Tarmmikrobiome i ortopædi: Revision af total knæarthroplastik (GUMBO)

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.

Study participants must be scheduled to receive a revision TKA.

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.

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.

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.

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.

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.

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.

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.

[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.

[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.