Return to play in football

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Return to Play

in Football

An Evidence-based Approach

123 Volker Musahl · Jón Karlsson

Werner Krutsch · Bert R. Mandelbaum

João Espregueira-Mendes · Pieter d’Hooghe

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Volker Musahl • Jón Karlsson

Werner Krutsch • Bert R. Mandelbaum

João Espregueira-Mendes

Pieter d'Hooghe

Editors

Return to Play

in Football

An Evidence-based Approach

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ISBN 978-3-662-55712-9 ISBN 978-3-662-55713-6 (eBook) https://doi.org/10.1007/978-3-662-55713-6

Library of Congress Control Number: 2017964012 © ESSKA 2018

This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed.

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Printed on acid-free paper

This Springer imprint is published by Springer Nature

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The registered company address is: Heidelberger Platz 3, 14197 Berlin, Germany

Volker Musahl

UPMC Rooney Sports Complex University of Pittsburgh Pittsburgh, Pennsylvania, USA Werner Krutsch

Department of Trauma Surgery University Medical Centre Regensburg Regensburg, Germany

João Espregueira-Mendes Clínica do Dragão

Espregueira-Mendes Sports Centre Porto, Portugal Jón Karlsson Department of Orthopaedics University of Gothenburg Gothenburg, Sweden Bert R. Mandelbaum

Santa Monica, California, USA Pieter d'Hooghe

Orthopaedic Surgery Aspetar Hospital Doha, Qatar

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v

Many recent innovations, particularly in the field of biotechnology, informat-ics, artificial intelligence, nanotechnology, and cognitive sciences, create a new vision upon the different aspects of football medicine.

They find their applications as well in the prevention, the diagnosis, and the therapy.

But at the end of all that comes the most difficult decision: the return to play.

Our English friends say: “The proof of the pudding is the eating.”

In my experience, “return to play” decisions are among the most difficult challenges for us, football doctors, whereby we must, of course, make good use of the classical criteria, without underestimating our clinical judgment and our personal experience.

The “return to play” moment is an important moment, in the first place for the player himself, reaching the end of a dark medical tunnel, but also for his medical and technical surrounding.

The surgeon, the team doctor, and the physiotherapist are concerned: they take the responsibility of giving the green light to the player, being under a constant pressure of coaches, directors, and fans, who consider every reha-bilitation as too long, but knowing that the most frequent reason for a new injury is an old injury.

Also concerned is the technical staff, particularly the fitness coach, respon-sible for a progressive evolution of the intensity and pressure of trainings and matches.

The “return to play” moment opens the door of the medical and paramedi-cal infrastructure and allows the player, at last, to enjoy again the smell of the grass.

It is the moment where medical and technical collaborators join their efforts, proving that only their perfect symbiosis reaches the best result.

Michel d’Hooghe Medical Committee of UEFA and FIFA, Nyon, Switzerland

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vii Part I Introduction

1 Basic Concepts in Functional Biomechanics . . . 3

Jonathan A. Gustafson, Tetsuya Takenaga, and Richard E. Debski

2 Emerging Concepts in Human Performance Optimization . . . 17

Christopher Connaboy, Matthew E. Darnell, Shawn Eagle, Caleb D. Johnson, and Bradley C. Nindl

3 How to Predict Injury Risk . . . 35

David Sundemo, Eduard Alentorn-Geli, and Kristian Samuelsson

4 How to Predict Knee Kinematics During an ACL Injury . . . 47

Zoe Englander, Shaun K. Stinton, and Thomas P. Branch

5 Match-Related Factors Influencing Injury Risk . . . 63

Jaakko Ryynänen, Mats Börjesson, and Jón Karlsson

6 Psychological Factors Influencing Return to

Sport After Anterior Cruciate Ligament Reconstruction . . . 73

Kate E Webster and Julian A Feller

7 Exercise Physiology of Football: Factors Related

to Performance and Health . . . 85

Tim Meyer, Ross Julian, and Chris Thompson Part II ACL: Criteria-based Return to Play

8 A Test Battery for Return to Play in Football . . . 99

Felix Fischer, Christian Hoser, Elmar Herbst, Peter Gföller, and Christian Fink

9 Principles and Limitations of Prehabilitation and

Return to Play Strategies . . . 111

Helmut Hoffmann, Werner Krutsch, and Oliver Loose

10 Return-to-Play Criteria: The Delaware Experience . . . 127

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11 Return to Play Criteria: The Norwegian Experience . . . 139

Håvard Moksnes and Lars Engebretsen

12 Criteria-Based Return to Play After ACL Reconstruction:

The Brazilian Experience . . . 149

Gustavo Gonçalves Arliani, Mario Ferretti, and Moises Cohen

13 Return to Sports Following Anterior Cruciate Ligament Reconstruction: Recommendations of the German Knee

Society (Deutsche Kniegesellschaft, DKG) . . . 159

Wolf Petersen, Christian Zantop, Andrea Achtnich, Thore Zantop, and Amelie Stöhr

14 Return to Play Criteria: The Swedish Experience . . . 173

Suzanne Werner and Magnus Forssblad

15 ACL: Criteria-Based Return to Play—Outcome

Predictor Analysis After ACL Reconstruction . . . 183

Francesco Della Villa, Jacopo Gamberini, Daniele Caminati, Margherita Ricci, and Stefano Della Villa

16 Laxity-Based Return to Play . . . 193

Stefano Zaffagnini, Luca Macchiarola, Ilaria Cucurnia, Alberto Grassi, and Cecilia Signorelli

17 MRI-Based Laxity Measurement for Return to Play . . . 205

Renato Andrade, Rogério Pereira, Ricardo Bastos, Hugo Duarte, Hélder Pereira, Sérgio Rodrigues- Gomes, and João Espregueira-Mendes

18 Development and Implementation of a Modular

Return-to-Play Test Battery After ACL Reconstruction . . . 217

Hendrik Bloch, Christian Klein, Patrick Luig, and Helge Riepenhof

19 Quadriceps Strength Recovery After ACL Reconstruction

Using Hamstrings Tendon Autograft and Return to Play . . . 237

Yuichi Hoshino and Ryosuke Kuroda Part III ACL: Time-based Return to Play

20 Time-Based Return to Play: The MOON Experience . . . 247

Mia Smucny and Kurt P. Spindler

21 How Can MRI Help with Decision-Making? . . . 255

Marcio Bottene Villa Albers, Jason Shin, and Freddie H. Fu

22 ACL: Time-Based Return to Play. “Role of Patient

Reporting in Return to Play” . . . 263

Adam J. Popchak, Mohammad A. Yabroudi, and James J. Irrgang

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23 The Role of Orthobiologics in Return to Play . . . 273

Graeme P. Whyte, Alberto Gobbi, and John G. Lane Part IV Joint Specific Return to Play Recommendations

24 Return to Play in Football: Diagnosis, Treatment,

Rehabilitation and Prevention of Spinal Injuries . . . 285

Adad Baranto

25 Return to Play After Rotator Cuff Surgery . . . 313

Luca Pulici, Beatrice Zanini, Livia Carrai, Alessandra Menon, Riccardo Compagnoni, and Pietro Randelli

26 Return to Play After Shoulder Stabilization . . . 321

Jason J. Shin and Bryson Lesniak

27 Joint Specific Return to Play Recommendations:

“Return to Play in Non-operative Hip/Groin Pain” . . . 331

Nolan S. Horner, Seper Ekhtiari, Allison A. Chan, Hema N. Choudur, and Olufemi R. Ayeni

