Asymmetric polyethylene inserts promote favorable kinematics and better clinical outcome compared to symmetric inserts in a mobile bearing total knee arthroplasty

  • Gianluca Castellarin
  • Silvia Pianigiani
  • Bernardo InnocentiEmail author



This study aims at comparing the effects of symmetric and asymmetric designs for the polyethylene insert currently available and also for mobile bearing total knee arthroplasty (TKA). The investigation was performed both clinically and biomechanically through finite element analysis.


303 patients, with a mobile bearing TKA, were analyzed retrospectively. All patients received the same femoral and tibial components; for the insert, 151 patients received a symmetric design (SD) and 152 an asymmetric design (AD). Additionally, a 3D finite element model of a lower leg was developed, resurfaced with the same TKAs and analysed during gait and squat activities. TKA kinematics, and bone-stresses were investigated for the two insert solutions.


After surgery, patients’ average flexion improved from 105°, with 5° of preoperative extension deficit, to 120° (AD-group) and 115° (SD-group) at the latest follow-up. There was no postoperative extension deficit. No pain affected the AD-group, while an antero-lateral pain was reported in some patients of the SD-group. Patients of the AD-group presented a better ability to perform certain physical routines. Biomechanically, the SD induced higher tibial-bone stresses than the AD. Both designs replicated similar kinematics, comparable to literature. However, SD rotates more on the tray, reducing the motion between femoral and polyethylene components, while AD permits greater insert rotation.


The biomechanical analysis justifies the clinical findings. TKA kinematics is similar for the two designs, although the asymmetric solution shows less bone stress, thus resulting as more suitable to be cemented, avoiding lift-off issues, inducing less pain. Clinically, and biomechanically, an asymmetric mobile bearing insert could be a valid alternative to symmetric mobile bearing insert.

Level of evidence

Case–control study retrospective comparative study, III.


TKA Mobile bearing Asymmetric insert Symmetric insert Insert congruency Biomechanics Kinematics 



This work was supported by FNRS (Fonds National de la Recherche Scientifique, CDR 19545501, CDR 29155446) and by FER ULB (Fonds d’Encouragement à la Recherche, FER 2014, FER 2017). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Compliance with ethical standards

Conflict of interest

All authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in this study involving human participants were in accordance with the ethical standard of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed consent

Every patient gave his/her written informed consent to have his/her clinical records later used for this prospective study.


