-biology, Scarless Healing, and Mechanisms of Injury and Repair), which are reviewed in this special issue and briefly presented in this review. Review articles in this special issue summarize the progress in the field and identify essential new research directions.
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http://dx.doi.org/10.1002/jor.22869DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4427041PMC
June 2015

Scaffolds for tendon and ligament repair and regeneration.

Ann Biomed Eng 2015 Mar 4;43(3):819-31. Epub 2015 Feb 4.

Synthasome, Inc., 3030 Bunker Hill Street, Suite 308, San Diego, CA, 92109, USA,

Enhanced tendon and ligament repair would have a major impact on orthopedic surgery outcomes, resulting in reduced repair failures and repeat surgeries, more rapid return to function, and reduced health care costs. Scaffolds have been used for mechanical and biologic reinforcement of repair and regeneration with mixed results. This review summarizes efforts made using biologic and synthetic scaffolds using rotator cuff and ACL as examples of clinical applications, discusses recent advances that have shown promising clinical outcomes, and provides insight into future therapy.
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http://dx.doi.org/10.1007/s10439-015-1263-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4380768PMC
March 2015

Development of a mouse model of supraspinatus tendon insertion site healing.

J Orthop Res 2015 Jan 18;33(1):25-32. Epub 2014 Sep 18.

Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, 10029, New York.

Supraspinatus (SS) tendon tears are common musculoskeletal injuries whose surgical repair exhibits the highest incidence of re-tear of any tendon. Development of therapeutics for improving SS tendon healing is impaired by the lack of a model that allows biological perturbations to identify mechanisms that underlie ineffective healing. The objective of this study was to develop a mouse model of supraspinatus insertion site healing by creating a reproducible SS tendon detachment and surgical repair which can be applied to a wide array of inbred mouse strains and genetic mutants. Anatomical and structural analyses confirmed that the rotator cuff of the mouse is similar to that of human, including the presence of a coracoacromial (CA) arch and an insertion site that exhibits a fibrocartilagenous transition zone. The surgical repair was successfully conducted on seven strains of mice that are commonly used in Orthopaedic Research suggesting that the procedure can be applied to most inbred strains and genetic mutants. The quality of the repair was confirmed with histology through 14 days after surgery in two mouse strains that represent the variation in mouse strains evaluated. The developed mouse model will allow us to investigate mechanisms involved in insertion site healing.
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http://dx.doi.org/10.1002/jor.22727DOI Listing
January 2015

Temporal effect of in vivo tendon fatigue loading on the apoptotic response explained in the context of number of fatigue loading cycles and initial damage parameters.

J Orthop Res 2014 Sep 16;32(9):1097-103. Epub 2014 May 16.

Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York.

Accumulation of damage is a leading factor in the development of tendinopathy. Apoptosis has been implicated in tendinopathy, but the biological mechanisms responsible for initiation and progression of these injuries are poorly understood. We assessed the relationship between initial induced damage and apoptotic activity 3 and 7 days after fatigue loading. We hypothesized that greater apoptotic activity (i) will be associated with greater induced damage and higher number of fatigue loading cycles, and (ii) will be higher at 7 than at 3 days after loading. Left patellar tendons were fatigue loaded for either 100 or 7,200 cycles. Diagnostic tests were applied before and after fatigue loading to determine the effect of fatigue loading on hysteresis, elongation, and loading and unloading stiffness (damage parameters). Cleaved Caspase-3 staining was used to identify and calculate the percent apoptosis in the patellar tendon. While no difference in apoptotic activity occurred between the 100 and 7,200 cycle groups, greater apoptotic activity was associated with greater induced damage. Apoptotic activity was higher at 7 than 3 days after loading. We expect that the decreasing number of healthy cells that can repair the induced damage in the tendon predispose it to further injury.
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http://dx.doi.org/10.1002/jor.22639DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4209741PMC
September 2014

Tendon extracellular matrix damage detection and quantification using automated edge detection analysis.

J Biomech 2013 Nov 18;46(16):2844-7. Epub 2013 Sep 18.

Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 5 East 98th Street, 9th Floor, New York, NY 10029, United States.

