Table 1 Inclusion and exclusion criteria

Metal on metal hip resurfacing

A minimum of two years follow-up was applied; Studies not reporting the specified outcomes (ref. table 2) such as laboratory only studies were excluded.

Watchful waiting

Observational data of people receiving WW with a follow-up of greater than five years were included

Total hip replacement

RCTs or systematic reviews of RCTs with a minimum of five years follow-up of different methods of THR and systematic reviews of such trials