An observational study in Revision Total Knee Arthroplasty and Osteoarthritis, Knee, sponsored by London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's. Recruiting at 1 site in Canada. Per ClinicalTrials.gov, last updated 2026-09-22.
Sponsored by London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's · Observational
Many patients who receive knee replacement surgery must return for a revision (or repeat) surgery due to ongoing pain, stiffness, infection, or implant loosening. The role of the gut microbiome-the collection of bacteria and other microbes within the human gastrointestinal tract-is just beginning to be recognized in orthopaedics. The gut microbiome has been found to affect the immune response and bone regulation, potentially contributing to infection or loosening after total joint replacement. Antibiotics are regularly used in orthopaedic surgery to reduce the risk of infection, yet they might also harm gut microbiota and reduce their potentially beneficial effects. As a result, understanding the relationship between gut microbiota and surgical outcomes has become increasingly important. Therefore, this study aims to determine if there are differences in gut microbiota composition between patients with well-functioning knee replacements and those requiring revision knee replacements. Additional study aims include assessing inflammation, implant loosening, metal ion levels, and circulating bacteria in blood or tissue between well-functioning or failed knee replacements.
3,292 studies on the registry are indexed under Osteoarthritis, Knee; 623 are open to participants now.
This study's planned enrollment of 30 is below the median of 100 across 486 observational studies indexed under Osteoarthritis, Knee.
Browse Osteoarthritis, Knee studies →London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's is the lead sponsor of 331 studies on the registry; 137 are open to participants now.
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Patients at University Hospital scheduled to undergo a revision TKA.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants scheduled to undergo a revision TKA will be recruited. They must be more than 3 months post-operation from their primary surgery, and the revision must be for something other than periprosthetic fracture, DAIR (debridement, antibiotics, and implant retention), or stage 2 periprosthetic joint infection.
Procedure: Revision Total Knee Arthroplasty
Study participants must be scheduled to receive a revision TKA.
Gut Microbiome Composition
The gut microbiome composition of the revision total knee arthroplasty (TKA) cohort prior to revision surgery will be compared to that of the well-functioning TKA cohort. Additionally, we will evaluate changes in the gut microbiome within the revision cohort from before surgery to six weeks after surgery.
Time frame: Gut microbiome composition will be assessed pre-operatively and at 5 days and 6 weeks post-operation to determine how it changes post-operation.
Inducible Displacement Measurements with Weight-Bearing Computed Tomography (WBCT)
Seated and standing WBCT exams will be performed. The bone and implant will be segmented, and a novel software (WBCT-based radiostereometric analysis (WBCT-RSA)) will be used to measure implant motion between the double seated exams (precision) or seated and standing exams (inducible displacement). Change in implant position will be measured in millimeters as maximum total point motion (MTPM). MTPM will be compared between the revision TKA cohort and a cohort with well-functioning implants.
Time frame: WBCT exams will be performed at one timepoint prior to the study participant's revision surgery.
Inflammation in the Knee Joint Based on [18F]FEPPA Standard Uptake Values (SUV)
Positron Emission Tomography/Computed Tomography (PET/CT) of the knee joint will be performed using the radiotracer \[18F\]FEPPA, which binds to molecules highly expressed on inflammatory cells. Radiotracer uptake will be quantified using SUV. SUV near the bone and joint will be calculated and compared between the revision TKA cohort and the well-functioning TKA cohort.
Time frame: PET/CT exams will be performed at one timepoint prior to the study participant's revision surgery.
Inducible Displacement and Microbiome Composition
Joint and gut microbiome composition, along with inducible displacement measurements, will be assessed to determine whether alterations in the gut microbiome lead to increased within-bone implant motion.
Time frame: Inducible displacement exams will be performed pre-operatively and will be compared to the gut microbiome from pre-operation to 6 weeks post-operation, and to the intra-operative joint microbiome.
Implant Wear Volume and Within-Bone Implant Motion from Inducible Displacement Exams
Seated and standing WBCT exams will be performed. The bone and implant will be segmented, and a novel software (WBCT-RSA) will be used to measure implant motion between the seated and standing exams (inducible displacement). Change in implant position will be measured in millimeters as MTPM. An optical coordinate measuring machine will be used to quantitatively measure the amount of volume loss from the retrieved implant components. Inducible displacement MTPM will be compared to volume loss to determine if greater within-bone implant motion may cause greater wear of the implant component resulting in more volume loss.
Time frame: Inducible displacement exams will be performed pre-operatively and will be compared to the amount of wear that has occurred on implants retrieved during revision surgery.
Metal Ion Levels and Within-Bone Implant Motion from Inducible Displacement Exams
Seated and standing WBCT exams will be performed. The bone and implant will be segmented, and a novel software (WBCT-RSA) will be used to measure implant motion between the seated and standing exams (inducible displacement). Change in implant position will be measured in millimeters as MTPM. Metal ion levels (cobalt, chromium, nickel, and titanium) will be measured from a blood draw prior to the revision surgery. Inducible displacement MTPM and metal ion levels will be compared to determine if greater within-bone implant motion causes greater levels of circulating metal ions.
Time frame: Inducible displacement exams will be performed pre-operatively and will be compared to the amount of circulating metal ions pre-operation.
[18F]FEPPA Activity and Microbiome Composition
Joint and gut microbiome composition will be compared to \[18F\]FEPPA activity, to assess whether alterations in the gut microbiome contribute to increased inflammation in the knee joint.
Time frame: PET/CT exams will be performed pre-operatively and will be compared to the gut microbiome from pre-operation to 6 weeks post-operation, and to the intra-operative joint microbiome.
[18F]FEPPA Activity and Implant Wear Volume
\[18F\]FEPPA activity from PET/CT will be used to detect the amount of inflammation present in the knee joint. An optical coordinate measuring machine will be used to quantitatively measure the amount of volume loss from the retrieved implant components as an indicator of wear. The relationship between volume loss and \[18F\]FEPPA activity will be assessed.
Time frame: PET/CT exams will be performed pre-operatively and will be compared to the amount of wear that has occurred on implants retrieved during revision surgery.
[18F]FEPPA Activity and Metal Ion Levels
\[18F\]FEPPA activity from PET/CT will be used to detect the amount of inflammation present in the knee joint. Metal ion levels (cobalt, chromium, nickel, and titanium) will be measured pre-operatively and the relationship between inflammation and circulating metal ions will be assessed.
Time frame: PET/CT exams will be performed pre-operatively and will be compared to the amount of circulating metal ions pre-operation.
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London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's →