PurposeMinimally　invasive　total　hip　arthroplasty　(MITHA)　is　a　treatment　for　hip　arthritis,　and　it　causes　less　tissue　trauma,　blood　loss,　and　recovery　time.　However,　the　limited　incision　makes　it　difficult　for　surgeons　to　perceive　the　instruments＇　location　and　orientation.　Computer-assisted　navigation　systems　can　help　improve　the　medical　outcome　of　MITHA.　Directly　applying　existing　navigation　systems　for　MITHA,　however,　suffers　from　problems　of　bulky　fiducial　marker,　severe　feature-loss,　multiple　instruments　tracking　confusion,　and　radiation　exposure.　To　tackle　these　problems,　we　propose　an　image-guided　navigation　system　for　MITHA　using　a　novel　position-sensing　marker.MethodsA　position-sensing　marker　is　proposed　to　serve　as　the　fiducial　marker　with　high-density　and　multi-fold　ID　tags.　It　results　in　less　feature　span　and　enables　the　use　of　ID　for　each　feature,　overcoming　the　problem　of　bulky　fiducial　markers　and　multiple　instruments　tracking　confusion.　And　the　marker　can　be　recognized　even　when　a　large　part　of　locating　features　is　obscured.　As　for　the　elimination　of　intraoperative　radiation　exposure,　we　propose　a　point-based　method　to　achieve　patient-image　registration　based　on　anatomical　landmarks.ResultsQuantitative　experiments　are　conducted　to　evaluate　the　feasibility　of　our　system.　The　accuracy　of　instrument　positioning　is　achieved　at　0.33　+/-　0.18　mm,　and　that　of　patient-image　registration　is　achieved　at　0.79　+/-　0.15　mm.　And　qualitative　experiments　are　also　performed,　verifying　that　our　system　can　be　used　in　compact　surgical　spatial　volume　and　can　address　severe　feature-loss　and　tracking　confusion　problems.　In　addition,　our　system　does　not　require　any　intraoperative　medical　scans.ConclusionExperimental　results　indicate　that　our　proposed　system　can　assist　surgeons　without　larger　space　occupations,　radiation　exposure,　and　extra　incision,　showing　its　potential　application　value　in　MITHA.