Failure of METS SMILES Total Knee Replacement at the Femoral Condylar-Stem Taper Junction: A Report of Six Cases

Wood, Matthew; Shearman, Alexander; Bayliss, Lee; Hasan, Yusuf

doi:10.22038/abjs.2025.85952.3914

Failure of METS SMILES Total Knee Replacement at the Femoral Condylar-Stem Taper Junction: A Report of Six Cases

Articles in Press

Document Type : CASE REPORT

Authors

Matthew Wood ¹

Alexander Shearman ²

Lee Bayliss ¹

Yusuf Hasan ¹

¹ Royal National Orthopaedic Hospital, Stanmore, London, UK

² Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK

10.22038/abjs.2025.85952.3914

Abstract

Constrained modular knee prostheses are a valuable tool in the armament of the revision knee surgeon, affording intra-operative flexibility in the restoration of anatomy, function, and stability in complex knee arthroplasty. However, these prostheses have been reported to increase stress at both modular implant junctions and bone-cement interfaces. In cases of poor femoral condylar fixation or condylar loosening, particularly when not augmented with metaphyseal fixation, stress can concentrate at the femoral condylar-stem junction, leading to loosening of the taper interface, toggling, metallosis, and even implant fracture. Whilst this mode of failure has been reported in other constrained modular knee systems, there are no reported cases of this mode of failure in the METS SMILES Total Knee Replacement to our knowledge. We present six cases of femoral condylar-stem junction failure, including two implant fractures, in six patients who presented to our institute (The Royal National Orthopaedic Hospital NHS Trust, Stanmore, UK).

Keywords

Total knee arthroplasty

revision

modular

constrained

failure

metallosis

fracture

Subjects