▁first ▁sur geon ▁to ▁perform ▁a ▁combined ▁la par os cop ic ▁removal ▁of ▁a ▁portion ▁of ▁the ▁pan cre as ▁and ▁a ▁kid ney ▁that ▁were ▁successfully ▁trans pl anted ▁simultaneously ▁into ▁a ▁di ab etic ▁patient ▁with ▁end - stage ▁ren al ▁disease . ▁In ▁ 1 9 9 8 , ▁Gru ess ner ▁performed ▁the ▁first ▁pre empt ive ▁li ver ▁trans plant ▁from ▁a ▁living ▁don or ▁in ▁an ▁infant ▁with ▁ox al osis . ▁In ▁ 2 0 1 2 , ▁he ▁and ▁his ▁team ▁performed ▁the ▁first ▁fully ▁robot ic ▁removal ▁of ▁the ▁pan cre as ▁and ▁simultane ous ▁is let ▁trans plant ▁in ▁a ▁patient ▁with ▁chron ic ▁pan cre at itis . ▁ ▁Gru ess ner ▁was ▁a ▁member ▁of ▁the ▁team ▁that ▁performed ▁the ▁world ' s ▁first ▁split ▁pan cre as ▁trans plant ▁and ▁the ▁world ' s ▁first ▁pan cre as ▁all otr ans plant ▁after ▁complete ▁removal ▁of ▁a ▁patient ' s ▁native ▁pan cre as ▁( both ▁in ▁ 1 9 8 8 ). ▁He ▁was ▁involved ▁in ▁the ▁development ▁of ▁trans anal ▁end os cop ic ▁mic ros urg ery ▁( TE M ) ▁techniques ▁and ▁conducted ▁the ▁first ▁pros pective ▁study ▁in ▁ 1 9 8 9 ▁that ▁demonstrated ▁the ▁superior ity ▁of ▁ul tras ound ▁in ▁comparison ▁to ▁per it one al ▁lav age ▁in ▁the ▁diagn osis ▁of ▁bl unt ▁ab dom inal ▁tra uma . ▁In ▁the ▁ 1 9 9 0 s , ▁he