• (2015-present) Editor–in–chief Journal of ISAKOS (JISAKOS)
• (2015-present) Founding editor–in–chief Journal of ISAKOS (JISAKOS)
• (2014) Congress president biannual ESSKA Congress Amsterdam
• (2012-2014) Board position as Past-president European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA)
• (Since 2012) Member strategic planning committee ISAKOS
• (2010-2012) President European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA)
• (2010-present) Head of the Foot and Ankle Section in the FIFA Medical Centre of Excellence Clínica Espregueira – Estádio do Dragão, Porto, Portugal
• (2009) Nominated member of the representative advisory board of the AMC
• (2008-2014) Vice–President Indo–European Arthroscopy/Arthroplasty Foundation (IEAAF)
• (2008-2010) Vice president European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA)
• (2008-2010) President Nordic Orthopaedic Federation (NOF)
• (2008-2010) President ESSKA–AFAS (Ankle and Foot Association)
• (2008) President biannual congres of Nordic Orthopaedic Federation (NOF) Amsterdam
• (2007-2011) Board Member International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) and vice–chair of the strategic planning committee
• (2005-2007) Chairman Arthroscopy Committee International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)
• (2005) Member Committee on outcome indicators for quality of care (NOV)
• (2005) Committee Internal Visitation AMC
• (2004-2016) Orthopedic Consultant AJAX Soccer Team
• (2004-2016) Orthopedic Consultant Dutch Gymnastic Association
• (2004-2005) Board Member Dutch Association for Endoscopic Surgery
• (2004) Advisory Board European Orthopaedic Research Society
• (2003-2005) President Dutch Orthopaedic Association (NOV)
• (2003-2005) Delegate for the Netherlands in the European Federation of National Associations of Orthopaedics and Traumatology (EFORT)
• (2002-2016) Full Professor in Orthopedic Surgery, Amsterdam UMC, University of Amsterdam and Head of the Orthopedic Department of the AMC Hospital (Academic Medical Center Amsterdam)
• (2002-2007) Chairman Committee Orthopedic Relationships and Education Indonesia
• (2002) Secretary Brace and Orthosis Committee, Dutch Orthopedic Association (NOV)
• (2001-2005) Chairman of the Arthroscopy Committee of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA)
• (2001-2002) Chairman “Quality of Orthopaedic Care” Committee, (NOV)
• (2001) Scientific Advisor or the European Federation of National Associations of Orthopaedics and Traumatology (EFORT)
• (2000-2001) President Dutch Arthroscopy Association (NVA)
• (1999-2003) Board Member Dutch Orthopaedic Association
• (1999-2001) Board Member Concilium Orthopaedicum
• (1999-2001) Board Member Dutch Association Orthopaedic Traumatology (NVOT)
• (1998-2016) Founder and Director of Orthopaedic Research Center Amsterdam (ORCA)
• (1998-2000) Board member at large European Society of Sports traumatology, Knee surgery and Arthroscopy (ESSKA)
• (1997-2008) Member of Medical Committee World Squash Federation
• (1997-1999) Member of communication comittee International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)
• (1997-1998) Consensus Committee “Acute kneepathology”
• (1996-1998) Chairman National Consensus Committee “Acute Ankle Injury”
• (1995-2002) Orthopaedic Consultant Olympic Center Noord–Holland
• (1994) Academic degree Ph.D. (Doctor), University of Amsterdam Ph.D. Thesis: “Diagnostic strategies in patients with severe ankle sprain” (promotor: Prof. Dr. R.K. Marti)
• (1991-1997) Teacher National Institute for Sport and Health (NISG)
• (1991-1999) Chairman Medical Committee Dutch Squash Rackets Federation
• (1989-1995) Treasurer Dutch Association Orthopaedic Traumatology (NVOT)
• (1986-2001) Instructor AO–basic course/AO–advance course Davos, Switserland
• (1985-2016) Orthopaedic consultant National Ballet, Amsterdam
• (1985-2016) Orthopaedic Surgeon, Amsterdam UMC, University of Amsterdam
• (1983-1991) Team Doctor Dutch Squash Federation
• (1975-1980) Board Member Dutch Squash Federation
• (1973-1976) Founder/Chairman Minerva Squash Rackets Club, Leiden