Mean and standard deviation ( SD ) of VAS improvement were 31.4 + / - 22.1 mm for the GGF group versus 34.3 + / - 22.6 mm for the GOF group ( p = 0.69 ) , within pre-specified 20 % non-inferiority margin ( difference 2.9 mm 95 % CI-17 .7 mm , 11.8 mm ) .