  1. 1.
    Arnout N, Vanlommel L, Vanlommel J, Luyckx JP, Labey L, Innocenti B, Victor J, Bellemans J (2015) Post cam mechanics and tibiofemoral kinematics: a dynamic in vitro analysis of eight posterior stabilized total knee designs. Knee Surg Sports Traumatol Arthrosc 23(11):3343–3353CrossRefPubMedCentralGoogle Scholar
  2. 2.
    Belvedere C, Leardini A, Catani F, Pianigiani S, Innocenti B (2017) In vivo kinematics of knee replacement during daily living activities: condylar and post-cam contact assessment by three-dimensional fluoroscopy and finite element analyses. J Orthop Res 35(7):1396–1403CrossRefPubMedCentralGoogle Scholar
  3. 3.
    Berend ME, Davis PJ, Ritter MA, Keating EM, Faris PM, Meding JB, Malinzak RA (2010) “Thicker” polyethylene bearings are associated with higher failure rates in primary total knee arthroplasty. J Arthoplasty 25(6):17–20CrossRefGoogle Scholar
  4. 4.
    Brihault J, Navacchia A, Pianigiani S, Labey L, De Corte R, Pascale V, Innocenti (2016) All-polyethylene tibial components generate higher stress and micromotions than metal-backed tibial components in total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 24(8):2550–2559CrossRefPubMedCentralGoogle Scholar
  5. 5.
    Caillouette JT, Anzel SH (1990) Fat embolism syndrome following the intramedullary alignment guide in total knee arthroplasty. Clin Orthop Relat Res 251:198–199Google Scholar
  6. 6.
    Carothers JT, Kim RH, Dennis DA, Southworth C (2011) Mobile-bearing total knee arthroplasty: a meta-analysis. J Arthroplasty 26(4):537–542CrossRefPubMedCentralGoogle Scholar
  7. 7.
    Catani F, Innocenti B, Belvedere C, Labey L, Ensini A, Leardini A (2010) The mark coventry award: articular contact estimation in TKA using in vivo kinematics and finite element analysis. Clin Orthop Relat Res 468(1):19–28CrossRefPubMedCentralGoogle Scholar
  8. 8.
    Castellarin G, Manili M, Tavella E (2013) A new methodological and surgical approach to total knee replacement. Sphera Med J 17:22–26Google Scholar
  9. 9.
    Dawson J, Fitzpatrick R, Murray D, Carr A (1998) Questionnaire on the perceptions of patients about total knee replacement. J Bone Jt Surg Br 80(1):63–69CrossRefGoogle Scholar
  10. 10.
    Donahue TLH, Hull ML, Rashid MM, Jacobs CR (2003) How the stiffness of meniscal attachments and meniscal material properties affect tibio-femoral contact pressure computed using a validated finite element model of the human knee joint. J Biomech 36(1):19–34CrossRefGoogle Scholar
  11. 11.
    El-Zayat BF, Heyse TJ, Fanciullacci N, Labey L, Fuchs-Winkelmann S, Innocenti B (2016) Fixation techniques and stem dimensions in hinged total knee arthroplasty: a finite element study. Arch Orthop Traum Surg 136(12):1741–1752CrossRefGoogle Scholar
  12. 12.
    Faul F, Erdfelder E, Buchner A, Lang AG (2009) Statistical power analyses using G*Power 3.1: tests for correlation and regression analyses. Behav Res Methods 41(4):1149–1160CrossRefGoogle Scholar
  13. 13.
    Faul F, Erdfelder E, Lang AG, Buchner A (2007) G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods 39(2):175–191CrossRefGoogle Scholar
  14. 14.
    Galbusera F, Freutel M, Dürselen L, D’Aiuto M, Croce D, Villa T, Sansone V, Innocenti B (2014) Material models and properties in the finite element analysis of knee ligaments: a literature review. Front Bioeng Biotechnol 2:54CrossRefPubMedCentralGoogle Scholar
  15. 15.
    Gardiner JC, Weiss JA (2003) Subject-specific finite element analysis of the human medial collateral ligament during valgus knee loading. J Orthop Res 21(6):1098–1106CrossRefPubMedCentralGoogle Scholar
  16. 16.
    Godest AC, Beaugonin M, Haug E, Taylor M, Gregson PJ (2002) Simulation of a knee joint replacement during a gait cycle using explicit finite element analysis. J Biomech 35(2):267–275CrossRefPubMedCentralGoogle Scholar
  17. 17.
    Hopley CD, Crossett LS, Chen AF (2013) Long-term clinical outcomes and survivorship after total knee arthroplasty using a rotating platform knee prosthesis: a meta-analysis. J Arthroplasty 28(1):68–77CrossRefPubMedCentralGoogle Scholar
  18. 18.
    Innocenti B, Truyens E, Labey L, Wong P, Victor J, Bellemans J (2009) Can medio-lateral baseplate position and load sharing induce asymptomatic local bone resorption of the proximal tibia? A finite element study. J Orthop Surg Res 4:26CrossRefPubMedCentralGoogle Scholar