28 Return to Play Following Hip Arthroscopy for

FAI and Labral Lesions . . . 347

Simon Lee, Tyrrell Burrus, Pete Draovitch, and Asheesh Bedi

29 Return to Play After Ankle Injuries . . . 365

Frank G.J. Loeffen, Yoshiharu Shimozono, Gino M.M.J. Kerkhoffs, and John G. Kennedy

30 Return to Play in Stress Fractures of the Foot . . . 387

Pieter d’Hooghe and Athol Thomson

31 Return to Play in Stress Fractures of the Hip,

Thigh, Knee, and Leg . . . 409

Hélder Pereira, Duarte Sousa, Pieter d’Hooghe,

Sérgio Gomes, Joaquim Miguel Oliveira, Rui L. Reis, João Espregueira-Mendes, Pedro L. Ripoll, and Kenneth Hunt

32 Return to Football Following Achilles Tendon Rupture . . . 429

Michael R. Carmont, Jennifer A. Zellers, Maurizio Fanchini, Jon Karlsson, and Karin Grävare Silbernagel

33 Return to Play in Muscle Injuries . . . 441

Peter Ueblacker and Hans-Wilhelm Mueller-Wohlfahrt

34 Return-to-Play After Minor Overuse or Traumatic

Injury: ‘Stay and Play on Field’ . . . 453

Werner Krutsch, Klaus Eder, and Hauke Mommsen

35 Return to Play with Degenerative Joint Disease . . . 471

Peter Angele, Johannes Zellner, Johannes Weber, and Matthias Koch

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36 Return to Sports, the Use of Test Batteries . . . 487

Alli Gokeler, Stefano Zaffagnini, Caroline Mouton, and Romain Seil

Part V Return to Play After Complex Knee Injuries

37 Return to Play After Complex Knee Injuries: Return

to Play After Medial Collateral Ligament Injuries . . . 509

Marcin Kowalczuk, Markus Waldén, Martin Hägglund, Ricard Pruna, Conor Murphy, Jonathan Hughes, Volker Musahl, and Matilda Lundblad

38 Managing Chronic Medial Collateral Injuries . . . 525

Peter B. Gifford and Fares S. Haddad

39 Return to Play Following Anterior Cruciate

Ligament Injury . . . 535

Simon Ball, Nathan White, Etienne Cavaignac, Vincent Marot, Jacques Ménétrey, and Andy Williams

40 Philosophical and Practical Approach to Dealing with Knee Injuries in Elite Football: Experience Based Rather

than Evidence Based . . . 547

Simon Ball, Nathan White, and Andy Williams

41 On Field Testing After Anterior Cruciate

Ligament Reconstruction . . . 559

Pelin Pişirici, Atakan Çağlayan, Mustafa Karahan, and Michael Hantes

42 Return to Play After Posterolateral Corner Injuries . . . 569

Pablo E. Gelber, Magnus Forssblad, and Dani Romero-Rodríguez

43 Return to Play Following Meniscal Injuries . . . 583

Cécile Batailler, Elvire Servien, Robert Magnussen, Sébastien Lustig, and Philippe Neyret

44 Return to Play Following Cartilage Injuries . . . 593

Renato Andrade, Rogério Pereira, Ricardo Bastos, Hélder Pereira, J. Miguel Oliveira, Rui L. Reis, and João Espregueira-Mendes

45 Surgical Management of Articular Cartilage

in Football Players . . . 611

Jarret Woodmass, Michael Stuart, and Aaron Krych

46 Advanced Techniques of Cartilage Repair

in Football Players . . . 625

Andrea Sessa, Francesco Perdisa, Giuseppe Filardo, and Elizaveta Kon

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47 Return to Play After Multiple Knee Ligament Injuries . . . 637

Jorge Chahla, Luke O’Brien, Jonathan A. Godin, and Robert F. LaPrade

48 Return to Soccer Following Acute Patellar Dislocation . . . 649

Robert A. Magnussen, Laura C. Schmitt, and Elizabeth A. Arendt

49 Return to Play Following Tendon Injuries . . . 661

Mirco Herbort, Christoph Kittl, and Hermann Mayr Part VI Concussion

50 Role of Baseline Testing . . . 671

Philip Schatz

51 Multimodal Concussion Assessment . . . 683

Alicia Sufrinko, Daniel Charek, and Brandon Gillie

52 Sport-related Concussion: Experience from the National

Football League . . . 699

Michael W. Collins, Natalie Sandel, John A. Norwig, and Sonia Ruef

53 Controversy Around Headers . . . 713

Anthony P. Kontos

54 Concussion: Predicting Recovery . . . 723

Robert J. Elbin, Nathan D’Amico, Tamara Valovich McLeod, Tracey Covassin, and Morgan Anderson

Part VII Medical Issues and Doping

55 Return to Play After Cardiac Conditions . . . 739

Mats Börjesson and Jonathan Drezner

56 Return to Play After Infectious Disease . . . 755

Mats Börjesson, Daniel Arvidsson,

Christa Janse Van Rensburg, and Martin Schwellnus

57 Return to Play in Asthma and Pulmonary Conditions . . . 771

David Espinoza, Thomas Sisk, George Chiampas, and Aaron V. Mares

58 Return to Play After Injury: A Medicolegal Overview . . . 783

Heiko Striegel, Werner Krutsch, and Raymond Best Part VIII Ethical Issues in Return to Play:

The Role of Clinical Judgment

59 Expectations and Responsibilities of Players and

Team Coaches in the Return-to-Play Process . . . 793

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60 Return to Play: Team Doctor Roles and Ethics . . . 811

Ricard Pruna, Matilda Lundblad, and Khatija Bahdur

61 Ethical Issues in Return to Play: RTP in Football:

An Evidence-Based Approach . . . 819

Philip Batty

62 Ethical Issues in Return to Play: Surgical

Implications for Return to Play . . . 825

Matthew A. Tao, Dean Wang, and Riley J. Williams

63 How to Work with Agents: Medical and

Ethical Aspects—Today’s Practice, Questions, Reality

and Solutions . . . 833

José F. Huylebroek, Francis Lemmens, and Kristof Sas

64 Ethical Issues in Return to Play: How to Deal with Parents

and Coaches . . . 841

Jeremy M. Burnham, Greg Gasbarro, Justin Arner, Thomas Pfeiffer, and Volker Musahl

65 Mental Health in Professional Football Players . . . 851

Vincent Gouttebarge and Gino M.M.J. Kerkhoffs Part IX Injury and Reinjury Prevention

66 The 11+ Injury Prevention Programme (2008–2016) . . . 863

Mario Bizzini

67 Training Load and Injury Risk . . . 873

Peter Angele, Helmut Hoffmann, and Leonard Achenbach

68 The Experience from the Oslo Sports Trauma

Research Center: Injury Prevention . . . 885

Thor Einar Andersen and John Bjørneboe

69 Special Considerations of Return to Play

in Football Goalkeepers . . . 893

Volker Krutsch, Michael Fuchs, and Werner Krutsch

70 Injury Prevention in Football: The Santa

Monica Experience . . . 907

Holly J. Silvers-Granelli, Robert H. Brophy, and Bert R. Mandelbaum

71 The Knee Control Prevention Programme . . . 919

Hanna Lindblom, Markus Waldén, Isam Atroshi, Annica Näsmark, and Martin Hägglund

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72 The Female Player: Special Considerations . . . 929

Markus Waldén, Mariann Gajhede Knudsen,

Matilda Lundblad, Jan Ekstrand, and Martin Hägglund

73 The Young Player: Special Considerations . . . 941

Jonas Werner, Martin Hägglund, Mariann Gajhede Knudsen, Jan Ekstrand, and Markus Waldén

74 Re-injuries in Professional Football:

The UEFA Elite Club Injury Study . . . 953

Martin Hägglund, Markus Waldén, Håkan Bengtsson, and Jan Ekstrand

Healthy Football Players in Different Playing Situations . . . 963

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xv Volker Musahl, M.D., is associate profes-sor of orthopedic surgery at the University of Pittsburgh School of Medicine, associate professor of bioengineering at the University of Pittsburgh’s Swanson School of Engineering, program director of the sports medicine fellowship program, and medical director of the UPMC Center for Sports Medicine. In addition to his work as a University of Pittsburgh associate professor and a leading orthopedic surgeon, he is cohead team physician for the University of Pittsburgh football team. Dr. Musahl has received various honors and awards and in 2015 was appointed assistant edi-tor-in-chief of Knee Surgery, Sports Traumatology, Arthroscopy (KSSTA). His research interests include knee and shoulder biomechanics. He is a member of ESSKA ISAKOS, AAOS, ORS, AOSSM, AANA, and AGA.

