Search methods
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 3); MEDLINE (1966 to August 2009); EMBASE (1974 to August 2009); CBM (1978 to August 2009); the National Research Register (August 2009) and Physiotherapy Evidence Database (PEDro) (1929 to August 2009).