100% chance of infection after 5 revisions.

[Discovernew]

Hey Guys,

I was looking at this study which says there is a 100% chance of infection by the 5th revision. Even if the 3rd revision seems to have 33% chance, which is huge.
Obviously this is a scary statistic for any of us who have an implant.

I am curious if you guys can find any weakness on this study?

The risk of specific device infection was strongly correlated and increased based on number of prior IPPs:

1st (6.8%; 3/44)
2nd (18.2%; 4/22)
3rd (33.3%; 4/12)
4th (50%; 4/8)
5th (100%; 2/2)

https://pubmed.ncbi.nlm.nih.gov/29795529/

Very curious about some objective view about this study or what may be a flaw in the design of the study.

[lasthope2.0]

From the same study:

The current series also has several notable limitations including the relatively small cohort, retrospective nature, and inclusion of non-contemporary devices and outcomes (given the historical series). This is particularly relevant in regards to the two men with five prior IPPs who experienced infections. Given the small population size, this calculates to a 100% infection rate with the fifth revision surgery. This is likely an overestimation and would be a lower value with additional patients with these characteristics. As our patient population only included those presenting for consideration of revision/salvage surgery, it is underrepresenting a percentage of men with IPPs. Notably, patients who would not be included are those whose devices malfunctioned or were infected and removed whom did not seek revision, patients who expired prior to developing an IPP issue, and those not yet experiencing an end-point with the IPP. It is unclear how inclusion of these patients would alter the percentage of infections in all categories. However, it is important to note that this would not be expected to impact the relative differences in infection rates based on increasing numbers of IPPs and each subsequent revision surgery. Therefore, the key finding of the current study that infection rates increase with each subsequent revision surgery is not affected by these limitations.

[lasthope2.0]

From the same study:

The current series also has several notable limitations including the relatively small cohort, retrospective nature, and inclusion of non-contemporary devices and outcomes (given the historical series). This is particularly relevant in regards to the two men with five prior IPPs who experienced infections. Given the small population size, this calculates to a 100% infection rate with the fifth revision surgery. This is likely an overestimation and would be a lower value with additional patients with these characteristics. As our patient population only included those presenting for consideration of revision/salvage surgery, it is underrepresenting a percentage of men with IPPs. Notably, patients who would not be included are those whose devices malfunctioned or were infected and removed whom did not seek revision, patients who expired prior to developing an IPP issue, and those not yet experiencing an end-point with the IPP. It is unclear how inclusion of these patients would alter the percentage of infections in all categories. However, it is important to note that this would not be expected to impact the relative differences in infection rates based on increasing numbers of IPPs and each subsequent revision surgery. Therefore, the key finding of the current study that infection rates increase with each subsequent revision surgery is not affected by these limitations.

I asked Dr. AI for an explanation of this limitation paragraph by the study authors:

Explanation of the Study's "Limitations" Paragraph
Source Link

The paragraph is the "Limitations" section of the study. The authors are being transparent about the flaws in their data to help the reader understand exactly what the results mean and what they don't mean.

Here is a simple breakdown of the four main points they are making:

1. The "100% Infection Rate" is a Fluke
The study data showed that men undergoing their 5th revision surgery had a 100% infection rate.

• The Reality: The authors admit this number is misleading because there were only two men in that specific group. Since both happened to get infections, the math comes out to 100%.
• The Takeaway: They acknowledge this is an overestimation. If they had looked at 50 men instead of 2, the rate would likely be much lower. It is a statistical anomaly caused by a tiny sample size.

2. The "Invisible" Patients (Selection Bias)
The authors admit their data is slightly skewed because they only studied men who came back to the doctor to fix or remove their implant ("revision/salvage"). This creates a "blind spot" because the study excludes three types of men:

• Men whose implants broke or got infected, but who decided to just live with it or have it removed elsewhere without seeking a new one.
• Men who died before their implant ever had a problem.
• Men whose implants are still working perfectly fine today (the success stories).

Because these groups are missing, the study cannot tell you the true infection rate for the entire population of implant owners—only for those who sought revision surgery.

3. The "Old Tech" Factor
Because the study looks back at historical data ("retrospective"), it includes older devices and older surgical techniques ("non-contemporary"). This means the infection risks from 15+ years ago are being counted alongside modern risks, which might make the overall risk look slightly different than it is today with modern antibiotic-coated implants.

4. The Bottom Line (The Conclusion)
Despite these flaws, the authors argue that their main finding is still valid.

• The Defense: Even if the specific percentages (like the 100% rate) aren't perfectly accurate because of the missing patients, the trend is undeniable.
• The Trend: Infection risk goes up with every subsequent revision surgery. (e.g., Surgery #3 is riskier than Surgery #2, which is riskier than Surgery #1).

In simple terms: "Our specific numbers might be slightly off because we didn't have enough people and used some old data, but the pattern is clear: the more times you have surgery on the device, the higher your risk of infection becomes."