Jon Karlsson, M.D., Ph.D., is professor of orthopedics and sports traumatology at Sahlgrenska Academy, mainly related to knee and foot and ankle injuries, including tendon injuries. Dr. Karlsson graduated from the medical school in Reykjavik, Iceland. He then moved to Sweden for orthopedic training, becoming a specialist in orthopedics in 1986. He has worked at the Sahlgrenska University Hospital ever since and is currently senior consultant and full-time professor. He has been clinical head of the Orthopaedic Department and is now its academic head. He has published more than 300 papers and 30 text-books in orthopedics and sports traumatology. He has held important posi-tions in both ESSKA and ISAKOS and is currently editor-in- chief of Knee

Surgery, Sports Traumatology, Arthroscopy (KSSTA), the official clinical

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Werner Krutsch, M.D., is associate pro-fessor of orthopaedic and trauma surgery and head of sports traumatology and knee surgery in the Department of Trauma Surgery at the University Medical Centre, Regensburg, Germany. He is deputy direc-tor of the FIFA Medical Centre of Excellence, Regensburg, and medical direc-tor of the Football Association Bayern. Dr. Krutsch is head of the AO Clinical Study Center of the University of Regensburg, member of the knee ligament committee of the AGA, and education secretary of ESMA-ESSKA. He has had an active professional football career with clubs including VFB Stuttgart and 1. FC Nürnberg. He is currently the captain of the German national football team of medical doctors. The focus of the scientific work of Dr. Krutsch is football medicine and injury prevention.

Bert R. Mandelbaum, M.D., practices with the Santa Monica Orthopaedic & Sports Medicine Group, where he serves as director of the sports medicine fellowship program and of the Research and Education Foundation and as medical director for the FIFA Medical Center of Excellence in Santa Monica. He was appointed as chief medical officer for the World Special Olympic Games 2015 in LA. Dr. Mandelbaum is a past president of the International Cartilage Repair Society. He was the chief medical officer for Women’s World Cup Soccer in 1999 and 2003 and has been assistant medi-cal director for Major League Soccer since 1996. He served as US team phy-sician for the football World Cups from 1994 to 2010 and was FIFA medical officer for the Brazil World Cup in 2014. He has published over 100 journal articles and several books.

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João Espregueira-Mendes, M.D., Ph.D., has been professor of orthopedic traumatology and chairman of the Orthopaedic Department at Minho University, Portugal, since 2005. In addi-tion, he is director of Clínica do Dragão– Espregueira-Mendes Sports Centre–FIFA Medical Centre of Excellence, FC Porto Dragão Stadium, Porto, Portugal. His fur-ther posts include orthopedic surgeon of FC Porto and senior researcher in biomaterials, biodegradables, and biomimetics in the Department of Polymer Engineering at Minho University. Dr. Espregueira-Mendes was president of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) from 2012 to 2014, and he is treasurer and chairman of the Publication Committee of ISAKOS. He is a member of the editorial board of Knee Surgery, Sports Traumatology, Arthroscopy.

Pieter d’Hooghe M.D., MSC, MBA is Assistant Professor at the Weill Cornell University and previous football captain of FC Bruges. He is an orthopedic sports sur-geon with special interest in lower limb bio-surgery at Aspetar Orthopaedic and Sports Medicine Hospital in Doha, Qatar. As ISAKOS LAF Chair, he is heading a global group of experts, active in the field of research and education on foot and ankle injuries. He is a passionate member of the International Sports Medical Family.

List of Associate Editors

Marcin Kowalchuk Department of Orthopaedic Surgery, University of

Pittsburgh, Pittsburgh, PA, USA

Christopher D. Murawski Department of Orthopaedic Surgery, University

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xix Leonard Achenbach Department of Trauma Surgery, University Medical

Centre Regensburg, Regensburg, Germany

Andrea Achtnich Sportorthopädie, Munich, Germany

Marcio Bottene Villa Albers Department of Orthopaedic Surgery, University

of Pittsburgh, Pittsburgh, PA, USA

Eduard Alentorn-Geli Artroscopia GC, SL, Hospital Quirón, Barcelona,

Spain

Fundación García-Cugat, Barcelona, Spain

Mutualidad Catalana de Futbolistas – Federación Española de Fútbol, Barcelona, Spain

Thor Einar Andersen Department of Sports Medicine, Oslo Sports Trauma

Research Center, Norwegian School of Sport Sciences, Ullevaal Stadion, Oslo, Norway

Morgan Anderson Department of Health, Human Performance and

Recreation, Office for Sport Concussion Research, University of Arkansas, Fayetteville, AR, USA

Renato Andrade Clínica do Dragão, Espregueira-Mendes Sports Centre—

FIFA Medical Centre of Excellence, Porto, Portugal Dom Henrique Research Centre, Porto, Portugal Faculty of Sports, University of Porto, Porto, Portugal

Peter Angele Department of Trauma Surgery, University Medical Centre

Regensburg, Regensburg, Germany

Sporthopaedicum Regensburg, Regensburg, Germany

Elizabeth A. Arendt Department of Orthopaedic Surgery, University of

Minnesota, Minneapolis, MN, USA

Gustavo Gonçalves Arliani Centro de Traumatologia do Esporte (CETE)/

Universidade Federal de São Paulo, São Paulo, Brazil

Justin Arner Department of Orthopaedic Surgery, UPMC Center for Sports

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Daniel Arvidsson Department of Food and Nutrition, and Sport Science,

Center for Health and Performance (CHP), University of Gothenburg, Gothenburg, Sweden

Isam Atroshi Department of Clinical Sciences—Orthopaedics, Lund

University, Lund, Sweden

Olufemi R. Ayeni Division of Orthopaedic Surgery, Department of Surgery,

McMaster University, Hamilton, ON, Canada

Khatija Bahdur Department of Human Movement Science, University of

Zululand, Kwadlangezwa, South Africa

Simon Ball Fortius Clinic, London, UK

Chelsea and Westminster Hospital, London, UK

Adad Baranto Department of Orthopaedics, Institute of Clinical Sciences at

the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Sahlgrenska University Hospital, Gothenburg, Sweden

Ricardo Bastos Clínica do Dragão, Espregueira-Mendes Sports Centre –

FIFA Medical Centre of Excellence, Porto, Portugal Dom Henrique Research Centre, Porto, Portugal

Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil

Cécile Batailler Orthopedic Surgery, Centre Albert Trillat – Croix-Rousse

Hospital, Lyon, France

Philip Batty Isokinetic Medical Centre, London, UK

University College, London, UK

Asheesh Bedi Domino’s Farms – MedSport, University of Michigan Health

System, Ann Arbor, MI, USA

Håkan Bengtsson Football Research Group, Division of Physiotherapy,

Department of Medical and Health Sciences, Linköping University, Linköping, Sweden

