Purpose: Most total knee arthroplasty tibial components are metal-backed, but an alternative tibial component made entirely of polyethylene (all-polyethylene design) exists. While several clinical studies have shown that all-poly design performs similarly to the metal-backed, the objective of this study is to perform a biomechanical comparison. Methods: Loads, constraints and geometries during a squat activity at 120° of flexion were obtained from a validated musculoskeletal model and applied to a finite element model. Stresses in the tibia and micromotions at the bone–implant interface were evaluated for several implant configurations: (1) three different thicknesses of the cement penetration under the baseplate (2, 3 and 4 mm), (2) the presence or absence of a cement layer around the stem of the tibial tray and (3) three different bone conditions (physiological, osteopenic and osteoporotic bone). Results: All-polyethylene tibial components resulted in significantly higher (p < 0.001) and more uneven stress distributions in the cancellous bone under the baseplate (peak difference: +128.4 %) and fivefold increased micromotions (p < 0.001). Performance of both implant designs worsened with poorer bone quality with peaks in stress and micromotion variations of +40.8 and +54.0 %, respectively (p < 0.001). Performance improvements when the stem was cemented were not statistically significant (n.s.). Conclusion: The metal-backed design showed better biomechanical performance during a squat activity at 120° of flexion compared to the all-polyethylene design. These results should be considered when selecting the appropriate tibial component for a patient, especially in the presence of osteoporotic bone or if intense physical activity is foreseen.
|Titolo:||All-polyethylene tibial components generate higher stress and micromotions than metal-backed tibial components in total knee arthroplasty|
PASCALE, VALERIO (Penultimo)
|Parole Chiave:||All-polyethylene; Implant micromotions; Metal-backed; Tibial stresses; TKA|
|Settore Scientifico Disciplinare:||Settore MED/33 - Malattie Apparato Locomotore|
|Data di pubblicazione:||10-mag-2015|
|Digital Object Identifier (DOI):||10.1007/s00167-015-3630-8|
|Appare nelle tipologie:||01 - Articolo su periodico|