Bone-cement interface of the glenoid component: stress analysis for varying cement thickness.
- 2005-06-18
Published in:
- Clinical biomechanics (Bristol, Avon). - 2005
Bone Cements
Cementation
Compressive Strength
Computer Simulation
Elasticity
Equipment Failure Analysis
Humans
Joint Prosthesis
Materials Testing
Models, Biological
Models, Chemical
Prosthesis Implantation
Shoulder Joint
Stress, Mechanical
Tensile Strength
Therapy, Computer-Assisted
English
BACKGROUND
Although shoulder arthroplasty is an accepted treatment for osteoarthritis, loosening of the glenoid component, which mainly occurs at the bone-cement interface, remains a major concern. Presently, the mechanical effect of the cement mantel thickness on the bone-cement interface is still unclear.
METHODS
Finite element analysis of a prosthetic scapula was used to evaluate the effect of cement thickness on stresses and micromotions at the bone-cement interface. The glenoid component was all-polyethylene, keeled and flat back. Cement mantel thickness was gradually increased from 0.5 to 2.0 mm. Two glenohumeral contact forces were applied: concentric and eccentric. Two extreme cases were considered for the bone-cement interface: bonded and debonded.
FINDINGS
Within cement, stress increased as cement thickness decreased, reaching the fatigue limit below 1.0 mm. Bone stress was below its ultimate strength and was minimum between 1.0 and 1.5mm. Interface stress was close to the interface strength, and also minimum between 1.0 and 1.5 mm. Both the decentring of the load and the debonding of the interface increased the stress.
INTERPRETATION
A cement thinning weakens the cement, but also the bone-cement interface, along the back-keel edges. Conversely, a cement thickening rigidifies the cemented implant, consequently increasing interfacial stresses and micromotions. To avoid both excessive cement fatigue and interface failure, an ideal cement thickness has been identified between 1.0 and 1.5 mm.
Although shoulder arthroplasty is an accepted treatment for osteoarthritis, loosening of the glenoid component, which mainly occurs at the bone-cement interface, remains a major concern. Presently, the mechanical effect of the cement mantel thickness on the bone-cement interface is still unclear.
METHODS
Finite element analysis of a prosthetic scapula was used to evaluate the effect of cement thickness on stresses and micromotions at the bone-cement interface. The glenoid component was all-polyethylene, keeled and flat back. Cement mantel thickness was gradually increased from 0.5 to 2.0 mm. Two glenohumeral contact forces were applied: concentric and eccentric. Two extreme cases were considered for the bone-cement interface: bonded and debonded.
FINDINGS
Within cement, stress increased as cement thickness decreased, reaching the fatigue limit below 1.0 mm. Bone stress was below its ultimate strength and was minimum between 1.0 and 1.5mm. Interface stress was close to the interface strength, and also minimum between 1.0 and 1.5 mm. Both the decentring of the load and the debonding of the interface increased the stress.
INTERPRETATION
A cement thinning weakens the cement, but also the bone-cement interface, along the back-keel edges. Conversely, a cement thickening rigidifies the cemented implant, consequently increasing interfacial stresses and micromotions. To avoid both excessive cement fatigue and interface failure, an ideal cement thickness has been identified between 1.0 and 1.5 mm.
- Language
-
- English
- Open access status
- green
- Identifiers
-
- DOI 10.1016/j.clinbiomech.2005.03.010
- PMID 15961203
- Persistent URL
- https://sonar.ch/global/documents/278988
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