Influence of investigator experience on reliability of adult acquired flatfoot deformity measurements using weightbearing computed tomography

BackgroundOur purpose was to assess the reliability of measurements of adult-acquired flatfoot deformity (AAFD) taken by investigators of different levels of clinical experience using weightbearing computed tomography (WBCT).MethodsNineteen AAFD patients underwent WBCT. Three investigators with different levels of clinical experience made AAFD measurements in axial, coronal, and sagittal planes. Intra- and interobserver reliability were assessed. Mean values for each measurement were compared between investigators.ResultsAfter a training protocol, substantial to perfect intra- and interobserver reliability was observed for most measures, regardless of the investigator’s experience level. Significant differences between investigators were observed in 2 of 21 measured parameters: medial cuneiform–first metatarsal angle (P = 0.003) and navicular–medial cuneiform angle (P = 0.001).ConclusionsAAFD radiographic measurements can be performed reliably by investigators with different levels of clinical experience using WBCT.Level of evidenceLevel II, prospective comparative study.     

Hindfoot alignment of adult acquired flatfoot deformity: A comparison of clinical assessment and weightbearing cone beam CT examinations

BackgroundClinical assessment of hindfoot alignment (HA) in adult acquired flatfoot deformity (AAFD) can be challenging and weightbearing (WB) cone beam CT (CBCT) may potentially better demonstrate this three-dimensional (3D) deformity. Therefore, we compared clinical and WB CBCT assessment of HA in patients with AAFD.MethodsIn this prospective study, we included 12 men and 8 women (mean age: 52.2, range: 20–88) with flexible AAFD. All subjects also underwent WB CBCT and clinical assessment of hindfoot alignment. Three fellowship-trained foot and ankle surgeons performed six hindfoot alignment measurements on the CT images. Intra- and Inter-observer reliabilities were calculated using intra-class correlation (ICC). Measurements were compared by paired T-tests, and p-values of less than 0.05 were considered significant.ResultsThe mean of clinically measured hindfoot valgus was 15.2 (95% confidence interval [CI]: 11.5–18.8) degrees. It was significantly different from the mean values of all WB CBCT measurements: Clinical Hindfoot Alignment Angle, 9.9 (CI: 8.9–11.1) degrees; Achilles tendon/Calcaneal Tuberosity Angle, 3.2 (CI: 1.3–5.0) degrees; Tibial axis/Calcaneal Tuberosity Angle, 6.1 (CI: 4.3–7.8) degrees; Tibial axis/Subtalar Joint Angle 7.0 (CI: 5.3–8.8) degrees, and Hindfoot Alignment Angle 22.8 (CI: 20.4–25.3) degrees. We found overall substantial to almost perfect intra- (ICC range: 0.87–0.97) and inter-observer agreements (ICC range: 0.51–0.88) for all WB CBCT measurements.ConclusionsUsing 3D WB CBCT can help characterize the valgus hindfoot alignment in patients with AAFD. We found the different CT measurements to be reliable and repeatable, and to significantly differ from the clinical evaluation of hindfoot valgus alignment.Level of evidence: Level II—prospective comparative study.     

Diagnostic accuracy of measurements in progressive collapsing foot deformity using weight bearing computed tomography: A matched case-control study

BackgroundWe aimed to investigate the diagnostic accuracy of known two-dimensional (2D) and three-dimensional (3D) measurements for Progressive Collapsing Foot Deformity (PCFD) in weight-bearing computed tomography (WBCT). We hypothesized that 3D biometrics would have better specificity and sensitivity for PCFD diagnosis than 2D measurements.MethodsThis was a retrospective case-control study, including 28 PCFD feet and 28 controls matched for age, sex and Body Mass Index. Two-dimensional measurements included: axial and sagittal talus-first metatarsal angles (TM1A and TM1S), talonavicular coverage angle (TNCA), forefoot arch angle (FFAA), middle facet incongruence angle (MF°) and uncoverage percentage (MF%). The 3D Foot Ankle Offset (FAO) was obtained using dedicated semi-automatic software. Intra and interobserver reliabilities were assessed. Receiver Operating Characteristic (ROC) curves were calculated to determine diagnostic accuracy (Area Under the Curve (AUC)), sensitivity and specificity.ResultsIn PCFD, mean MF% and MF° were respectively 47.2% ± 15.4 and 13.3° ± 5.3 compared with 13.5% ± 8.7 and 5.6° ± 2.9 in controls (p < 0.001). The FAO was 8.1% ± 3.8 in PCFD and 1.4% ± 1.7 in controls (p < 0.001). AUCs were 0.99 (95%CI, 0.98–1) for MF%, 0.96 (95%CI, 0.9–1) for FAO, 0.90 (95%CI, 0.81–0.98) for MF°. For MF%, a threshold value equal or greater than 28.7% had a sensitivity of 100% and specificity of 92.8%. Conversely, a FAO value equal or greater than 4.6% had a specificity of 100% and a sensitivity of 89.2%. All other 2D measurements were significantly different in PCFD and controls (p < 0.001).ConclusionsMF% and FAO were both accurate measurements for PCFD. MF% demonstrated slightly better specificity. FAO better sensitivity. A combination of threshold values of 28.7% for MF% and 4.6% for FAO yielded 100% sensitivity and specificity.     

