Increasing reaming depth enhances implant stability while minimizing bone strain

Listen to Simon and Amy discuss the paper 'Increasing reaming depth enhances implant stability while minimizing bone strain' published in the June 2025 issue of Bone & Joint Research.

Click here to read the paper.

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Transcript

[00:00:00] Welcome back to another episode of AI Talks with Bone & Joint from the publishers of Bone & Joint Research. Today we are discussing the paper 'Increasing reaming depth enhances implant stability while minimizing bone strain'. Published in June 2025 by M Karia, R Doyle, A Reynolds, J Jeffers, and J Cobb. I'm Simon, and I'm here with my co-host Amy.

Hello Simon and a warm welcome to our listeners. This paper has some fascinating insights on implant stability and bone strain during hip arthroplasty, particularly concerning reaming depth. Shall we begin by discussing the rationale behind this study?

Certainly, Amy. The research aimed to enhance the primary stability of the acetabular component in hip implants while minimizing strain on the surrounding bone. Implant stability is critical, as it is a good indicator of long-term success. However, achieving the stability often increases bone strain, which can lead to fractures.

Exactly and this study looked at adjusting the reaming technique to [00:01:00] improve stability without increasing bone strain. The researchers tested various reaming depths to observe their impact on stability and strain in a synthetic bone model. Could you explain the methods used?

Of course. They employed a custom drop rig to replicate impaction strikes. They compared seating acetabular components with either a 1 mm or a 2 mm interference fit into synthetic sawbones, reamed to varying depths, either a true hemisphere or enhanced by 2 mm or 4 mm. Strain gauges measured bone strain and push-out tests, evaluated implant stability. In essence, they recorded how well the implant maintained its position under pressure and the strain experienced by the surrounding bone.

Interesting. So what were their findings? I believe they had some compelling evidence for increased reaming depth.

Indeed, the results were significant. Enhancing the reaming depth substantially increased the primary stability of the implants whilst reducing bone strain. Specifically, a [00:02:00] 4 mm reaming depth markedly increased the push-out force for both 1 mm and 2 mm interference fits. For instance, the push-out force for a 1 mm fit increased by 26%, and for a 2 mm fit, it saw a 35% rise between no reaming and 4 mms.

And this resulted in reduced bone strain, correct?

Precisely, increasing the reaming depth, reduced peak bone strain, especially at 4 mms. For example, the peak strain for a 1 mm interference fit dropped by more than half. This indicates that deeper reamed cavities provided better stability without causing excessive bone strain.

That's a crucial finding. It suggests that modifying the reaming depth could be a viable strategy for surgeons to enhance implant stability and minimize the risk of fractures. Were there any limitations noted in the study?

Yes, the authors mentioned several limitations. A key point is that the study used synthetic bone, which might not exactly mimic the behavior of live human bone, especially in the transition zones between subchondral and cancellous [00:03:00] bone.

Additionally, they only tested one type of acetabular component and one density of synthetic bone. So while the findings are promising, further research under more varied and real world conditions is needed.

Good points. They also noted that increasing reaming depth might lead to greater bone loss and could complicate surgery by altering the components positioning. These are important considerations for actual surgical practice.

Indeed, clinicians need to balance the improved stability with potential biomechanical consequences, such as the risk of impingement and changes in femoral offset. Nevertheless, the strategy of enhancing reaming depth offers a straightforward and reproducible method to optimize implant stability, making it highly relevant for clinical practice.

In summary, this study provides new insights into how adjusting reaming depth can improve primary stability in hip implants while reducing the risk of bone fractures. It's a promising development with significant potential to enhance surgical [00:04:00] outcomes. Thanks for discussing it with me today, Simon.

My pleasure, Amy and thank you to our listeners for tuning into AI Talks with Bone & Joint. Do check out the full paper for more in-depth information and we look forward to catching up in the next episode.