The accumulation of sub-rupture tendon fatigue damage in the extracellular matrix, particularly of type I collagen fibrils, is thought to contribute to the development of tendinopathy, a chronic and degenerative pathology of tendons. Quantitative assessment of collagen fibril alignment is paramount to understanding the importance of matrix injury to cellular function and remodeling capabilities. This study presents a novel application of edge detection analysis to calculate local collagen fibril orientation in tendon. This technique incorporates damage segmentation and stratification by severity which will allow future analysis of the direct effect of matrix damage severity on the cellular and molecular response.
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http://dx.doi.org/10.1016/j.jbiomech.2013.09.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3869460PMC
November 2013

Musculoskeletal regeneration and its implications for the treatment of tendinopathy.

Int J Exp Pathol 2013 Aug 17;94(4):293-303. Epub 2013 Jun 17.

Leni and Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

Tendinopathies are common muskoloskeletal injuries that lead to pain and disability. Development and pathogenesis of tendinopathy is attributed to progressive pathological changes to the structure, function, and biology of tendon. The nature of this disease state, whether acquired by acute or chronic injury, is being actively investigated. Scarring, disorganized tissue, and loss of function characterize adult tendon healing. Recent work from animal models has begun to reveal the potential for adult mammalian tendon regeneration, the replacement of diseased with innate tissue. This review discusses what is known about musculoskeletal regeneration from a molecular perspective and how these findings can be applied to tendinopathy. Non-mammalian and mammalian models are discussed with emphasis on the potential of Murphy Roths Large mice to serve as a model of adult tendon regeneration. Comparison of regeneration in non-mammals, foetal mammals and adult mammals emphasizes distinctly different contributing factors to effective regeneration.
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http://dx.doi.org/10.1111/iep.12031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3721460PMC
August 2013

Proximal humeral fractures: internal fixation.

J Bone Joint Surg Am 2012 Dec;94(24):2280-8

Department of Orthopaedic Surgery, Mount Sinai Hospital, 5 East 98th Street, Box 1188, New York, NY 10029, USA.

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December 2012

Proximal humeral fractures: prosthetic replacement.

Instr Course Lect 2013 ;62:155-62

Department of Orthopaedic Surgery, Mount Sinai School of Medicine, New York, NY, USA.

Shoulder arthroplasty has emerged as a reliable treatment for displaced or comminuted fractures of the proximal humerus. The outcomes of humeral head replacement have improved as technology and techniques have evolved. Reverse shoulder arthroplasty has yielded promising results in early investigations. With either type of instrumentation, meticulous surgical technique is critical to achieving a good outcome. Prosthesis height and version and the stable fixation of anatomically reduced tuberosities are essential variables. Shoulder arthroplasty for fracture treatment remains a technically challenging procedure that demands knowledge of shoulder anatomy and implant options.
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July 2013

Proximal humeral fractures: internal fixation.

Instr Course Lect 2013 ;62:143-54

Department of Orthopaedic Surgery, Mount Sinai School of Medicine, New York, NY, USA.

Fractures of the proximal humerus are common injuries that are increasing in incidence as the population ages. These fractures are often treated nonsurgically; however, surgery is indicated if displacement, concurrent dislocation, or unacceptable alignment is present. Knowledge of the anatomic and physiologic characteristics of the proximal humerus and shoulder joint and familiarity with the available fixation elements will help surgeons make informed and patient-specific decisions regarding treatment. Reduction and internal fixation of proximal humeral fractures has expanding indications in comparison with arthroplasty, in part because of improvements in fixation technology and a better understanding of anatomy and physiology. The outcomes of proximal humeral fractures managed with percutaneous pinning, open reduction and locked-plate fixation, and intramedullary fixation are being actively investigated.
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July 2013

Long-term follow-up of shoulder hemiarthroplasty for glenohumeral osteoarthritis.

J Bone Joint Surg Am 2012 Nov;94(22):e164

Center for Shoulder, Elbow and Sports Medicine, Columbia University Medical Center, 622 West 168th Street, PH-1117, New York, NY 10032, USA.

Background: There is major controversy surrounding the use of hemiarthroplasty as compared with total shoulder arthroplasty for glenohumeral osteoarthritis, and long-term clinical outcomes of hemiarthroplasty are lacking.

