title: Unicompartmental knee resurfacing: enlarged tibio-femoral contact area and reduced contact stress using novel patient-derived geometries.
abstract: Advances in imaging technology and computer-assisted design (CAD) have recently enabled the introduction of patient-specific knee implant designs that hold the potential to improve functional performance on the basis of patient-specific geometries, namely a patient-specific sagittal and coronal curvature, as well as enhanced bone preservation. The objective of this study was to investigate the use of a novel implant design utilizing a patient specific sagittal J-curve on the femoral component combined with a novel constant, patient-derived femoral coronal curvature and to assess tibio-femoral contact area and contact stress on a femur matched curved tibial polyethylene insert. Mean contact area and standard deviations were 81+/-5, 96+/-5 and 74+/-4 mm(2) for the heel strike, toe off and mid-stance positions, respectively. Mean contact stress and standard deviations were 23.83+/-1.39, 23.27+/-1.14 and 20.78+/-0.54 MPa for the heel strike, toe off and mid-stance positions, respectively. Standard deviations of the measurements were small, not exceeding 6-7% confirming the consistency of loading conditions across different flexion angles. The results were comparable to those reported for standard, off-the-shelf fixed-bearing implants with paired femoral and tibial geometries. These data show that a constant coronal curvature can be applied to a patient-specific implant by measuring coronal curvatures across the femoral condyle in each patient and by deriving an average curvature. This novel approach combines unique benefits of patient-specific geometry with proven design concepts for minimizing polyethylene wear.
authors.affiliation: Shiley Center for Orthopedic Research and Education Center (SCORE), 11025 N. Torrey Pines Road, Suite 140, LaJolla, CA, 92037, USA.
authors.forename: Nick
authors.initials: N
authors.lastname: Steklov
authors.forename: John
authors.initials: J
authors.lastname: Slamin
authors.forename: Sudesh
authors.initials: S
authors.lastname: Srivastav
authors.forename: Darryl
authors.initials: D
authors.lastname: D'Lima
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