General
British Orthopaedic Association   http://www.boa.ac.uk/
American Association of Orthopaedic Surgerons  http://www.aaos.org/
Arthroscopy Association of North America  http://www.aana.org/
American Orthopaedic Association http://aoassn.org
NICE (National Institute for Clinical Excellence) http://www.nice.org.uk
National Joint Registry http://www-new.njrcentre.org.uk/njrcentre/default.aspx
Royal College of Surgeons of England http://www.rcseng.ac.uk/

Knee
British association for surgery of the knee  http://www.baskonline.com/
American Association of Hip and Knee Surgeons   http://www.aahks.org/
Arthritis Research Campaign: A New Knee    http://www.arc.org.uk/arthinfo/patpubs/6021/6021.asp
Mayo clinic ACL guide  http://www.mayoclinic.com/health/acl-injury/AC99999

Hip
British Hip Society  http://www.britishhipsociety.com/
American Association of Hip and Knee Surgeons   http://www.aahks.org/
Arthritis Research Campaign: A New Hip    http://www.arc.org.uk/arthinfo/patpubs/6018/6018.asp
Mayo Clinic Hip Replacement  http://www.mayoclinic.com/health/hip-replacement/AR00028

Shoulder/Elbow

British Elbow and Shoulder Society     http://www.bess.org.uk
American Shoulder and Elbow Surgeons  http://www.ases-assn.org
Arthritis Research Campaign: A New  Shoulder/ Elbow   http://www.arc.org.uk/arthinfo/patpubs/6056/6056.asp

Sports Medicine

British Orthopaedics Sports Trauma Association   http://www.bosta.ac.uk/
British Association of Sport and Exercise Medicine  http://www.basem.co.uk/
American Orthopaedic Society for Sports Medicine http://www.sportsmed.org/