What does this research mean for the field?

A newly developed finite element model, validated by cadaveric testing, demonstrates that adding a collar to uncemented press-fit stems substantially increases the load required for peri-prosthetic fracture by increasing axial compressive strains rather than critical hoop strains. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This study aims to estimate the benefit of adding a collar to uncemented tapered press-fit stems in total hip arthroplasty.

May 16, 2026Orthopaedic Proceedings

Estimating the Benefit of a Collar on Uncemented Press-Fit Stems

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Authors

MMM MorlockUniversität Hamburg THT HarpengUniversität Hamburg GHG HuberUniversität Hamburg

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Implication

Randomized trial estimates the impact of collars on fracture rates in uncemented hip arthroplasty, suggesting design improvements.

Key Points

This study aims to estimate the benefit of adding a collar to uncemented tapered press-fit stems in total hip arthroplasty.
Two human cadaveric femurs were tested with collared and collarless CORAIL stems until failure using a material testing machine.
Shear, axial compressive and tangential tensile strains, as well as fracture load, were recorded using digital image correlation.
A finite element model was utilized to estimate parameters for three different stem types with and without a collar.
The collar increased fracture load for the CORAIL stem by nearly 100% (6824N vs. 3465N, ratio 1.96).
The FEM model showed a greater benefit ratio of 3.37 for the CORAIL stem with a collar.
The EMPHASYS stem demonstrated a similar benefit ratio of 3.47, while the ACTIS stem showed a lower ratio of 1.69.

Cite This Study

Morlock et al. (2026) studied this question.

synapsesocial.com/papers/6a080acea487c87a6a40cc94 https://doi.org/10.1302/1358-992x.2026.4.042

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Estimating the Benefit of a Collar on Uncemented Press-Fit Stems

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Cite This Study

Estimating the Benefit of a Collar on Uncemented Press-Fit Stems

Discussion

Member takes

Implication

Key Points

Cite This Study

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