Rubuta ci gaba don wannan sakin layi - Osoro ya wakilci Kenya sau biyu a fagen duniya a 1991, yana gudana a gasar tseren tsere ta duniya ta 1991 IAAF (inda ya zo na biyar a tseren tsere mai tsawo) sannan kuma a kan hanyar a gasar tseren tsere ta duniya ta 1991 (an cire shi a tseren mita 5000 ta hanyar kunkuntar bambanci da Dionísio Castro). Koyaya, ya sami lambar yabo a tseren mita 5000 a Wasannin Duk Afirka na shekarar 1991. Ya bayyana a cikin tawagar 'yan wasan kasar Kenya ta duniya a karo na biyu a gasar tseren tseren tseren kasa ta duniya ta 1992.
, kodayake bai yi nasara ba a wannan yunƙurin kamar yadda ya gama a matsayi na 23. Daga cikin tafiye-tafiyensa a kan hanyar, ya ci nasara a Belfast International Cross Country meet.