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Knee Implant
Jonelle M. Petscavage-Thomas, MD, MPH; B. J. Manaster, MD, PhD, FACR
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KEY FACTS

  • Terminology

    • Imaging

      • Diagnostic Checklist

        TERMINOLOGY

        • Definitions

          • Total knee arthroplasty (TKA): replacement of femoral and tibial articular surfaces
            • May or may not resurface patella also
            • Nonconstrained components
              • Posterior cruciate ligament (PCL) is usually retained
              • Other soft tissues, including collateral ligaments, provide stability
              • Posterior stabilizing/PCL substituting design limits excessive posterior tibial translation in flexion
                • Tibial post and femoral cam with deeper dished articular surfaces
            • Varus-valgus constrained
              • Tall tibial post and deep femoral box with no link connecting components
              • Provides stability in coronal plane but allows varus and valgus tilt and rotation
            • Constrained/rotating hinge
              • Hinged femoral and tibial components; rarely used due to high rate of loosening
              • Restricts varus, valgus, and translational stresses
              • Used as limb salvage option for distal femur malignancies, and after multiple revision TKAs with substantial loss of bone stock
          • Single compartment (unicompartmental) implant: medial, lateral, or patellofemoral
            • Considered when only single compartment involved with significant osteoarthritis
            • Especially in younger patients: delays 1st TKA for 1-2 decades
            • Also very old patients: less invasive, easier rehabilitation
          • Arthroplasty = name for procedure (surgery), not for device (prosthesis/implant)

        IMAGING

        • Radiographic Findings

          • CT Findings

            • MR Findings

              • Imaging Recommendations

                PATHOLOGY

                • Staging, Grading, & Classification

                  CLINICAL ISSUES

                  • Demographics

                    • Natural History & Prognosis

                      DIAGNOSTIC CHECKLIST

                      • Consider

                        Selected References

                        1. Hernandez NM et al: Varus-valgus constrained implants in revision total knee arthroplasty: mean clinical follow-up of six years. J Arthroplasty. 36(7S):S303-7, 2021
                        2. von Hintze J et al: Outcomes of the rotating hinge knee in revision total knee arthroplasty with a median follow-up of 6.2 years. BMC Musculoskelet Disord. 22(1):336, 2021
                        3. Li N et al: Radiographic evidence of soft-tissue gas 14 days after total knee arthroplasty is predictive of early prosthetic joint infection. AJR Am J Roentgenol. 214(1):171-6, 2020
                        4. Pasquier G et al: The role of rotating hinge implants in revision total knee arthroplasty. EFORT Open Rev. 4(6):269-78, 2019
                        5. Song SJ et al: What to know for selecting cruciate-retaining or posterior-stabilized total knee arthroplasty. Clin Orthop Surg. 11(2):142-50, 2019
                        6. Cyteval C: Imaging of knee implants and related complications. Diagn Interv Imaging. 97(7-8):809-21, 2016
                        7. Fritz J et al: MR imaging of knee arthroplasty implants. Radiographics. 35(5):1483-501, 2015
                        8. Helito CP et al: Severe metallosis following total knee arthroplasty: a case report and review of radiographic signs. Skeletal Radiol. 43(8):1169-73, 2014
                        9. Mulcahy H et al: Current concepts in knee replacement: features and imaging assessment. AJR Am J Roentgenol. 201(6):W828-42, 2013
                        10. Plodkowski AJ et al: Lamellated hyperintense synovitis: potential MR imaging sign of an infected knee arthroplasty. Radiology. 266(1):256-60, 2013
                        11. Mannan K et al: The medial rotation total knee replacement: a clinical and radiological review at a mean follow-up of six years. J Bone Joint Surg Br. 91(6):750-6, 2009
                        12. Cobb JP et al: The anatomical tibial axis: reliable rotational orientation in knee replacement. J Bone Joint Surg Br. 90(8):1032-8, 2008
                        13. Mukherjee K et al: The Oxford unicompartmental knee arthroplasty: a radiological perspective. Clin Radiol. 63(10):1169-76, 2008
                        Related Anatomy
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                        Related Differential Diagnoses
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                        References
                        Tables

