Gradual　correction　using　external　fixator　has　been　advocated　as　a　minimally　invasive　so-lution　for　limb　deformity　and　is　widely　used　in　the　clinic.　This　treatment　manner　requires　a　long-term　distraction　process,　which　is　guided　by　a　preplanned　correction　path.　How-ever,　bone　cross-section　(BCS)　collision　and　soft　tissue　(ST)-distraction　rod　(DR)　collision　may　occur　on　the　path　and　then　affect　the　continuity　of　the　process.　Thus,　collision　detec-tion　should　be　carried　out　before　performing　distraction.　Existing　detection　solutions　do　not　simultaneously　consider　these　two　types　of　collisions,　and　primarily　target　long-bone　deformity.　To　solve　these　issues,　taking　more　complex　foot　and　ankle　deformity　as　the　re-search　object,　a　novel　analytical　detection　approach　is　proposed　in　this　paper.　By　modelling　the　contours　of　BCS,　ST,　and　DRs　as　convex　envelope　planes/bodies　using　different　spatial　line　styles,　the　spatial　posture　relations　of　their　boundaries　can　be　reproduced　on　the　cor-rection　path,　and　collision　detection　can　be　transformed　into　the　mathematical　problem　of　calculating　point-plane　and　point-line　distances.　Subsequently,　two　algorithms　are　pro-posed　for　BCS　and　ST-DR　collision　detections,　and　adjustment　strategies　are　provided　to　resolve　algorithm　anomalies.　Clinical　case　simulation　proves　the　effectiveness　and　applica-bility　of　the　approach.　Since　the　detection　is　used　for　pre-distraction　prediction　rather　than　real-time　monitoring,　the　correction　path　with　potential　collision　risk　can　be　re-planned　before　distraction,　and　finally,　guarantees　the　safety　of　gradual　correction.(c)　2022　Elsevier　Inc.　All　rights　reserved.