Natural Postoperative Bone Metabolic Changes after Total Knee Arthroplasty Determined by Positron Emission Tomography Scans

Abstract

Artificial joint replacement surgery is the orthopedic procedure of choice to relieve pain, correct joint deformities, and help patients resume everyday activities. However, the detailed mechanisms regulating peri-implant bone remodeling at the bone-prosthesis interface remain elusive. To address this gap in knowledge, we evaluated the natural postoperative course of bone metabolism by using [ 18 F] NaF positron emission tomography (PET)/computed tomography in 57 patients (104 joints) who underwent asymptomatic total knee arthroplasty (TKA). First, we measured total tracer uptake around TKA to determine the total bone metabolism (TBM) and used the ischial tuberosity as the reference tissue for normalization of PET images. Second, we calculated the TBM ratio (TBMR) by dividing the TBM by tracer uptake in the reference tissue. A moderate increase in TBMR was observed 4-5 days after implantation, and its intensity reached the maximum on the seventh postoperative day. The TBMR showed no differences until 12 weeks, after which it decreased slowly and returned to the basal levels. The new parameter TBMR and the unique pattern of postoperative metabolic changes in the bone around the prosthesis may help set accurate interpretation criteria to diagnose complications such as loosening or infections.

18F‐sodium fluoride positron emission tomography may help diagnose nondisplaced peri‐prosthetic and peri‐implant fracture

“…Due to severe pain and gait disturbance, 18 F‐sodium fluoride positron emission tomography (NaF PET) was performed. 2 A high intensity surrounding the entire middle portion of her right femur was observed (Figure 1B ), indicating the presence of a complete fracture without femur misalignment. The rigid fixation prevented displacement.…”

18F‐sodium fluoride positron emission tomography may help determine better treatment for thigh pain after hip arthroplasty—A case report

“…Most of the NaF transported to the bone is only retained following a single pass of blood, making it a suitable radiopharmaceutical agent for assessing subtle changes in bone metabolic activity. 5,6 Here, to the best of our knowledge, we present the first case where NaF PET/CT substantially assisted the diagnosis of persistent activity-limiting thigh pain following hip arthroplasty, leading to the selection of the most appropriate treatment strategy.…”

“…The recently developed 18 F‐sodium fluoride PET/computed tomography ([ 18 F] NaF PET/CT) is a more accurate diagnostic tool for specific bone disorders. Most of the NaF transported to the bone is only retained following a single pass of blood, making it a suitable radiopharmaceutical agent for assessing subtle changes in bone metabolic activity 5,6 …”