Upright Cone CT of the hindfoot: Comparison of the non-weight-bearing with the upright weight-bearing position
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To prospectively compare computed tomography (CT) of the hindfoot in the supine non-weight-bearing position (NWBCT) with upright weight-bearing position (WBCT).
Institutional review board approval and informed consent of all patients were obtained. NWBCT and WBCT scans of the ankle were obtained in 22 patients (mean age, 46.0 ± 17.1 years; range 19–75 years) using a conventional 64-row CT for NWBCT and a novel cone-beam CT for WBCT. Two musculoskeletal radiologists independently performed the following measurements: the hindfoot alignment angle, fibulocalcaneal and tibiocalcaneal distances, lateral talocalcaneal joint space width, talocalcaneal overlap and naviculocalcaneal distance. Significant changes between NWBCT and WBCT were sought using Wilcoxon signed-rank test. P values <0.05 were considered statistically significant.
Significant differences were found for all measurements except the hindfoot alignment angle and tibiocalcaneal distance. Significant measurement results were as follows (NWBCT/WBCT reader 1; NWBCT/WBCT reader 2, mean ± standard deviation): fibulocalcaneal distance 3.6 mm ± 5.2/0.3 mm ± 6.0 (P = 0.006); 1.4 mm ± 6.3/-1.1 mm ± 6.3 (P = 0.002), lateral talocalcaneal joint space width 2.9 mm ± 1.7/2.2 mm ± 1.1 (P = 0.005); 3.4 mm ± 1.9/2.4 mm ± 1.3 (P = 0.001), talocalcaneal overlap 4.1 mm ± 3.9/1.4 mm ± 3.9 (P = 0.001); 4.5 mm ± 4.3/1.4 mm ± 3.7 (P < 0.001) and naviculocalcaneal distance 13.5 mm ± 4.0/15.3 mm ± 4.7 (P = 0.037); 14.0 mm ± 4.4/15.7 mm ± 6.2 (P = 0.100). Interreader agreement was good to excellent (ICC 0.48–0.94).
Alignment of the hindfoot significantly changes in the upright weight-bearing CT position. Differences can be visualised and measured using WBCT.
• Cone-beam computed tomography (CBCT) offers new opportunities for musculoskeletal problems
• Visualization and quantification of hindfoot alignment are possible in upright weight-bearing CBCT
• Hindfoot alignment changes significantly from non-weight-bearing to weight-bearing CT
• The weight-bearing position leads to a decrease in the fibulocalcaneal distance and talocalcaneal overlap
• The naviculocalcaneal distance is increased in the weight-bearing position
KeywordsHindfoot alignment Cone-beam computed tomography Weight-bearing Talocalcaneal overlap Fibulocalcaneal distance
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