Methods: Of a cohort of thirty patients (thirty-one shoulders) who were treated with hemiarthroplasty for glenohumeral osteoarthritis and followed longitudinally at our institution, twenty-five were available for long-term follow-up; five died, and one refused to participate. Three of the five patients who died had revision arthroplasty before death, and the data from those three were therefore included in the final follow-up (final follow-up data therefore included twenty-seven patients and twenty-eight shoulders). Follow-up through phone conversations and postal mail surveys included the following: Short Form-36, American Shoulder and Elbow Surgeons (ASES) shoulder outcome score, EuroQol, Simple Shoulder Test, modified Neer Score, and a unique, validated self-administered range-of-motion questionnaire. Correlations between clinical outcome and age, type of glenoid wear, and cause of osteoarthritis were determined.

Results: The average follow-up was 17.2 years (range, thirteen to twenty-one years). There were eight revisions (three of fifteen shoulders with concentric glenoids, and five of sixteen shoulders with eccentric glenoids). For those shoulders not revised, the average ASES score was 70.54 (range, 36.67 to 91.67). Overall, active shoulder forward elevation and external rotation with the arm at 90° of abduction increased from 104° preoperatively to 141.8° (range, 45° to 180°) and 20.7° to 61.0° (range, 30° to 90°), respectively (p < 0.05), at the time of final follow-up. Of those who required revision arthroplasty, the average patient age at the time of the index procedure was 51.0 years (range, twenty-six to eighty-one years), while those not requiring revision averaged 57.1 years (range, twenty-seven to sixty-three years). The overall Neer satisfaction rating was 25%. The average Neer score and Neer rating for unrevised cases were significantly higher for concentric glenoid wear compared with eccentric glenoid wear (p = 0.015 and p = 0.001, respectively). Patients who had concentric glenoid wear had higher EuroQol scores (p = 0.020). The average Neer scores were 65.29 (range, forty-seven to seventy-eight) for primary osteoarthritis and 54.46 (range, forty to seventy-seven) for secondary osteoarthritis (p = 0.036).

Conclusions: Only 25% of patients with glenohumeral osteoarthritis treated with shoulder hemiarthroplasty are satisfied with their outcome at an average of seventeen years after the operation. Patients with concentric glenoid wear and primary osteoarthritis have better outcomes than those with eccentric glenoid wear and secondary osteoarthritis do, but patients in both groups experienced deterioration of results over time.

Level Of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.2106/JBJS.K.00603DOI Listing
November 2012

Intermediate outcomes following percutaneous fixation of proximal humeral fractures.

J Bone Joint Surg Am 2012 Jul;94(13):1223-8

Mount Sinai School of Medicine, New York, NY, USA.

Background: Mini-open reduction and percutaneous fixation of proximal humeral fractures historically results in good outcomes and a low prevalence of osteonecrosis reported with short-term follow-up. The purpose of this study was to determine the midterm results of our multicenter case series of proximal humeral fractures treated with percutaneous fixation.

Methods: Between 1999 and 2006, thirty-nine patients were treated with percutaneous reduction and fixation for proximal humeral fractures at three tertiary shoulder referral centers. Twenty-seven of these patients were available for intermediate follow-up at a minimum of three years (mean, eighty-four months; range, thirty-seven to 128 months) after surgery; the follow-up examination included use of subjective outcome measures and radiographic analysis to identify osteonecrosis and posttraumatic osteoarthritis on radiographs.

Results: Osteonecrosis was detected in seven (26%) of the total group of twenty-seven patients at a mean of fifty months (range, eleven to 101 months) after the date of percutaneous fixation. Osteonecrosis was observed in five (50%) of the ten patients who had four-part fractures, two (17%) of the twelve patients who had three-part fractures, and none (0%) of the five patients who had two-part fractures. Posttraumatic osteoarthritis, including osteonecrosis, was present on radiographs in ten (37%) of the total group of twenty-seven patients. Posttraumatic osteoarthritis was observed in six (60%) of the ten patients who had four-part fractures, four (33%) of the twelve patients who had three-part fractures, and none (0%) of the five patients who had two-part fractures.

