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ANDREAS PANAGOPOULOS   Dr.  Other 
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ANDREAS PANAGOPOULOS published an article in July 2016.
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Ch. Bouras

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Christos N. Pitelis

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Article 2 Reads 0 Citations Clinical Outcomes and Complications of Cortical Button Distal Biceps Repair: A Systematic Review of the Literature Andreas Panagopoulos, Irini Tatani, Pantelis Tsoumpos, Dimit... Published: 21 July 2016
Journal of Sports Medicine, doi: 10.1155/2016/3498403
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Objectives. The purpose of the present study was to investigate the clinical outcomes and complications of the cortical button distal biceps fixation method. Material and Methods. All methods followed the PRISMA guidelines. Included studies had to describe clinical outcomes and complications after acute distal biceps repair with cortical button fixation. Eligibility criteria also included English language, more than 5 cases with minimum follow-up of 6 months, and preferably usage of at least one relevant clinical score (MEPS, ASES, and/or DASH) for final outcome. A loss of at least 30° in motion—flexion, extension, pronation, or supination—and a loss of at least 30% of strength were considered an unsatisfactory result. Results. The review identified 7 articles including 105 patients (mean age 43.6 years) with 106 acute distal biceps ruptures. Mean follow-up was 26.3 months. Functional outcome of ROM regarding flexion/extension and pronation/supination was satisfactory in 94 (89.5%) and 86 (82%) patients in respect. Averaged flexion and supination strength had been reported in 6/7 studies (97 patients) and were satisfactory in 82.4% of them. The most common complication was transient nerve palsy (14.2%). The overall reoperation rate was 4.8% (5/105 cases). Conclusion. Cortical button fixation for acute distal biceps repair is a reproducible operation with good clinical results. Most of the complications can be avoided with appropriate surgical technique. 1. IntroductionRationale. Distal biceps tendon ruptures are estimated to occur at a rate of 1.2 per 100,000 persons per year and are most commonly seen in the dominant elbow of men who are in the fourth decade of life [1]. A single traumatic event in which an unexpected eccentric force is applied to a flexed elbow is the most common mechanism of injury. Tobacco and anabolic steroid use and the use of statin drugs are known to be associated with an increased risk of distal biceps tendon ruptures [1, 2].Results of surgical repair have been superior to nonsurgical treatment in terms of improving elbow strength in flexion and supination, as well as overall upper extremity endurance [3, 4]. Single-incision techniques and two-incision approaches have been described using a variety of fixation methods, including transosseous suture repair [5–7], suture anchors, [8, 9] cortical button fixation, [7, 10–13] double intramedullary cortical button, [14] interference screws (alone [15] or in conjunction with a cortical button [16]), and endoscopic assisted techniques [17].Cortical button repair of distal biceps tendon ruptures was first described by Bain et al. in 2000 [10]. Biomechanical studies have demonstrated higher load to failure when compared to other techniques [18, 19] thus allowing for earlier postoperative rehabilitation [20]. Excellent clinical results of the cortical button technique have been reported with respect to patient satisfaction and restoration of functional outcome with minimal complications [10, 11, 21]. Recently, Chavan et al. [22] in a systematic review showed that repairs using a cortical button performed better than other repair methods. The authors also compared two different approaches and found no difference in the overall incidence of complications between 2-incision approaches (16%) and single-incision approaches (18%), although they noted more instances of loss of forearm rotation with the 2-incision approach.Clinical studies that report on clinical outcomes and complication rates of cortical button fixation are scarce and are generally of small numbers with low levels of evidence [7, 23–28]. Despite the reported good clinical results and high patient satisfaction, the technique has been associated with several complications such as heterotopic ossification (HO), nerve injuries, and failure of the repair [25, 29–33].Objectives. To our knowledge, a systematic review of clinical outcomes and complications after cortical button fixation for acute distal biceps ruptures has not been performed yet. The purpose of the present study is to critically evaluate the relevant literature to better quantify the expected outcomes and complications in a larger patient population. Such information would be potentially helpful in developing an evidence-based approach in the management of these injuries.2. Material and Methods2.1. Identification of StudiesA research protocol was developed as described by Wright et al. [34] and used throughout the study process. This protocol was not registered. All methods followed the PRISMA guidelines. Analytic searches of PubMed, Embase, Web of Science, Google Scholar, and the Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials were performed, restricting search results to the years 2000, when the technique was first reported, through May 2015. The query was distal biceps alone or with rupture, repair, injury, button, cortical button, endobutton, suspensory fixation, and/or complications (Figure 1). All titles and s were reviewed to identify potentially relevant articles. The full manuscript was retrieved for all potentially relevant articles and when the title, keywords, or revealed insufficient information to determine appropriateness for inclusion. The bibliographies of the retrieved studies were manually checked for potential relevant articles that were missed in the initial search. Second-stage screening of the full-text articles was performed unblended by 2 of the authors (A. Panagopoulos and I. Tatani). Duplicates were deleted. On November 30, 2015, we updated the search to provide a complete up-to-date interpretation of available data. Disagreements were discussed and resolved in consensus.Figure 1: Search methodology and flowchart of excluded studies.2.2. Eligibility CriteriaClinical trials, observational studies, and case series involving patients with distal biceps ruptures treated with cortical button fixation from 2000 onwards were included. To be eligible regarding the final outcome, studies had to describe at least 1 of the following functional outcome measures: range of motion (ROM) (flexion/extension, pronation/supination); strength of the elbow after and before surgical treatment or strength of the elbow after surgical treatment compared with the contralateral side (unaffected elbow); at least one relevant score (MEPS, ASES, or DASH); and complication type and rates. Eligibility criteria also included English language, acute repairs (<6 weeks after injury), more than 5 cases, and minimum follow-up of 6 months. We excluded studies of other distal biceps fixation methods (suture anchors, transosseous sutures, double button fixation, or cortical button with supplementary interference screw) as well as studies conducted on children (mean age < 18), cadavers, review and editorial articles, or anatomical and biomechanical studies.3. Data ExtractionIncluded studies were divided into 2 groups based on patient’s demographic and clinical data. Group A included studies presenting comprehensive patient flowcharts with complete demographic, outcome, and complications data, thus allowing us to extract separate information for the acute cases. Group B included studies that met our inclusion criteria but presented their data in mean values without separate information for each patient. Unlike similar reviews, in the present study, we decided to exclude chronic ruptures (older than 6 weeks) supposing that the overall clinical outcome and complication rate would be worse in comparison with acute repairs. In accordance with Chavan et al. [22], the functional outcome of ROM and strength was divided into satisfactory or unsatisfactory. A loss of at least 30° in motion (flexion, extension, pronation, or supination) and a loss of at least 30% of strength were considered an unsatisfactory result. A loss of <30° in motion and a loss of <30% of flexion or supination strength were considered a satisfactory result. Heterotopic ossification was not considered a complication unless it was noted to be associated with pain or to cause a loss of greater than 30° of motion in any plane or required revision operation. All inclusion and exclusion criteria as well as our definitions of complications were defined before performing the literature review. Each clinical study was given a level of evidence by consensus agreement of the investigators [35]. The heterogeneity and low