Raymond Best Department of Sports Orthopaedics and Sports Traumatology,

Sportklinik Stuttgart, Stuttgart, Germany

Mario Bizzini Schulthess Clinic, Zurich, Switzerland

John Bjørneboe Department of Sports Medicine, Oslo Sports Trauma

Research Center, Norwegian School of Sport Sciences, Ullevaal Stadion, Oslo, Norway

Hendrik Bloch VBG, German Social Accident Insurance Institution for the

Administrative Sector, Hamburg, Germany

Mats Börjesson Department of Food and Nutrition, and Sport Science,

Center for Health and Performance (CHP), University of Gothenburg, Gothenburg, Sweden

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Department of Neuroscience and Physiology, Sahlgrenska Academy and Sahlgrenska University Hospital/Östra, Göteborg, Sweden

Thomas P. Branch University Orthopedics, Decatur, GA, USA

ERMI Inc., Atlanta, GA, USA

Robert H. Brophy Department of Orthopaedic Surgery, Washington

University School of Medicine, St. Louis, MO, USA

Jeremy M. Burnham Department of Orthopaedic Surgery, UPMC Center

for Sports Medicine, University of Pittsburgh, Pittsburgh, PA, USA

Tyrrell Burrus Domino’s Farms – MedSport, University of Michigan

Health System, Ann Arbor, MI, USA

Atakan Ça_{ğlayan Sports Sciences, School of Sports Sciences, Duzce}

University, Duzce, Turkey

Daniele Caminati Education and Research Department, Isokinetic Medical

Group, FIFA Medical Centre of Excellence, Bologna, Italy

Jacob J. Capin Biomechanics and Movement Science, University of

Delaware, Newark, DE, USA

Michael R. Carmont Department of Orthopaedic Surgery, Princess Royal

Hospital, Shrewsbury & Telford Hospital NHS Trust, Shrewsbury, UK Department of Neurosciences, Biomedicine and Movement Science, University of Verona, Verona, Italy

Livia Carrai Laboratory of Applied Biomechanics, Department of

Biomedical Sciences for Health, University of Milan, Milan, Italy

U.O.C. 1° Divisione, Azienda Socio Sanitaria Territoriale Centro Specialistico Ortopedico Traumatologico Gaetano Pini-CTO, Milan, Italy

Etienne Cavaignac Département de Chirurgie Orthopédique, CHU

Toulouse, Toulouse, France

Jorge Chahla Steadman Philippon Research Institute—The Steadman

Clinic, Vail, CO, USA

Allison A. Chan Michael G. DeGroote School of Medicine, McMaster

University, Hamilton, ON, Canada

Daniel Charek Sports Concussion Program, Department of Orthopedic

Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA

George Chiampas Department of Orthopaedics, Northwestern University,

Chicago, IL, USA

Hema N. Choudur Department of Radiology, Hamilton General Hospital,

East Hamilton, ON, Canada

Moises Cohen Centro de Traumatologia do Esporte (CETE)/ Universidade

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Michael W. Collins Sports Medicine Concussion Program, Department of

Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA

Riccardo Compagnoni U.O.C. 1° Divisione, Azienda Socio Sanitaria

Territoriale Centro Specialistico Ortopedico Traumatologico Gaetano Pini- CTO, Milan, Italy

Christopher Connaboy Neuromuscular Research Laboratory/Warrior

Human Performance Research Center, Department of Sports Medicine and Nutrition, School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, PA, USA

Tracey Covassin Department of Kinesiology, Michigan State University,

East Lansing, MI, USA

Ilaria Cucurnia Clinica Ortopedica e Traumatologica II, Istituto Ortopedico

Rizzoli, Bologna, Italy

Laboratorio di Biomeccanica e Innovazione Tecnologica, Istituto Ortopedico Rizzoli, Bologna, Italy

Nathan D’Amico Department of Health, Human Performance and

Recreation, Office for Sport Concussion Research, University of Arkansas, Fayetteville, AR, USA

Pieter d’Hooghe Department of Orthopaedic Surgery, Aspetar Orthopaedic

and Sports medical Hospital, Aspire Zone, Doha, Qatar

Matthew E. Darnell Neuromuscular Research Laboratory/Warrior Human

Performance Research Center, Department of Sports Medicine and Nutrition, School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, PA, USA

Richard E. Debski Departments of Bioengineering and Orthopaedic

Surgery, University of Pittsburgh, Pittsburgh, PA, USA

Francesco Della Villa Education and Research Department, Isokinetic

Medical Group, FIFA Medical Centre of Excellence, Bologna, Italy

Stefano Della Villa Education and Research Department, Isokinetic Medical

Pete Draovitch The Hip, James M. Benson Sports Rehabilitation Center,

New York, NY, USA

Jonathan Drezner Department of Family Medicine, University of

Washington, Washington, DC, USA

Hugo Duarte Hospital Riviera Chablais, Vaud-Valais, Switzerland

Shawn Eagle Neuromuscular Research Laboratory/Warrior Human

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Klaus Eder Eden Reha Rehabilitation Centre, Eden-Reha, Donaustauf,

Germany

Seper Ekhtiari Michael G. DeGroote School of Medicine, McMaster

University, Hamilton, ON, Canada

Jan Ekstrand Football Research Group, Division of Community Medicine,

Department of Medical and Health Sciences, Linköping University, Linköping, Sweden

Robert J. Elbin Department of Health, Human Performance and Recreation,

Office for Sport Concussion Research, University of Arkansas, Fayetteville, AR, USA

Lars Engebretsen Oslo Sport Trauma Research Center, The Norwegian

School of Sport Sciences, Oslo, Norway

Department of Orthopaedic Surgery, Oslo University Hospital, Faculty of Medicine, University of Oslo, Oslo, Norway

Zoe Englander Department of Orthopedics, Duke University, Durham, NC,

USA

Department of Biomedical Engineering, Duke University, Durham, NC, USA

David Espinoza Department of Orthopaedics, University of Pittsburgh,

Pittsburgh, PA, USA

João Espregueira-Mendes Clínica do Dragão, Espregueira-Mendes Sports

Centre – FIFA Medical Centre of Excellence, Porto, Portugal Dom Henrique Research Centre, Porto, Portugal

3B’s Research Group – Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal

ICVS/3B’s – PT Government Associate Laboratory, Braga/Guimarães, Portugal

Department of Orthopaedics, Minho University, Braga, Portugal

Maurizio Fanchini Department of Neurosciences, Biomedicine and

Movement Science, University of Verona, Verona, Italy

Julian A Feller OrthoSport Victoria, Epworth HealthCare, Richmond,

Australia

Mario Ferretti Hospital Israelita Albert Einstein, São Paulo, Brazil

Giuseppe Filardo I Clinic – Nano-Biotechnology Lab, Rizzoli Orthopedic

Institute, Bologna, Italy

Christian Fink Research Unit of Orthopaedic Sports Medicine and Injury

Prevention, ISAG/UMIT, Hall in Tirol, Austria

FIFA Medical Centre of Excellence, Innsbruck/Tirol, Austria Gelenkpunkt – Sport and Joint Surgery, Innsbruck, Austria

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Felix Fischer Research Unit of Orthopaedic Sports Medicine and Injury

