Injection of larger volumes caused significantly more pain [ VAS least square mean differences 1600 vs. 400 l , 7 2 mm ( 95 % confidence interval - CI ; 4.6-9 .7 ; p < 0.0001 ) ; 1600 vs. 800 l , 7.2 mm ( 4.4-10 .0 ; p < 0.0001 ) ; 1200 vs. 400 l , 3.5 mm ( 0.4-6 .6 ; p = 0.025 ) and 1200 vs. 800 l , 3.6 mm ( 0.4-6 .7 ; p = 0.027 ) ] .