level of evidence of the studies that met our inclusion criteria prevented us from performing a meta-analysis.4. ResultsThe final trial selection identified a total of 644 study records. After screening of the titles, the literature search yielded 115 studies that were eligible for assessment. After screening of the s and removal of duplicates, the literature search yielded 36 studies that were eligible for full-text assessment. Seven of the reviewed articles met our inclusion and exclusion criteria. Two of the included articles reported on 2 study groups; one study compared two different protocols of rehabilitation [20] and one study compared patients with or without complications [20, 23]. Three studies referred to acute repairs only [20, 23, 27] and four studies presented a mixed population predominantly of acute repairs [10, 11, 21, 26]. The included studies reported on 126 patients with 127 acute or chronic distal biceps ruptures. After removal of chronic cases (16), partial ruptures (4), and revisions of acute repairs (1), the final study group represented 105 patients that were included in our systematic review.All clinical studies were designated level IV evidence by both reviewers; there were no randomized, prospective, or retrospective comparative studies. According to our criteria, 4 studies were included in Group A (having patient flowchart), thus allowing us to extract personalized data for each patient with acute repair, and 3 studies were included in Group B where data were extracted as means and percentages. All
Article 1 Read 1 Citation Sword-Like Trauma to the Shoulder with Open Head-Splitting Fracture of the Head Andreas Panagopoulos, Konstantinos Pantazis, Ilias Iliopoulo... Published: 05 July 2016
Case Reports in Orthopedics, doi: 10.1155/2016/3539503
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Head-splitting fractures occur as a result of violent compression of the head against the glenoid; the head splits and the tuberosities may remain attached to the fragments or split and separate. Isolated humeral head-splitting fractures are rare injuries. Favorable results with osteosynthesis can be difficult to achieve because of the very proximal location of the head fracture and associated poor vascularity. We present a case of a 67-year-old man who sustained a severe, sword-like trauma to his left shoulder after a road traffic accident with associated isolated open Gustilo-Anderson IIIA humeral head-splitting fracture. Bony union was achieved with minimal internal fixation but the clinical outcome deteriorated due to accompanying axillary nerve apraxia. To our knowledge, this type of sword-like injury with associated humeral head-split fracture has not previously been reported.1. IntroductionHead-splitting fractures are extremely rare and indicate a severe trauma to the shoulder joint. The head is violently compressed against the glenoid and split with or without associated dislocation. We present a case of an isolated open Gustilo-Anderson IIIA humeral head-splitting fracture after a road traffic accident treated with minimal internal fixation. To our knowledge, this type of sword-like injury has not previously been reported.2. Case PresentationA 67-year-old man was admitted to our department following a high-speed road traffic accident. He was sited at the back of a car when a lateral-frontal collision happened crushing the back door to his left shoulder. He sustained an open, Gustilo-Anderson IIIA fracture of the proximal humerus with a large overlying sword-like contaminated wound and significant skin loss (Figure 1(a)). There was no neurovascular deficit to the distal forearm and hand. He sustained also fractures of the 1st, 2nd, and 6th rib without any intrathoracic injury. Plain radiographs and CT scan indicated an anteroposterior directed head-splitting fracture of the humeral head involving ~30% of the lateral articular surface with a sagittal extension pattern of the greater tuberosity and without any evidence of humeral head dislocation (Figures 1(b) and 1(c)). He was transferred immediately to the operating theatre as there was uncontrolled bleeding from the wound and hemoglobin level had been dropped by 4 degrees during resuscitation.Figure 1: (a) Photography of the trauma during patient resuscitation indicated severe, sword-like injury to the left shoulder, with open fracture of the humeral head (arrow). (b) Preoperative anteroposterior X-ray of the left shoulder showing head-splitting fracture of the proximal humerus and presence of multiple foreign