Prevention, ISAG/UMIT, Hall in Tirol, Austria

FIFA Medical Centre of Excellence, Innsbruck/Tirol, Austria

Magnus Forssblad Stockholm Sports Trauma Research Center, Karolinska

Institutet, Stockholm, Sweden

Freddie H. Fu Department of Orthopaedic Surgery, University of Pittsburgh,

Pittsburgh, PA, USA

Michael Fuchs 1.FC Nürnberg, Nürnberg, Germany

Jacopo Gamberini Education and Research Department, Isokinetic Medical

Greg Gasbarro Department of Orthopaedic Surgery, UPMC Center for

Sports Medicine, University of Pittsburgh, Pittsburgh, PA, USA

Pablo E. Gelber Orthopaedic Surgery, Hospital de la Santa Creu i Sant Pau,

ICATME-Hospital Universitari Dexeus, ReSport Clinic, Universitat Autònoma de Barcelona, Barcelona, Spain

Peter Gföller FIFA Medical Centre of Excellence, Innsbruck/Tirol, Austria

Gelenkpunkt – Sport and Joint Surgery, Innsbruck, Austria

Peter B. Gifford University College Hospital, London, UK

Brandon Gillie Sports Concussion Program, Department of Orthopedic

Alberto Gobbi Orthopaedic Arthroscopic Surgery International (OASI)

Bioresearch Foundation, NPO, Milan, Italy

Jonathan A. Godin Steadman Philippon Research Institute—The Steadman

Alli Gokeler University of Groningen, University Medical Center

Groningen, Center for Human Movement Sciences, Groningen, The Netherlands

Sérgio Gomes International Sports Traumatology Centre of Ave, Taipas

Termal, Caldas das Taipas, Portugal

Clínica do Dragão, Espregueira-Mendes Sports Centre—FIFA Medical Centre of Excellence, Porto, Portugal

Vincent Gouttebarge World Players’ Union (FIFPro), Hoofddorp, The

Netherlands

Academic Center for Evidence based Sports Medicine (ACES), Academic Medical Center, Amsterdam, The Netherlands

Department of Orthopaedic Surgery, Academic Medical Center, University of Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands

Alberto Grassi Clinica Ortopedica e Traumatologica II, Istituto Ortopedico

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Jonathan A. Gustafson Department of Bioengineering, University of

Fares S. Haddad University College Hospital, London, UK

Martin Hägglund Football Research Group, Department of Medical and

Health Sciences, Linköping University, Linköping, Sweden

Michael Hantes Department of Orthopedic Surgery, University of Thessalia,

Larissa, Greece

Mirco Herbort Clinic for Trauma-, Hand- and Reconstructive Surgery,

University Clinic Muenster, Muenster, Germany

Elmar Herbst FIFA Medical Centre of Excellence, Innsbruck/Tirol, Austria

Helmut Hoffmann Eden Reha, Private Clinic for Orthopaedic/

Traumatologic Rehabilitation, Donaustauf, Germany

Nolan S. Horner Division of Orthopaedic Surgery, Department of Surgery,

McMaster University, Hamilton, ON, Canada

Christian Hoser FIFA Medical Centre of Excellence, Innsbruck/Tirol, Austria

Yuichi Hoshino Department of Orthopaedic Surgery, Kobe University

Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan

Jonathan Hughes Department of Orthopaedic Surgery, University of

Kenneth Hunt Department of Orthopaedic Surgery, University of Colorado

School of Medicine, Aurora, CO, USA

José F. Huylebroek Sportsmed Orthopaedic Centre, Parc Leopold, Brussels,

Belgium

James J. Irrgang Department of Physical Therapy, University of Pittsburgh,

Pittsburgh, PA, USA

Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA

Caleb D. Johnson Neuromuscular Research Laboratory/Warrior Human

Ross Julian Institute of Sports and Preventive Medicine, Saarland University,

Saarbrücken, Germany

Mustafa Karahan Department of Orthopedic Surgery, Acibadem University,

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Jon Karlsson The Department of Orthopaedic Surgery, Institute of Clinical

Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

John G. Kennedy Hospital for Special Surgery, New York, NY, USA Gino M.M.J. Kerkhoffs Department of Orthopaedic Surgery, Academic

Medical Center, Amsterdam, The Netherlands

Academic Center for Evidence-based Sports Medicine (ACES), Amsterdam, The Netherlands

Amsterdam Collaboration for Health and Safety in Sports (ACHSS), AMC/ VUmc IOC Research Center, Amsterdam, The Netherlands

Christoph Kittl Clinic for Trauma-, Hand- and Reconstructive Surgery,

University Clinic Muenster, Muenster, Germany

Christian Klein VBG, German Social Accident Insurance Institution for the

Mariann Gajhede Knudsen Football Research Group, Linköping, Sweden Matthias Koch Department of Trauma Surgery, University Medical Centre

Regensburg, Regensburg, Germany

Elizaveta Kon Department of Biomedical Sciences – Humanitas Clinical

and Research Center, Knee Joint Reconstruction Center - 3rd Orthopaedic Division, Humanitas Clinical Institute, Humanitas University, Milan, Italy

Anthony P. Kontos Department of Orthopaedic Surgery, University

UPMC Rooney Sports Complex, Pittsburgh, PA, USA

Marcin Kowalczuk Department of Orthopaedic Surgery, University

Volker Krutsch Department of Otorhinolaryngology, Nuremberg General

Hospital, Paracelsus Medical University, Nürnberg, Germany

Werner Krutsch Department of Trauma Surgery, University Medical Centre

Regensburg, FIFA Medical Centre of Excellence, Regensburg, Germany

A.J. Krych Department of Orthopedic Surgery and the Sports Medicine

Center, Mayo Clinic and Mayo Foundation, Rochester, MN, USA

Ryosuke Kuroda Department of Orthopaedic Surgery, Kobe University

Graduate School of Medicine, Chuo-ku, Kobe, Hyogo, Japan

John G. Lane Orthopaedic Arthroscopic Surgery International (OASI)

Musculoskeletal and Joint Research Foundation, San Diego, CA, USA

Robert F. LaPrade Steadman Philippon Research Institute—The Steadman

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F. Lemmens Paediatrics ZOL, Genk, Belgium

Bryson Lesniak Division of Sports Medicine, University of Pittsburgh

Medical Center, Pittsburgh, PA, USA

Hanna Lindblom Division of Physiotherapy, Department of Medical and

Frank G.J. Loeffen Department of Orthopaedic Surgery, Academic Medical

Center, Amsterdam, The Netherlands

Academic Center for Evidence-based Sports Medicine (ACES), Amsterdam, The Netherlands

Amsterdam Collaboration for Health and Safety in Sports (ACHSS), AMC/ VUmc IOC Research Center, Amsterdam, The Netherlands

Oliver Loose Department of Pediatric Surgery, Hospital St. Hedwig,

Regensburg, Germany

Patrick Luig VBG, German Social Accident Insurance Institution for the

Matilda Lundblad Football Research Group, Department of Medical and

Department of Orthopaedics, Sahlgrenska University, Gothenburg, Sweden

Sébastien Lustig Orthopedic Surgery, Centre Albert Trillat – Croix-Rousse

Jacques Ménétrey Department of Surgery, University of Geneva, Geneva,

Switzerland

Luca Macchiarola Clinica Ortopedica e Traumatologica II, Istituto

Ortopedico Rizzoli, Bologna, Italy

Robert Magnussen Department of Orthopaedics, OSU Sports Medicine,

The Ohio State University, Columbus, OH, USA

Bert R. Mandelbaum Santa Monica Orthopaedic Group, Santa Monica,

CA, USA

Aaron V. Mares Department of Orthopaedics, University of Pittsburgh,

Pittsburgh, PA, USA

Vincent Marot Département de Chirurgie Orthopédique, CHU Toulouse,

Toulouse, France

Hermann Mayr Schoen Clinic Munich-Harlaching, Munich, Germany

Tamara Valovich McLeod Athletic Training Programs, School

of Osteopathic Medicine in Arizona, A.T. Still University, Mesa, AZ, USA

Alessandra Menon Laboratory of Applied Biomechanics, Department

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Tim Meyer Institute of Sports and Preventive Medicine, Saarland University,

