The study is called After Total Ankle Arthroplasty, When Does Bone Perfusion and Metabolic Activity at the Bone Implant Interface Normalize? It is a PET-CT study. Thank you to my co-authors. These are our disclosures. Just some background. So radionuclide bone scintigraphy and computed tomography, most commonly SPECT-CT, has been used to evaluate painful total joint arthroplasties. In patients with normal radiographs and no evidence of infection, these studies may identify prosthetic loosening or failure of bony ongrowth. However, in the total hip and knee literature, there is substantial overlap in activity between symptomatic and asymptomatic patients. In asymptomatic total hip arthroplasties, activity may even remain elevated up to two years postoperatively. SPECT-CT, single positron emission computed tomography, is increasingly used to evaluate the painful total ankle replacement, with results often prompting surgical intervention. However, we do not know that increased tracer uptake always indicates loosening, and we do not know how much tracer uptake is normal after asymptomatic total ankle replacement. Our research question was, when does tracer uptake around the implants normalize, if at all, in asymptomatic patients after total ankle replacement? We used PET-CT with 18-sodium fluoride instead of SPECT-CT with bisphosphonates because PET-CT has more favorable pharmacokinetics and similar sensitivity to detect aseptic loosening. Asymptomatic patients were enrolled at various time intervals after total ankle replacement, 6, 12, 18, or 24 months after surgery. Standard uptake values were measured at the bone implant interface for the tibial and tailor components on static PET and regions of interest defined on CT. So those were the regions right around the implants. Perioprosthetic bone blood flow, or K1, and bone turnover, or flux, were assessed using dynamic PET. We enrolled 16 asymptomatic total ankle patients. We are still in the middle of enrollment. There were not enough patients at the 18-month time point, therefore they were excluded. All patients underwent modern fixed-bearing total ankle replacement with either the Vantage or Infinity systems. You can see here the patients that were enrolled and which implants they received as well as their age and sex. These were our results. So this is just an example of the images that you can see. You can see the increased uptake around the implant. And you can see the small regions of interest in this area that were identified, and that's where we were mainly measuring the uptake. And you can see here how the results were reported in the software. So this shows our results for both the talus and the tibia. You can see in the top row there is bone blood flow, or K1, and then in the bottom row, bone turnover, or flux. For the talus shown on the left, you can see that both blood flow and bone turnover appeared to increase between 6 and 12 months, and then decreased between 12 and 24 months. And then on the right, you can see for the tibia, both measures seemed to decrease between 6 and 12 months, although bone turnover or flux actually remained fairly stable from 6 all the way to 24 months. There were no statistically significant differences between time points in terms of both K1 and flux. Like I mentioned, talus, K1, and flux appeared to increase between 6 and 12 months, and then remained variable at 24 months. Tibial K1 and flux appeared to decrease between 6 and 12 months, and then remained stable between 12 and 24 months. In conclusion, even in asymptomatic patients, periprosthetic bone blood flow and bone turnover remained elevated up to 24 months following modern fixed-bearing total ankle replacement. There were no significant decreases in values between 6 and 24 months. The results should therefore be cautiously interpreted when performed within two years of total ankle replacement, and taken together, an interpretation with patient symptoms. These are my references. Thank you.

bone perfusion

metabolic activity

total ankle arthroplasty

PET-CT

periprosthetic bone blood flow