bodies (glass). (c) CT scan of the left shoulder indicating involvement of ~30% of the articular surface and the greater tuberosity. (d) Intraoperative picture after muscle and skin closure. (e) Postoperative X-ray of the left shoulder showing adequate reduction of the fragment. (f) Condition of the skin at the 10th postoperative day just before a split skin graft was about to apply.At surgery, thorough debridement was carried out and foreign bodies (glass particles) were removed where possible. There was a large circumferential wound to the deltoid involving its anterior, middle, and part of its posterior fibers. The platysma muscle was also ruptured exposing the medial and lateral end of the clavicle. The fractured head was palpable under the deltoid being totally uncovered from rotator cuff muscles. Severe bleeding was detected from the posterior circumflex artery and vein; both vessels were ligated. The axillary artery and the brachial plexus were recognized unmarked. We were not able to identify the axillary nerve at that time. The fractured humeral head was reduced with pointed clamps and fixed with two 4 mm AO cancellous screws (Figure 1(e)). The torn RC was repaired primarily with transosseous nonabsorbable sutures. Deep soft tissue closure was achieved by loosely approximated absorbable sutures (Figure 1(d)). Skin has been closed partially and a Penrose drain was applied. From the wound was cultivated E. coli and Staphylococcus warneri. The patient was treated with intravenous antibiotics for 3 weeks and oral administration for another 3 weeks after his discharge. At the 10th postoperative day, the wound showed signs of reepithelialization and a split-thickness skin graft was applied for terminal closure (Figure 1(f)).The arm was placed in a sling for 4 weeks. Shoulder physiotherapy and passive assisted mobilization were commenced as soon as the wound was closed, at the second postoperative week. Soft tissue and bony healing occurred without further surgical intervention. The humeral head fracture united with no evidence of avascular necrosis, confirmed radiologically within 12 months (Figures 2(a)–2(c)). The patient unfortunately did not recover shoulder abduction and forward elevation as an ENG assessed a complete neurapraxia of the axillary nerve (Figures 2(d)–2(f)). He had a Constant score of 47 at the latest clinical follow-up 17 months postoperatively. A nerve transfer has been offered to him but he denied any further surgical intervention.Figure 2: ((a)–(c)) Radiological examination at 12 months with anteroposterior views in external (a) and internal (b) rotation as well as axillary view of the shoulder (c) indicated solid union of the fracture. ((d)-(e)) Poor clinical outcome especially in forward elevation due to axillary nerve neurapraxia. (f) Clinical picture of the wound at 17 months after surgery.3. DiscussionHead-splitting fractures indicate a severe trauma to the shoulder joint. The head is violently compressed against the glenoid and split. A segment of the humeral head is fractured and is subluxated or dislocated, while the articular surface of the unfractured part of the head remains attached to the shaft. Neer II [1] defined splitting fractures as those in which the fractured fragments measure more than 20% of the articular surface. Classic radiographic “trauma series” of the shoulder and computed tomography are valuable for delineating the configuration of the fracture and helping to plan surgical reconstruction [2, 3]. Robinson et al. [4] proposed two patterns of injury in complex humeral head fractures with dislocation (or splitting) depending on a prospective assessment of the pattern of soft tissue and bony injury and the degree of devascularisation of the humeral head. In type I injuries, the head retains capsular attachments and arterial back-bleeding whereas in type II injuries the head is devoid of significant soft tissue attachments with no active arterial bleeding. ORIF is recommended in type I injuries as only two of 23 patients with type I injuries developed radiological evidence of osteonecrosis of the humeral head, compared with four of seven patients with type II injuries. The mechanism of injury in our case was more unique as the split in the humeral head was probably caused by direct extrinsic trauma to the shoulder by the distorted metallic parts of the back door during the crush. This explains the severe damage to deltoid and rotator cuff muscles as well as the neurologic damage to the axillary nerve.The outcome of head-split