Saarbrücken, Germany

Håvard Moksnes Oslo Sport Trauma Research Center, The Norwegian

School of Sport Sciences, Oslo, Norway

The Norwegian Olympic Training Center, Oslo, Norway

The Norwegian Sports Medicine Center (Idrettens Helsesenter), Oslo, Norway

Hauke Mommsen Endo-Reha Zentrum, Hamburg, Germany

Caroline Mouton Department of Orthopedic Surgery, Centre Hospitalier de

Luxemburg, Luxembourg City, Luxembourg

Sports Medicine Research Laboratory, Department of Population Health, Luxembourg Institute of Health, Luxembourg City, Luxembourg

Hans-Wilhelm Mueller-Wohlfahrt MW Center of Orthopedics and Sports

Medicine, Munich, Germany

Conor Murphy Department of Orthopaedic Surgery, University of

Volker Musahl Department of Orthopaedic Surgery, UPMC Center for

Sports Medicine, University of Pittsburgh, Pittsburgh, PA, USA

Annica Näsmark Capio Artro Clinic, Swedish Football Association,

Stockholm, Sweden

Philippe Neyret Orthopedic Surgery, Centre Albert Trillat – Croix-Rousse

Bradley C. Nindl Neuromuscular Research Laboratory/Warrior Human

John A. Norwig Pittsburgh Steelers Football Club, Pittsburgh, PA, USA Luke O’Brien Howard Head Sports Medicine, Vail, CO, USA

Joaquim Miguel Oliveira 3B’s Research Group–Biomaterials,

Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal

ICVS/3B’s–PT Government Associate Laboratory, Braga, Guimarães, Portugal

Department of Orthopedic, Centro Hospitalar Póvoa de Varzim, Vila do Conde, Portugal

Ripoll y De Prado Sports Clinic—FIFA Medical Centre of Excellence, Murcia, Madrid, Spain

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International Sports Traumatology Centre of Ave, Taipas Termal, Caldas das Taipas, Portugal

Dom Henrique Research Centre, Porto, Portugal

Francesco Perdisa I Clinic – Nano-Biotechnology Lab, Rizzoli Orthopedic

Hélder Pereira 3B’s Research Group–Biomaterials, Biodegradables and

Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal

ICVS/3B’s–PT Government Associate Laboratory, Braga, Guimarães, Portugal Department of Orthopedic, Centro Hospitalar Póvoa de Varzim, Vila do Conde, Portugal

Ripoll y De Prado Sports Clinic—FIFA Medical Centre of Excellence, Murcia, Madrid, Spain

International Sports Traumatology Centre of Ave, Taipas Termal, Caldas das Taipas, Portugal

Dom Henrique Research Centre, Porto, Portugal

Rogério Pereira Clínica do Dragão, Espregueira-Mendes Sports Centre –

FIFA Medical Centre of Excellence, Porto, Portugal Dom Henrique Research Centre, Porto, Portugal Faculty of Sports, University of Porto, Porto, Portugal

Faculty of Health Science, University Fernando Pessoa, Porto, Portugal

Wolf Petersen Martin Luther Hospital, Berlin, Germany

Thomas Pfeiffer Department of Orthopaedic Surgery, Traumatology, and

Sports Medicine, Kliniken der StadtKoelngGmbH, Köln, Germany

Pelin Pi_{şirici Private Pendik Regional Hospital, Istanbul, Turkey}

Adam J. Popchak Department of Physical Therapy, University of Pittsburgh,

Pittsburgh, PA, USA

Ricard Pruna FC Barcelona Medical Services, FIFA Medical Centre of

Excellence, Barcelona, Spain

Luca Pulici Laboratory of Applied Biomechanics, Department of

Pietro Randelli Laboratory of Applied Biomechanics, Department of

Rui L. Reis 3B’s Research Group – Biomaterials, Biodegradables and

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Excellence on Tissue Engineering and Regenerative Medicine, Barco, Guimarães, Portugal

ICVS/3B’s – PT Government Associate Laboratory, Braga/Guimarães, Portugal

Christa Janse Van Rensburg Faculty of Health Sciences, Section Sports

Medicine, Sport, Exercise Medicine and Lifestyle Institute (SEMLI), University of Pretoria, Pretoria, South Africa

Margherita Ricci Education and Research Department, Isokinetic Medical

Helge Riepenhof BG Clinic Hamburg, Hamburg, Germany

Pedro L. Ripoll Ripoll y De Prado Sports Clinic—FIFA Medical Centre of

Excellence, Murcia, Madrid, Spain

Sérgio Rodrigues-Gomes Clínica do Dragão, Espregueira-Mendes Sports

Centre—FIFA Medical Centre of Excellence, Porto, Portugal SMIC Serviço Médico de Imagem Computorizada, Porto, Portugal

Dani Romero-Rodríguez EUSES (University School of Health and Sport,

University of Girona), Barcelona, Spain

Sonia Ruef Pittsburgh Steelers Football Club, Pittsburgh, PA, USA Jaakko Ryynänen University of Helsinki, Helsinki, Finland

Kristian Samuelsson Department of Orthopedics, Institute of Clinical

Sciences, The Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden

Natalie Sandel Sports Medicine Concussion Program, Department of

Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA

K. Sas Urgentist AZ Glorieux, Ronse, Belgium

Philip Schatz Saint Joseph’s University, Philadelphia, PA, USA

Laura C. Schmitt Division of Physical Therapy, School of Health and

Rehabilitation Sciences, Ohio State University, Columbus, OH, USA

Tobias Schweinsteiger FC Bayern München e.V., Munich, Germany Martin Schwellnus Faculty of Health Sciences, Section Sports Medicine,

Sport, Exercise Medicine and Lifestyle Institute (SEMLI), University of Pretoria, Pretoria, South Africa

Romain Seil Department of Orthopedic Surgery, Centre Hospitalier de

Luxemburg, Luxembourg City, Luxembourg

Sports Medicine Research Laboratory, Department of Population Health, Luxembourg Institute of Health, Luxembourg City, Luxembourg

Elvire Servien Orthopedic Surgery, Centre Albert Trillat – Croix-Rousse

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Andrea Sessa I Clinic – Nano-Biotechnology Lab, Rizzoli Orthopedic

Yoshiharu Shimozono Hospital for Special Surgery, New York, NY, USA Jason Shin Department of Orthopaedic Surgery, University of Pittsburgh,

Pittsburgh, PA, USA

Division of Sports Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, USA

Cecilia Signorelli Laboratorio di Biomeccanica e Innovazione Tecnologica,

Istituto Ortopedico Rizzoli, Bologna, Italy

Karin Grävare Silbernagel The Department of Physiotherapy, University

of Delware, Newark, DE, USA

The Department of Orthopaedic Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

Holly J. Silvers-Granelli Biomechanics and Movement Science, University

of Delaware, Newark, DE, USA

Velocity Physical Therapy, Los Angeles, CA, USA

Thomas Sisk Department of Orthopaedics, University of Pittsburgh,

Pittsburgh, PA, USA

Mia Smucny Department of Orthopaedic Surgery, Cleveland Clinic

Foundation, Garfield Heights, OH, USA

Lynn Snyder-Mackler Biomechanics and Movement Science, University

of Delaware, Newark, DE, USA

Department of Physical Therapy, University of Delaware, Newark, DE, USA

Duarte Sousa Orthopedic Department, Centro Hospitalar Póvoa de Varzim,

Vila do Conde, Portugal

Kurt P. Spindler Department of Orthopaedic Surgery, Cleveland Clinic

Foundation, Garfield Heights, OH, USA

Amelie Stöhr Orthopaedic Surgery Munich OCM, Munich, Germany Shaun K. Stinton University Orthopedics, Decatur, GA, USA