Conclusions: Intermediate follow-up of patients with percutaneously treated proximal humeral fractures demonstrates an increased prevalence of osteonecrosis and posttraumatic osteoarthritis over time, with some patients with these complications presenting as late as eight years postoperatively. Development of osteonecrosis did not have a universally negative impact on subjective outcome scores.
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http://dx.doi.org/10.2106/JBJS.J.01371DOI Listing
July 2012

How to minimize complications in shoulder instability and rotator cuff surgery.

Instr Course Lect 2012 ;61:131-41

Department of Orthopaedic Surgery, Mt. Sinai Medical Center, New York, NY, USA.

Arthroscopic instability and rotator cuff repair techniques have rapidly evolved over the past decade with expanding indications; however, there has been a corresponding increase in complications. Careful attention to detail and patient selection will result in satisfactory outcomes for most patients.
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June 2013

National trends in rotator cuff repair.

J Bone Joint Surg Am 2012 Feb;94(3):227-33

Department of Orthopaedic Surgery, Mount Sinai School of Medicine, 5 East 98th Street, Box 1188, New York, NY 10029, USA.

Background: Recent publications suggest that arthroscopic and open rotator cuff repairs have had comparable clinical results, although each technique has distinct advantages and disadvantages. National hospital and ambulatory surgery databases were reviewed to identify practice patterns for rotator cuff repair.

Methods: The rates of medical visits for rotator cuff pathology, and the rates of open and arthroscopic rotator cuff repair, were examined for the years 1996 and 2006 in the United States. The national incidence of rotator cuff repairs and related data were obtained from inpatient (National Hospital Discharge Survey, NHDS) and ambulatory surgery (National Survey of Ambulatory Surgery, NSAS) databases. These databases were queried with use of International Classification of Diseases, Ninth Revision (ICD-9) procedure codes for arthroscopic (ICD-9 codes 83.63 and 80.21) and open (code 83.63 without code 80.21) rotator cuff repair. We also examined where the surgery was performed (inpatient versus ambulatory surgery center) and characteristics of the patients, including age, sex, and comorbidities.

Results: The unadjusted volume of all rotator cuff repairs increased 141% in the decade from 1996 to 2006. The unadjusted number of arthroscopic procedures increased by 600% while open repairs increased by only 34% during this time interval. There was a significant shift from inpatient to outpatient surgery (p < 0.001).

Conclusions: The increase in national rates of rotator cuff repair over the last decade has been dramatic, particularly for arthroscopic assisted repair.
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http://dx.doi.org/10.2106/JBJS.J.00739DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3262185PMC
February 2012

Molecular response of the patellar tendon to fatigue loading explained in the context of the initial induced damage and number of fatigue loading cycles.

J Orthop Res 2012 Aug 6;30(8):1327-34. Epub 2012 Jan 6.

Leni and Peter W. May Department of Orthopaedics, Mount Sinai School of Medicine, Mount Sinai School of Medicine, 5 East 98th Street, New York, New York 10029, USA.

Accumulation of sub-rupture fatigue damage has been implicated in the development of tendinopathy. We previously developed an in vivo model of damage accumulation using the rat patellar tendon. Our model allows us to control the input loading parameters to induce fatigue damage in the tendon. Despite this precise control, the resulting induced damage could vary among animals because of differences in size or strength among their patellar tendons. In this study, we used number of applied cycles and initial (day-0) parameters that are indicative of induced damage to assess the molecular response 7 days after fatigue loading. We hypothesized that day-0 hysteresis, elongation, and stiffness of the loading and unloading load-displacement curves would be predictive of the 7-day molecular response. Results showed correlations between the 7-day molecular response and both day-0 elongation and unloading stiffness. Additionally, loading resulted in upregulation of several extracellular matrix genes that suggest adaptation; however, several of these genes (Col-I, -XII, MMP 2, and TIMP 3) shut down after a high level of damage was induced. We showed that evaluating the 7-day molecular profile in light of day-0 elongation provides important insight that is lost from comparing number of fatigue loading cycles only. Our data showed that loading generally results in an adaptive response. However, the tendon's ability to effectively respond deteriorates as greater damage is induced.
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http://dx.doi.org/10.1002/jor.22059DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3763927PMC
August 2012

Structural and mechanical effects of in vivo fatigue damage induction on murine tendon.

J Orthop Res 2012 Jun 9;30(6):965-72. Epub 2011 Nov 9.

