Evaluation of the role of ImplantMovement Analysis in diagnosing asepticloosening of total hip arthroplasty

Introduction: Aseptic loosening is the most common indication for revision surgery of hipimplants. However, sometimes diagnosis from planar radiography is uncertain, makingdecision regarding revision surgery problematic. Implant Movement Analysis (IMA) is anewly introduced method of analysing uncertain aseptic loosening of hip prostheses. It usescomputer tomography with rotational provocation to expose movement of the implantrelatively to the surrounding bone. Aim: To evaluate the role of IMA as a complementary method to planar radiography indiagnosing aseptic loosening of total hip artroplasty (THA) at Lindesberg Hospital. 1) HasIMA improved diagnosing of uncertain cases of aseptic loosening? 2) Has IMA reduced thenumber of unnecessary THA revision surgeries? Methods: Retrospective cohort study analysing 43 cases of uncertain aseptic looseningexamined with IMA at Lindesberg Hospital. Paired results from planar radiography and IMAwere statistically compared with McNemar’s test, IMA held as the reference. Additional datawas also collected (i.e. age and symptoms). Results: Planar radiography had 70 % sensitivity and 65 % specificity compared to certainresults from IMA. IMA provided diagnoses in 84 % of the cases and changed the diagnosisfor 33 % compared to planar radiography. Eight cases got their diagnosis changed from looseto not loose. Conclusions: IMA has improved diagnosing cases of uncertain aseptic loosening and cantherefore be seen as a good complementary method to planar radiography in these cases.However, as it is a new method further evaluation is needed