A team consists of
Consultant: one who has his FRCS and other qualifications, has undergone the 5 years post-graduate orthopaedic rotation training and has now been appointed as a consultant orthopaedic (or whatever) surgeon and is employed by the hospital as such.
Senior registrar: one who has his FRCS and is under going the post-grad rotation training. He might be assigned to this team from anything from 6 months to 2 years before getting himself a consultancy
Registrar: one who is studying for his FRCS. These appointments are often for 1-2 years and may be renewed.
SHO (senior house officer): is in training but able to work without too much supervision. Assists consultant and/or registrars in theatre but only does a few minor surgeries under close supervision.
HO (house officer): is fresh out of medical school (uni) and has to work under close supervision all the time. Rarely gets to theatre and does no hands on surgery except maybe suturing in the A&E.
In larger hospitals or those associated to a local university, there might also be a Professor who is in charge of a team of consultants and dictates department policy though each consultant is still permitted to work to his own preferences.
FRCS is Fellowship of the Royal College of Surgeons. Doctors are generally not allowed to perform surgery without this qualification.
Orthopaedic rotation training is undertaken in one of the 5 centres of excellence in the UK (RNOH, Manchester, Birmingham, Oswestry and Oxford) and lasts 5 years.