Leni and Peter W. May Department of Orthopaedics, Mount Sinai School of Medicine, New York, New York 10029, USA.

The purpose of this study was to develop and validate an in vivo mouse model of tendon fatigue and use this model to investigate and quantify the physical manifestations of fatigue damage in mouse tendon. Patellar tendons of C57BL/6J mice were fatigue loaded at 2 Hz to three endpoints (4 N peak force per cycle for 1 h, 6 N for 1 h, and 4 N for 2 h), during which hysteresis, tangent stiffness, and peak strain of each cycle were measured. Damage accumulation was then quantified using in situ histology, and each tendon was loaded monotonically to failure. Histological damage increased significantly in all three groups (≥2-fold), and monotonic stiffness decreased significantly in the 6 N, 1 h and 4 N, 2-h groups (~25%), suggesting that damage initially manifests as changes to the collagen structure of the tendon and subsequently as changes to the function. For the fatigue loading protocols used in this study, none of the evaluated real-time parameters from fatigue loading correlated with damage area fraction measured structural damage or monotonic stiffness, suggesting that they are not suited to serve as proxies for damage accumulation. In future studies, this model will be used to compare the biological response of mouse tendon to fatigue damage across genetic strains.
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http://dx.doi.org/10.1002/jor.22012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3755359PMC
June 2012

The relationships between cyclic fatigue loading, changes in initial mechanical properties, and the in vivo temporal mechanical response of the rat patellar tendon.

J Biomech 2012 Jan 4;45(1):59-65. Epub 2011 Nov 4.

Leni & Peter W May Department of Orthopaedics Surgery Mount Sinai School of Medicine, New York, NY 10029, United States.

Damage accumulation underlies tendinopathy. Animal models of overuse injuries do not typically control loads applied to the tendon. Our in vivo model in the rat patellar tendon allows direct control of the loading applied to the tendon. Despite this advantage, natural variation among tendons results in different amounts of damage induced by the same loading protocol. Our objectives were to (1) assess changes in the initial mechanical parameters (hysteresis, stiffness of the loading and unloading load-displacement curves, and elongation) after fatigue loading to identify parameters that are indicative of the induced damage, and (2) evaluate the relationships between these identified initial damage indices with the stiffness 7 day after loading. Left patellar tendons of adult, female retired breeder, Sprague-Dawley rats (n = 68) were fatigue loaded per our previously published in vivo fatigue loading protocol. To induce a range of damage, fatigue loading consisted of either 5, 100, 500 or 7200 cycles that ranged from 1 N to 40 N. Diagnostic tests were applied before and immediately after fatigue loading, and after 45 min of recovery to deduce recoverable and non-recoverable changes in initial damage indices. Relationships between these initial damage indices and the 7-day stiffness (at sacrifice) were determined. Day-0 hysteresis, loading and unloading stiffness exhibited cycle-dependent changes. Initial hysteresis loss correlated with the 7-day stiffness. k-means cluster analysis demonstrated a relationship between 7-day stiffness and day-0 hysteresis and unloading stiffness. This analysis also separated samples that exhibited low from high damage in response to both high or low number of cycles; a key delineation for interpretation of the biological response in future studies. Identifying initial parameters that reflect the induced damage is critical since the ability of the tendon to repair depends on the damage induced and the number of applied loading cycles.
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http://dx.doi.org/10.1016/j.jbiomech.2011.10.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3763928PMC
January 2012

Subacromial impingement syndrome.

J Am Acad Orthop Surg 2011 Nov;19(11):701-8

Department of Orthopaedic Surgery, University of Minnesota Medical School, MN, USA.

Subacromial impingement syndrome (SIS) represents a spectrum of pathology ranging from subacromial bursitis to rotator cuff tendinopathy and full-thickness rotator cuff tears. The relationship between subacromial impingement and rotator cuff disease in the etiology of rotator cuff injury is a matter of debate. Both extrinsic compression and intrinsic degeneration may play a role. Management includes physical therapy, injections, and, for some patients, surgery. There remains a need for high-quality studies of the pathology, etiology, and management of SIS.
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http://dx.doi.org/10.5435/00124635-201111000-00006DOI Listing
November 2011
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