                        Tables

                        KEY FACTS

                        • Terminology

                          • Imaging

                            • Diagnostic Checklist

                              TERMINOLOGY

                              • Definitions

                                • Total knee arthroplasty (TKA): replacement of femoral and tibial articular surfaces
                                  • May or may not resurface patella also
                                  • Nonconstrained components
                                    • Posterior cruciate ligament (PCL) is usually retained
                                    • Other soft tissues, including collateral ligaments, provide stability
                                    • Posterior stabilizing/PCL substituting design limits excessive posterior tibial translation in flexion
                                      • Tibial post and femoral cam with deeper dished articular surfaces
                                  • Varus-valgus constrained
                                    • Tall tibial post and deep femoral box with no link connecting components
                                    • Provides stability in coronal plane but allows varus and valgus tilt and rotation
                                  • Constrained/rotating hinge
                                    • Hinged femoral and tibial components; rarely used due to high rate of loosening
                                    • Restricts varus, valgus, and translational stresses
                                    • Used as limb salvage option for distal femur malignancies, and after multiple revision TKAs with substantial loss of bone stock
                                • Single compartment (unicompartmental) implant: medial, lateral, or patellofemoral
                                  • Considered when only single compartment involved with significant osteoarthritis
                                  • Especially in younger patients: delays 1st TKA for 1-2 decades
                                  • Also very old patients: less invasive, easier rehabilitation
                                • Arthroplasty = name for procedure (surgery), not for device (prosthesis/implant)

                              IMAGING

                              • Radiographic Findings

                                • CT Findings

                                  • MR Findings

                                    • Imaging Recommendations

                                      PATHOLOGY

                                      • Staging, Grading, & Classification

                                        CLINICAL ISSUES

                                        • Demographics

                                          • Natural History & Prognosis

                                            DIAGNOSTIC CHECKLIST

                                            • Consider

                                              Selected References

                                              1. Hernandez NM et al: Varus-valgus constrained implants in revision total knee arthroplasty: mean clinical follow-up of six years. J Arthroplasty. 36(7S):S303-7, 2021
                                              2. von Hintze J et al: Outcomes of the rotating hinge knee in revision total knee arthroplasty with a median follow-up of 6.2 years. BMC Musculoskelet Disord. 22(1):336, 2021
                                              3. Li N et al: Radiographic evidence of soft-tissue gas 14 days after total knee arthroplasty is predictive of early prosthetic joint infection. AJR Am J Roentgenol. 214(1):171-6, 2020
                                              4. Pasquier G et al: The role of rotating hinge implants in revision total knee arthroplasty. EFORT Open Rev. 4(6):269-78, 2019
                                              5. Song SJ et al: What to know for selecting cruciate-retaining or posterior-stabilized total knee arthroplasty. Clin Orthop Surg. 11(2):142-50, 2019
                                              6. Cyteval C: Imaging of knee implants and related complications. Diagn Interv Imaging. 97(7-8):809-21, 2016
                                              7. Fritz J et al: MR imaging of knee arthroplasty implants. Radiographics. 35(5):1483-501, 2015
                                              8. Helito CP et al: Severe metallosis following total knee arthroplasty: a case report and review of radiographic signs. Skeletal Radiol. 43(8):1169-73, 2014
                                              9. Mulcahy H et al: Current concepts in knee replacement: features and imaging assessment. AJR Am J Roentgenol. 201(6):W828-42, 2013
                                              10. Plodkowski AJ et al: Lamellated hyperintense synovitis: potential MR imaging sign of an infected knee arthroplasty. Radiology. 266(1):256-60, 2013
                                              11. Mannan K et al: The medial rotation total knee replacement: a clinical and radiological review at a mean follow-up of six years. J Bone Joint Surg Br. 91(6):750-6, 2009
                                              12. Cobb JP et al: The anatomical tibial axis: reliable rotational orientation in knee replacement. J Bone Joint Surg Br. 90(8):1032-8, 2008
                                              13. Mukherjee K et al: The Oxford unicompartmental knee arthroplasty: a radiological perspective. Clin Radiol. 63(10):1169-76, 2008