ERMI Inc., Atlanta, GA, USA

Heiko Striegel Department of Sports Medicine, University Hospital

Tübingen, Tuebingen, Germany

M.J. Stuart Department of Orthopedic Surgery and the Sports Medicine

Alicia Sufrinko Sports Concussion Program, Department of Orthopedic

David Sundemo Department of Orthopedics, Institute of Clinical

Sciences, The Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden

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Tetsuya Takenaga Department of Orthopaedic Surgery, University of

Matthew A. Tao Hospital for Special Surgery, New York, NY, USA

Athol Thomson Department of Sports Podiatry, Aspetar Orthopaedic and

Sports medical Hospital, Aspire Zone, Doha, Qatar

Chris Thompson Institute of Sports and Preventive Medicine, Saarland

University, Saarbrücken, Germany

Peter Ueblacker MW Center of Orthopedics and Sports Medicine, Munich,

Germany

Markus Waldén Football Research Group, Department of Medical and

Dean Wang Hospital for Special Surgery, New York, NY, USA

Johannes Weber Department of Trauma Surgery, University Medical

Centre Regensburg, Regensburg, Germany

Kate E Webster School of Allied Health, La Trobe University, Bundoora,

Melbourne, Australia

Jonas Werner Football Research Group, Department of Orthopaedics,

Vrinnevisjukhuset, Norrköping, Sweden

Suzanne Werner Stockholm Sports Trauma Research Center, Karolinska

Institutet, Stockholm, Sweden

Nathan White Fortius Clinic, London, UK

Chelsea and Westminster Hospital, London, UK

Graeme P. Whyte Orthopaedic Arthroscopic Surgery International (OASI)

Cornell University, Weill Medical College, New York Presbyterian Hospital/ Queens, New York, NY, USA

Andy Williams Fortius Clinic, London, UK

Riley J. Williams Hospital for Special Surgery, New York, NY, USA J.M. Woodmass Department of Orthopedic Surgery and the Sports Medicine

Frank Wormuth Deutscher Fußball-Bund, Frankfurt am Main, Germany Mohammad A. Yabroudi Department of Rehabilitation Sciences, Jordan

University of Science and Technology, Irbid, Jordan

Stefano Zaffagnini Clinica Ortopedica e Traumatologica II, Istituto

Ortopedico Rizzoli, Bologna, Italy

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Beatrice Zanini U.O.C. 1° Divisione, Azienda Socio Sanitaria Territoriale

Centro Specialistico Ortopedico Traumatologico Gaetano Pini-CTO, Milan, Italy

Christian Zantop Return to Play, Straubing, Germany Thore Zantop Sporthopaedicum, Straubing, Germany

Jennifer A. Zellers The Department of Physiotherapy, University of

Delware, Newark, DE, USA

Johannes Zellner Department of Trauma Surgery, University Medical

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3 © ESSKA 2018

V. Musahl et al. (eds.), Return to Play in Football, https://doi.org/10.1007/978-3-662-55713-6_1

Basic Concepts in Functional

Biomechanics

Jonathan A. Gustafson, Tetsuya Takenaga,

and Richard E. Debski

1.1 Introduction... 3 1.2 Statics ... 4 1.2.1 Newton’s Law of Static Equilibrium ... 4 1.2.2 Free-Body Diagrams... 4 1.2.3 Ligament and Joint Contact Forces ... 6 1.3 Dynamics ... 7 1.3.1 Kinematics ... 7 1.4 Mechanics of Materials ... 8 1.4.1 Rigid Body Mechanics ... 8 1.4.2 Structural Properties of a Complex ... 9 1.4.3 Mechanical Properties of Tissue ... 10 1.4.4 Viscoelasticity ... 11 1.5 Applications ... 12 1.5.1 Injury Diagnosis ... 13 1.5.2 Surgical Reconstruction ... 13 1.5.3 Improving Rehabilitation ... 13 References ... 14

1.1 Introduction

Sports-related injuries in pediatric and adolescent athletes are common and provide challenges in determining the best course of care and appropri-ate criteria for the athletes return to sport. Injuries to adults are also significant in that they can per-manently impair function and severely limit activities of daily living. In football, the knee joint is one of the most common sources of both contact and noncontact injuries. Current work in the field of sports medicine aims to diagnose injuries accurately, implement appropriate surgi-cal/nonsurgical treatment solutions and, ulti-mately, develop the best criteria for early return to sport. In order to best achieve these goals, it is important to understand the normal function of the body in response to daily loading. Functional biomechanics plays a large role in evaluating the body’s response to both normal and excessive loading, such as in an injury event.

Biomechanics is an interdisciplinary field that utilizes principles of mechanics applied to the human body in order to improve function through design and development of equipment, as well as analysis of systems and therapies. Applied bio-mechanics can provide additional knowledge of the effect of loading on the musculoskeletal sys-tem and the mechanical responses of the body to these loads, which can be used to assess both nor-mal and abnornor-mal function, as well as predict changes and propose interventions. Additionally,

J.A. Gustafson, Ph.D.

Department of Bioengineering, University of Pittsburgh, 408 Center for Bioengineering, 300 Technology Drive, Pittsburgh, PA, 15219, USA T. Takenaga, M.D., Ph.D.

Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA

R.E. Debski, Ph.D. (*)

Departments of Bioengineering and Orthopaedic Surgery, University of Pittsburgh, 408 Center for Bioengineering, 300 Technology Drive, Pittsburgh, PA, 15219, USA

e-mail: genesis1@pitt.edu

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basic biomechanics explores the effects of exter-nal forces and moments required for movement and, in effect, the consequence of internal loads on soft tissue deformation. This chapter will explore important, sports-related biomechanics concepts and is divided into four different topics: statics, dynamics, mechanics of materials, and applications. Throughout the chapter are exam-ples of applying these biomechanical princiexam-ples to sports medicine problems and improving return to play following injury.

Functional biomechanics allows one to appre-ciate the relationships and interactions that various systems, segments, and body parts have with one another that contribute to its ability to perform. These relationships are the foundation for under-standing the complexities of human function.

1.2 Statics

Statics analysis of structures evaluates the effect of external loads on a rigid body at rest or in motion at a constant velocity. When applied to the body, statics analysis allows for the determi-nation of the magnitudes and directions of pas-sive, soft tissue forces (e.g., ligaments), muscle forces, and joint reaction forces. In order to per-form a statics analysis, a basic principle of phys-ics must be applied.

1.2.1 Newton’s Law of Static Equilibrium

Newton’s law of static equilibrium states that a body at rest remains at rest and a body in motion tends to stay in motion at a constant speed and in the same direction unless acted on by an unbal-anced force. Additionally, every force of action has an opposite and equal reaction in order to maintain this balance. An example of this con-cept is the ground reaction force. Every time a person places his/her foot on the ground, there is an equal and opposite force exerted from the ground up through the foot. This ground reaction force is transmitted through the kinetic chain of the body (foot, ankle, knee, hip, back, etc.),

which loads our joints. As the body prefers a state of equilibrium, drastic changes in the ground reaction force, in terms of magnitude and direc-tion, can lead to potential injury. Similarly, within joints, there are muscles and connective tissues that create a joint reaction force in order to main-tain proper joint stability.

