Peri-implant stress correlates with bone and cement morphology: Micro-FE modeling of implanted cadaveric glenoids.
Aseptic loosening of cemented joint replacements is a complex biological and mechanical process, and remains a clinical concern especially in patients with poor bone quality. Utilizing high resolution finite element analysis of a series of implanted cadaver glenoids, the objective of this study was to quantify relationships between construct morphology and resulting mechanical stresses in cement and trabeculae. Eight glenoid cadavers were implanted with a cemented central peg implant. Specimens were imaged by micro-CT, and subject-specific finite element models were developed. Bone volume fraction, glenoid width, implant-cortex distance, cement volume, cement-cortex contact, and cement-bone interface area were measured. Axial loading was applied to the implant of each model and stress distributions were characterized. Correlation analysis was completed across all specimens for pairs of morphological and mechanical variables. The amount of trabecular bone with high stress was strongly negatively correlated with both cement volume and contact between the cement and cortex (r = -0.85 and -0.84, p < 0.05). Bone with high stress was also correlated with both glenoid width and implant-cortex distance. Contact between the cement and underlying cortex may dramatically reduce trabecular bone stresses surrounding the cement, and this contact depends on bone shape, cement amount, and implant positioning.
Department of Orthopaedics and Rehabilitation, Penn State College of Medicine, 500 University Drive, Hershey, PA, 17033.
Hwabok
H
Wee
Department of Orthopaedics and Rehabilitation, Penn State College of Medicine, 500 University Drive, Hershey, PA, 17033.
April D
AD
Armstrong
Department of Orthopaedics and Rehabilitation, Penn State College of Medicine, 500 University Drive, Hershey, PA, 17033.
Wesley W
WW
Flint
Department of Public Health Sciences, Penn State College of Medicine, 500 University Drive, Hershey, PA, 17033.
Allen R
AR
Kunselman
Department of Orthopaedics and Rehabilitation, Penn State College of Medicine, 500 University Drive, Hershey, PA, 17033.
Gregory S
GS
Lewis
D000368:Aged; D001843:Bone Cements; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D020342:Finite Element Analysis; D006801:Humans; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D055114:X-Ray Microtomography
D001843:Bone Cements
cement morphology; finite element; glenoid implant; implant fixation