fractures, regardless of management, is thought to be worse than other types of humeral head fractures because of a perceived higher energy of injury and disruption of the terminal blood supply to the articular fragments [5]. Lee and Hansen [6] reported on 19 patients with displaced 4-part fracture or fracture dislocation treated with ORIF and having no signs of AVN after a mean follow-up period of 23.6 months. They hypothesized a mechanism of revascularization with capillary ingrowth sequence and new bone formation during the healing process (e.g., creeping substitution). As the humeral head is surrounded by rich vascular tissue and has wide fractured surfaces relative to the thickness of the head, a reduced mechanical stress is expected as the healing is progressed, thus reducing the incidence of AVN. The available evidence on optimal treatment of head-splitting fractures is scarce: apart from some case reports [7–9], only two case series have been published on minimal [10] or locking plate osteosynthesis [11], one case series has been published on hemiarthroplasty [12], and two recent studies have been published on reverse shoulder arthroplasty [13, 14] of isolated head-splitting fractures.Collopy and Skirving [7] reported on a 20-year-old patient who sustained a “transchondral fracture dislocation” involving 60% of the articular surface and fixed with two 4.0 mm cancellous screws; at 7-year follow-up, the patient had full range of motion and no evidence of AVN or arthritis. Gokkus et al. [8] reported a complex head-splitting fracture with anterior dislocation of the fractured part on a 40-year-old patient. Surgery was performed within 6 hours and the osteochondral fragment, carrying approximately 65% of the articular surface, was found firmly entrapped between the anterior glenoid rim and the subscapularis. Anatomical reduction was achieved with two k-wires and three 4 mm AO cancellous screws. After the 15-month follow-up, the patient had 130° of forward elevation, no shoulder pain, and a Constant score of 76 points. Bailie and McAlinden [9] reported a case of a 17-year-old man with a compound comminuted fracture of the proximal third of the humeral shaft with complete head-splitting extension and a large overlying contaminated wound with skin loss (Gustilo-Anderson grade IIIB). This is the only case in the literature describing an open head-splitting fracture. The mechanism of injury was high-speed road traffic accident. At surgery, fixation with a bridging plate was impossible as the proximal third of the humeral shaft was found to be highly comminuted with marked degloving and soft tissue stripping of multiple fragments in this segment. Fixation of the head part was ac
Article 1 Read 9 Citations Entrepreneurial universities and overt opportunism Peter T. Gianiodis, Gideon D. Markman, Andreas Panagopoulos Published: 27 June 2016
Small Business Economics, doi: 10.1007/s11187-016-9753-6
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Entrepreneurial universities are a catalyst for regional economic development and growth. Yet, the entrepreneurial university may not always capture the full gains made by the broader economy due to opportunistic behavior by its faculty scientists. We expand agency theory to address conditions when opportunistic behavior persists in the face of substantial information symmetry and where principals appear to tolerate opportunism despite the authority to sanction their agents. Using a sample of 105 US research universities and 73,603 scientists, we demonstrate that some scientists privately leak discoveries invented while working for their universities. Counter to prior prediction, we find that universities acting as principals often do not retaliate even when having knowledge of such opportunistic behavior and the capability to punish non-complying agents. To extend theory, we examined contexts that exacerbate and alleviate such overt opportunism: High-value discoveries and sizable entrepreneurial activity are associated with greater opportunistic behavior, whereas efforts to empower those who have close professional ties with scientists—their departments and technology commercialization offices—are related to reduced opportunism. To complement our empirical analyses, we provide a stylized mathematical model that shows how agency theory can improve its predictive power once it formally recognizes certain conditions under which agents wield substantial bargaining power over their principals, who in turn seem to tolerate agents’ overt opportunistic behavior.