Weightbearing Computed Tomography as a Novel Imaging Modality: Assessment of Peritalar Instability

Peritalar instability is a complex pathological entity of the hindfoot. The main characteristics of peritalar instability include pathological alignment of the talus at the talocalcaneal joint level. Very often, peritalar instability is observed in patients with progressive collapsing foot deformity (PCFD). In the last decade, weightbearing computed tomography (WBCT) is increasingly accepted as an advanced imaging modality among foot and ankle surgeons. In patients with PCFD, WBCT can provide invaluable information for a better understanding of underlying deformity, including the presence of subfibular and/or sinus tarsi impingement, subluxation of the subtalar joint at the posterior and/or middle facet, and extent of degeneration of the subtalar and talonavicular joints.     

Preoperative assessment of idiopathic scoliosis in adolescent and young adult with three-dimensional T2-weighted spin-echo MRI

PurposeTo compare tridimensional (3D) T2-weighted spin-echo MRI and CT for minimal pedicle width measurements in the preoperative assessment of adolescent idiopathic scoliosis (AIS) in adolescent and young patients.Materials and methodsA total of 22 adolescents/young patients suffering from AIS were retrospectively included. There were 18 females and 4 males with a mean age of 15.3 ± 2.3 (SD) years (range: 11–21 years). Preoperative lumbar spine MRI and CT examinations of the 22 patients were reviewed by two independent readers who measured the minimal width of 259 pedicles. Inter-reader agreement for CT and MRI was assessed using intra-class correlation coefficient (ICC). Intra-reader agreement and relative differences in measurements between MRI and CT were also assessed for each reader.ResultsInter-reader agreement was excellent (ICC ≥ 0.8) for both CT and MRI. Relative differences in measurements between CT and MRI was 10.3% for reader 1 and 9.4% for reader 2.Conclusion3D T2-weighted spin-echo MRI underestimates minimal pedicle width by only 9.4 - 10.3% compared to CT. 3D T2-weighted MRI appears as a valuable alternative to CT for preoperative measurements of vertebral pedicles in AIS.     

CT and MRI characteristics of ovarian mature teratoma in patients with anti-N-methyl-D-aspartate receptor encephalitis

PurposeThe purpose of this study was to determine the computed tomography (CT) and magnetic resonance imaging (MRI) characteristics of ovarian mature teratoma in patients with anti-N-methyl-d-aspartate receptor encephalitis (NMDAR-E).Materials and MethodsA total of 125 women (mean age, 40.9 ± 17.8 [SD] years; age range: 12–85 years) with 146 histopathologically or radiologically proven ovarian mature teratomas who underwent preoperative CT and MRI examinations were retrospectively included. Eight patients with 11 teratomas had NMDAR-E, whereas 117 patients with 135 teratomas did not have NMDAR-E. CT and MRI examinations were retrospectively reviewed and teratomas in patients with NMDAR-E were compared to those in patients without NMDAR-E. Comparisons were performed using Mann-Whitney U test or Fisher exact test.ResultsIn patients with NMDAR-E, maximum diameter of teratomas (26.1 ± 9.3 [SD] mm), prevalence of teeth/calcification (36%) and rate of occupation by fat components (26%) were lower than those in patients without NMDAR-E (67.0 ± 37.6 [SD] mm [P < 0.01]; 75% [P < 0.05]; and 65%[P < 0.01], respectively). More than 75% of space was occupied by fat components in 76/135 teratomas (56%) in patients without NMDAR-E, whereas this was not observed in any teratoma in patients without NMDAR-E.ConclusionBy comparison with teratomas in patients without NMDAR-E, teratomas in patients with NMDAR-E are smaller, have few teeth/calcification, and the amount of space occupied by fat components is smaller.