When considering a state of static equilib-rium, the forces and moments acting on the body must equate to zero (i.e., no motion). The result-ing equations for force and moment equilibrium in three dimensions are:

∑Fx = 0; ∑ Mx = 0 ∑Fy = 0; ∑ My = 0 ∑Fz = 0; ∑ Mz = 0

Forces provide both mobility and stability to the body but can also introduce the potential to deform and injure the body. Healthy tissue can typically withstand the deformations caused by these action and reaction forces; however, injured or diseased tissue may not be able to sustain the same loads required to perform activities of daily living. Statics analysis allows the researcher to represent the complex interactions of the forces and moments acting on the body through the use of vectors and free-body diagrams.

1.2.2 Free-Body Diagrams

To better evaluate a biomechanical system, such as forces or moments being applied to a specified part of the body, free-body diagrams are an effec-tive tool to simplify a complex analysis. Free- body diagrams provide a “snapshot” that represent the interaction between body and envi-ronment and allow for visualization and ease of calculation by properly identifying all the forces and moments acting on the body of interest in order to successfully achieve equilibrium.

Force vectors generate the “push and pull” to a system and can originate from internal sources (i.e., muscle forces and joint contact forces) as well as external sources (i.e., friction forces and gravitational forces). A moment (or torque) is a force applied at a distance from a fixed point that tends to cause the rigid segment to rotate.

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The magnitude of the moment is a product of the force applied and the perpendicular distance from the applied force to the fixed point. This distance is commonly defined as the moment or lever arm. A larger moment arm requires less force to achieve equivalent angular motion about the axis of rotation. Although a moment can be calculated about any point, typically when performing biomechanical analyses, it is calculated about a joint axis of rotation.

Using the example of a leg extension exercise (Fig. 1.1a) in evaluating the forces about the knee joint, a free-body diagram can assess the change in tension in the quadriceps muscles when adding a weight to the ankle (Fig. 1.1b). The applied forces (both external and internal forces) through-out the system are drawn in order visualize the problem. External forces in the leg extension problem are represented by the weight of the leg and the ankle weight, and internal forces are

rep-resented by the force in the quadriceps and the joint reaction force (Fig. 1.1c). The external weight, combined with the weight of leg, causes the leg to experience a flexion moment, while the force from the quadriceps acts in extension in order to balance these external moments (Fig. 1.1d). It is important to note the significant difference in the moment arm between the quad-riceps force and the external forces. It is not uncommon for muscle forces to exhibit force magnitudes several times greater than the applied external loads for balance, due to the significantly shortened moment arm of the muscle. Once all of the forces in the free-body diagram have been defined, the laws of static equilibrium are applied to solve for the unknown muscle forces and joint reaction forces.

Reducing the joint reaction force is a common strategy in rehabilitation programs aimed at pre-venting further joint degeneration in persons with

FR FQuadriceps FWLeg FExt X a b FR FR MQuadriceps FQuadriceps y x y x MWLeg FWLeg MExt FExt a b c c d

Fig. 1.1 (a) Simulation of a person performing a leg extension. (b) The ankle weight applies an external force (FExt)

downward in addition to the gravitational force due to the weight of the lower leg (FWLeg). The

quadriceps muscle generates a force

(FQuadriceps) to the lower

leg and causes a joint reaction force (FR) at the

knee to keep the joint stabilized. (c) A free-body diagram of the lower leg representing each force as an arrow, with the head of the

arrow pointing in the

direction of the applied force. (d) The quadriceps muscle creates a

counterclockwise moment (MQuadriceps) to

resist the clockwise moments due to the weight of the lower leg (MWLeg) and ankle

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arthritis. This is commonly achieved by changing the magnitudes of muscle forces or reducing external loads transmitted through the body. For example, a person with medial tibiofemoral osteoarthritis may use a cane on their contralat-eral side in order to reduce the joint reaction forces in the painful/affected knee joint. When obesity is a factor, a weight reduction program may be implemented to reduce the joint reaction forces. Alternatively in sports rehabilitation, stat-ics analysis can be implemented to improve strengthening programs tailored to best target the proper muscles for the recovering athlete and expedite return to play.

1.2.3 Ligament and Joint Contact Forces

These concepts of statics analysis can be applied not only to whole-body analyses but also at the joint and tissue level. For the typical joint, forces can be related to compression and shear. The tib-ial plateau and femoral condyles experience com-pressive forces in the direction perpendicular to each articular surface while standing with the

knee in full extension (Fig. 1.2a). Shear forces are experienced in the tangential direction along the surface of interest (Fig. 1.2a), such as when per-forming an anterior drawer test. Forces can also be transmitted through the soft tissue structures. During a pivoting maneuver, the anterior cruciate ligament (ACL) can become significantly loaded to resist anterior tibial translation and provide sta-bility for the joint. This represents functional loading of the joint and soft tissue. However, after an injury such as an ACL rupture, opposing shear forces cannot be transferred through the ligament, resulting in anterior laxity (Fig. 1.2b).

ACL TornACL

a b

Fig. 1.2 (a) At the joint surface, the knee can undergo compressive forces (blue arrows), which act in the direction perpendicular to both surfaces, or shear forces (orange arrows), which act in the tangential direction to both surfaces. (b) Forces applied to the knee joint are transmitted through the ACL (solid tibia;

blue arrows), which

resist anterior motion. Rupture of the ACL (shaded tibia; orange

arrow) leads to

excessive anterior motion and instability as the forces are unable to be transmitted properly

Fact Box 1 Statics

• Statics analysis assumes state of equilibrium.

• Utilizes Newton’s laws of static equilib-rium and action-reaction.

• Free-body diagrams aid to simplify complex systems to understand net external and internal forces and moments.

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1.3 Dynamics

Dynamics is the study of systems in motion, where the laws of equilibrium have been violated and the net forces and moments of a system do not equate to zero. Analysis of bodies in motion can be subdi-vided into two subgroups: kinematics and kinetics. Kinematics describes the motion of the bodies with-out regard to the forces causing the motion. This is typically done by characterizing the geometric and time-dependent aspects of motion. Conversely, kinetics utilizes concepts from kinematics but addi-tionally includes the effects of the forces and moments within a system. Both kinematic and kinetic analyses are commonly performed in sports biomechanics for evaluating motion. This section will primarily focus on kinematics.

1.3.1 Kinematics

As previously stated, kinematics studies motion without regard to the forces and moments caus-ing the motion, which include translations and

rotations. Translations are simply the linear motions in which all the points of a rigid body move simultaneously in the same direction and at the same velocity. Rotations are the angular motions of a rigid body along a circular path and about an axis of rotation. During passive knee flexion, the tibiofemoral joint undergoes both lin-ear and angular motions, and both of these motions can occur in multiple planes, such as combined flexion-extension with internal- external tibial rotation.

Motion at an articular surface can be described in terms of three motions that exist resulting from a convex surface moving on a concave surface (Fig. 1.3). Rolling motion occurs when the con-vex surface rotates. This causes a change in the point of contact for both articular surfaces. A sliding motion is experienced when one articular surface translates across the other with no rota-tion and progressively changes the point of con-tact. Lastly, spinning motion occurs at a single point of contact on the fixed surface, where the point of contact changes on the rotating surface and no linear motion occurs. At the tibiofemoral

Rolling

Sliding

Spinning Fig. 1.3 Three

fundamental motions that occur between articular surfaces. The point of contact changes on both articular surfaces during rolling motion. The point of contact on the moving surface remains constant during sliding motion. A single point of contact occurs on the fixed surface during a spinning motion. Some joints, such as the tibiofemoral joint, experience up to all three of these motions simultaneously