Article 2 Reads 0 Citations Least possible fixation techniques of 4-part valgus impacted fractures of the proximal humerus: a systematic review Andreas Panagopoulos, Irini Tatani, Dimitrios Ntourantonis, ... Published: 25 March 2016
Orthopedic Reviews, doi: 10.4081/or.2016.6211
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The valgus-impacted (VI) 4-part fractures are a subset of fractures of the proximal humerus with a unique anatomic configuration characterized by a relatively lower incidence of avascular necrosis after operative intervention. We systematically reviewed clinical studies assessing the benefits and harms of least possible fixation techniques (LPFT) for this unique fracture type. Such information would be potentially helpful in developing an evidence-based approach in the management of these complex injuries. We performed analytic searches of PubMed, Embase, Web of Science, Google Scholar and the Cochrane Library, restricting it to the years 1991-2014. Included studies had to describe outcomes and complications after primary osteosynthesis with any type of LPFT apart from plate-screws and intramedullary nailing. Eligibility criteria were also included English language, more than 5 cases, minimum follow up of one year and report of clinical outcome using at least one relevant score (Constant, Neer or ASES). Based on 292 database hits we identified 12 eligible studies including 190 four-part valgus impacted fractures in 188 patients. All eligible studies were case series composed of min 8 to max 45 patients per study. The gender distribution was 60% (112) female and 40% (76) male. The average age of the patients at the time of injury was 54.5 years. In 8/12 studies an open reduction was used for fracture fixation using different surgical techniques including KW, cerclage wires, cannulated screws and osteosutures. Closed reduction and percutaneous fixation was used in 4 studies. Mean follow-up time ranged from 24 to 69 months. A good functional outcome (constant score >80) was reported in 9/12 studies. The most common complication was avascular necrosis of the humeral head with an overall incidence of 11% (range, 0-26.3%). Total avascular necrosis (AVN) was found in 15/188 patients (7.9%) and was more common in percutaneous techniques and partial AVN in 6/188 (3.1%) being more common in open techniques. The overall re-operation rate was very low (3.7%). Insufficient study designs cannot provide definite treatment recommendations and quantitative data synthesis of outcome. In general, LPFT for 4-part VI fractures leads to satisfactory outcomes with low incidence of complications. A considerable risk of biases can be attributed to fracture classification, proper radiological control, mean age of patients, mixed types of fixation methods, nonage adjusted clinical scoring and small follow up periods. These factors are discussed in detail. Level of evidence: systematic review of literature (level IV) as most of the studies were level IV.
Article 0 Reads 0 Citations International Collaboration through Market Co-Creation: Strategies for Emerging Country Firms Andreas Panagopoulos, Panos Desyllas, Christos N. Pitelis Published: 01 January 2015
Academy of Management Proceedings, doi: 10.5465/ambpp.2015.17341abstract
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Drawing on ideas centred on market co-creation and complementary assets, we propose that developing and emerging country (DEC) pharmaceutical firms, which operate in an increasingly challenging environment with the emergence of a stronger intellectual property (IP) regime and competitive pressures from developed countries multinational enterprises (MNEs), can profit by collaborating rather than directly competing with MNEs. We develop a game theoretic model in order to study the conditions under which collaboration becomes the most preferable strategic outcome for both parties. Our conceptual model suggests that when trade agreements (such as Trade Related Aspects of IP Rights) allow MNEs to take legal action against DEC firms whose products are perceived as infringing their IP, collaboration between firms can prove preferable to both parties if DEC firms can help engender opportunities for market co-creation and expansion, by leveraging complementary assets and capabilities. In this context and counter to conventional wisdom, challenges by DECs to MNEs’ attempts to extend the scope and length of their IP rights can foster collaboration. Important implications for business strategy and public policy are also discussed.
Article 1 Read 4 Citations Integrated Groundwater Resources Management Using the DPSIR Approach in a GIS Environment Context: A Case Study from the... Christos Mattas, Konstantinos S. Voudouris, Andreas Panagopo... Published: 24 April 2014
Water, doi: 10.3390/w6041043
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The Gallikos River basin is located in the northern part of Greece, and the coastal section is part of a deltaic system. The basin has been influenced by anthropogenic activities during the last decades, leading to continuous water resource degradation. The holistic approach of the Driver-Pressure-State-Impact-Response (DPSIR) framework was applied in order to investigate the main causes and origins of pressures and to optimize the measures for sustainable management of water resources. The major driving forces that affect the Gallikos River basin are urbanization, intensive agriculture, industry and the regional development strategy. The main pressures on water resources are the overexploitation of aquifers, water quality degradation, and decrease of river discharge. Recommended responses were based on the Water Framework Directive (WFD) 2000/60/EC, and sum up to rationalization of water resources, land use management and appropriate utilization of waste, especially so effluent. The application of the DPSIR analysis in this paper links the socioeconomic drivers to the water resource pressures, the responses based on the WFD and the national legislation and is as a useful tool for land-use planning and decision making in the area of water protection.