  19. 19.
    Innocenti B, Pianigiani S, Labey L, Victor J, Bellemans J (2011) Contact forces in several TKA designs during squatting: a numerical sensitivity analysis. J Biomech 44(8):1573–1581CrossRefPubMedCentralGoogle Scholar
  20. 20.
    Innocenti B, Bilgen OF, Labey L, van Lenthe GH, Sloten JV, Catani F (2014) Load sharing and ligament strains in balanced, overstuffed and understuffed UKA. A validated finite element analysis. J Arthroplasty 29(7):1491–1498CrossRefPubMedCentralGoogle Scholar
  21. 21.
    Innocenti B, Bellemans J, Catani F (2016) Deviations from optimal alignment in TKA: is there a biomechanical difference between femoral or tibial component alignment? J Arthroplasty 31(1):295–301CrossRefPubMedCentralGoogle Scholar
  22. 22.
    Innocenti B, Robledo Yagüe H, Alario Bernabé R, Pianigiani S (2015) Investigation on the effects induced by TKA features on tibio-femoral mechanics part I: femoral component designs. J Mech Med Biol 15(2):1540034CrossRefGoogle Scholar
  23. 23.
    Innocenti B, Salandra P, Pascale W, Pianigiani S (2016) How accurate and reproducible are the identification of cruciate and collateral ligament insertions using MRI? Knee 23(4):575–581CrossRefPubMedCentralGoogle Scholar
  24. 24.
    Innocenti B, Pianigiani S, Ramundo G, Thienpont E (2016) Biomechanical effects of different varus and valgus alignments in medial unicompartmental knee arthroplasty. J Arthroplasty 31(12):2685–2691CrossRefPubMedCentralGoogle Scholar
  25. 25.
    Kayabasi O, Ekici B (2007) The effects of static, dynamic and fatigue behavior on three-dimensional shape optimization of hip prosthesis by finite element method. Mater Des 28(8):2269–2277CrossRefGoogle Scholar
  26. 26.
    Kurtz SM, Ong KL, Lau E, Widmer M, Maravic M, Gómez-Barrena E, de Pina Mde F, Manno V, Torre M, Walter WL, de Steiger R, Geesink RG, Peltola M, Röder C (2011) International survey of primary and revision total knee replacement. Int Orthop 35(12):1783–1789CrossRefPubMedCentralGoogle Scholar
  27. 27.
    Kwak JY, Jeong JH, Lee SH, Jung HJ, Jung YB (2012) Comparison of the Clinical outcomes after total knee arthroplasty with the LCS rotating platform mobile bearing knee system and the PFC sigma RP-F mobile bearing knee system. Clin Orthop Surg 4(4):256–262CrossRefPubMedCentralGoogle Scholar
  28. 28.
    Leppin J, O’Sullivan P, Winston K (2016) Effect size—large medium and small. Perspect Med Educ 5(6):347–349CrossRefGoogle Scholar
  29. 29.
    Li YL, Wu Q, Ning GZ, Feng SQ, Wu QL, Li Y, Hao Y (2014) No difference in clinical outcome between fixed- and mobile-bearing TKA: a meta-analysis. Knee Surg Sports Traumatol Arthrosc 22(3):565–575CrossRefPubMedCentralGoogle Scholar
  30. 30.
    Luyckx T, Didden K, Vandenneucker H, Labey L, Innocenti B, Bellemans J (2009) Is there a biomechanical explanation for anterior knee pain in patients with patella alta? Influence of patellar height on patellofemoral contact force, contact area and contact pressure. J Bone Jt Surg (Br) 91(3):344–350CrossRefGoogle Scholar
  31. 31.
    McNamara BP, Cristofolini L, Toni A, Taylor D (1997) Relationship between bone-prosthesis bonding and load transfer in total hip reconstruction. J Biomech 30(6):621–630CrossRefPubMedCentralGoogle Scholar
  32. 32.
    Oh KJ, Pandher DS, Lee SH, Sung Joon SD Jr, Lee ST (2009) Meta-analysis comparing outcomes of fixed-bearing and mobile-bearing prostheses in total knee arthroplasty. J Arthroplasty 24(6):873–884CrossRefPubMedCentralGoogle Scholar
  33. 33.
    Peña E, Calvo B, Martinez MA, Doblaré M (2006) A three-dimensional finite element analysis of the combined behavior of ligaments and menisci in the healthy human knee joint. J Biomech 39(9):1686–1701CrossRefPubMedCentralGoogle Scholar
  34. 34.
    Pianigiani S, Chevalier Y, Labey L, Pascale V, Innocenti B (2012) Tibio-femoral kinematics in different total knee arthroplasty designs during a loaded squat: a numerical sensitivity study. J Biomech 45(13):2315–2323CrossRefPubMedCentralGoogle Scholar
  35. 35.
    Pianigiani S, Alario Bernabé R, Robledo Yagüe H, Innocenti B (2015) Investigation on the effects induced by TKA features on tibio-femoral mechanics part II: tibial insert designs. J Mech Med Biol 15(2):1540035CrossRefGoogle Scholar
