Acetabular Cup Stiffness and Implant Orientation Change Acetabular Loading Patterns

Small, Scott R.; Berend, Michael E.; Howard, Leah; Tunç, Didem; Buckley, Christine; Ritter, Merrill A.

doi:10.1016/j.arth.2012.05.026

Cited by 31 publications

(20 citation statements)

References 35 publications

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“…To analyze stress changes, a normal hip FE model was used as a control. From the predicted von Mises stress distributions on the cortical bone in the 16 simulations of reconstructed acetabula, the stress distribution above the acetabular dome varies considerably with different abduction or anteversion angles, which differs from the conclusions of a previous study in which component inclination generated minimal and significant changes in strain response in the acetabular dome. This apparent discrepancy is likely attributable to the limited abduction angles concerned in that study.…”

Section: Discussioncontrasting

confidence: 77%

Finite Element Modelling for Assessing Effect of Acetabular Component Orientation on the Basic Stress Path above Acetabular Dome

Nie

Pei

2015

Orthopaedic Surgery

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Section: Discussioncontrasting

confidence: 77%

Finite Element Modelling for Assessing Effect of Acetabular Component Orientation on the Basic Stress Path above Acetabular Dome

Nie

Pei

2015

Orthopaedic Surgery

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“…Previous literature demonstrates the value of these models to draw important conclusions . To account for variation in bone properties, we modeled two bone densities based upon previous literature . We used a different press‐fit for each bone density which limits the comparisons between our different density models, but these were chosen to represent the lower press fit that would be used clinically for the more dense bone.…”

Section: Discussionmentioning

confidence: 99%

“…23,37,48 To account for variation in bone properties, we modeled two bone densities based upon previous literature. 6,35,45,49,50 We used a different press-fit for each bone density which limits the comparisons between our different density models, but these were chosen to represent the lower press fit that would be used clinically for the more dense bone. The milled bone cavity has also been previously demonstrated to be a surrogate for the anatomy of the acetabular socket.…”

Section: Discussionmentioning

confidence: 99%

Effect of impaction energy on dynamic bone strains, fixation strength, and seating of cementless acetabular cups

Doyle

Arkel

Jeffers

2019

Journal Orthopaedic Research

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Seating a cementless acetabular cup via impaction is a balancing act; good cup fixation must be obtained to ensure adequate bone in‐growth and cup apposition, while acetabular fracture must be avoided. Good impaction technique is essential to the success of hip arthroplasty. Yet little guidance exists in the literature to inform surgeons on “how hard” to hit. A drop rig and synthetic bone model were used to vary the energy of impaction strikes in low and high‐density synthetic bone, while key parameters such as dynamic strain (quantifying fracture risk), implant fixation, and polar gap were measured. For high energy impaction (15 J) in low‐density synthetic bone, a peak tensile strain was observed during impaction that was up to 3.4× as large as post‐strike strain, indicating a high fracture risk. Diminishing returns were observed for pushout fixation with increasing energy. Eighty‐five percent of the pushout fixation achieved using a 15 J impaction strike was attained by using a 7.5 J strike energy. Similarly, polar gap was only minimally reduced at high impaction energies. Therefore it is suggested that higher energy strikes increase fracture risk, but do not offer large improvements to fixation or implant‐bone apposition. It may difficult be for surgeons to accurately deliver specific impaction energies, suggesting there is scope for operative tools to manage implant seating. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2367–2375, 2019

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“…An increased press-fit close at the equatorial rim of the acetabular cavity results in high radial compressive forces to fixate the cup (Widmer et al, 2002). Transfer of the load through the peripheral cortical bone of the acetabulum is hereby reconstructing the force transmission of the natural hip (Dorr et al, 2000;Small et al, 2013). However, increasing the equatorial press-fit might result in insufficient cup seating, decreasing the bone coverage of the implant, which is important to enable bone ingrowth and to provide a good long-term fixation (Jasty et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Deformation of acetabular press-fit cups: Influence of design and surgical factors

Messer-Hannemann

Campbell

Morlock

2019

Clinical Biomechanics

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Background: Deformation of acetabular cups when press-fitted into an undersized cavity is inevitable due to the inhomogeneous stiffness of acetabular bone. Thinner cups or screw holes might increase the risk of high cup deformation. The aim of this study was to examine the influence of cup design and liner assembly on the deformation response during cup implantation. Methods: Acetabular cups with different designs were implanted into polyurethane foam models simulating the anatomical situation with nominal press-fits of 1mm and without nominal press-fits (line-toline). Deformations were determined using a tactile coordinate measuring machine. A 3D laser scanner was used to determine the contact conditions at the cup-cavity interface. Polyethylene and ceramic liners were assembled to the implanted cups and the influence of the insertion on the deformation response evaluated. Fixation strength of the cups was determined by push-out testing. Findings: Cup deformation increased with smaller wall thickness (P<0.037) and screw holes (P<0.001). Insertion of ceramic liners reduced the deformation (P<0.001), whereas polyethylene liners adapted to the deformation of the implanted cups (P>0.999). Thin-walled cups exhibited a higher fixation strength for similar implantation forces (P=0.011). Interpretation: Thin-walled cups achieved higher fixation strengths and might be more bone-preserving. However, in combination with screw holes and high press-fit levels, wall thickness should be considered carefully to avoid excessive cup deformations leading to potential complications during liner assembly. Line-to-line insertion of thin-walled cups should be accompanied with a rough surface coating to minimize the loss of fixation strength due to the low press-fit fixation.

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Acetabular Cup Stiffness and Implant Orientation Change Acetabular Loading Patterns

Cited by 31 publications

References 35 publications

Finite Element Modelling for Assessing Effect of Acetabular Component Orientation on the Basic Stress Path above Acetabular Dome

Finite Element Modelling for Assessing Effect of Acetabular Component Orientation on the Basic Stress Path above Acetabular Dome

Effect of impaction energy on dynamic bone strains, fixation strength, and seating of cementless acetabular cups

Deformation of acetabular press-fit cups: Influence of design and surgical factors

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