Cemented short-stem total hip arthroplasty
Journal Contribution - Journal Article
Short-stems are becoming increasingly popular in total hip arthroplasty since they preserve the bone stock and simplify the implantation process. Short-stems are advised mainly for patients with good bone stock. The clinical use of short-stems could be enlarged to patients with poor bone stock if a cemented alternative would be available. Therefore, this study aimed to quantify the mechanical performance of a cemented short-stem and to compare the 'undersized' cementing strategy (stem one size smaller than the rasp) to the 'line-to-line' technique (stem and rasp with identical size). A prototype cemented short-stem was implanted in eight pairs of human cadaveric femora using the two cementing strategies. Four pairs were experimentally tested in a single-legged stance condition; stiffness, strength,and bone surface displacements were measured. Subject-specific nonlinear finite element models of all the implanted femora were developed, validated against the experimental data, and used to evaluate the behavior of cemented short-stems under physiological loading conditions resembling level walking. The two cementing techniques resulted in non-significant differences in stiffness and strength. Strength and stiffness as calculated from finite element were 8.7% ± 16% and 9.9% ± 15.0% higher than experimentally measured. Displacements as calculated from finite element analyses corresponded strongly (R2 ≥ 0.97) with those measured by digital image correlation. Stresses during level walking were far below the fatigue limit for bone and bone cement. The present study suggests that cemented short-stems are a promising solution in osteoporotic bone, and that the line-to-line and undersized cementing techniques provide similar outcomes. This article is protected by copyright. All rights reserved.