In　this　paper,　we　determine　the　instability　effects　of　a　phase　twist　superposed　on　a　quantum　vortex　defect　governed　by　the　Gross-Pitaevskii　equation.　For　this,　we　consider　the　modified　form　of　the　equation　in　two　cases:　when　a　uniform　phase　twist　is　present　everywhere　in　the　condensate,　and　when　the　defect　is　subject　to　a　localized　phase　twist　confined　to　the　defect　healing　region.　In　the　first　case,　we　show　that　a　secondary,　new　defect　is　produced　as　manifestation　of　an　Aharonov-Bohm　type　effect.　In　the　second　case,　we　prove　that　due　to　energy　minimization,　the　defect　changes　its　configurational　energy　by　converting　localized　twist　to　writhe.　This　mechanism,　typical　of　classical　elastic　systems,　is　shown　to　occur　also　in　quantum　defects,　and　it　may　find　useful　applications　in　science　and　technology.