An in vitro model of impaction during hip arthroplasty

Impaction is required to properly seat press-fit implants and ensure initial implant stability and long term bone ingrowth, however excessive impaction or press-fit presents a high fracture risk in the acetabulum and femur. Current in-vitro impaction testing methods do not replicate the compliance o...

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Bibliographic Details
Published in:Journal of biomechanics 2019-01, Vol.82, p.220-227
Main Authors: Doyle, Ruben, Boughton, Oliver, Plant, Daniel, Desoutter, George, Cobb, Justin P., Jeffers, Jonathan R.T.
Format: Article
Language:English
Subjects:
Acetabulum
Acetabulum - cytology
Acetabulum - surgery
Aged, 80 and over
Arthroplasty (hip)
Arthroplasty, Replacement, Hip
Biomedical materials
Bone (long)
Bone implants
Boundary conditions
Cadavers
Compliance
Computer simulation
Female
Femur
Femur - cytology
Femur - surgery
Fractures
Hip
Hip arthroplasty
Hip Prosthesis
Humans
Impact loads
Impaction
In-vitro testing
Joint surgery
Laboratories
Laboratory tests
Male
Mechanical Phenomena
Soft tissues
Surgery
Surgical implants
Transplants & implants
Velocity
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Description
Summary:Impaction is required to properly seat press-fit implants and ensure initial implant stability and long term bone ingrowth, however excessive impaction or press-fit presents a high fracture risk in the acetabulum and femur. Current in-vitro impaction testing methods do not replicate the compliance of the soft tissues surrounding the hip, a factor that may be important in fracture and force prediction. This study presents the measurement of compliance of the soft tissues supporting the hip during impaction in operative conditions, and replicates these in vitro. Hip replacements were carried out on 4 full body cadavers while impact force traces and acetabular/femoral displacement were measured. Compliance was then simulated computationally using a Voigt model. These data were subsequently used to inform the design of a representative in-vitro drop rig. Effective masses of 19.7 kg and 12.7 kg, spring stiffnesses of 8.0 kN/m and 4.1 kN/m and dashpot coefficients of 595 N s/m and 322 N s/m were calculated for the acetabular and femoral soft tissues respectively. A good agreement between cadaveric and in-vitro peak displacement and rise time during impact is found. Such an in-vitro setup is of use during laboratory testing, simulation or even surgical training.
ISSN:0021-9290
1873-2380
DOI:10.1016/j.jbiomech.2018.10.030