EVALUATION OF TIBIAL COMPONENT ROTATION IN PAINFUL TOTAL KNEE ARTHROPLASTIES BY MRI ENHANCED WITH METAL ARTIFACT REDUCTION TECHNIQUE

Abstract

Background: Tibial component malrotation is one of the commonest causes of pain and stiffness following total knee arthroplasties, however, the assessment of tibial component malrotation on imaging is not clear-cut. The objective of this study was to assess tibial component rotation in cases with pain following total knee replacement using MRI with metal artifact reduction technique. Methods: In 15 consecutive patients presented in our clinic — a high-volume arthroplasty institution — between January 2017 and June 2017 with persistent unexplained moderate to severe pain for at least 6 months following total knee arthroplasties, which were ALL done outside our institution, after exclusion of infection and loosening (tibial or femoral), MRI evaluation of tibial component rotation using metal artifact reduction for orthopedic implants (O-MAR) technique — to improve visualization of soft tissue and bone by reducing artifacts caused by metal implants — was done according to the technique of Berger et al. [Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res 144–153, 1998]. Results: Eleven cases showed an internal rotation of tibial components (73.3%), four cases showed a neutral or external rotation of tibial components (26.6%), however, with the presence of abnormal intraarticular fibrous bands in two of them. Conclusions: Two main conclusions are obtained from this study: Firstly, internal rotation of tibial component must be excluded in all cases of persistent pain following total knee replacement. Secondly, magnetic resonance imaging with the newly developed metal artifact reduction techniques is a very useful tool in evaluating cases of unexplained pain following total knee replacement.