  36. 36.
    Pianigiani S, Vander Sloten J, Pascale W, Labey L, Innocenti B (2015) A new graphical method to display data sets representing biomechanical knee behaviour. J Exp Orthop 2(1):18CrossRefPubMedCentralGoogle Scholar
  37. 37.
    Pianigiani S, Labey L, Pascale W, Innocenti B (2016) Knee kinetics and kinematics: what are the effects of TKA malconfigurations? Knee Surg Sports Traumatol Arthrosc 24(8):2415–2421CrossRefPubMedCentralGoogle Scholar
  38. 38.
    Ramaniraka NA, Terrier A, Theumann N, Siegrist O (2005) Effects of the posterior cruciate ligament reconstruction on the biomechanics of the knee joint: a finite element analysis. Clin Biomech 20(4):434–442CrossRefGoogle Scholar
  39. 39.
    Raut VV, Stone MH, Wroblewski BM (1993) Reduction of postoperative blood loss after press-fit condylar knee arthroplasty with use of a femoral intramedullary plug. J Bone Jt Surg Am 75(9):1356–1357CrossRefGoogle Scholar
  40. 40.
    Rho YJ, Kuhn-Spearing L, Zioupos P (1998) Mechanical properties and the hierarchical structure of bone. Med Eng Phys 20(2):92–102CrossRefPubMedCentralGoogle Scholar
  41. 41.
    Sarathi Kopparti P, Lewis G (2007) Influence of three variables on the stresses in a three-dimensional model of a proximal tibia-total knee implant construct. Biomed Mater Eng 17(1):19–28PubMedPubMedCentralGoogle Scholar
  42. 42.
    Scuderi GR, Bourne RB, Noble PC, Benjamin JB, Lonner JH, Scott WN (2012) The new knee society knee scoring system. Clin Orthop Relat Res 470(1):3–19CrossRefPubMedCentralGoogle Scholar
  43. 43.
    Smith TO, Ejtehadi F, Nichols R, Davies L, Donell ST, Hing CB (2010) Clinical and radiological outcomes of fixed-versus mobile-bearing total knee replacement: a meta-analysis. Knee Surg Sports Traumatol Arthrosc 18(3):325–340CrossRefPubMedCentralGoogle Scholar
  44. 44.
    Smith H, Jan M, Mahomed NN, Davey JR, Gandhi R (2011) Meta-analysis and systematic review of clinical outcomes comparing mobile bearing and fixed bearing total knee arthroplasty. J Arthroplasty 26(8):1205–1213CrossRefPubMedCentralGoogle Scholar
  45. 45.
    Sobieraj MC, Rimnac CM (2009) Ultra high molecular weight polyethylene: mechanics, morphology, and clinical behavior. J Mech Behav Biomed Mater 2(5):433–443CrossRefPubMedCentralGoogle Scholar
  46. 46.
    Soenen M, Baracchi M, De Corte R, Labey L, Innocenti B (2013) Stemmed TKA in a femur with a total hip arthroplasty: is there a safe distance between the stem tips? J Arthroplasty 28(8):1437–1445CrossRefPubMedCentralGoogle Scholar
  47. 47.
    Verdini F, Zara C, Leo T, Mengarelli A, Cardarelli S, Innocenti B (2017) Assessment of patient functional performance in different knee arthroplasty designs during unconstrained squat. Muscles Ligaments Tendons J 7(3):514–523CrossRefPubMedCentralGoogle Scholar
  48. 48.
    Viceconti M, Casali M, Massari B, Cristofolini L, Bassini S, Toni A (1996) The ‘standardized femur program’. Proposal for a reference geometry to be used for the creation of finite element models of the femur. J Biomech 29(9):1241CrossRefPubMedCentralGoogle Scholar
  49. 49.
    Victor J, Van Doninck D, Labey L, Innocenti B, Parizel PM, Bellemans J (2009) How precise can bony landmarks be determined on a CT scan of the knee? Knee 16(5):358–365CrossRefPubMedCentralGoogle Scholar
  50. 50.
    Victor J, Labey L, Wong P, Innocenti B, Bellemans J (2010) The Influence of muscle load on tibio-femoral knee kinematics. J Orthop Res 28(4):419–428PubMedPubMedCentralGoogle Scholar
  51. 51.
    Wen Y, Liu D, Huang Y, Li B (2011) A meta-analysis of the fixed-bearing and mobile-bearing prostheses in total knee arthroplasty. Arch Orthop Trauma Surg 131(10):1341–1350CrossRefPubMedCentralGoogle Scholar
  52. 52.
    Yau WP, Ng TP, Chiu KY (2001) Unusual complication associated with femoral intramedullary alignment guide in total knee arthroplasty. J Arthroplasty 16(2):247–249CrossRefPubMedCentralGoogle Scholar

Copyright information

© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2018

Authors and Affiliations

  1. 1.II Unit Orthopaedic DepartmentOspedale di SuzzaraMantuaItaly
  2. 2.BEAMS Department, École polytechnique de Bruxelles, Université Libre de BruxellesBrusselsBelgium

Personalised recommendations