Marcello Papini

Learn More
To assess the performance of femoral orthopedic implants, they are often attached to cadaveric femurs, and biomechanical testing is performed. To identify areas of high stress, stress shielding, and to facilitate implant redesign, these tests are often accompanied by finite element (FE) models of the bone/implant system. However, cadaveric bone suffers from(More)
Intramedullary nails are routinely used in the treatment of fractures of the femur. While their effectiveness has been demonstrated clinically, a number of complications, including bone refracture and implant failure, persist. This paper presents novel three-dimensional finite element (FE) models, at four stages of gait, of: (i) a realistic femur analogue(More)
Soft-tissue balancing and the amount of tension applied to the ligaments in a well-functioning total knee arthroplasty (TKA) has, thus far, not been accurately quantified. A ligament-tensioning device was used to measure displacement between the tibia and femur versus load during 86 consecutive TKAs. Measurements were made in flexion and extension following(More)
Notching of the anterior femoral cortex during primary total knee arthroplasty can occur when making an anterior femoral bone cut. To examine the increased stress caused by a notch, we used a validated 3-dimensional finite element model of the femur under gait loads. Three factors that affected the stress concentration were identified: First, larger notches(More)
BACKGROUND The use of artificial bone analogs in biomechanical testing of orthopaedic fracture fixation devices has increased, particularly due to the recent development of commercially available femurs such as the third generation composite femur that closely reproduce the bulk mechanical behavior of human cadaveric and/or fresh whole bone. The purpose of(More)
Intramedullary instrument/device insertion during total joint replacement can generate high intramedullary pressures, with potential for clinical fat embolism syndrome. We evaluated effects of process parameters on intramedullary pressure generated when hammering an implant into a simulated femur analogue. Lower implant insertion speed, lower hammering(More)
A nonlinear biphasic fiber-reinforced porohyperviscoelastic (BFPHVE) model of articular cartilage incorporating fiber reorientation effects during applied load was used to predict the response of ovine articular cartilage at relatively high strains (20%). The constitutive material parameters were determined using a coupled finite element-optimization(More)
Hip resurfacing is an alternative to total hip arthroplasty in which the femoral head surface is replaced with a metallic shell, thus preserving most of the proximal femoral bone stock. Accidental notching of the femoral neck during the procedure may predispose it to fracture. We examined the effect of neck notching on the strength of the proximal femur.(More)
BACKGROUND The bone loss associated with revision surgery or pathology has been the impetus for developing modular revision total hip prostheses. Few studies have assessed these modular implants quantitatively from a mechanical standpoint. METHODS Three-dimensional finite element (FE) models were developed to mimic a hip implant alone (Construct A) and a(More)
BACKGROUND Conventional models to evaluate degenerated cartilage do not consider nonlinear permeability and proteoglycan viscous effects. Some models also utilize spring elements to represent the viscous effects of the fibers, thus application tothe modeling of nonuniform deformations such as those that occur in indentation tests. The purpose of this study(More)