PURPOSE: To clarify the concordance rate of the location of uptake on positron emission tomography/computed tomography (PET/CT) and the impingement point demonstrated in computer simulation in femoroacetabular impingement (FAI) syndrome with cam morphology. METHODS: We included hip joints with FAI syndrome that underwent 18F-fluoride PET/CT. We also excluded hips with SUVmax <6. Each hip was evaluated for the region of the SUVmax point on PET/CT as well as the impingement point by computer simulation. We used ZedHip software (Lexi, Tokyo, Japan) for impingement simulation analysis based on CT data. Bony impingement is identified if there is a mesh in acetabular and femoral side contact in at least one unit. We investigated the rate of concordance between these 2 regions for each 10° flexion angle of the hip, ranging from 0° to 90°. RESULTS: Twenty-two hips of 22 patients were evaluated. The SUVmax region was most frequently distributed in the proximal middle region in 12 hips. In 18 of 22 hips (81.8%), the SUVmax region was concordant with the impingement region for at least one flexion angle. The concordance rates in 50° (P = .034), 60° (P = .007), 70° (P = .011), and 80° (P = .046) of flexion were significantly higher than in 90° of flexion. CONCLUSIONS: It was possible to visualize and clarify the detailed location of abnormal uptake in FAI syndrome patients with cam morphology by applying 18F-fluoride PET/CT. The concordance rates in 50°, 60°, 70°, and 80° of flexion were significantly higher than in 90° of flexion, which suggested that impingement may more frequently occur at less than 90° of flexion in FAI syndrome with cam morphology. LEVEL OF EVIDENCE: Level III, cross-sectional diagnostic study.
PURPOSE: To clarify the concordance rate of the location of uptake on positron emission tomography/computed tomography (PET/CT) and the impingement point demonstrated in computer simulation in femoroacetabular impingement (FAI) syndrome with cam morphology. METHODS: We included hip joints with FAI syndrome that underwent 18F-fluoride PET/CT. We also excluded hips with SUVmax <6. Each hip was evaluated for the region of the SUVmax point on PET/CT as well as the impingement point by computer simulation. We used ZedHip software (Lexi, Tokyo, Japan) for impingement simulation analysis based on CT data. Bony impingement is identified if there is a mesh in acetabular and femoral side contact in at least one unit. We investigated the rate of concordance between these 2 regions for each 10° flexion angle of the hip, ranging from 0° to 90°. RESULTS: Twenty-two hips of 22 patients were evaluated. The SUVmax region was most frequently distributed in the proximal middle region in 12 hips. In 18 of 22 hips (81.8%), the SUVmax region was concordant with the impingement region for at least one flexion angle. The concordance rates in 50° (P = .034), 60° (P = .007), 70° (P = .011), and 80° (P = .046) of flexion were significantly higher than in 90° of flexion. CONCLUSIONS: It was possible to visualize and clarify the detailed location of abnormal uptake in FAI syndromepatients with cam morphology by applying 18F-fluoride PET/CT. The concordance rates in 50°, 60°, 70°, and 80° of flexion were significantly higher than in 90° of flexion, which suggested that impingement may more frequently occur at less than 90° of flexion in FAI syndrome with cam morphology. LEVEL OF EVIDENCE: Level III, cross-sectional diagnostic study.